Revision as of 22:19, 8 January 2006 editBethefawn (talk | contribs)46 edits →What?!← Previous edit | Latest revision as of 00:51, 27 December 2024 edit undoLambiam (talk | contribs)Autopatrolled, Extended confirmed users, Page movers63,481 edits →Mass of oscillating neutrino: ReplyTag: Reply | ||
Line 1: | Line 1: | ||
<!--- Please DO NOT enter your question at the top here. Put it at the bottom of the page. An easy way to do this is by clicking the "new section" tab ---><noinclude>{{Misplaced Pages:Reference desk/header|WP:RD/S}} | |||
{{/How_to_ask_and_answer|] or ]|Science}} | |||
] | |||
] | |||
] | |||
] | |||
] | |||
] </noinclude> | |||
=January 4= | |||
==Champagne and soft drink bubbles== | |||
Where do these bubbles come from it often appears that they start from the middle of the fluid in random positions what governs this? they simply flow constantly from what appears to be a point of no gaseous pressure significance. (] 01:55, 4 January 2006 (UTC)) | |||
= December 13 = | |||
::The ] bubbles form from ] present in both. As for the location of ] sites, where the bubbles form, they can be node points on sound waves when you ping the glass, a small particle in the fluid, etc. ] 02:19, 4 January 2006 (UTC) | |||
== What is the most iconic tornado photo == | |||
:Very interesting question. As StuRat said, the bubbles form wherever there are particles in the fluid, or on the sides where there are imperfections in the glass. A fun thing to do is put a raisin in the soda. It will become covered with bubbles until it floats up to the top, where the bubbles pop and it falls again. —] 08:09, 4 January 2006 (UTC) | |||
{{hat|Request for opinions}} | |||
What photo of a tornado would you say is the most iconic? I'm researching the history of tornado photography for an eventual article on it and I've seen several specific tornadoes pop up over and over again, particularly the ] and the "dead man walking" shot of the ]. Which would be considered more iconic? ] | ] | ] 17:21, 13 December 2024 (UTC) | |||
:At the top of this page is a bullet point stating "We don't answer requests for opinions, predictions or debate": this reads to me like a request for subjective opinions. Perhaps you would like to consider what quantifiable and referenceable metric would answer what you want to know? | |||
==X-ray machines at airports== | |||
:Presumably you also want only real tornadoes considered? Otherwise some might nominate the the twister from ], or from more recent tornado-related movies – ], anyone? :-). {The poster formerly known as 87.81.230.195} ] (]) 18:07, 13 December 2024 (UTC) | |||
:"Swegle Studios" has a couple of YouTube videos dedicated to the backstories of famous tornado photos and video; you might find them useful in your research. , . ] (]) 18:40, 13 December 2024 (UTC) | |||
:I googled "most iconic tornado photo" and a bunch of different possibilities popped up. I don't see how you could say that any given photo is the "most iconic". ←] <sup>'']''</sup> ]→ 18:57, 13 December 2024 (UTC) | |||
1) HOw is it that the X-rays from these machines do not in the sightest damage film from cameras or laptops yet still be strong enough to penetrate luggage? | |||
{{hab}} | |||
2) How is a thin strip of plastic able to protect those working around these machines from tissue damage? | |||
= December 15 = | |||
3) Finally, When viewing objects being scanned there are usually two screens used by operators, one of a darker image and another in greenish tints what does each one do? (] 01:55, 4 January 2006 (UTC)) | |||
== help to identify ] == | |||
:The X-ray machines used to scan carry-on luggage are not as strong as the ones to scan checked luggage as the items being scanned are generally smaller and can be more easily checked by hand. This is why the carry-on x-ray does not cause damage to film, electronics or people. The screens are different because one is looking for metal (such as knives or guns) and the other is looking for organic material (explosives, drugs, live animals). See for a good explanation of airport X-rays. --] 02:18, 4 January 2006 (UTC) | |||
] in New South Wales Australia]] Did I get species right? Thanks. ] (], ]) 06:56, 15 December 2024 (UTC) | |||
:: I think also that X-ray machines, both medical and for security, have become much much more sensitive, and so can use much less radiation than they used to. For medical machines, in addition to the obvious radiological benefit, it allows subtler detail to be visible. A few years ago I needed a foot x-ray, and on looking at it you could see the granular structure of my foot bones - it wasn't just white for bone, black for not-bone. That added sensitivity will be vital for looking for those soft things like explosives. -- ] | ] 02:37, 4 January 2006 (UTC) | |||
:related: https://species.wikimedia.org/Wikispecies:Village_Pump#help_to_identify_species ] (], ]) 06:57, 15 December 2024 (UTC) | |||
: Photographic film isn't really very sensitive to X-rays; it's sensitive to visible light. In the bad old days of very high intensity airport X-rays, people did find fogging on their higher-speed films, but today's moderate or low-intensity scanners don't pose a threat to normal films. (Medical X-ray films aren't directly sensitive to X-rays either; a fluorescent plate is used to convert X-rays to visible light.) But I don't think it's just plastic that's protecting workers and bystanders; I think you'll find it's a plate of lead or other heavy metal. ] 16:59, 4 January 2006 (UTC) | |||
:FWIW, I can't detect any visible differences between the plant in this photo and the ones illustrated in the ] and the ] articles. However, the latter makes it clear that ''Polygala'' is a large genus, and is cultivated, with hybrids, so it's possible that this one could be a close relative that differs in ways not visible here, such as in the bark or roots. That may or may not matter for your purposes. {The poster formerly known as 87.81.230.195} ] (]) 10:11, 15 December 2024 (UTC) | |||
==Possibility of X-ray goggles== | |||
== How to address changes to taxonomy == | |||
By X-ray googles i don't mean goggles that emit X-ray's, which i know is odd i simply refer to a (portable) device able to penetrate clothing (and no not just of beautiful yound women, security too!) and reveal an image we can see, is this possible without using harmful high energy waves, if not what alternatives are there which come close? (] 01:55, 4 January 2006 (UTC)) | |||
Hi all, | |||
:There are many devices that use infrared (heat) cameras. Many clothing items allow heat to pass through. Any item between the body and the clothing will then show up easily. There is a lot of concern about these because show the outline of the body beneath the clothing. Also, pubic hair blocks visible body heat, so it the outline is visible. In the United States, anything related to nudity must be forbidden. So, we won't have publicly advertised infrared security systems anytime soon. As for hidden infrared security systems, they are probably installed and used in many locations already. | |||
I am a biology student brand new to wiki editing who is interested in cleaning up small articles/stubs for less known taxa. One that I've encountered is a mushroom that occurs in the pacific northwest ('']''). The article mentions that this fungus is occasionally mistaken for another fungus, '']''. <br> | |||
:Want to make your own? Get a camera with a cheap pickup. It will have an infrared filter to block the infrared light (that makes the picture fuzzy). Remove the filter that blocks infrared and replace it with one that blocks visible light. Presto - you have an infrared camera. Then, hang out at the pool (where clothing is designed to allow the most heat to pass through), get arrested for taking semi-nude photos, and try to explain that you are just trying to make security better. --] <small><sup>]</sup></small> 02:29, 4 January 2006 (UTC) | |||
::Cheap CCD cameras are only sensetive to near infrared, and thus are only giving you a view of things that are slightly redder than red (it may see through some fabrics but only ones that pretty transparent to visable light). True heat cameras generally use expensive cooled CCDs. The cutting edge for this security scanning technology is ]. --]-<small>]</small> 07:07, 4 January 2006 (UTC) | |||
However, the issue I've run into is that ''F. pinicola'' used to be considered a single species found around the world, but relatively recently was split into a few different species. The original name was given to the one that occurs in Europe, and the one in the pacific northwest (and thus could be mistaken for ''F. ochracea'') was given the name '']''. | |||
:::That is accurate, but I think it needs to be put more simply. Infrared vision does not equal thermal vision, and unless all the babes are wearing several layers of "Congo Blue" filter gel (or if her body is, for some reason, hotter than 250 degrees C), you'll just get freaked out by how weird people look. Why would anyone want to make Geordi-LaForge-porn, anwyay? -] 0206; 1.8.06 | |||
<br> | |||
The wiki page says <blockquote><p>Historically, this fungus has been misidentified as ''F. pinicola.'' When both species are immature, they can look very similar, but can be distinguished by lighting a match next to the surface of the fungus. ''F. pinicola'' will boil and melt in heat, while F. ochracea will not.</p></blockquote> | |||
<br>Since the source says ''pinicola'' (as likely do most/all other sources of this info given the change was so recent), and since technically it's true that they used to be mistaken for it... what would be the most appropriate way to modernize that section? | |||
<br> | |||
<B>My questions are</b>: | |||
This was also asked at the miscellaneous ref desk. Please don't double post. ] 10:53, 5 January 2006 (UTC) | |||
Should I replace ''F. pinicola'' with ''F. mounceae''? Or is that wrong because the source doesn't refer to it by that name? Would it be better to write something like (now known as/considered ''F. mounceae'') next to the first mention of the species? Or is that a poor choice because it implies all the members of ''F. pinicola'' were renamed ''F. mounceae''? | |||
<br> | |||
Any advice on how to go about updating this section is incredibly appreciated | |||
See ] - it is effectively a "X-ray goggles". ] 22:34, 6 January 2006 (UTC) | |||
<br> | |||
] (]) 10:21, 15 December 2024 (UTC) | |||
:::First, take these sorts of questions to the relevant Wikiproject, in this case ]. I am not as familiar with the consensus at ], but it seems like they defer to '']'' and ] to decide. Those sources presently seem to consider '']'' a good species. Also, be careful about "replacing", there are rules to ensure the continuity of the article history. By the way, there is a hilarious but unencyclopedic/copyvio recipe appended to the '']'' article. <span style="font-family: Cambria;"> ] (])</span> 11:09, 15 December 2024 (UTC) | |||
::::Thanks for the tips, I didn't know about projects so I'll go read up on that. And thanks for the warnings about replacing things. I've been reading a lot of help pages, but I'm still in the process of learning the all conventions and what mechanics break if you do things the wrong way. | |||
::::I actually saw the recipe ages ago before I made my account and completely forgot about it... it was one of many things that prompted me to get into wiki editing. ] (]) 23:12, 15 December 2024 (UTC) | |||
== Does stopping masturbation lead to sperm DNA damage? == | |||
== Help with heat! == | |||
I'm looking for information on the potential link between the frequency of ejaculation (specifically through masturbation) and sperm DNA damage. I've come across some conflicting information and would appreciate it if someone could point me towards reliable scientific studies or reviews that address this topic. | |||
Hello, I don't have a calorimetre and I need to find the specific heat of lemon juice and any kind of antacid! I can't calculate specific heat, so If anyone can help me by just telling me that would really help out!!! Thank you all so much! Aberforthbil1657 | |||
:* | |||
:*] | |||
Specifically, I'm interested in whether prolonged periods of abstinence from ejaculation might have any negative effects on sperm DNA integrity. Any insights or links to relevant research would be greatly appreciated. ] (]) 17:08, 15 December 2024 (UTC) | |||
:Here's a sample equation: | |||
:Only males may abstain from sperm-releasing ] that serves to flush the genital tract of old sperm that in any case will eventually dissipate. No causal relationship between masturbation and any form of mental or physical disorder has been found but abstinence may be thought or taught]]] to increase the chance of wanted conception during subsequent intercourse. ] (]) 00:51, 16 December 2024 (UTC) | |||
::There's many rumors about that topic. One is that not ejaculating frequently increases the risk of developing ]. <span style="font-family: Cambria;"> ] (])</span> 01:02, 16 December 2024 (UTC) | |||
:Nothing really conclusive but there's some evidence that short periods are associated with lower DNA fragmentation, see<small> | |||
:* {{Cite journal |last=Du |first=Chengchao |last2=Li |first2=Yi |last3=Yin |first3=Chongyang |last4=Luo |first4=Xuefeng |last5=Pan |first5=Xiangcheng |date=10 January 2024 |title=Association of abstinence time with semen quality and fertility outcomes: a systematic review and dose–response meta‐analysis |url=https://onlinelibrary.wiley.com/doi/10.1111/andr.13583 |journal=Andrology |language=en |volume=12 |issue=6 |pages=1224–1235 |doi=10.1111/andr.13583 |issn=2047-2919}} | |||
:* {{Cite journal |last=Hanson |first=Brent M. |last2=Aston |first2=Kenneth I. |last3=Jenkins |first3=Tim G. |last4=Carrell |first4=Douglas T. |last5=Hotaling |first5=James M. |date=16 November 2017 |title=The impact of ejaculatory abstinence on semen analysis parameters: a systematic review |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC5845044/ |journal=Journal of Assisted Reproduction and Genetics |language=en |volume=35 |issue=2 |pages=213 |doi=10.1007/s10815-017-1086-0 |issn=2047-2919 |pmc=5845044 |pmid=29143943}} | |||
:* {{Cite journal |last=Ayad |first=Bashir M. |last2=Horst |first2=Gerhard Van der |last3=Plessis |first3=Stefan S. Du |last4=Carrell |first4=Douglas T. |last5=Hotaling |first5=James M. |date=14 October 2017 |title=Revisiting The Relationship between The Ejaculatory Abstinence Period and Semen Characteristics |url=https://pmc.ncbi.nlm.nih.gov/articles/PMC5641453/ |journal=International Journal of Fertility & Sterility |language=en |volume=11 |issue=4 |pages=238 |doi=10.22074/ijfs.2018.5192 |issn=2047-2919 |pmc=5641453 |pmid=29043697}} | |||
:</small> | |||
:for example. ] (] • ]) 02:12, 16 December 2024 (UTC) | |||
:Mature sperm cells do not have ] capability.<sup></sup> Inevitably, as sperm cells get older, they will naturally and unavoidably be subject to more and more ]. Obviously, freshly produced spermatozoa will, on average, have less DNA damage. It is reasonable to assume that the expected amount of damage is proportional to the age of the cells, which is consistent with what studies appear to find. Also, obviously, the more the damage is to a spermatozoon fertilizing an oocyte, the larger the likelihood that the ] in the resulting zygote, which does have DNA repair capability, will be incomplete. The studies I've looked at did not allow me to assess how much this is of practical significance. --] 09:40, 16 December 2024 (UTC) | |||
= December 16 = | |||
:''Calculate the specific heat capacity of copper given that 204.75 J of energy raises the temperature of 15g :of copper from 25˚C to 60˚C. | |||
:q = m x Cg x (Tf - Ti) | |||
:q = 204.75 J | |||
:m = 15g | |||
:Ti = 25˚C | |||
:Tf = 60˚C | |||
:204.75 = 15 x Cg x (60 - 25) | |||
:204.75 = 15 x Cg x 35 | |||
:204.75 = 525 x Cg | |||
:Cg = 204.75 ÷ 204.75 = 0.39 J˚C^-1 g^-1'' | |||
:Sorry, I can't do ]. | |||
== ] == | |||
:Here's a short guide for the military , and ]'s . Do you know how to do the experiment? -- ] ] ] 05:50, 4 January 2006 (UTC) | |||
Thanks to those who answered my ], I think it should be added to a disambiguation page. If anyone wants to help me write that, reach out. | |||
== pain and screaming == | |||
A sandpile seems disorganized and inert, but these are critically self-organizing. Do the frequency and size of disturbances on sand dunes and snowy peaks follow power law distribution? | |||
What is the reason that people scream when subjected to intense pain? I understand the reasons for pain and its beneficial nature, but the reason as to why people scream when they hit their finger with a hammer, for instance, eludes me. Is there a reason? | |||
] (]) 01:18, 16 December 2024 (UTC) | |||
:Shouldn't this be at the Math Desk? <span style="font-family: Cambria;"> ] (])</span> 05:12, 16 December 2024 (UTC) | |||
::If the question is not about the model mentioned in the heading but about the physical properties of sand dunes and snowy peaks, this here is the right section of the Reference desk. --] 08:51, 16 December 2024 (UTC) | |||
:::I await a non-mathematical answer. <span style="font-family: Cambria;"> ] (])</span> 09:23, 16 December 2024 (UTC) | |||
::::It depends is probably a fairly reasonable non-mathematical answer for these kinds of systems. For sand dunes anyway, sometimes avalanche frequency is irregular and the size distribution follows a power law, and sometimes it's close to periodic and the avalanches span the whole system. It seems there are multiple regimes, and these kinds of systems switch between them. ] (]) 09:35, 16 December 2024 (UTC) | |||
:::::Thank you! I'm impressed this seems so casual, but surely you read this somewhere that might have a URL? | |||
:::::] (]) 22:29, 19 December 2024 (UTC) | |||
:Hi, this is an interesting and somewhat open question! A lot of work is done on these models but much less on careful analyses of real dunes. I did find that is freely accessible and describes some physical experiments and how well they fit various models. The general answer seems to be that the power law models are highly idealized, and determining the degree to which any real system's behavior is predicted by the model ahead of time is very difficult. Update: and it does include discussion of how well the model fits experiments.] (]) 17:21, 16 December 2024 (UTC) | |||
--] 02:26, 4 January 2006 (UTC) | |||
::That dissertation is great! | |||
::] (]) 22:30, 19 December 2024 (UTC) | |||
== Polar night == | |||
: To enlist the assistance of other members of the tribe ("help, I'm being bitten by a lion") or to warn them of danger ("beware: I'm being bitten by a lion"). -- ] | ] 02:30, 4 January 2006 (UTC) | |||
Are there any common or scientific names for types of polar night? The types that I use are: | |||
::Ever wonder if humans scream differently when wanting others to come help or wanting them to run away? --] <small><sup>]</sup></small> 02:36, 4 January 2006 (UTC) | |||
* ''polar night'' - meaning a day when sun's altitude remains below horizon entire day (there is no daylight at solar noon, only civil twilight), occurring poleward from 67°24′ north or south | |||
* ''civil polar night'' - meaning a day when sun's altitude remains below -6° entire day (there is no civil twilight at solar noon, only nautical twilight), occurring poleward from 72°34′ north or south | |||
* ''nautical polar night'' - meaning a day when sun's altitude remains below -12° entire day (there is no nautical twilight at solar noon, only astronomical twilight), occurring poleward from 78°34′ north or south | |||
* ''astronomical polar night'' - meaning a day when sun's altitude remains below -18° entire day (there is no astronomical twilight at solar noon, only night), occurring poleward from 84°34′ north or south | |||
These names were changed on ] article, and I wnat to know whether these named I listed are in use in any scientific papers, or in common language. (And I posted that question here and not in language desk because I think that this is not related to language very tightly.) | |||
:::Or how about other animals? — ] ] 06:18, 4 January 2006 (UTC) | |||
--] (]) 18:56, 16 December 2024 (UTC) | |||
:Some definitions at from the ]. ] (]) 22:55, 16 December 2024 (UTC) | |||
::::Nah, we animals react in the same way in both cases, we're just programmed to scream, without ''thinking'' whether it is meant to attract others for help, or to warn them, or whether it is futile. Pigs/cows, etc. scream out loud in intense pain in slaughterhouses, and I guess humans will do the same, regardless of the fact that it's not going to make any difference. The screaming is not a result of a ''design'', but it just happened that the mutants that screamed had better rate of survival in the natural selection process. And it's a reflex action, it doesn't involve thinking and decision making ("should I request help or should I warn?"). ] (]) 06:29, 4 January 2006 (UTC) | |||
::These seem to be generalizable as: X polar night is a period, lasting not less than 24 hours, during which the sun remains below the horizon and there is no X twilight. The specific definitions depend then on the specific definitions of ]/]/]. These can be defined with a subjective observational standard or with an (originally experimentally determined) objective standard. --] 10:36, 17 December 2024 (UTC) | |||
:::FWIW, I as a former amateur astronomer have never previously thought about the question of ''Polar'' twilight and night nomenclatures, but immediately and completely understood what the (previously unencountered) terms used in the query must mean without having to read the attached descriptions. {The poster formerly known as 87.81.230.195} ] (]) 16:34, 17 December 2024 (UTC) | |||
= December 17 = | |||
::::: Wouldn't say whether it is a reflex action: it is more like a subconscious thing. After all, it only seems that animals with some developed brain: jellyfish don't scream, for instance, nor do a lot of insects. Dinosaurs and reptiles, probably moan in pain or something, or maybe that's a ] from watching ]. Anyhow, it's probably not so much that screaming has an evolutionary function, than having a brain does. It's just a primitive, basic, quick and forceful way to communicate: I mean, after all, having a language, or developing ]s and ]s aren't really evolutionary features than advantages that developed due to the evolutionary feature of having a brain. Then again, perhaps I'm arguing semantics: but there is a difference. A brain is more flexible because it can think of new ways to communicate; and perhaps change communication: after all, you can suppress your scream, and convert it into a more effective way of communication, if possible. ] (]) 13:58, 7 January 2006 (UTC) | |||
== differential equations with complex coefficients == | |||
: Also because screaming, through some mechanism that eludes me at present, helps stimulate the release of catecholamines (adrenaline/epinephrine etc) for the fight/flight reponse, and endorphines (the endogenous opioids) for pain relief. ] 00:12, 8 January 2006 (UTC) | |||
In an intro ODE class one basically studies the equation <math>\dot x=Ax</math> where x is a real vector and A is a real matrix. A typically has complex eigenvalues, giving a periodic or oscillating solution to the equation. That is very important in physics, which has various sorts of harmonic oscillators everywhere. If A and x are complex instead of real, mathematically the ODE theory works out about the same way. I don't know what happens with PDE's since I haven't really studied them. | |||
== earth == | |||
My question is whether the complex case is important in physics the way the real case is. Can one arrive at it through straightforward coordinate transformations? Do the complex eigenvalues "output" from one equation find their way into the "input" of some other equation? Does the distance metric matter? I.e. in math and old-fashioned physics we use the Euclidean metric, but in realtivity one uses the Minkowski metric, so I'm wondering if that leads to complex numbers. This is all motivated partly by wondering where all the complex numbers in quantum mechanics come from. Thanks. ] (]) 22:54, 17 December 2024 (UTC) | |||
i am working on a class project and i want to know how high u can jump on earth--] 02:39, 4 January 2006 (UTC) | |||
:Perhaps I don't understand what you are getting at but simple harmonic motion is xdot=j*w*x where w is angular frequency and j is i ] (]) 00:35, 18 December 2024 (UTC) | |||
:Well, you're on ], why don't you try it and measure how high ''you'' can jump? You could also look at the records for the sport ]. See also ] and ]. --] 02:59, 4 January 2006 (UTC) | |||
:If PDEs count, the ] and the ] are examples of differential equations in the complex domain. A linear differential equation of the form <math>\dot x=Ax</math> on the complex vector space <math>\mathbb{C}^n</math> can be turned into one on the real vector space <math>\mathbb{R}^{2n}</math>. For a very simple example, using <math>n=1,</math> the equation <math>\begin{bmatrix}\dot z\end{bmatrix} = \begin{bmatrix}i\end{bmatrix}\begin{bmatrix}z\end{bmatrix}</math> can be replaced by | |||
::<math>\begin{bmatrix}\dot x\\\dot y\end{bmatrix} = \begin{bmatrix}0&-1\\1&0\end{bmatrix}\begin{bmatrix}x\\y\end{bmatrix}.</math> | |||
: --] 01:11, 18 December 2024 (UTC) | |||
:::Shouldn't this be at the Math Desk? It almost seems like the IP could be trolling, given the same question just above. <span style="font-family: Cambria;"> ] (])</span> 14:49, 18 December 2024 (UTC) | |||
::::The question whether the complex case is important <u>in physics</u> the way the real case is, is not a maths issue. IMO the Science section is the best choice. I do not see another post that asks the same or even a related question. --] 21:51, 18 December 2024 (UTC) | |||
:::::Just as above, I await a non-mathematical answer to this question. <span style="font-family: Cambria;"> ] (])</span> 07:01, 19 December 2024 (UTC) | |||
Thanks all. Greglocock, your SHO example is 1-dimensional but of course you can have a periodic oscillator (such as a planetary orbit) in any orientation in space, you can have damped or forced harmonic oscillators, etc. Those are all described by the same matrix equation. The periodic case means that the matrix eigenvalues are purely imaginary. The damped and forced cases are where there is a real part that is negative or positive respectively. Abductive, of course plenty of science questions (say about how to calculate an electron's trajectory using Maxwell's equations) will have mathematical answers, and the science desk is clearly still the right place for them, as they are things you would study in science class rather than math class. Lambiam, thanks, yes, PDE's are fine, and of course quantum mechanics uses complex PDE's. What I was hoping to see was a situation where you start out with real-valued DEs in some complicated system, and then through some coupling or something, you end up with complex-valued DEs due to real matrices having complex eigenvalues. Also I think the Minkowski metric can be treated like the Euclidean one where the time coordinate is imaginary. But I don't know how this really works, and Misplaced Pages's articles about such topics always make me first want to go learn more math (Lie algebras in this case). Maybe someday. ] (]) 07:25, 19 December 2024 (UTC) | |||
:: How can she know how high ''you'' can jump on the Earth unless you tell her? ] (]) 15:50, 4 January 2006 (UTC) | |||
= December 18 = | |||
::Why do you assume he/she is on Earth? The question only makes sense if he/she has never been to Earth, so doesn't know what 10 m/s<sup>2</sup> gravity feels like. =P —] 08:23, 4 January 2006 (UTC) | |||
:::Doesn't the question specifically ask "''how high u can jump on earth''"? It all depends how you define how high you can jump. Is it the highest from the ground? Then high jump records are what you need to look for, specifically ] who has jumped higher than anyone. However, there is also the highest jump above ones head. It currently stands at 59cm. ] ] 08:30, 4 January 2006 (UTC) | |||
== Why don't all mast radiators have top hats? == | |||
{|{{prettytable}} | |||
|- | |||
!|height above <br>head (cm) | |||
!|height of<br>athlete (cm) | |||
!|height jumped (cm) | |||
!|name | |||
!|nationality | |||
!|place | |||
!|date | |||
|- | |||
|59 ||173 ||232 ||Franklin Jacobs ||USA || New York|| 27 jan 78 | |||
|- | |||
|59 ||181 ||240 ||Stefan Holm ||SWE || Madrid|| 6 mar 05 | |||
|- | |||
|} | |||
]Our ] article describes a device called a "top hat" which increases the range for mast radiators that can't be built tall enough. | |||
The ] as an international athetics event has a rule that the competitor must jump using only one foot. So these records don't tell the whole story: it may be possible to jump higher using both feet. ] 12:07, 4 January 2006 (UTC) | |||
So, why would you bother building a mast radiator without a top hat? Couldn't you just build it shorter with the top hat, and save steel? ] (]) 15:00, 18 December 2024 (UTC) | |||
:It is not possible to jump higher with two feet than one. In the high jump, the trailing leg is used to provide much of the upwards momentum during 'take off', converting the lateral momentum of the run up into vertical motion. Watch the way the trailing leg kicks during a ]. It is nowhere near possible to jump higher using both feet. For one, you wouldn't be able to have a fluent run up, thus there'd be no momentum to convert into upwards motion. ]<small> ] ]</small> 12:41, 4 January 2006 (UTC) | |||
:The main source cited in our article states, "{{tq|Top loading is less desirable than increased tower height but is useful where towers must be electrically short due to either extremely low carrier frequencies or to aeronautical limitations. Top loading increases the base resistance and lowers the capacitive base reactance, thus reducing the ''Q'' and improving the bandwidth of towers less than 90° high.}}"<sup></sup> If "reducing the {{serif|''Q''}}" is an undesirable effect, this is a trade-off design issue in which height seems to be favoured if circumstances permit. --] 21:41, 18 December 2024 (UTC) | |||
::I assume ] is refering to the vertical jump test. It is described at the following (note i am not sure how reliable this article is since they cite an incorrect world record for the high jump). | |||
== Name of our solar system == | |||
:::"''The best measure of jumping ability one that does not depend on the jumper's height is the standing vertical jump. The individual stands facing a wall, and with arm extended and feet on the floor, makes a mark on the wall at the top of his or her reach. The person jumps vertically, making a second mark at the peak of the jump. The distance between these two marks measures the vertical leap. This is an accurate measure of leaping ability, as each part of the jumper's body rises the same distance. A typical athlete has a vertical leap of 1 1/2 to 2 feet; the best male jumpers attain heights of 3 1/2 to 4 feet.''" | |||
Is our star system officially called "Sol", or is that just something that came from science fiction and then became ubiquitous? ] (]) 22:06, 18 December 2024 (UTC) | |||
::The claimed maximum height for the vertical jump is 4 ft (I could not find a verifiable wordl record) and equates to reaching a maximum height of 122 cm. This is quite a bit lower than Sotomayors 143 cm world record high jump. ] ] 00:08, 5 January 2006 (UTC) | |||
:It's called the ], and its star is called Sol, from Latin via French. Hence terms like "solstice", which means "sun stands still" in its apparent annual "sine wave" shaped path through the sky. ←] <sup>'']''</sup> ]→ 23:31, 18 December 2024 (UTC) | |||
:::Via French? According to the OED, it came direct from Latin.<sup></sup> --] 11:45, 19 December 2024 (UTC)}} | |||
::::Old French plus Latin. ←] <sup>'']''</sup> ]→ 14:25, 19 December 2024 (UTC) | |||
:::::Also in Old French, the word meaning "sun" was '']''. --] 23:42, 19 December 2024 (UTC) | |||
::Let's say {{fact}} to that claim. The star is indeed called Sol if you're speaking Latin, but in English it's the Sun (or sun). Of course words like "solar" and "solstice" derive from the Latin name, but using "Sol" to mean "the Sun" does seem to be something from science fiction. --] (]) 06:04, 19 December 2024 (UTC) | |||
:::"Sol" is occasionally used to mean the Sun by astronomers. I feel like it is used in contexts where it is necessary to distinguish our experience with the Sun here on Earth, such as sunsets, from more "sterile" aspects of the Sun one might experience off the Earth. <span style="font-family: Cambria;"> ] (])</span> 08:56, 19 December 2024 (UTC) | |||
::::Being an astronomer myself, I don't think I've ever heard anyone use "Sol" outside of a science fiction context. --] (]) 09:06, 19 December 2024 (UTC) | |||
::::::Scientific articles that use the term Sol; and . These are rather speculative but as I mentioned, the usage is for off-planet situations. <span style="font-family: Cambria;"> ] (])</span> 13:05, 19 December 2024 (UTC) | |||
:::::Using Sol, Terra and Luna to refer to the Sun, Earth and Moon only happens if you write your entire article in Latin and in science fiction, not in regular science articles. They are capitalised though. Just as people write about a galaxy (one of many) or the Galaxy (the Milky Way Galaxy, that's our galaxy). The Solar System is also capitalised. ] (]) 10:38, 19 December 2024 (UTC) | |||
::::::The article says "Sol" is the "personification" of the sun. Google Image the term "old Sol" and you'll see plenty of images of the sun with a face, not just Sci-Fi stuff. And "Luna" is obviously the basis for a number of words not connected with Sci-Fi. Lunar orbit, lunar module, etc. And the term "terra firma" has often been used in everyday usage. ←] <sup>'']''</sup> ]→ 11:34, 19 December 2024 (UTC) | |||
::::::: And yet, if you ask 1,000 people "What's that big yellow thing up in the sky called?", you'll get 1,000 "the Sun"s and zero "Sol"s. Yes, in specialised contexts, Sol is used; but that doesn't justify saying our solar system's star "is called Sol" without any qualification, as if that were the normal, default term. It's not. -- ] </sup></span>]] 12:16, 19 December 2024 (UTC) | |||
:::::::::And after you've gotten that response, ask them why it isn't the "Sunner System". And why a sun room attached to a house isn't called a "sunarium". And why those energy-gathering plates on some roofs are not called "sunner panels". ←] <sup>'']''</sup> ]→ 14:22, 19 December 2024 (UTC) | |||
::::::::::What does that have to do with anything? The question was 'Is our star system ''officially'' called "Sol"?' (my emphasis). The answer is it is not. And that does not preclude other terms being derived from Latin ''sol'' (or, often enough, from Greek ''helios''), nobody denies that, it is irrelevant to the question. --] (]) 14:52, 19 December 2024 (UTC) | |||
:::::::::::The problem is that the OP's question contains false premises. One is the question of what the "official" name is. There is no "official" name. It's the "conventional" name. And the second part, claiming that "Sol" comes from Sci-fi, is demonstrably false. ←] <sup>'']''</sup> ]→ 15:05, 19 December 2024 (UTC) | |||
::::::::::::Then demonstrate (that the usage of "Sol" as a name for the Sun, in English, not its use to derive adjectives, originated outside of SF), with references. The original question does not even include any premises, with maybe the exception of "ubiquitous". --] (]) 15:18, 19 December 2024 (UTC) | |||
:::::::::::::"Is our star system officially called "Sol" , or is that just something that came from science fiction and then became ubiquitous? ". And the wording of your own question, just above, does not make sense. ←] <sup>'']''</sup> ]→ 15:24, 19 December 2024 (UTC) | |||
::::::::::::::Looking at Newspapers.com (pay site), I'm seeing colloquial references to "old Sol" (meaning the sun) as far back as the 1820s. No hint of sci-fi derivation. ←] <sup>'']''</sup> ]→ 15:32, 19 December 2024 (UTC) | |||
:::::::::::::::Great! Well done. --] (]) 15:41, 19 December 2024 (UTC) | |||
::::::::::::::::Feel free to box up this section. ←] <sup>'']''</sup> ]→ 15:52, 19 December 2024 (UTC) | |||
:::::::::::::The 1933 OED entry for ''Sol'', linked to above, gives several pre-SF uses, the earliest from 1450. --] 23:48, 19 December 2024 (UTC) | |||
::::::::::::::Yes, of course, but that's not surprising, is it? 15th century humanists, astrologers and pre-Victorian poets liked to sprinkle their texts with Latin words. But I don't think this is what the question is about. It's a matter of context, but it should be up to OP to clarify that. --] (]) 08:48, 20 December 2024 (UTC) | |||
:::::::::::::::It's not surprising, but the discussion was not whether the use of ''Sol'' in English texts is surprising, but whether it originated outside of SF. --] 10:52, 20 December 2024 (UTC) | |||
::::::::::::::::In my view, the question has a clear scifi bent, and that particular usage ("Where shall we go for our vacation? Alpha Centauri or Sol?") does not originate in the 15th century. The word is much older, of course it is, but the usage is not. In the 15th century people didn't even know that the Sun is just an ordinary star and could do with a particular name to distinguish it from the others. The connotations of ''sol'' were vastly different from what they are today and from what is implied in OP's question. Incidentally, the ] doesn't even define a name , although they recommend using capitalised "Sun". Certainly no "Sol" anywhere. --] (]) 12:04, 20 December 2024 (UTC) | |||
::::::::{{small|Does that make it a Sol-ecism? ] (]) 12:19, 19 December 2024 (UTC)}} | |||
:::::::::<small>More like a ]. Meaning a factory where suns are made. From Sol = sun, and ipso = facto. Thus endeth the entymogology lesson for today. Go in peace to love and serve whomsoever. -- ] </sup></span>]] 19:37, 19 December 2024 (UTC) </small> | |||
== |
== Mountains == | ||
Why there are no mountains on Earth with a height above 10,000 m? As the death zone is about at 8,000 m, and above 19,000 m, there is an Armstrong limit, where water boils at normal human body temperature, it is good that there are no more mountains higher than 8,000 km than just 14, but if there were hundreds of mountains above 9,000 m, then these were bad to climb. If there were different limits for death zone and Armstrong limit, would then there be possible to have higher mountains? I have just thought that, it is not a homework? --] (]) 22:29, 18 December 2024 (UTC) | |||
See the search box on the left of the screen? Try searching for "hepatitis" and see what turns up. --] 02:53, 4 January 2006 (UTC) | |||
:There are ] that are over 20km high. Given that some of those are on airless worlds, I don't think the air pressure has any bearing on it. ] (]) 22:57, 18 December 2024 (UTC) | |||
== Solutions == | |||
:Multiple sources from web searching suggest the ''theoretical'' maximum height for mountains on Earth is around 15,000 m – the limiting factor is ]; the higher (therefore more voluminous) a mountain is, the more its weight causes the crust beneath it to sink. The actual heights of mountains are a trade-off between how fast tectonic movements can raise them versus isostatic sinking ''and'' how quickly they are eroded, and tectonic movements do not last for ever. See also ]. {The poster formerly known as 87.81.230.195} ] (]) 00:25, 19 December 2024 (UTC) | |||
If I have a solution with several components such as milk, water, and ammonia, how can I find the specific heat of the solution? I know the specific heat of the individual reactants but I don't know how to determine the specific heat of the overall solution. If anyone knows please list in J/g degrees celsius, Thanks! johnbog456 | |||
::And erosion goes faster as the mountain gets higher, in particular when it's high enough to support glaciers – one reason why mountains can get higher on an airless world. Now it gets interesting for a mountain high enough to reach into the stratosphere, as it would be too dry to have anything but bare rock. I suppose it would locally raise the tropopause, preventing that. ] (]) 11:13, 19 December 2024 (UTC) | |||
= December 19 = | |||
:If a chemical reaction is involved, then I guess it's not really possible to get the sp. heat of the products from that of reactants. ] (]) 03:24, 4 January 2006 (UTC) | |||
== Does human DNA become weaker with each generation? == | |||
:: As long as there is no chemical reaction (ammonia and milk might react; not sure) The specific heat of a mixture is the sum of (the specific heat of each part * the proportion of the mass of each part). Post again if that doesn't make sense to you. (found at http://www.carnicom.com/drought1.htm ) | |||
:: There seems to have been lots of similar questions lately. --]]] 05:44, 4 January 2006 (UTC) | |||
As with photocopying something over and over, the text becomes less clear each time. | |||
Yeah, that's right. Basically ''heat capacity'' (mass*sp. heat)is additive. So, (m1+m2)*C = m1*c1+m2*c2, where C is the sp. heat of the overall soln.] (]) 05:51, 4 January 2006 (UTC) | |||
Does human DNA become weaker with each generation? ] (]) 21:22, 19 December 2024 (UTC) | |||
== Cracking a Linux box == | |||
:Sure, DNA replication is not perfect, although ] reduces the error rate to about 1 mistake per 10<sup>9</sup> nucleotides (see our article on ]). But that is per generation of cells, not of the whole organisms. Many mutations will be neutral in effect (because much of our DNA is redundant), some will be deleterious, and a few might be advantageous. It is the process of natural selection that hinders the spread of deleterious mutations: sometimes this aspect is called ]. One thus usually expects a stable ] over time rather than that "DNA becomes weaker with each generation". Medical science is reducing the selection pressure against some mutations, which consequently may become more common. One of the problems for asexual organisms is referred to as ]; assuming that reverse mutations are rare, each generation has at least the mutational load of its predecessor. In contrast, in sexual organisms ] generates the variation that, combined with selection, can repair the situation. Sexual organisms consequently have a lighter genetic load. ] (]) 22:42, 19 December 2024 (UTC) | |||
::So ] won't work properly in case of ] ? ] (]) 23:16, 19 December 2024 (UTC) | |||
:::The larger the degree of inbreeding, the larger the chance that deleterious traits are expressed. But this very expression of traits leading to decreased biological fitness of their bearers is what actually enables purifying selection in the longer term. --] 23:36, 19 December 2024 (UTC) | |||
::::@] so ] won't stop these deleterious traits to get expressed? ] (]) 14:11, 20 December 2024 (UTC) | |||
:::::No, this is not an issue of ]. The genes involved are faithfully reproduced and passed on from generation to generation. --] 15:53, 20 December 2024 (UTC) | |||
:Or stronger e.g. "", and those guys live for centuries and have much more DNA than us. ] (]) 15:21, 20 December 2024 (UTC) | |||
::@] If not due to DNA damage, why do babies from inbreeding appear like DNA-damaged species? ] (]) 17:29, 20 December 2024 (UTC) | |||
:::Inbred offspring of species that normally outcross may show abnormalities because they are more likely than outcrossed offspring to be ] for ] that are deleterious. In individuals that are heterozygous at these loci, the recessive alleles will not be expressed (because the other wild-type dominant allele is sufficient to do their job adequately). See our article on ]. ] (]) 19:26, 20 December 2024 (UTC) | |||
== Larvae going south == | |||
I half don't expect and answer to this or I'm afraid I already know the answer. Can I crack the root password on a Linux box without root access? I set one up several months ago and it has been sitting on my network contently doing nothing. Today when I tried to log in as root I found I'd forgotten my password. I tried all the various combinations I might have used to no avail. I still have a regular user but that's about worthless. It's running slakware 9.0 and I've upgraded the kernel to 9.4.22. I figure I might be able to make a boot/root floppy set and run setup. Will that work? Can I do the same from an iso image CD. I'd start searching Google, but I've gotten spoiled by Misplaced Pages's reference desk. It's not as fast but I don't have to choose from sixteen gizzilion possibilities. Thanks.--]] 04:48, 4 January 2006 (UTC) | |||
In a novel I've just finished ('']'' by ]) he writes: | |||
:Try booting with <code>init=/bin/sh</code> in the kernel command line. —] 07:33, 4 January 2006 (UTC) | |||
* '' leave the body in an orderly fashion, following each other in a neat procession that always heads south. South-east or south-west sometimes, but never north. No-one knows why''. | |||
::I'm going to try that with an ISO CD, but I was kind of hoping to do it remotely. I don't have a keyboard or monitor attached and I don't really want to have to lug one into the other room. If I have to go through all that I may just wax the whole thing and put the slakware distro on it, assuming that will even work on a p133. Thanks.--]] 07:54, 4 January 2006 (UTC) | |||
The author has done considerable international research on the science of forensic identification of decayed bodies and I assume his details can be trusted. | |||
:::Hmm, remotely. Let's think about that. If '''you''' can get root access without a password remotely, then '''anyone''' can, right? =P The reason why the init=/bin/sh thing isn't a security hole is because you need '''physical''' access to the box. —] 08:17, 4 January 2006 (UTC) | |||
::::That was kind of what I meant by ''I'm afraid I already know the answer.'' Security bites at times.--]] 08:55, 4 January 2006 (UTC) | |||
:::::Others mentioned local root exploits. If it's been several months and you haven't accessed the machine to apply patches, there is probably a local root exploit you could use to gain access. Basically go to http://www.securityfocus.com/vulnerabilities, pull down linux and kernel or your specific distribution and look for the local root exploits. They're not just going to show you how to do it, so if you didn't already know how to use an exploit you're not going to be able to easily. Better solution is to go get physical access and use a livecd as others mentioned. - ] <sup><small>]</small></sup> 18:13, 6 January 2006 (UTC) | |||
:Boot from a rescue CD which gives you write access to the boot partition with root access. If you don't have a suitable CD, then take out the hard disk and mount it in another Linux box. On a Linux box where you know the root password, look at /etc/passwd or /etc/shadow (depending on your configuration) and note the encrypted version of your password there. Then edit the passwd or shadow file on the disk of the system you've forgotten the password for. You now have a known password on that system.-] 08:06, 4 January 2006 (UTC) | |||
::I ''think'' the slackware install CD will give write access, if not I know I've got knopix around here somewhere. I do have another box where I know the root password. So what you're saying is if I edit /etc/shadow on the box I'm locked out of so that root has the same hash as the box I can get into that should fix it? That makes sense if I'm understanding you right.--]] 08:55, 4 January 2006 (UTC) | |||
I've looked online for any verification of this surprising statement, but found only , which seems to debunk it. | |||
:One other thought: are you trying to login as root at the console? It is likely to be forbidden from remote sessions. It's easy to mistake this symptom as "forgotten password". ] 10:25, 4 January 2006 (UTC) | |||
::I vaguely recall that when remote root is disabled you get an message saying so. I rarely disable remote root becuase the boxes are inaccessable to the outside world unless you can get through two NAT boxes. Anyway, I'm logged in as my regular user and trying to su. I've most definitely forgotten the password.--]] 10:37, 4 January 2006 (UTC) | |||
:::For completeness, if the box is running old software for which there are local root exploits, you could use that root exploit to get root and reset the password. Note that if you can exploit it, so can anybody else with shell access to the box (or can use a remote exploit to execute that command as an unprivileged user), so fix the hole after you use it. --] 12:54, 5 January 2006 (UTC) | |||
Is there any truth to this? -- ] </sup></span>]] 23:38, 19 December 2024 (UTC) | |||
== Forgot my user password on Windows XP Professional== | |||
On my desktop, I forgot my user password, and the hint word doesn't make any sense to me any more. How can I get into my account again? ] (]) 05:22, 4 January 2006 (UTC) | |||
:Take it to a computer repair place, and tell them. That's the easiest way. -- ] | |||
::Yeah, it is, but if you have to do it often, such as when supporting people who can't understand how to use , using it works like a charm every time. It's probably what the guys at the repair place will use. I just wish I had the same thing for my Linux box.--]] 07:47, 4 January 2006 (UTC) | |||
:::For Linux, just stick in a ] CD, mount your normal root partition and edit /etc/shadow under it. The install CD for your distro probably also works, you just need to get into a shell somehow (try ''Ctrl-Alt-F2''). —] <small>(])</small> 12:42, 4 January 2006 (UTC) | |||
:Can't speak to its truth, but . . . | |||
:Thanks, that was informative. I'll check ntpasswd out! ] (]) 22:31, 4 January 2006 (UTC) | |||
:* Does Beckett state this in his own auctorial voice (i.e. as an ])? If so, he might be genuinely mistaken. | |||
:* The book was published nearly 20 years ago, what was the accepted wisdom ''then''? | |||
:* What specific species (if any) is the book describing? – your linked Quora discussion refers only to "maggots" (which can be of numerous species and are a kind of larva, but there are many others, including for example ]). | |||
:*Alternatively, if the statement is made by a character in the book, is that character meant to be infallible, or is he portrayed as less than omniscient, or an ']'? | |||
:Regarding the statement, in the Northern hemisphere the arc of South-east to South-west is predominently where the Sun is found well above the horizon, the North never, so the larvae involved might simply be seeking maximum warmth or light. {The poster formerly known as 87.81.230.195} ] (]) 02:18, 20 December 2024 (UTC) | |||
:: This appears in the very first paragraph of Chapter I, which starts out: | |||
== Movement of the Earth == | |||
::* ''A human body starts to decompose four minutes after death. Once the encapsulation of life, it now undergoes its final metamorphoses. It begins to digest itself. Cells dissolve from the inside out. Tissue turns to liquid, then to gas. No longer animate, the body becomes an immovable feast for other organisms. Bacteria first, then insects. Flies. Eggs are laid, then hatched. The larvae feed on the nutrient-rich broth, and then migrate. They leave the body in an orderly fashion ...'' (then the quote above completes the paragraph). | |||
:: It's not until para 2 that he starts talking about any human characters, and not until para 4 that he invokes the first person. | |||
:: That's as much as I know. But I find it hard to believe he'd just make up a detail and put it in such a prominent place if it could so easily be debunked if it were not true. -- ] </sup></span>]] 02:39, 20 December 2024 (UTC) | |||
:::I wonder how they would measure the migratory path of maggots within a sealed coffin. ←] <sup>'']''</sup> ]→ 02:51, 20 December 2024 (UTC) | |||
:::: The context of the novel is about finding decaying corpses that have been dumped in a forest. No coffins involved. -- ] </sup></span>]] 06:08, 20 December 2024 (UTC) | |||
::::::], see also ] research facilities. ] (]) 13:44, 20 December 2024 (UTC) | |||
:::::Could it be that the larvae are setting off in search of another corpse? The prevailing wind in the UK is from the south-west, so by heading into the wind they won't be distracted by the frangrance of the one they've just left. ]|] 09:30, 20 December 2024 (UTC) | |||
If you can, have a look at 'Heinrich, Bernd. “Coordinated Mass Movements of Blow Fly Larvae (Diptera: Calliphoridae).” Northeastern Naturalist, vol. 20, no. 4, 2013, pp. N23–27. JSTOR, http://www.jstor.org/stable/43288173.' Here are some extracts | |||
] has a bit of information under the subheading Earth in the solar system and there is also some information at ].--] 07:57, 4 January 2006 (UTC) | |||
* On the fourth day, after a cooling night with dew on the grass, a stream of tens of thousands of larvae exited from beneath the carcass within 1 h after sunrise, and proceeded in a single 1-2-cm-wide column directly toward the rising sun... | |||
* However, in this case, the larvae left at night, within 1 h after a cloudburst (at 21 :00 hours). But, unlike before, this nocturnal larval exodus in the rain was diffuse; thousands of larvae spread out in virtually all directions over an 8 m2area. Apparently, the sudden moisture had cued and facilitated the mass exodus, but the absence of sun had prevented a unidirectional, en masse movement. | |||
* However, on the following morning as the sun was starting to illuminate the carcass on the dewy grass, masses of larvae gathered at the east end of the carcass at 07:00 hours. In one half hour later, they started streaming in a column directly (within one degree) toward the rising sun, and the carcass was then nearly vacated. | |||
It goes on. Maggot migration appears to be a bit more complicated than the novel suggests. ] (]) 09:39, 20 December 2024 (UTC) | |||
I suppose you could try to address it from the other direction and look at the technology your average maggot has access to in terms of light detection, heat detection, olfactory systems, orientation in magnetic fields (like many arthropods) etc. They presumably have quite a lot of tools. ] (]) 10:13, 20 December 2024 (UTC) | |||
:If orderly migrating maggots tend to move towards the sun, they should display a northward tendency in Oztralia. --] 10:31, 20 December 2024 (UTC) | |||
:And don't forget ]. ] 22:46, 4 January 2006 (UTC) | |||
:: Maybe, but the novel is set in England. | |||
:: I must say, as soon as I read the quoted para for the first time, my immediate thought was that it might have something to do with the magnetic field of the earth. -- ] </sup></span>]] 10:42, 20 December 2024 (UTC) | |||
:::Prime suspect might be the Bolwig organ, the photoreceptor cluster many fly larvae have. ] (]) 10:49, 20 December 2024 (UTC) | |||
:::Obviously, Jack, you need to create a corpse, place it in a nearby forest, and carefully observe which way the maggots go. For Science! And Literary Criticism! {The poster formerly known as 87.81.230.195} ] (]) 21:01, 20 December 2024 (UTC) | |||
= December 20 = | |||
== seeking widest possible concensus == | |||
== Winter solstice and time of sunrise? == | |||
I'm seeking a concensus on the subject of mergers at ]. ]<small>(])</small> 14:46, 4 January 2006 (UTC) | |||
How is it that despite December 21st supposedly being the shortest day of the year, sunrise here happens later and later until December 26 and only on January 05 starts to turn around to occur earlier and earlier. On December 25 it takes place at about 08:44, between December 26 and January 04 it takes place at about 08:45, and on January 05 it takes place again at about 08:44. (Google rounds out the seconds). Is it Google's fault? Is it everywhere the same? Confused in Brussels, Belgium. ] (]) 12:06, 20 December 2024 (UTC) | |||
== shadows caused by albedo == | |||
:The pertinent article is ], start with the section ]. The details are not that simple to understand, but it's basically due to the ellipticity of Earth's orbit and its axial tilt. --] (]) 12:22, 20 December 2024 (UTC) | |||
::Also note that sunset begins to be later on 22 December so that the time between sunrise and sunset is a few seconds longer than on 21 December (3 seconds longer on 22/12/24 in Brussels according to ). ] (]) 13:33, 20 December 2024 (UTC) | |||
::Also see ]. The obliquity of the ecliptic (that is, the Earth's axial tilt) is the main component and hardest to understand. But the idea is that the time when the Sun is exactly south (that is, the true noon) moves some minutes back and forth throughout the year and it moves quite rapidly to later times in late December. ] (]) 19:05, 20 December 2024 (UTC) | |||
== Three unit questions == | |||
I was wondering if there is a specific term for the shadow created from a reflective body such as the moon. In a sense, we know something is a shadow from a "direct" source of light whether it be natural(the sun) or artificial(a light bulb) but as far as these producing the light to something else and then ''this'' specific body reflecting the light: shouldn't there be a different term? | |||
# Why territorial waters are defined by nautical miles instead of kilometers? | |||
Your input would be much appreciated. I've been pondering this thought for some time now. | |||
# Why GDP is usually measured in US dollars rather than euros? Euro would be better because it is not tied into any country. | |||
# Are there any laws in United States that are defined by metric units? | |||
--] (]) 23:30, 20 December 2024 (UTC) | |||
:#There were nautical miles in use before there were kilometers. | |||
:#There were US dollars in use before there were Euros. | |||
:#Yes. | |||
:The questions all reduce to Why can't millions of people make a change of historically widely accepted units that continue to serve their purpose, and convert to different units that would have no substantive difference, because someone has an opinion. ] (]) 00:52, 21 December 2024 (UTC) | |||
::Do any people use metric units in marine and air navigation like "The ship is 10 kilometers from the port", "The plane is 10 kilometers from the destination? And is there any European country with metric flight levels? --] (]) 07:22, 21 December 2024 (UTC) | |||
:::Inland shipping (rivers, canals and lakes) in Europe (except the UK) is fully metric. Ships going for example ] – ] may have to switch units along the way. Gliders and ultralight aircraft in Europe often use metric instruments and airport dimensions are also metric (including runway length). Countries are free to define their territorial waters in whatever way they deem fit, so with nautical miles having no legal status in a fully metric country, they may define their territorial waters as extending 22224 metres. ] (]) 11:23, 21 December 2024 (UTC) | |||
::::Our ] article says: {{xt|"In 1929 the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1,852 metres (which is 6,076.12 ft). The United States did not adopt the international nautical mile until 1954. Britain adopted it in 1970..."}} | |||
::As the US customary units are actually defined in terms that relate them to metric units, any US law based on measurements is technically defined by metric units.--] (]) (]) 01:55, 21 December 2024 (UTC) | |||
:::The US dollar has been the world's dominant ] for about 75 years. As for the metric system in the US, it is standard in scientific, medical, electronics, auto manufacturing and other highly technical industries. By law, all packaged foods and beverages have metric quantities as well as customary quantities. See ]. ] (]) 02:28, 21 December 2024 (UTC) | |||
The Wikipaedia article on the Nautical Mile talks about how the term originated, it was originally defined in terms of latitude not as a number of meters ] (]) 10:03, 24 December 2024 (UTC) | |||
The euro is tied to multiple specific countries is it not? If you use euros you're just changing from one "dependency" to a "dependency" on the ] countries. A statement of the problem or problems intended to be addressed would be useful. Currency values are interconvertible in any case. Economics does sometimes use the "]" for certain things, which is intended to adjust for differences in ] between countries and over time. But since it's not an actual "real" currency it's not something one can easily "visualize" in their heads, which is likely why it's not used more. --] (]) 05:41, 26 December 2024 (UTC) | |||
Sincerely, | |||
= December 24 = | |||
Christopher Cole | |||
Chardon, Ohio | |||
:Now you've done it. I'm going to have "Moonshadow" playing in my head all day. Well, at least it's not "My Sharona". --] 15:47, 4 January 2006 (UTC) | |||
== Unknown species of insect == | |||
:It took me a long time to understand the question, but I suppose you simply mean "What should one call a shadow that is cast by reflected light?" I don't see why there should be a different term and anyway, most light we see is reflected. Consider what what shadows would be like if the Sun's light weren't reflected all over the place by the atmosphere (or whatever). They would be totally absolutely completely pitchblack. Most of the light around us is reflected light. And I imagine that light that is created in the Sun gets reflected many times there, too, so even our main source of light is mostly reflection (don'\t know this, just seems plausible). ] 11:03, 5 January 2006 (UTC) | |||
Am I correct in inferring that ] this guy is an ]? I was off-put by the green head at first, but the antennae seem to match. ''']]''' 03:00, 24 December 2024 (UTC) | |||
== RHEUMATOID ARTHRITIS CURE == | |||
(no text in body of question)<br> | |||
(reference: https://www.genesdigest.com/macro/image.php?imageid=168&apage=0&ipage=1) | |||
*Please read the instructions at the top of the page and try again. - ]|] 19:09, 4 January 2006 (UTC) | |||
:<s>It looks like one of the invasive ]s that happens to like my blackberries in the summer.</s> ] (]) 13:11, 24 December 2024 (UTC) | |||
*I don't believe there is a cure, just ways to treat it. Aspirin, for example, relieves pain and reduces associated swelling. ] 22:40, 4 January 2006 (UTC) | |||
::I would say not necessarily a Japanese beetle, but almost certainly one of the other ] beetles, though with 35,000 species that doesn't help a lot. Looking at the infobox illustration in that article, 16. & 17., "]" looks very similar, but evidently we either don't have an article or (if our ] article is a complete list) it's been renamed. {The poster formerly known as 87.81.230.195} ] (]) 14:18, 24 December 2024 (UTC) | |||
== element lead == | |||
:::Yes, it's not the Japanese beetle for this beetle appears to lack its white-dotted fringe although its condition is deteriorated. Its shape is also more or less more slender; and not as round. ] (]) 15:02, 24 December 2024 (UTC) | |||
what is the melting point of the element ]? | |||
* I added a few square brackets to your question. Does that help? —] <small>(])</small> 22:24, 4 January 2006 (UTC) | |||
:: (If you're confused, that means "click on the ] link".) --]]] 04:34, 5 January 2006 (UTC) | |||
:Perhaps it is the ] ]. Shown . ] (]) 16:09, 24 December 2024 (UTC) | |||
== ]s == | |||
: |
::That looks like easily the best match I've seen so far, and likely correct. {The poster formerly known as 87.81.230.195} ] (]) 17:09, 24 December 2024 (UTC) | ||
= December 25 = | |||
== Energy Conservation 2== | |||
== Mass of oscillating neutrino == | |||
If a virtual particle appears in a vacuum, hits another particle, losing energy, and bounces off into it antiparticle, then then wouldn't energy conservation be violated because it has lost some of the borrowed energy? Thanks ] 23:24, 4 January 2006 (UTC) Max | |||
:If you look above, to ], the question has already been answered. ] <sub>] ]</sub> <small>• </small><small>23:43, 4 January 2006 (UTC)</small> | |||
::It's the same guy. -] ] 23:47, 4 January 2006 (UTC) | |||
I answered above. -] ] 01:45, 5 January 2006 (UTC) | |||
From the ] it follows that a particle that is not subject to external forces must have constancy of mass. | |||
== Universal IDs == | |||
If I am right, this means that the mass of the neutrino cannot change during the ], although its flavoring may. Is this written down somewhere? Thank you. ] (]) 19:24, 25 December 2024 (UTC) | |||
Greetings: | |||
:Any (flavored) neutrino that is really observed is a superposition of two or three mass eigenstates. This is actually the cause of ]. So, the answer to your question is complicated. ]_] 19:40, 25 December 2024 (UTC) | |||
:Important note: particle physicists today generally only ever use "mass" to mean "]" and never anything else: . Like the term says, invariant mass is well, invariant, it never changes ever, no matter what "external forces" may or may not be involved. Being proper particle-icans and following the standard practice in the field, then, the three neutrino masses are constant values. ..."Wait, three?" Yeah sure, turns out ]. As mentioned, due to Quantum Weirdness we aren't able to get these different states "alone by themselves" to measure each by itself, so we only know the differences of the squares of the masses. Yeah welcome to quantum mechanics. | |||
:]: "Quantum mechanics describes nature as absurd from the point of view of common sense. And yet it fully agrees with experiment. So I hope you can accept nature as She is {{snd}} absurd." --] (]) 06:06, 26 December 2024 (UTC) | |||
::The equation <math>E^2 = (p c)^2 + \left(m_0 c^2\right)^2</math> uses invariant mass {{math|''m''<sub>0</sub>}} which is constant if {{math|''E''}} and {{math|''p''}} are constant. The traveling neutrino has a varying mass mixture of different flavors with different masses. If a mixture of different masses changes, you would expect the resulting mass to change with it. But somehow this does not happen as the neutrino mass mixture changes. These mixture changes cannot be any changes. The changes must be such that the resulting mass of the traveling neutrino remains constant. My question is whether this is described somewhere. ] (]) 11:16, 26 December 2024 (UTC) | |||
:::I freely confess I'm uncertain exactly what's being "asked for" or "gotten at" here. Have you looked at the ] article? From it: {{tpq|That is, the three neutrino states that interact with the charged leptons in ]s are each a different ] of the three (propagating) neutrino states of definite mass. Neutrinos are emitted and absorbed in weak processes in flavor ]s '''but travel as mass eigenstates.'''}} | |||
:::What is it that we're "doing" with the ] here? For the neutrino, we don't have a single value of "mass" to plug in for <math>m_0</math>, because we can't "see" the individual mass eigenstates, only some ] of them. What you want for describing neutrino interactions is ], which is special relativity + QM. (Remember, relativity is a "classical" theory, which presumes everything always has single well-defined values of everything. Which isn't true in quantum-world.) --] (]) 18:41, 26 December 2024 (UTC) | |||
::::Not all potential evolutions of a linear combination of unequal values produce constant results. Constancy can only be guaranteed by a constraint on the evolutions. Does the fact that this constraint is satisfied in the case of neutrino oscillation follow from the ], or does this formulation allow evolutions of the mass mixture for which the combination is not constant? If the unequal values are unknown, I have no idea of how such a constraint might be formulated. I think the OP is asking whether this constraint is described somewhere. --] 00:51, 27 December 2024 (UTC) | |||
I'm trying to find material relating to the concept of "Universal ID", which, in my case, is defined using the following scenario: | |||
= December 27 = | |||
" A group of government officials and information managers at major corporations who point out that the proliferation of single-use identifying keys for individuals is causing major inefficiency, embarrassing and costly cases of mistaken identity, and considerable waste of time and money. They propose a single lifetime ID for every Canadian resident that would be used for everything from tax returns to grocery check-cashing cards." | |||
And I have to argue along the lines of: | |||
"a universal ID would lead to loss of privacy and essential freedoms, and would be open to considerable abuse." | |||
I would highly appreciate any pointers to wikipedia entries, books, journal articles, web site materials pertaining to "universal ID" in the above sense. | |||
Regards, | |||
] 23:30, 4 January 2006 (UTC) | |||
:I believe ] is what youre looking for, but I don't think it examines the Canadian case in great detail. ] <sub>] ]</sub> <small>• </small> <small>23:45, 4 January 2006 (UTC)</small> | |||
:I'm not sure how much they've written about this topic in particular, but the folks at the ] would certainly have something opposing it. Similarly, you might want to search ]. --] 14:27, 5 January 2006 (UTC) | |||
=January 5= | |||
== Lungs == | |||
How do the lungs Work? | |||
:Perhaps you didn't realize this is an encyclopedia. Have you tried looking up ]? -- ] <small>(])</small> 00:24, 5 January 2006 (UTC) | |||
==Oxygen Planet== | |||
Ok, in theory if i took a planet the size of earth same atmospherical structure but 100% oxygen consistency, landed on this planet (with a suit) and lighted a match, would the planet exploded? I have been told 'No' by various sources, why not? | |||
And as another interesting point when I light a match on Earth why doesn't 20% or so of the earth atmosphere explode? (] 00:50, 5 January 2006 (UTC)) | |||
:Oxygen alone isn't an optimal fuel for an explosion. Oxygen atoms will combine with other oxygen atoms to create 0<sub>2</sub>. When you heat up the O<sub>2</sub> to break it apart and force it to combine with another oxygen atom, you don't get much heat surplus. Now, if you use a molecule that is a little unstable, provide it with something it wants (usually oxygen), and then add heat to give it a nudge, the molecule will break, release a lot of heat, and the halves will combine with the oxygen. So, all in all, you really need fuel, heat, and oxygen to get something good going. Consider going to a planet that has an atmosphere of well mixed 50% oxygen and 50% methane - then light a match. Of course, I doubt you'd ever get the chance since some flaming meteorite will beat you to it. --] <small><sup>]</sup></small> 00:59, 5 January 2006 (UTC) | |||
::Of course the planet's surface might also be flammable, but then the same would apply - a meteor would probably have beaten you to it. Other than that there are two (potential) fuel sources. First there is the match, which will burn up incredibly fast - you'll see small 'poof' and then nothing. The second source is you. Better make that a very non-combustible suit or the little 'poof' will be followed by a somewhat bigger one... ] 11:11, 5 January 2006 (UTC) | |||
:::Of course, the heat of atmospheric entry would have blown the entire place up even if a meteor hadn't wandered along yet. ] 13:11, 6 January 2006 (UTC) | |||
::::Or lightning. Eek. ] 2206, 6.1.06 | |||
==A new form of fire?== | |||
What other examples are there of fire, in the sense of rather than rapid oxidisation, an exothermic reaction with another element or compound? | |||
With these examples could one make a new type of more efficient combustion which can remain more prolonged? | |||
Or, just came up with this the other extreme, cold fire, an rapid endothermic reaction which emits cold as it sucks in lights and sinks to the ground like a really cold dark heavy smoke, is it possible to be created? (] 00:50, 5 January 2006 (UTC)) | |||
:Similar to the question above, your question is limited to oxygen combustion. There is nuclear fusion and fission also - neither of which requires oxygen and both are capable of being prolonged for very long times. However, I cannot think of any chain reaction that absorbs energy. You might try to call a black hole a chain reaction that absorbs energy, but I'd say you are being very liberal with the idea of a chain reaction. --] <small><sup>]</sup></small> 01:01, 5 January 2006 (UTC) | |||
:There really can't be any other form, since that is the definition of fire. An endothermic reaction like your "cold fire" is not self sustaining and won't have the power to suck in light, something that only black holes can do. Matter can absorb light or heat that hits it directly, but won't "suck it in." There's no such thing as emitting cold, since cold is a lack of heat. An endothermic reaction like the one inside a chemical cold pack will absorb heat from the environment, but it won't necessarily be dark, nor will it exist in the form of smoke or have a particular density. ] 01:10, 5 January 2006 (UTC) | |||
] is oxidation of ]. Is it exothermic? ]|] 16:41, 5 January 2006 (UTC) | |||
:I believe it is, but it happens at such a slow rate that the temperature difference generated is negligable. -] | ] 17:58, 5 January 2006 (UTC) | |||
:: Yes, and reversing rusting is endothermic - I can't remember the chemical, but I did it in chemistry class and the beaker happened to turn cold. I can't remember if it was an acid (most likely not, because it simply just allows it to slide off, it doesn't reverse the reaction as more just excise the rusted parts). ] (]) 10:11, 8 January 2006 (UTC) | |||
==Most expensive chemical element and compund== | |||
What is the most expensive chemical element and compound by market price currently? and i have also heard ridiculous prices on antimatter, but has it ever been made, surely none exists now? (] 01:34, 5 January 2006 (UTC)) | |||
:Bear in mind, the most expensive elements are all only available in very, very small quantities, usually as the result of high-energy collisions in ], and aren't feasibly producable in reasonable quantities. As such, any cost-figure attached to elements are simply scaled up from the cost per atom. Because of this, any element of about 110+ is going to be hideously, mind-bogglingly expensive. As for antimatter, yep, it's been produced. It's used in ] among other things, though again, only on the order of a relative handful of particles. ] <sub>] ]</sub> <small>• </small> <small>04:11, 5 January 2006 (UTC)</small> | |||
:: What's the most expensive ''stable'' element? ] 03:04, 6 January 2006 (UTC) | |||
::: ], probably. Of course, "stable" can be a tad subjective (of course, I'm just playing with semantics here) - ]. ;-) ] (]) 20:01, 7 January 2006 (UTC) | |||
== lizard regeneration == | |||
Is it possible for a new lizard to grow from a piece of tail broken off an original? I know that it can grow a new tail if it loses one, but can one grow from the piece that has fallen off? | |||
]s are better than ]s at leg regeneration. The "fallen off piece" does not grow a new salamander. For an up-to-the-minute review of limb regeneration and how some of our new understanding may be applied to human organ regeneration, see this week's issue of ''Science'': | |||
] 02:19, 5 January 2006 (UTC) | |||
:While lizards can't do that, note that ], a type of ], can do so. ] 10:26, 5 January 2006 (UTC) | |||
::Also, the ], a major blight on Australian reefs, can do this. The method of population control used was to hack them to bits and throw the bits into the ocean, an unfortunately each of the little bits grew into a new starfish, increasing the numbers dramatically. <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 15:43, 5 January 2006 (UTC) | |||
:: The secret of regeneration in general is in the cells' genetic programming: they have to learn to recognise certain chemical signals in order to grow again, trigerring off a complex biochemical pathway (as it does in ]), or develop into a new stage (often they are all intermediary) - often mature, specialised cells in humans can't do that, either that, or we don't know the signals yet. ] (]) 10:14, 8 January 2006 (UTC) | |||
:::Some trees can also do that trick. You can grow a willow tree from a larger willow branch. – ] 15:52, 8 January 2006 (UTC) | |||
== Earths location == | |||
Lets say the Earth was 1 foot closer to the sun as it is now...how much would that affect the climate here in Earth?{{unsigned|68.117.16.64|2006-01-05 05:32:13 (UTC)}} | |||
:None.--]] 05:47, 5 January 2006 (UTC) | |||
:: Go outside and stand in the sun. Then get a stool and stand on that a foot higher. Any difference? The Earth's orbit wobbles a bit and has been speculated to cause changes in climate, e.g. the ice ages, but that's likely to be more than a foot. ] (]) 05:51, 5 January 2006 (UTC) | |||
:Interesting question. The Earths orbit is elliptical so as it goes round the sun at certain times of the year it is closer than at other times. The 1 foot you mention is a trivial difference. At its closest distance to the sun, ], the Earth is 147 million km from the Sun. At its greatest distance, ], it is 152 million km from the Sun. So there is a difference during the year of approximately 5 million km. The Earth is closest to the Sun in <s>July</s> January and furthest away in <s>January</s> July. ] ] 05:52, 5 January 2006 (UTC) | |||
::Actually this year Earth was at closest, perihelion, on Jan 4 (yesterday), it will be farthermost away, aphelion, July 3..--]] 06:07, 5 January 2006 (UTC) | |||
:::To demonstrate how insignificant this difference would be, let's do some calculations. The amount of light which hits the Earth from the Sun is inversely proportional to the square of the distance. Since the average distance is around 93 million miles, this is about 491 billion feet. The difference in the squares of 491 billion feet and 490,999,999,999 feet is about 0.0000000004%, so it would change the Earth's temp by about that percentage. This would work out to around 0.000000002 degrees F. These calcs are very approximate, but give some idea of how insignificant the change would be. ] 10:06, 5 January 2006 (UTC) | |||
::::Of course the Earth's orbital period would have to decrease too, but even if there is an exponential relation between the two (how ''do'' they relate again?) then that would also be too minute a change. | |||
::::But how much would the distance have to change for it to have any effect? And suppose global warming would really get out of control, could we use nuclear explosions (like in the tv series ]) to achieve this? And while we're at it, alter the rotational period too, so we get 100 or 1000 days per year, so timekeeping can be made nice and decimal too. :) ] 11:33, 5 January 2006 (UTC) | |||
:::: About the relations, I suspect you would need to use some ]s in order to replot the new orbit after you've pushed it in by one foot. ;-) ] (]) 10:17, 8 January 2006 (UTC) | |||
:::::Use nukes to move the earth? No, no ... no. All of about 0% of an explosions energy (no matter how big) affects the momentum of the planet. The most effective way to move the planet would be to sling HUGE amounts of matter in the opposite direction, at high speed. A Moon-sized chunk should get you a few percent further out from the Sun, if you could get it faster than ~11km/s (escape velocity). And then you'd have to make sure its orbit won't ever intersect the Earth's new orbit, or KaPOW! ] 23:09, 5 January 2006 (UTC) | |||
:::In case one is wondering how the Earth can be closer to the Sun in winter, the answer is that the effect of Earth's ] completely overwhelms any difference made by the varying distance. Plus, it's summer south of the equator. -- ]|] 07:51, 6 January 2006 (UTC) | |||
::::Which would mean that the differences between summer and winter would be much greater in the southern hemisphere if it weren't for the fact that it's mostly ocean, which has a stabilising effect. I think. ] 10:07, 7 January 2006 (UTC) | |||
== How to copy/paste wikipedia articles '''including images''' == | |||
To make a long story short, I would like to be able to copy and paste entire wikipedia articles (including text and images) onto my usb drive so that I can take those articles and view them on a different (offline) computer. | |||
When I select everything on a wikipedia article and copy and paste it into a microsoft word document, all I get is text, no images. If I individually select the pictures and copy/paste them it works fine, but that would take an extremely long time. How can I do this efficiently? (Please note that I have no intention whatsoever of using this for any illegal or immoral reasons) ] 06:53, 5 January 2006 (UTC) | |||
: If you're using IE, have you tried File --> Save As... ? The resulting files are somewhat messy and inefficient, but it might work, and it's fast and easy. --]]] 06:59, 5 January 2006 (UTC) | |||
::I'm actually using firefox, and I just tried using the 'save page as' function. I saved the page to the desktop, and when I opened that file (still on the first computer), the page was a little garbled (but certainly readable) and the pictures showed up fine. When I transferred the file to the offline computer, the text showed up fine, but the where the images should have been there were little red "x"s in the corners, and it displayed the text name of each image. Can anyone think of anything else? (thanks for trying, aysz88) ] 07:13, 5 January 2006 (UTC) | |||
:::That's because IE bundles the html file, the css file (if present), the image files, and possibly other used files into one file on your harddrive (a .mht file, multipart html file). So when you copy it to the other computer, everything works fine. Firefox, unfortunately, DOESN'T do it. It puts all files except the HTML file in a separate folder next to the HTML file. If you want to transfer it to another computer after that you'll have to copy ''both'' the HTML file and the folder. It's a pity really - the MHT feature is one of the few REALLY GOOD features of IE, I think. There seems to be a Firefox , but I haven't tested it. ] 21:52, 5 January 2006 (UTC) | |||
I actually just received the answer to this question from a friend via msn messenger. In case anybody else is wondering, here's how it's done. File--> Save As, (be sure 'web page, complete' is selected) and save it DIRECTLY to the usb drive. It works fine then. aysz88, you were right after all, but my mistake at the time was not saving it DIRECTLY to the usb drive. Ahh.. Feels so good to solve a problem. ] 07:46, 5 January 2006 (UTC) | |||
: Glad you got the answer to your problem. :) --]]] 07:56, 5 January 2006 (UTC) | |||
:An alternative would be to use ], a very powerful tool (so be careful what you do). It will not only download the page but also all the pages it links to. In case of Misplaced Pages this would download the whole site because everything is ultimately interlinked. Actually, without restraints, it would download the entire internet. To only get the pics you can limit the linkdepth to one and specify only image links (or something similar - I haven't used it for a long time). ] 11:45, 5 January 2006 (UTC) | |||
== astrology == | |||
Is the prediction by astrology correct? Is the basis of astrology is firm? | |||
:Answer to first question is sometimes. Answer to second is no. ] ] 07:09, 5 January 2006 (UTC) | |||
::The predictions seem correct because typically a horoscope contains four or five vague "predictions" (You will meet a stranger, you will face challenges today). According to probability, at least one of these should come true in some way, and since people want to believe the horoscope, they will see minor coincidences as fulfillment of the prophecy. <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 08:16, 5 January 2006 (UTC) | |||
::: Let's define our terms here. Without necessarily wanting to add credence to astrology, there is a huge difference between the "astrology" advice columns in the daily newspapers which use Sun signs only, that apply to 1/12 of the entire population; and a serious natal chart drawn and interpreted by a professional astrologer that uses an individual's precise birth data and which applies to that person alone. The latter is astrology (whether you think it has any validity or not), the former is not. ] 08:33, 5 January 2006 (UTC) | |||
::::And I stand by my answer above. Smurrayinchester is correct when he says that people want to see it work and will shoe horn the predictions into known events or cherry pick their character traits to fit. For those with a less cynical view I suspect it is often self fulfilling (obviously this is a POV comment). In this sense it may be comforting and even positive with regard to ones life. ] ] 08:41, 5 January 2006 (UTC) | |||
::::: I wouldn't dispute any of that. I'm just saying that, mostly, what people think of as "astrology" is a misnomer, it's something that has virtually no relevance to true astrology at all. ] 08:51, 5 January 2006 (UTC) | |||
::::::Oh, maybe it was not clear, i agree with your comments. May be I am missing this too. I thought the astrologers were all about prediciting character and to a certain extent fate. Certainly I would not call the daily horoscopes astrology, although i thought they did 'pretend' to make some similar statements but there is just no method i.e. fiction ] ] 09:00, 5 January 2006 (UTC) | |||
Also note that the "theory" behind astrology, if it can be called that, is based on the actions of Greek and Roman gods. If you don't believe in Roman gods, like Mars/Ares, you shouldn't believe that people born when Mars is visible will have the traits of that god (combative, for example). There is a basic incompatibility in believing in Christianity or any other modern religion and also believing in astrology. There is also a basic incompatibility in believing in science and astrology. ] 10:22, 5 January 2006 (UTC) | |||
:This is not true at all. Astrology was never so limited and many Christians (and scientists) were astrologers throughout the early modern period. Our ] does a fairly good job of outlining that. A belief in astrology does not necessitate a belief in Roman or Greek mythology, it simply requires the believe that "heavenly bodies" could have influences on individual people. The place where astrology and Christianity usually butted heads was the issue of free will, not in gods. --] 03:12, 6 January 2006 (UTC) | |||
See ]. --] 12:47, 5 January 2006 (UTC) | |||
== dandruff == | |||
how to cure dandruff | |||
:Read the article ]. There's a section on Treatment. --] 09:10, 5 January 2006 (UTC) | |||
== agriculture == | |||
How can science help agricultutre?--~~how science can help agriculture?--] 10:37, 5 January 2006 (UTC) | |||
:Is this, by any chance, homework? ] 11:37, 5 January 2006 (UTC) | |||
:Must be a very important question, because (s)he asks it twice. ] 11:47, 5 January 2006 (UTC) | |||
:Here's a hint to start you off when you '''do your own homework''': ]. --] 12:48, 5 January 2006 (UTC) | |||
== computers == | |||
what is an operating system? | |||
who is considered the father of modern computers? | |||
:See ]. As for the father of modern computers, depends on what you call a modern computer and whether you're thinking about hardware or software. ] and ] constructed mechanical computers. ] is said to be the first programmer (in which it would be a 'mother' - you male chauvinist pig :) ). If by 'modern computer' you mean the use of ]s then it could be ] (funny, I thought the transistor was a British invention 'stolen' by the Japanese). If you mean the third generation computers, with ]s, then it would be ]. See also ]. ] 12:06, 5 January 2006 (UTC) | |||
::Some other luminaries include ], who in large part founded ], ], who developed ], ] and ] for the ] and the design of the stored program computer, ] for writing up Eckhart and Mauchly's work and circulating it, and ], for apparently doing most of this independently in Germany before the collapse of Nazi Germany interrupted his work. But the modern computer was the product of many people developing a lot of technologies and figuring out how to combine them, working in collaboration and sometimes in competition, and it's simply impossible to assign one person credit for it all. --] 12:43, 5 January 2006 (UTC) | |||
:::Thus I have read: "The Atanasoff-Berry Computer was the world's first electronic digital computer. It was built by John Vincent Atanasoff and Clifford Berry at Iowa State University during 1937-42." This would be without transitors. Tubes and/or relays , I guess. see http://www.cs.iastate.edu/jva/jva-archive.shtml ] --] 00:55, 6 January 2006 (UTC) | |||
::::Yes, you can Atanasoff to the list, but the ABC wasn't a modern "computer" as we would understand it. It was a major development that pioneered a number of key features of modern computers, but it was a special-purpose machine as distinct from the later ENIAC and the von Neumann machines that followed it. --] 03:46, 6 January 2006 (UTC) | |||
==Pure copper 3,000 yrs ago== | |||
What procedure would people in the bronze age have used to produce pure copper from copper oxide? | |||
:From about 5000BC, ], usually charcoal-fuelled, was used to process the ores into pure copper. ] <sub>] ]</sub> <small>• </small> <small>13:52, 5 January 2006 (UTC)</small> | |||
== Particle accelerators == | |||
Hi just wondring if anyone could help me on this. | |||
How has the UNILAC accelerator been used to increase our knowledge about chemical elements? How does the technique work and how does it rely on an understanding of the structure of atoms? | |||
Thanks | |||
Why is science such important in our daily life? | |||
:See the articles ], ] and ]. --] 22:12, 5 January 2006 (UTC) | |||
== Eye Strain == | |||
Is it possible to strain your eyes by reading or watching tv with little or almost no light? It is an old wive's tale that I would like to know the rationality and/or proof behind. Any help will be greatly appreciated! -- Chloe | |||
: has a pretty good explanation on the subject. ] <sub>] ]</sub> <small>• </small> <small>14:06, 5 January 2006 (UTC)</small> | |||
Thanks! That was very helpful! any other sources are still greatly appreciated. -- Chloe | |||
:That article was about reading in low light. Reading is done at close range, which means it requires your ]s' focusing muscles to work harder. (Unfortunately, the article "]" is a stub.) Watching TV, you're not sitting so close to the screen, so this is less of an issue. (And at a ] you're even farther from the screen and your eyes are practically focused at infinity, so being in the dark matters even less.) -- Anonymous, 21:20 UTC, January 5. | |||
::Also, the brightness on the TV should be adjusted to match the brightness of the room. A dim TV in a bright room causes as much eye strain as a bright TV in a dim room. ] 22:13, 5 January 2006 (UTC) | |||
== Speed of a horse == | |||
How fast can the average horse run? | |||
--] 14:42, 5 January 2006 (UTC) | |||
:For a sprint (100 yards)? Or for miles? ] 16:15, 5 January 2006 (UTC) | |||
::I don't know much about horses, but the fastest horse in the ] last year ran 3200 m (10 500 ft) in 3m 19 sec. That's an average speed of 58 km/h (36 mi/h). Average horses must be a bit slower than that.--] 23:15, 5 January 2006 (UTC) | |||
:::According to a quick google search(animals speed): | |||
:::*A normal 'quarter horse' can run 47.50mph (top speed) for a quarter mile | |||
:::*A ridden horse can go 40mph | |||
:::*The distance record for a horse may be 100 miles in 9 hours | |||
:::Also, it turns out lots of people use the exact same chart of animal speeds. ] 02:56, 7 January 2006 (UTC) | |||
:I've read in a book that a gallopping horse goes 43 km/h. – ] 15:45, 8 January 2006 (UTC) | |||
==Teaching myself Geology== | |||
I am teaching myself geology for a course and i am looking through some old exams, some help please i am lost on this q. What name is given to the process which causes surface layer rock to break off? --15:33, 5 January 2006 (UTC) | |||
:I don't believe you; you're eroding people's patience. ]<small> ] ]</small> 15:48, 5 January 2006 (UTC) | |||
:: I believe we can weather it. Weathering = breaking up of rock into smaller particles. Erosion = movement of those particles from one area to another. This should be in even the most basic geology/Earth science texts. ] 15:59, 5 January 2006 (UTC)TheSPY | |||
== erasables( computer storage devices) == | |||
:] / ] ? ] 22:49, 5 January 2006 (UTC) | |||
::Or ] of course :) ] <sub>] ]</sub> <small>• </small> <small>02:28, 6 January 2006 (UTC)</small> | |||
== astatine == | |||
How many protrons does the element Astatine have? How many nuetrons does the element Astatine have? | |||
Thank you Amy T] 23:37, 5 January 2006 (UTC) | |||
: From ]: The ] gives you the number of protons in an atom; in this case it's 85. The ] gives you the total number of protons and neutrons; in this case it's 210. To find the number of neutrons, subtract 85 from 210. Sometimes there are many common ]s of the element, in which case the number of neutrons would vary; in this case, it looks like there's only one common isotope. ] (]) 23:41, 5 January 2006 (UTC) | |||
How many electrons does the element astatine have? | |||
Thank you Amy T] 23:50, 5 January 2006 (UTC) | |||
:As many as it has protons. (Unless it's ], in which case it may have more or less.) —] <small>(])</small> 01:37, 6 January 2006 (UTC) | |||
=January 6= | |||
== Size of internet, size of wikipedia == | |||
If you were able to download the entire internet, how much space would it take up on a (rediculously massive) hard drive? How about if you were able to download all of wikipedia? ] 01:13, 6 January 2006 (UTC) | |||
:Don't know about the entire Internet, but for Misplaced Pages, see ]. —] <small>(])</small> 01:34, 6 January 2006 (UTC) | |||
::I thought wikipedia was the whole thing. -] ] 02:28, 6 January 2006 (UTC) | |||
:::Wow, it's mindboggling! ] (]) 02:34, 6 January 2006 (UTC) | |||
:The Internet Archive Wayback Machine is about 1 petabyte in size and is growing at a rate or 20 terabytes a month according to its FAQ (compaired to a mere 40 gigs for a wikipedia database dump). The Wayback is presumably larger than the internet because it includes multiple versions of each site. Then again, because its all accessable online its really part of the internet itself, making the actual size of the internet somewhat larger. If you were to include the size of all such caches, including search engine indexes, not to mention material available through filesharing networks and Bittorent, and twenty-some years of newsgroups, the number quickly becomes astronomically large. | |||
:Or for a more succinct response, a quick googling yields this.... ] 03:22, 6 January 2006 (UTC) | |||
::Since 1 GB of hard disk space costs about half a € storing Misplaced Pages would cost about 8 €. Storing the Internet would however cost half a million €. ] 08:13, 6 January 2006 (UTC) | |||
:::] found a website which offered the entire web for download at 22.2877482 petabytes, or 23 931 287 382 megabytes . Trying to download it however resulted in "Insufficient memory on drive C: for the internet. Insert disc in drive A". <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 17:02, 6 January 2006 (UTC) | |||
::::LOL. ] 10:11, 7 January 2006 (UTC) | |||
:Don't forget that the internet is much bigger than just the web. While the ] may have lots of web sites and images on it, the ] at any moment has a whole lot of other bytes flying around, including emails, IMs, P2P traffic, etc. That is to say that the more-static web is a tiny fraction of the more-dynamic internet. I recall hearing an ISP study that showed that WWW (web) traffic was actually less than 20% of their traffic. --] 19:41, 6 January 2006 (UTC) | |||
::And of course you couldn't (or else shouldn't :) ) download other people's emails. ] 10:11, 7 January 2006 (UTC) | |||
== Digital cable to DVD Recorder == | |||
Can i hook a Wireless Transmitter to my Digital Cable and then hook my wireless receiver to my DVD recorder to record things from Digital Cable? | |||
:Generally, no, because digital TV is always encrypted to stop people accessing channels they do not pay for. This has the side effect that you can't get the raw digital video feed out of the set top box. See ] for more details on this. You can attach a ] type device to a digital TV box because it uses an analog interlink. So, you could build a device that takes an analog signal from your digital cable box, re-encodes it as a compressed digital video stream, sends it to a computer which has a DVD burner in it, and then burn it to that. But this would be quite a significant feat of DIY home engineering ;) If you want to record programs from your digital cable box, a PVR like TiVo is still the best way to do it, alternatively I think some home DVD recorder devices can be connected directly to your box like VCR tape recorders could be. Hope that helps -- Anonymous Guy | |||
== NSAIDs for dogs == | |||
My dog is taking an ] called ] (no article yet). Why shouldn't dogs take human NSAIDs like ] or ]? Why shouldn't people take carprofen? —] 02:57, 6 January 2006 (UTC) | |||
:All I can tell you is what a Google search turns up, so take it with a grain of salt. Carprofen has apparently gone through some human trials in Europe, but was never put on the market for economic reasons. Dogs can be given aspirin, but the toxic doses are relatively low and ulcers are likely. Veterinary aspirin is available. Ibuprofen causes stomach ulcers far more readily in dogs than in humans. -- ]|] 07:46, 6 January 2006 (UTC) | |||
== Free circuit simulator software == | |||
I'm looking for a compreensive circuit simulator that can manage things like ], ]s, an arbitrary number of ]s, etc. I found but it doesn't support flyback circuits, and the controls are rather annoying to deal with. The program I'm looking should run on Windows XP. | |||
Anyone knows of such a thing? ☢ ]⌇] 03:49, 6 January 2006 (UTC) | |||
== blogs == | |||
]s? Wouldn't that be better on the ]? ☢ ]⌇] | |||
== Would my ISP be able to know what websites I visit == | |||
Would my ISP be able to know what websites I visit? | |||
I am in a very small town and there are only two companies offering services here. | |||
One ia a big telecom company which I at present use. | |||
But, the other company is a new, small and a local company which has given some 50 connections in my town. I plan to move to the small ISP because it is cheap. | |||
But, I am afraid whether they would be able to see what websites I visit. | |||
Can anyone please tell me? | |||
Do you have any other advice or tips? | |||
*Yes, they could, but they probably won't unless you get involved in something which would result in the police requesting the information from them. If they got a website, try reading their ]. If I remember correctly, employees are not allowed to look up such info unless there's good reason to. - ] 08:24, 6 January 2006 (UTC) | |||
*Your ISP can potentially see everything you do (except when visiting secure web sites, where they can see where you go, but not what you type). Your e-mails too. In some places they may be allowed to record this information. In some places they may be ''required'' to do this, in case the police later want to investigate something. The solution is to not visit illegal sites, I guess. ] 10:14, 6 January 2006 (UTC) | |||
:*on a side note visiting certian websites will probably get you put on an FBI watchlist, doesn't take much these days, certianly wikipedia users are all on such a list, very subversive website, grounds for concern--] 14:25, 6 January 2006 (UTC) | |||
::*Heck using the phrase 'FBI watchlist' on the internet is probably enough to get you on such a list--] 14:26, 6 January 2006 (UTC) | |||
:::*We've got our Eye on you. And you. - ] <sup><small>]</small></sup> 16:36, 6 January 2006 (UTC) | |||
::How do you know if a site is 'illegal' before you visit it? And whose law determines what is illegal on an international medium? ] 10:19, 7 January 2006 (UTC) | |||
You could also get an encrypted connection to a proxy service and use some sort of ] or ] type thing from there. Not perfect, but does make it hard to tell where you are visiting. - ] <sup><small>]</small></sup> 16:38, 6 January 2006 (UTC) | |||
:I would suggest ], being widely supported free / open software. No proprietary protocols or single business in control. ] 06:07, 7 January 2006 (UTC) | |||
These rules might also vary by nation. Depending on how you connect to the Internet, a bunch of other people in addition to your ISP might know all about what you doing. Even though secured websites are protected from normal spying, they are not protected from keylogger spyware. ]|] 07:06, 7 January 2006 (UTC) | |||
:About the privacy policy. Who guarantees that they stick to that? My ISP has the ability to follow my actions. Who has the ability to follow my ISP's actions? And would they be interrested in protecting my privacy (they'll probably be in the business of violating privacy themselves and without incentive thieves don't snitch on thieves, do they?) ] 10:19, 7 January 2006 (UTC) | |||
== Electrophysiology == | |||
I am an electronics engg student. | |||
My interest is to study about a subject that links | |||
electronics with biology or rather human physiology. | |||
Is it apt for me to do my higher studies in "'''ELECTROPHYSIOLOGY"'''? | |||
If yes plz let me know about the books i've to refer to | |||
and the '''universities in the U.S.A and the U.K. which offer this course. | |||
--] 09:01, 6 January 2006 (UTC) | |||
:], who have a list of all the courses available in the UK, don't recognise "Electrophysiology". However, they do have several courses for ]s: . Doubtless the US has similar. <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 17:27, 6 January 2006 (UTC) | |||
: A quick read of our article on ] might also help. At ] we had an undergraduate program in ] which sounds like it may be of interest to you. I'm sure there are other schools with similar degree programs as well . --] (]) 22:12, 6 January 2006 (UTC) | |||
== aromol? == | |||
Can someone Please tell me what Aromol is? It is in Smith's Rosebud Salve and I want to know what it is? I have looked everwhere and can't find anything on it? So please someone help me, what is Aromol? Thanks | |||
:You could always try contacting the manufacturer and asking them. --Anonymous, 10:00 UTC, January 6, 2006 | |||
== optics - experiment == | |||
how to make an achromatic doublet ? | |||
mail answer to : | |||
:It's pretty much summed up by this diagram: ] | |||
:] and ] can be replaced by any two materials with different ]. —] 13:35, 6 January 2006 (UTC) | |||
*Also, if you look at our ] article, you will see how to calculate the focal lengths of each part of the lens you need, if you know some data about the materials. --] 16:11, 6 January 2006 (UTC) | |||
== viral/ infectious diseases == | |||
Are there any viruses, bacteria, etc., that live in the cold weather? I know that the cold weather just weakens the immune system and makes the body more succeptible to infection, but i was just wondering whether or not there are any viruses that actually just live in the cold environments and are strong enough to infect people. Thanks! ----- Eryn | |||
Short answer: yes. Long answer is more complicated. There are bacteria and viruses that thrive in extreme environments: freezing and boiling hot environments, but these rarely affect (or infect) humans. Shall we assume that you are only interested in bacteria and viruses that can cause human disease and the degree of cold is the winter temperature range away from the poles where most of us live (like down to 10 degrees below water freezing)? Moderate freezing cold will kill many bacteria and some viruses, but the main effect of cold on bacteria is just to slow down reproduction and activity (which is why refrigeration retards bacterial growth). Bacteria and viruses vary greatly in their abilities to survive outside a host but the temperature is less of a factor in this than availability of water and food and absence of harmful substances like soap or high osmolality or intense sunlight. Dehydration will kill most bacteria faster than cold will, but some viruses can survive dehydration and some can survive indefinitely being frozen. Some pathogenic bacteria require direct person-to-person contact (e.g., bacteria of gonorrhea or the AIDS virus), but others (e.g., the spores of tetanus) can survive in the environment for long periods of time in various forms. For example, there has been concern about whether smallpox or influenza viruses can remain infectious in graves. The most recent example was the investigation a few years ago of 1919 flu victims buried in the permafrost of extreme northern arctic islands for 80 years. Precautions were taken to avoid releasing potentially infectious material. That said, I don't know of any cases of smallpox or plague or influenza known to have been contracted from graves or crypts. Cold weather does have an effect on transmissibility of respiratory viruses by affecting human behavior and perhaps altering mucous membrane defenses. Complex topic. ] 13:45, 6 January 2006 (UTC) | |||
Thanks... I know this is a complicated question. You were very helpful. However, are there any specific instances in which entering a cold environment would promote the spread and possible contraction of a virus or bacteria into a human body? And if so, what are they???? ----- Eryn | |||
Ah, this sounds simple, so I'll wade in. This site explains the #1 myth, ie. if you go outside 'You'll catch your death of cold!', which is usually uttered by an old lady in a Jane Austen novel. --] 18:05, 6 January 2006 (UTC) | |||
Thanks for your input. I think i worded my second question poorly though. Are there any bacteria, viruses, etc., that live only in the cold weather and are then contrsacted by humans or animals? For example, a virus taht lives and thrives outdoors in cool temperatures and then infects the first host that it encounters. possibly this bacteria/virus stayes dormant until contact with a host is made.... (Maybe this has been answered already in a previous reply and i just dont see it.) But if there is such a virus/bacteria, a name or description would be most helpful. Thanks! ----- Eryn | |||
:I asked our disease control doctor here (MUSC hospital). She said that there are many bacteria and viral-like lifeforms documented in the South Pole. In her opinion, it is heat that is harmful to them, not cold. They usually freeze and thaw well. They overheat and die easily - which is why running a fever is a good thing. --] <small><sup>]</sup></small> 20:39, 6 January 2006 (UTC) | |||
== Physicists == | |||
Hi, I read in several places that ''the fundamental building block of the universe is information'' or ''events''...I know how it sounds, but I haven't read it in new agey looney pages, I read it in like, news articles, and in some physics pages which I cannot remember,but I can't distinguish real science from far fetched claims...so, do you think this is true or somewhat true? because I am aware that the building blocks of matter are quarks and subatomic particles like gluons and stuff. | |||
also, quite apart from that, here's this quote :''We are now synergetically forced to conclude that all phenomena are metaphysical; wherefore, as many have long suspected — like it or not — 'life is but a dream.' ''- Buckminster Fuller. | |||
see? I mean, stuff like this... what do u think of what he says?, or am I taking it too litarally and he meant something else.--] 14:35, 6 January 2006 (UTC) | |||
:''Comment:'' I think, apart from subtle philosophical difference, ''information'' in this context can mean energy of which matter is another manifestation, and ''events'' can mean time. Space is left out, but again, some people think space it no existence independent of matter. I find this statement a bit vague though. ] (]) 16:02, 6 January 2006 (UTC) | |||
:''Comment2:'' Well, I don't know the context, but he's probably referring to something related to the ] and ]. For more about the "life is a dream" proposition, see ], ], ]. ] (]) 16:12, 6 January 2006 (UTC) | |||
Thank u :), but what I actually meant to ask was if this notions are somewhat supported by current respectable science? or just by speculation, like eastern philosophies.--] 16:21, 6 January 2006 (UTC) | |||
::Yeah, this wasn't intended as a reply, just some comments. ] should give an idea though of how far physicists entertain these views. ] (]) | |||
::I've seen similar scientific speculations, in particular in the book Information - The New Language of Science by Hans Christian von Bayer. As I understand it, the basic idea is to think about a hypothetical perfect theory of everything -- what if you knew all the equations governing reality at the lowest level, and had all the data about everything (knew the full quantum wavefunctions etc), then you could imagine the whole universe evolving as a computational process -- in other words, we don't need to assume any reality beyond the information process. What I got from Bayer's book is that physicists are finding applications for ] in physics, so that the ] encoded in a system of particles may in fact have real physical meaning. The traditional basic connection is between ] in statistical physics and information theory. But I'm no expert on any of this - I can't tell if these physicists have simply confused their models with reality. ] 19:09, 6 January 2006 (UTC) | |||
cool, so you mean that, information theory implies that nothing ''outside'' or ''besides'' the universe is required for the universe to exist? I mean, nothing besides the information and computations of our universe?... if so, how can it know that? I mean, can't the universe be like a big videogame? it can seem the only thing for us, but we can never know that which lies ''outside the computer'' that ''contains'' it ... maybe we can only know ''the software''... it sounds really crazy and hard to understand, but i think that the information theory has space for a videogame conception of reality, or a simulation for that matter, but I know nothing about physicists, so I need the expert's opinion. --] 19:30, 6 January 2006 (UTC) | |||
:The expert is just another character in the video game. But anyway, take a look at ], ]; they attempt to show reality is a large computation in some machine. ] 03:04, 7 January 2006 (UTC) | |||
I really suck at math and physics, but I believe that if everything is quantizied ( I'm sure I spelled that wrong :S )if everything is, I think the universe is no diferent than a videogame... but then, if it is, we can't know much about philosphy since the physics of ''the real universe'' (the one outside) aren't known to us...and maybe are even irrational to our brain...but that would surely signify there is a trickster God ...or a kid out there, haha --] 16:52, 7 January 2006 (UTC) | |||
You should really check out interesting things like ] and ]. Information represents order: it can affect energy almost take on physical properties because of the laws of ] about things tending towards disorder. For example, destroying information in a hard drive, or in a computer processor, will result in a rise of ] and therefore heat. ] (]) 20:25, 7 January 2006 (UTC) | |||
== who are the five google billionaires? == | |||
who are the five google billionaires? | |||
:], ], ], ] and ] --] 19:30, 6 January 2006 (UTC) | |||
== A query regarding Pepper Pad == | |||
Have anyone of you used a Pepper pad? | |||
I am just interested in buying a pepper pad, but want to know this- | |||
I heard that its resolution is 800x600. | |||
I just want to know how would a 8.4" screen placed horizontally compare with a screen placed vertically with respect to size. | |||
Would the 8.4" Pepper pad be equialant to a 15" CRT monitor in 800x600 resolution or would it be equivalent like viewing a 14" CRT screen? | |||
Or would it be equivalent to viewing some other screen with someother resolution? | |||
Can you please tell me the equivalents? | |||
Can we view full page in a Pepper pad without sideways scrolling? | |||
:Thanks for making me look that up That was really interesting! This seems to be the legendary Linux PDA that everybody has said will come one day. The resolution is good enough to get in most web pages without scrolling (just set your computer to this and see!). The specs look good, but you really need to get some independent reviews. Never be the first on the block! I find the info a bit misleading, since they seem to be marketing to the 'ipod' generation, with all sorts of promises, like browsing in your car. This thing only has Wifi which has a raft of access problems. There is no such thing as free broadband wireless (which is what they seem to be implying). My Blackberry costs $100 a month, for very slow Internet access. --] 18:18, 6 January 2006 (UTC) | |||
== how does the cable car work? == | |||
:Depending what you mean by cable car, see the links on ]. <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 16:54, 6 January 2006 (UTC) | |||
== Is the pen mightier than the keyboard and mouse? == | |||
Which one do you feel is better of the following. | |||
A touchscreen pen? or a mouse with keyboard? | |||
Which do you think is the easier, and which one do you prefer if given a choice? | |||
:Personally, I'd go for the mouse and keyboard. ] 17:57, 6 January 2006 (UTC) | |||
:Habit. I began using a keyboard in 1978. I didn't use a mouse until about 1992. So, to this day, I am more comfortable with a keyboard for 90% of my tasks and a mouse for simply moving windows around. If I were to have started with a mouse, I would probably use the mouse more. If I had started with a touchscreen pen, I'd probably use the touchscreen pen more. If I had started with a neural implant, I'd probably use the neural implant more. --] <small><sup>]</sup></small> 19:30, 6 January 2006 (UTC) | |||
::The touchscreen pen seems to have the disadvantage that the weight of your arm is not supported, as it is with a mouse. Thus, after hours of use, your arm will get tired. ] 20:47, 6 January 2006 (UTC) | |||
:::It depends on the application. For regular computing like editing Misplaced Pages, writing emails, browsing the internet, etc. I'm comfortable with a mouse and keyboard combo. But at my work a keyboard would just clutter things, so a touch screen is preferred. ]|] 22:14, 6 January 2006 (UTC) | |||
:::: I have a tablet PC... you can actually rest your arm on the screen with no problems, it's strong enough. For text entry, e.g. in my law lectures, I still find keyboard faster and more accurate. But in my maths lectures, I'll write with my stylus instead of writing on paper, because it's searchable. For other applications, I actually find that if there isn't much text entry (because handwriting is slow and inaccurate), using the stylus is far more natural, e.g. when casually browsing the net, or playing cards. ] (]) 04:52, 7 January 2006 (UTC) | |||
:As said before, depends on the purpose. Generally, I prefer the keyboard over anything else (including the mouse) because it's easier on my mouse arm, much more versatile (try typing with a mouse :) )and much faster once you know the shortcuts (if any - which is the main reason I still prefer Photoshop over ], even though that means rebooting to msWindows). I don't have a touchscreen but a tablet and I haven't gotten the hang of that yet, but that's a matter of what one's used to. I suppose it would be better for graphical stuff (using a mouse in a graphical application is the worst for my mouse-arm), but for quick notes and diagrams and such I still use old fashioned pen and paper. ] 12:02, 7 January 2006 (UTC) | |||
== how to teach newborn to swim? == | |||
Why would you want to? ] 17:37, 6 January 2006 (UTC) | |||
:This is actually common, 198. It can be a good idea for saftey reasons to introduce "swimming" at an early age. Read more here: --] 19:25, 6 January 2006 (UTC) | |||
:My older sister almost drowned quite a few times as a toddler before she was finally taught to swim. It seems she simply didn't know any better and walked off piers or into the deep ends of pools. Since then me and my three other siblings were all taught to swim as infants. None of us had any near-drownings, and we all love the water. Seems like a good reason to me. | |||
:As the the how, I've only seen it done in special classes. You usually first teach how to blow bubbles under water, and then when that comes naturally, you have one parent release the kid and another call them and they do the rest. — ] ] 20:45, 6 January 2006 (UTC) | |||
*Infants are surprisingly good at swimming in an controlled environment (after all they have been swimming for 9 months before). All you need to do is make sure they know to close their mouth and not breath for a little time, while underwater. ] baby Dexter went to a swimming class long before he turned 1. - ]|] 11:22, 8 January 2006 (UTC) | |||
== Los Angeles-class submarine mast pattern == | |||
Does anyone know the story behind the giraffe-like black-and-white pattern on the masts of this of a surfaced ]? (In case that link doesn't work, it's the . ] 17:56, 6 January 2006 (UTC) | |||
:I can't find an answer either, but if I had to guess, it's probably camouflage for when the sub is running just under the surface with its masts extended. -- ]|] 02:54, 7 January 2006 (UTC) | |||
== deepest part on the planet == | |||
what is the deepest part on the planet below sea level? | |||
:The ] ] 18:31, 6 January 2006 (UTC) | |||
::] is the exact point. ] (]) 01:03, 8 January 2006 (UTC) | |||
:]. ] 12:04, 7 January 2006 (UTC) | |||
== Finding Research Papers Online == | |||
I'm working on a project for science fair, and having some trouble tracking down the earlier research papers my sources cite. Google doesn't turn anything up, and I don't know many good search sites. How do professional scientist find papers? ] 18:37, 6 January 2006 (UTC) | |||
:Try rather than just Google. Also, if you leave near a University or College, just pop in the library and ask what journals you should search. Most major universities have free access to journals as long as you're on a campus computer. Good luck. --] 19:18, 6 January 2006 (UTC) | |||
::Thanks. That's a start, but it doesn't have the papers I'm looking for, probably because they're a bit obscure and outside the mainstream. I'm using my project to test Rupert Sheldrake's experiments with 'the sense of being stared at'. Any other suggestions? ] 20:28, 6 January 2006 (UTC) | |||
There is a psychology database similar to Medline and I think it includes ] research. It will be available through most college or university libraries. Ask a librarian for help. The best starting point is often a paper that you do have, because the librarian can see how it is catalogued in the database and can then help you look for older but similar papers. There are a couple of American universities that have supported "paranormal" research, usually in association with the psychology dept, often under the name of parapsychology. You could call one of those depts and ask a secretary if a faculty member would be willing to talk to you once for an "interview to help with a school science project" and you might get lucky enough to get a few minutes of time. If so, ask their opinion of the research in that area and ask for suggestions on how to most efficiently find published research on the topic. They may be able to suggest specific journals, search terms or even authors to look for. Good luck. ] 20:53, 6 January 2006 (UTC) | |||
You may also go directly to ]'s books. He may describe his research there, or at least point you to more information in the notes. However, you may have trouble since often these sorts of ] authors take great care to hide their research from scrutiny. --] 20:57, 6 January 2006 (UTC) | |||
If your campus is subscribed, you'll also be able to use and . ] (]) 23:35, 6 January 2006 (UTC) | |||
You should check if your school or local library (etc.) subscribes to databases such as or ; These sites contain digital copies of articles from various scientific journals, some of which may be found as a hard copy in your library. If you live in a state such as Pennsylvania that has something similar to the AcessPA system, you can get access to these databases free with a library card. --] 04:17, 7 January 2006 (UTC) | |||
== inventing a source of perpetual energy == | |||
How close are mankind from inventing a source of perpetual energy? | |||
: As close as we always were. As far as anyone knows, it's prohibited by the laws of physics. -- ] 18:41, 6 January 2006 (UTC) | |||
::With one exception. The universe is believed to obey the law of conservation of energy. Therefore, the universe has a universal constant supply of energy. It never loses or gains any. It is just perpetually there. --] <small><sup>]</sup></small> 19:27, 6 January 2006 (UTC) | |||
:::It's a closed system, though. Doesn't count. ] 06:13, 7 January 2006 (UTC) | |||
::Though that doesnt stop people from trying. ] shows the various attempts at creating one. ] <sub>] ]</sub> <small>• </small> <small>19:37, 6 January 2006 (UTC)</small> | |||
Of course, there are many energy sources that will last for billions of years, so are as good as perpetual, like hydro, solar, tidal, wave, wind, and geothermal energy. And while each chunk of fuel for a nuclear reactor may only last a few years, there is enough nuclear fuel to power the world virtually forever. Renewable sources, like wood, are also good forever if properly managed. Only fossil fuels will be "used up" someday soon, perhaps decades or centuries, that's not certain. ] 20:40, 6 January 2006 (UTC) | |||
:What if we were to figure out how to accelerate the transition from bio-waste into crude oil? Then, fossil fuels would also be a renewable energy source. We could keep pumping out those greenhouse gasses until we need a huge umbrella to cut down on solar heat. --] <small><sup>]</sup></small> 20:46, 6 January 2006 (UTC) | |||
::Well, you definitely can get methane from bacterial action on waste products, but I call this a "biofuel", not a "fossil fuel", to show it's source isn't "fossils". I don't know of any way to generate crude oil or coal from current waste products using bacteria, but I don't see why you would want to, as those forms both require refining and pollution controls while methane is ready to burn as is. ] 23:00, 6 January 2006 (UTC) | |||
It's a bit more abstract, but the questioner might like to read ] which states that energy is never created or destroyed, but is a constant. However, the ] states that the energy of an isolated system, while constant, is in a constant process of equalling out, meaning that the contained energy becomes more and more difficult to obtain in a general sense. --] 20:52, 6 January 2006 (UTC) | |||
:While energy can theoretically be changed into mass according to <math>E = mc^2</math>, this doesn't appear to happen anywhere on Earth. Energy seems to end up in the least usable form, which is heat. While usable energy can be generated from a heat differential, as in the case of geothermal energy, constant temperature heat is not a usable form of energy. ] 22:52, 6 January 2006 (UTC) | |||
:: Conversions from mass to energy do happen on Earth, but on a small scale; see ] for example - in nuclear fusion/fission. ] (]) 04:55, 7 January 2006 (UTC) | |||
:::Have to disagree. <math>E = mc^2</math> is true always and everywhere, in every energy transition. It tells the equivalence of mass and energy. What it doesn't tell you is how to do it, or even if there is a way to do it, just that IF you do it, this is what you get. If I burn a gram of gasoline I get 42 kilojoules. I compare the mass of the oxygen and gasoline that went in and the CO2 and H2O that came out, the numbers of atoms are exactly equal, but the products have a mass 4.6e-13 kg less than the reactants. 42 kJ = 4.6e-13 kg c^2 Just because 4.6e-13kg is too small for you to measure conveniently doesn't mean it isn't happening. -- ] 07:08, 7 January 2006 (UTC) | |||
::::I'm not quite sure what you mean. In combustion, the energy is not achieved through <math>E = mc^2</math>; it comes from the formation of ] in the ] and ]. <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 09:47, 7 January 2006 (UTC) | |||
:::::You say, in combustion the energy comes from the energy difference in the broken bonds and the reformed bonds, true, but it is still true that the rest masses of the reactants is greater than the rest masses of the products, and that mass difference is equal to the energy produced divided by c^2, regardless of the fact that this wasn't mentioned in chemistry class (because the mass is too small to measure). I encourage you to not let go of this question, ask around wikipedia, ask at Wikipedia_talk:WikiProject_Physics . I will explain more if asked. One thing to think about: In a nuclear reaction, (which I assume you accept as an E=mc^2 process), it's the same thing-- breaking of one bond and forming others (except it's bonds of the strong force, whereas in chemistry it's electromagnetic forces.) ] 12:57, 7 January 2006 (UTC) | |||
:::::: Yes, chemical bonds affect mass, if I recall correctly. For example, the quarks that make up atomic nuclei are pretty light: it's the ]s that carry the nuclear forces and result in the sheer mass of the nucleus. The more stable something is, the less energy it needs in its bonds to make it stable, and therefore it weighs lighter than its component parts in a less stable state. | |||
:If you don't mean 'eternal' too literally, the ]. Almost all other energy sources are derivatives of solar energy. Plants get their energy from the Sun and animals from the plants, so all biofuel is solar energy. Fossil fuels are dead plants. Wind is caused by uneven solar heating of the atmosphere. And hydro-energy comes from water evaporated by the Sun. The only exceptions I can think of are tidal energy (caused by planetary movement) and geothermal energy. And of course nuclear energy, but that's also the source of the Sun's energy. ] 12:14, 7 January 2006 (UTC) | |||
:: Well, nuclear energy's source is ultimately ] and ] that formed before the sun - their immense mass would have formed the heavy metals like uranium et al in their dying stages. Which of course, some became unstable, resulting in fissionable material. Fission isn't the source of the sun's energy, anyway, but it was the product of stars. Geothermal energy (also aided by nuclear decay) is also due to star formation somewhat. ] (]) 09:39, 8 January 2006 (UTC) | |||
:::As far as I know, there is research done with the ultimate purpose to make a power station operating on ]. Such a power station would give much more energy cheaper than any energy source we currently have available. It would also eliminate the problem of digging ] as it doesn't produce any. So, in some sense, it would be "a source of perpetual energy" for some values of perpatual. | |||
:::See ] and ] to see what state these researches are currently. – ] 15:08, 8 January 2006 (UTC) | |||
== mining the moon == | |||
When mining the moon, what useful minerals would i find? | |||
:According to ], you will find uranium, thorium, potassium, oxygen, silicon, magnesium, iron, titanium, calcium, aluminium and hydrogen. It doesn't state the quantities of each. --] <small><sup>]</sup></small> 20:12, 6 January 2006 (UTC) | |||
Also note that the cost of getting the minerals back to Earth would far exceed their value. ] 20:33, 6 January 2006 (UTC) | |||
::You're assuming that they actually want to get it down to the Earth though. If they have a mining operation in place, then with just a bit more money (What's a few billion more?) they could refine the minerals there and start a sustainable colony. ]|] 00:16, 7 January 2006 (UTC) | |||
:::Then they would need to get oxygen and water (not to mention a smelting plant) up to the colony on the moon, which would be just as prohibitively expensive. ] 00:45, 7 January 2006 (UTC) | |||
:Supposedly the most valuable thing (probably the only economically exportable good) to mine on the Moon is ].--] 05:09, 7 January 2006 (UTC) | |||
: Well, till we get a ], that is. ] (]) 20:27, 7 January 2006 (UTC) | |||
::Even so, the thing that makes mining practical on Earth is that geological (and sometimes biological) processes create local concentrations of useful materials that far exceed the global levels. The moon is geologically and biologically dead; as I understand it that moon rock is pretty much the same everywhere upon the moon. The only things worth mining (except for helium-3) might be any asteroids that have crashed into the moon - however, it might be easier in the future just to mine the asteroids in the asteroid belt directly. | |||
== Why does a pendulum work? == | |||
(no question) | |||
:A mass at one end the pendulum is pulled downard by gravity. It accelerates, but it redirected by a pivot point so that the momentum is going back upward. Gravity then pulls it down again. This repeats. A pendulum will eventually stop due to air resistance, friction in the rotation joint, and so on. By adding energy (like the big weights in a grandfather clock), you can keep a pendulum going. For more, see ]. --] <small><sup>]</sup></small> 20:44, 6 January 2006 (UTC) | |||
::The characteristic of a pendulum which makes it ideal for time-keeping is that the period (amount of time for it to complete one full swing) is constant, even as the magnitude (distance of the full swing) reduces due to air resistance and friction. Thus, a pendulum can be used to measure time until it comes to a complete stop. ] 22:45, 6 January 2006 (UTC) | |||
:::I've always had trouble buying that. It seems like, if it takes a certain amount of time to get, say, from out horizontally to pointing at the floor (multiply by 4 for period), it will take less time to get from lower than horizontal to the floor. --] 04:32, 7 January 2006 (UTC) | |||
::The Black Carrot is right to be suspicious; it's not actually quite true. (See the ] article for a look at the math, but it's not simple.) ''However, it is a very good approximation.'' If the pendulum starts out horizontally, its full weight is acting perpendicular to the string and this sets it in motion very fast. If it starts out near the bottom of the swing, its weight is almost parallel to the string, so the force on it is a lot less, and so is its speed. As it works out, the period is not exactly the same in the two cases, but it's very close to the same (especially for small angles). | |||
::Try it yourself. Take a ball of string and some tape. Unreel a few feet of string and tape the string to the ball where it comes off the ball. Tape the end of the string to the top of a doorframe. Set the ball to swinging just a couple of inches and time it for 10 swings back and forth. Then swing it up to a high angle, let it go, and time it again. I just did this and the times I got were between 19 and 20 seconds for 10 swings every time: my error in timing was probably larger than the difference between a long and a short swing. Of course, you will get different numbers according to how long you make the pendulum, but they will still agree with each other. (Because friction reduces the length of swing very fast with such a light pendulum, you might also try timing just 2 or 3 swings, but then the relative error of measurement is greater.) | |||
::In order for it to be accurately true that the period is fixed, the pendulum would have to follow a ]al path rather than a circular one: see ]. However, this turns out not to be useful for practical clockmaking, because the mechanism necessary to do that introduces too much friction. Instead, pendulum clocks were designed so that the drive mechanism would keep the angle of the swing relatively small, and as constant as possible. For the really accurate pendulum clocks that astronomers used before electronics superseded them, very long pendulums were were used (like say 10 feet), but they would swing a very short distance (just a few inches). | |||
::--Anonymous, 05:45 UTC, January 7, 2006 | |||
== Fooling credit score calculators == | |||
Is there any truth in ]'s claim that people can and do arrange their finances in bizarre ways in order to get an improved ]? ~~ ''']''' (]/]) 21:19, 6 January 2006 (UTC) | |||
:The rules seem to be sufficiently bizarre that such opportunities would present themselves. For example, a similarly bizarre policy by airlines of charging more for a one-way trip than the corresponding round-trip led to the technique of buying a round-trip ticket and only using the first half. ] 02:04, 7 January 2006 (UTC) | |||
== Neural Net Image Categorization == | |||
Most of the information I can find on neural nets is either very basic and general, or owned by a company and unavailable to outsiders. Where can I find information on the construction of neural nets that leans towards the conceptual (I only know Java, and don't have time to decipher other languages) and towards a large number of inputs, say on the order of millions? ] 21:46, 6 January 2006 (UTC) | |||
:I hope you realize such a neural net will require massive computing power to run at a reasonable speed. Also, what is the application ? Fluid dynamics ? ] 22:38, 6 January 2006 (UTC) | |||
::I do realize that it will take some work to apply it the way I'm hoping to, but I don't think it's impossible, and I'm certainly willing to try. There are worse ways to waste time. I especially hope to find ways, as you mention, to reduce the number of inputs to a more manageable level, but I don't think I can go below the tens of thousands. I'm trying to find a way to search the web for actual images. Google is great, but it only does keyword searches, and I would like to be able to do more than that. I'd like something that can sepearate a set of pictures into a Yes pile and a No pile accurately, such as Tree v Not Tree. Naturally, neural nets lept to mind. The structures I've found so far, however, don't lend themselves well to this. It's not that they can't be set to sort into the right piles, it's that you have to have the piles sorted in the first place for backpropagation to work, and then the setup is fairly rigid, not dealing well with cases outside its specific expertise, and not dealing too well with new cases being added. The ideal search, though, would involve a progressive narrowing down, and would anticipate related cases. I've come up with some things I haven't seen anyone write about that I think would help, but I think things would go a lot faster if I could find out what the people who've been working on this for years have thought of. Any suggestions are appreciated. ] 01:04, 7 January 2006 (UTC) | |||
:::Wow, that's quite an ambitious project. It sounds like the problems you are having are quite similar to those for voice recognition software. Specifically, the software can recognize the difference between "circumvent" and "circumnavigate" if programmed specifically for that task and adjusted for a given voice, but does a poor job of identifying a random word in a random voice. Also, such software needs to "learn" differences between similar words, which requires a great deal of user input to "train" it. I'm not even sure how you would define which picture is a tree and which is not, considering cases like a tree and a person, a tree branch, a tree sprout, a bush, a flower, etc. | |||
:::I have thought of a much less ambitious search method, which could search for copies of an exact picture, possibly with a different scale. This could compare number of pixels of each color and look for a given ratio, as well as looking for colors to be in the same relative position on the pic. Complications such as mirror images, pics trimmed differently, non-uniform scaling, and different color balances would require quite a bit of coding to solve, but does seem doable. I've often found a pic via a web search which is just what I want as far as subject, but is too small. I would like a way to search for a full sized copy of the pic, even if the page doesn't contain the keywords I used in the initial picture search. Is that a project which would interest you ? ] 01:31, 7 January 2006 (UTC) | |||
::'Fraid not. I would expect that to be one of the functions of what I'm going for, but it's not by itself what I want. Besides, how many duplicate pictures are there floating around? | |||
::You see the problem pretty clearly. What I think I have to go for is something that, in its structure, mimics the way we see things. Not that it mimics the brain, that would be a waste of time and I don't have the background anyway. Here's how I see it. The integer inputs(from 0-255 in Java), form a massively multidimensional graph, at each point of which the output(a real number, ideally either 0 or 1) can be represented by a color, either red or blue, with black or white at the boundaries. Makes a nice, manageable picture, except for the countless thousands of unimaginable axes. I think 'phase space' is the technical name for things like this. Now, the most basic form of neural net (sans sigmoid) will draw a beautiful diagonal gradient, which is useless to me. A single-layer network that makes use of the sigmoid function will have a straight line(plane, hyperplane, however many dimensions) between one clear area of blue and one clear area of red, at any slant and position you want. Good start. A two-layer one will draw as many of those as you want(with colors strengthening each other where they overlap), then shove all the outputs above a certain value to one color, and all the ones below it to another, and you have a shape on the graph, most any basic shape you want. Great. Add another layer, and you can have a bunch of shapes scattered across the graph, making it nice and flexible. Now, within those shapes the output will be 0(No), and beyond them it will be 1(Yes), or vice versa, and you can clearly see which pictures(which points) will be accepted and which will be rejected. Dandy. Except that that's not what the graph needs to look like to mimic the trends in the positions of actual images. It's hard to say exactly what it would look like, but I can get the concepts down and let the program take care of the rest. A few characteristics of the goal graph: area around image points, axis-parallel lines out from points, perpendicular rotation of shape about origin, image point shadows, threads between points, and quite a few others I haven't nailed down. I've solved the first one. The idea there is that, for any clear picture, there is some amount of error or static you can add to each pixel and still keep the picture essentially and recognizably what it is. On the graph, this means that there is a certain distance out you can go in any direction (direction=one color of one pixel in the image, or movement parallel to an axis) or combination of directions from the point that represents the clear image, and still be in essentially the same place. So, if that point is one color, the area around it must be as well, but not the area beyond that. It's possible to draw a nice simple square/box/hypercube around that area with a two-level bit of neural net, but with the number of sides needed(two per axis, >80000 axes), that box is prohibitively expensive in terms of how many nodes the net contains. I eventually worked out that if, instead of multiplying each input by a weight, then summing them and running them through the sigmoid, you add a bias to each input, square each result, then do all the rest, it draws a nice little resizable egg of whichever color around any point you want, with one layer, startlingly few nodes, and the added benefit that the list of the biases, laid out in a rectangle, is the clear picture you started with. So, that's where I'm coming from. Any suggestions? --] 03:59, 7 January 2006 (UTC) | |||
Wow, you've really given this a lot of thought, I'm impressed. I still think the number of calculations necessary to search all of Google for all pictures of trees would take way too long to be practical for a search at present, but perhaps it would be good to have the technology ready and waiting for when such computing capacity comes along. Of course, just like voice recognition, I doubt if once you have the program optimized to find trees if it will be any good at finding, say, birds, until you alter the program significantly, then the same for every other object it needs to recognize. | |||
I think some of the steps necessary for this to work might be valuable in and of themselves, however. I listed one above, another that interests me is "reverse pixelization". That is, I would like to be able to take a bitmap of a line and a circle, say, and create a vector representation of the geometric elements. One application would be to take a low res picture and generate a higher res pic of the same thing. Edge recognition is one aspect of any such program, that might be mentioned under ]. | |||
Well, as I say, I'm quite skeptical that you will get the full program to work anytime soon, but still think it is valuable for it's side benefits. And, if you can write and sell such a program, I'm sure it would be worth millions! ] 06:14, 7 January 2006 (UTC) | |||
:I have done this before. The approach outlined is feasible, but I think you need to make your project a bit more well defined before you will be able to achieve much. It seems that you know what you need to look for, but to really get your project up and running, I would suggest that you simplify the problem first before proceeding. Try this: take a 8 by 8 grid, and see if you can create a neural network which can distinguish the characters A, O and E written on the grid in a pixelated form. Also, for your tree recognition scheme, you may want to consider alternative measures of classification which do not rely on the network of sigmoidal functions. There are plenty of quality papers on complexity analysis, image processing which will be handy. You may also want to search for imaging journals which deal specifically with diagnosis and such - many image processing/recognition algorithms are well established and used in the medical field. --] 06:23, 7 January 2006 (UTC) | |||
::I definitely agree with starting with small, simple tasks and working your way up. Then again, this approach is recommended for any complex problem. ] 07:29, 7 January 2006 (UTC) | |||
::You might wanna look into Military Image Recognition Systems. ''--Jvh, 7 January 2006'' | |||
Neural nets are (amoungst other, equivilent descriptions) a statistics object. It might be worth persuing them from that angle, particularly if you're looking for rigourus descriptions. Also, with the resoulution upscaling, there's a lot of work on statistics applied to images that would be useful background reading. ] 22:42, 7 January 2006 (UTC) | |||
:::StuRat- I don't see why a well-designed system would take any more processing than what they already do, which is substantial in itself. Actually running something once through a net doesn't take much, and training it isn't that different from running something through it a few thousand times, so although I wouldn't be able to set it up on my laptop, I think the technology to do so is already sitting in Google's basement. Also, what I was talking about above is a system for describing the entire theoretical graph of all images in existence. Once I've got some idea of how that would work(like the example above), an idea of what mathematical and computational structure it would take to efficiently seperate all recognizable images from the near infinity of static surrounding them(and it is near infinity, try calculating the area of the graph), I'm pretty sure any net I base on it will work for all search terms. If you meant, once I'd done a search on trees it would be hard to move it to something else, that's no problem. I expect to start with a blank net each time I run a search anyway. I believe software is available that turns pictures into collections of vectors, if you're looking for it. My brother is into art, and his pad does that. As to the selling- I hope so, but I kind of like the idea of providing it for free. Also, according to the google searches I've been doing for hints on how to build nets, there are companies that are already marketing things a lot like this, and I'm not interested in competing for business. | |||
:::HappyCamper- What do you mean by 'done this before'? Which bit? Professionally, or as a hobby? And what about the outline is feasible? What's undefined about it? Is it important to use A, O and E specicifically, or any set of letters? Or all letters? Using specific drawings of them, or a range of styles? What papers or how-tos, specifically, would you recommend, and how do I get to them? | |||
:::Jvh- I wouldn't think they'd be sharing any of that information, but if you know how I can get it, I'd love to learn it. | |||
:::Syntax- ??? | |||
:::Also, six clarifying statements, which I think should be more common in long discussions: I would prefer to use just neural nets, I don't care about the complexities of optimization until I have something up and running, I (as a highschooler) don't have access to anything and don't have experience finding it, I'm pretty sure going below 150x150 pixels would radically change the structure of what I'm doing (how we recognize things begins to change at that level) which means anything that works at 8x8 has limited application except as general practice, I support general practice as a way of getting an intuitive grasp of a system and have been doing it for quite a while already, and I don't care about most of the things the papers I can get to are about, like facial recognition and 3D recognition, just making a reliable searching tool. | |||
:::One further question: does anyone know how to take a y=1/x graph and get a higher-dimensional version of it? I've decided I can combine two functions(area around image points, axis-parallel lines out from points) by taking each point that represents a clear image, and drawing curves asymptotically out in all axial directions. With three inputs(axes,dimensions), this would resemble six cones attached to the corners of an octahedron. With two inputs, this would resemble the graphs y=1/x and y=-1/x combined, meaning that if I made a two-input, two-level, three-node net out of the formulae O1= I1*12, O2= -I1*I2, and O3= O1+O2, or more accurately, O1= sig(B1+W1*((I1-B2)*(I2-B3))), O2= sig(B1-W1((I1-B2)*(I2-B3))), and O3= sig(-W3(O1+O2-.5)), where W means weight and B means bias, I would have what I wanted. This has proved difficult to extend to three inputs, and beyond. Another I need, beside the one above, is another way of taking 1/x to higher dimensions, three planes perpendicular to each other with curves asympotically approaching them, which would resemble a cube with all six corners carved out. | |||
:::I appreciate all the help. --] 23:06, 7 January 2006 (UTC) | |||
:::BTW, since this is getting pretty long, should we move it to my talk page? --] 23:13, 7 January 2006 (UTC) | |||
== can normal people get atum bombe? == | |||
using household stuff | |||
:No, not unless you keep enriched ] and ] in the cupboard next to the enriched flour. If so, you need to be extra careful when baking bread. ] 00:02, 7 January 2006 (UTC) | |||
::See ] ]|] 00:04, 7 January 2006 (UTC) | |||
=January 7= | |||
== Penis == | |||
Is it average for a 14 year old to have a 6 3/4 inch long penis and have 4 inches gurth? | |||
:That depends on if you are looking at a naked 14 year old girl at the time. ] 00:10, 7 January 2006 (UTC) | |||
:Studies on penis size are generally done on adults. So you probably will not find a study anywhere that gives averages for teenagers. Although, according to the ] article, you're off to a good start. ]|] 00:12, 7 January 2006 (UTC) | |||
:I second the above. I'm very familiar with the research on ], and there has never been any research on 14 year olds (for obvious reasons). That said, let me warn you that there has never been high-quality research done on human penis size, regardless of age - it's just not a practical undertaking. The best we can say, given the limits of our current research, is that the average American penis is between 5 and 7 inches. So you're doing fine. --] 05:18, 7 January 2006 (UTC) | |||
::You are not as familiar as you think you are. I put a reference to such a study on the talk page of that very article last year at someone's request; it is still there. ] 01:42, 8 January 2006 (UTC) | |||
::"Very familiar" ? As the measurer or the measuree ? LOL ] 07:14, 7 January 2006 (UTC) | |||
:::Alas, it's mostly an academic familiarity at this point. But I'm always seeking volunteers... --] 00:48, 8 January 2006 (UTC) | |||
:Wow, wikipedia really does have everything. Check out ]. It says, "the human penis is larger than that of the common chimpanzee, both proportional to body size and in absolute terms; one study has found that the average human penis is 5 inches (12.7 cm) in length when fully engorged with blood during arousal." No source though. --] 15:53, 7 January 2006 (UTC) | |||
exactly why would anyone like to know this subject??????? | |||
:Penis data envy ? ] 18:45, 7 January 2006 (UTC) | |||
::Who was that? ] 23:17, 7 January 2006 (UTC) | |||
== Ethanol as fuel == | |||
If the U.S. capitalizes on the ethanol gas, how much do you think gas would go down? How much would Americans be saving? | |||
:Cars can run up to about 25% ethanol with conventional engines, which would make some difference, but not too much, on a global scale, especially since 10% ethanol is already used in many areas. On the other hand, if car engines were retooled to use 99% ethanol (with 1% gasoline in a special tank for cold weather starting), then that would have quite a significant impact on world petroleum consumption and thus prices. Unfortunately, ethanol prices would likely skyrocket, at least until production caught up with demand. A mixture of technologies, like ethanol, diesel, electric, hydrogen fuel cell, and compressed natural gas, is likely to avoid the type of supply shocks we get when solely dependent on one type of fuel. For example, if a family owns a gasoline car and an ethanol car, they could switch which one they drive dependent on the relative prices of each. This ] would cause price stability, unlike the current inelastic price curve for gasoline, which causes price instability. Flexible fuel vehicles are thus ideal for managing prices. ] 00:16, 7 January 2006 (UTC) | |||
::Pay close attention to Brazil. They are in the middle of an attempted transition between petrol and ethanol. There are problems. Many of them appear to be solved. --] <small><sup>]</sup></small> 00:35, 7 January 2006 (UTC) | |||
:::However, Brazil has warmer weather than the US, so doesn't need the same alternate cold-weather gasoline starting tank. ] 00:38, 7 January 2006 (UTC) | |||
:::: Or, you could just provide better insulation for the tank. Gasoline would probably be cut down into a "backup" fuel source should the temperature dip below 13 degrees Celsius. The thing about ethanol is at least it's renewable: you can just keep on growing sugarcane or glucose-producing plants. I mean heck, someone could probably invent some new process to convert ] into ethanol. I guess the alcoholic beverage industry would probably boom with this, perhaps. (This reminds me that someone could possibly make a joke about ethanol as fuel, and "drunk" driving. Heh heh.) ] (]) 12:45, 7 January 2006 (UTC) | |||
:::::The problem isn't that ethanol freezes in the tank, but rather that when it evaporates in the carbuerator it lowers the temp too much, which causes moisture in the air to ice up and block the carb. After it has been running for a while, engine heat can be used to counter this tendency. But, using gasoline until the engine reaches operating temp is a good fix until then. ] 17:08, 7 January 2006 (UTC) | |||
:::::: I was thinking more about the ] (since ethanol freezes at negative 114 degrees Celsius and freezing isn't so much of a concern anyhow), but then you just reminded me what a great coolant ethanol actually is. ] (]) 20:35, 7 January 2006 (UTC) | |||
::::::::I wonder if the evaporative cooling of ethanol could be used to significantly cool the passenger compartment on hot days, prior to burning the ethanol in the engine. This would have the disadvantage that a broken heat exchanger could potentially spray ethanol into the passenger compartment (instead of the current antifreeze), so a more reliable heat exchanger design would be needed. Somehow I doubt if the cooling would be sufficient to replace A/C, but perhaps could help it out a bit. Alternatively, if used to cool the engine, perhaps a slightly smaller radiator would be needed. In the case of a tiny engine, perhaps air-cooling would be sufficient, like the old ]. This could improve fuel economy by eliminating the weight of a conventional liquid cooling system. ] 20:49, 7 January 2006 (UTC) | |||
:::::::Two notes: Brazil has some very cold areas both in the mountains and in the deep south. So, it does have a problem with starting in cold weather. The common solution is a mini-gasoline tank for cold weather starting. As for why ethanol causes a problem. The boiling point of gasoline is 40°C and ethanol is 60-80°C (I'm going from memory, I'm sure the articles here have the specific temp). So, in cold weather, ethanol doesn't vaporize as well and liquid doesn't like to burn. --] <small><sup>]</sup></small> 20:40, 7 January 2006 (UTC) | |||
::::::::I would state it slightly differently, that vaporizing ethanol takes more energy, in the form of heat, than gasoline, so the temp drops more when it is vaporized in the carb, thus causing the icing mentioned previously. ] 20:56, 7 January 2006 (UTC) | |||
== computer display screen readability == | |||
Hello, | |||
What makes some handheld computer and cell phone displays easier to read than others, both indoors and outside? If i was looking at a specification for different types of displays, what attributes contribute to readability the most? | |||
thank you so much for answering my question! | |||
--Linda | |||
:A backlight is very important, as is the text size, those should be in the specs. However, the contrast of the display relative to the background and the reflectivity and hardness of the glass or plastic bezel (and thus the resistance to scratches) is not something you are likely to see in the specs, so you should check each one out in person, if possible. One warning, don't fall for the stupid plastic film that "shows you" what it will look like when running, actually test it out. ] 00:26, 7 January 2006 (UTC) | |||
I always have trouble pertaining to the subject at hand. I can never read what is on my laptop while i'm on the bus. I would also say that text size is important, but you may also want to keep your files private from peering eyes. i've also found that my laptop has had a clearer and brighter screen ever since i have gotten that new screen protector that is on television. | |||
:The vibrations from the bus will make it even more difficult to read. Hmmm, that sounds like something that could be improved, maybe with goggles with LCD screens inside them. That way, the screen would move in synch with your eyes. ] 20:36, 7 January 2006 (UTC) | |||
== internet? problem == | |||
hey | |||
i am really having a hard time. can you give me a website to find background information on linear dynamics? i've been working on it for 10 hours and can't find anything about background stuff. grateful for all help. | |||
--sami | |||
:Hi Sami. Have you seen ] already? --] 03:55, 7 January 2006 (UTC) | |||
== pendullum == | |||
ON which principle does pendulum of clock work?I have a clock which has pendulum to show seconds measurement.It is not getting any energy from gear etc..but still it oscillates continuously.It is just placed on a pivot and after giving just slight push it gains its original motion with increased oscilations.How it doesn't loose energy by friction? | |||
:It does lose energy by friction, just very slowly. You will eventually need to push the pendulum again, unless it is one of those you also plug in. That type uses electricity to give the pendulum a little push with each swing. ] 07:11, 7 January 2006 (UTC) | |||
::It doesn't have to be electric. Wind-up pendulum clocks feed energy from the spring into the pendulum to keep it swinging. If you look closely, you will always find a mechanism that gives energy to the pendulum. --] 15:53, 7 January 2006 (UTC) | |||
:::There's a fun desk toy that's based around a pendulum that never stops, and climbs back up to full swing if you reduce its arc. It uses a magnet in the weight and an electromagnet in the base that turns rhythmically on and off, or north and south, or something like that, based on an electric timer on a chip. Every time the pendulum swings near the base, it's given a little magnetic kick to keep it going. Of course, that would be a pretty pointless pendulum to use for a clock, since you could just hook the clock straight up to the chip and cut out the middleman. Apparently, people do it anyway, if StuRat is right. --] 23:26, 7 January 2006 (UTC) | |||
::::Yes, they do it because people like clocks that look traditional, but don't require winding, lifting weights, etc. If you think about it, the old rotating dial clocks are all quite silly and old-fashioned now that we have easier to read digital clocks, but many people still prefer those, too. ] 09:00, 8 January 2006 (UTC) | |||
== VIRUS == | |||
How would I go about to make a virus from normal pathogens and atoms that you would find in many house holds? | |||
:There are machines that can assemble short DNA strands from the amino acids, but I don't think they are yet to the point where they could build even a simple retrovirus, which is basically just DNA. To build a virus at present, you would start from an existing virus and alter it to have the desired characteristics. ] 07:06, 7 January 2006 (UTC) | |||
:: It would be an interesting consequence of ] when we could start engineering retroviruses from scratch as biological weapons. Morbid, as well. ] (]) 13:50, 7 January 2006 (UTC) | |||
::Just to be pedantic, the '']'' are RNA viruses. That is, they have an RNA genome and require enzymes such as reverse transcriptase and integrase to convert their RNA to DNA and integrate it into the host cell genome, or use the host's transcription machinery to make viral proteins. The thing that eludes me is: Why don't retroviruses just start using host transciption to make viral proteins directly from their native RNA? Why not just bypass that whole reverse transcription thing? All I can think of is the extra transcription may allow for incresed genetic variability through spontaneous mutations (transcription errors), but I'm just guessing. Anyone else know? -- ] 00:57, 8 January 2006 (UTC) | |||
::: For one, not having its RNA converted to DNA would mean it couldn't incorporate into the host's genome and therefore wouldn't be replicated. --] (]) 16:17, 8 January 2006 (UTC) | |||
:If you want to do it with household equipments, not a laboratory, I guess it's much easier to build a computer virus. – ] 14:42, 8 January 2006 (UTC) | |||
== Eye sight question (dim light) == | |||
I know that reading and other nearwork may lead to myopia, but does darkness have anything to do with it? Say reading with a very little light, or using a computer late at night with no lights on? Thanks in advance. ] <sup>]</sup> 07:11, 7 January 2006 (UTC) | |||
:I think I answered a very similar question earlier. It is important to have the room light match to light on or from the object you are viewing. That is, dim the lights when reading a dim computer screen, and brighten them when reading a bright computer screen. ] 07:18, 7 January 2006 (UTC) | |||
:The short answer is yes, because in dim light you may inconsciously hold the book closer to your eyes or lean too close to the computer monitor. – ] 14:39, 8 January 2006 (UTC) | |||
== global warming == | |||
if the effects of global warming starts to increase which city/region would be most affected?.....thank you! {{unsigned|59.92.36.232}} | |||
It greatly depends on exactly what the patterns are and is very uncertain, and it depends on whether the warming is greater in some areas or others. Presumably, ] might start to suffer the effects first, or any low-lying areas. (], perhaps). ] is an interesting field. You might want to check out ]. | |||
:Which region is way too specific (let alone which city). Firstly, it is quite certain now that pumping all sorts of gases (most notably CO2) in the atmosphere will be a climatic effect, so there will be a ]. This will most likely be ], which means just that. There will be a warming that is global, meaning worldwide. At least, that is what is most likely to happen in the near future. But the climate is so complex that it's hard to say what will happen next. One possibility is that the Atlantic ], which warms North America and Europe will stop, which might trigger an ice age. Of course, if heat no longer gets transported to the North it will remain at the equator, meaning that cold regions get colder and hot regions get hotter. But, like I said, what exactly will happen is very uncertain. It's a global experiment. | |||
:But one thing that is very likely to happen is the rising of sea levels, which will indeed threaten Holland and other lowlying parts of the Netherlands. But also other lowlying countries, some of which are among the poorest on Earth, such as ] and the ], which don't have the means to protect themselves (we Dutch do, though even for us the expense might be crippling). Especially the latter get a lot of attention because the islands are so idyllic. Now isn't that a shame? Sure, but the population of 350 thousand is almost negligible compared to the 150 million of Bangladesh. Other densely populated lowlying areas can be found in the southern US, such as Florida. And New Orleans will get hit again unless a decent defence is put up this time. This won't hit as fast as a hurricane, though (a few decades maybe). But speaking of hurricanes. These get fed by hot sea water and global warming will of course also heat up the oceans. So there will be many more hurricanes. And one famous hurricane zone is the Caribbean. So again, the southern US. If you have any property there you'd better sell it now before other people start to wisen up too. ] 14:23, 7 January 2006 (UTC) | |||
::I vote for ]: http://www.cia.gov/cia/publications/factbook/geos/tl.html | |||
::Since it is only 3 meters above sea level, I'm amazed it doesn't get wiped out by big waves now. Global warming and rising sea levels are sure to do it in, though. Also note that some areas will benefit. ], for example, is covered by glaciation now. If those glaciers melt, it will be an enormous chunk of land available for development. ] and ] might also benefit, as most of their land masses are unusable arctic tundra at present. ] 17:54, 7 January 2006 (UTC) | |||
== computer rays == | |||
how do the rays from computers affect our eyes? | |||
:Look up, way up! (for Friendly Giant fans). It's the same as the general eyesight question. This must be a big thing on the homework front these days. --] 15:02, 7 January 2006 (UTC) | |||
well not exactly...i was just curious:) | |||
:What rays did you have in mind? Light rays enable us to see them, but see ] for a description of other sorts of rays. I think the item that will best answer you question is ]. --] 16:28, 7 January 2006 (UTC) | |||
== ancient indian text on aviation == | |||
ancient indian hermit & philosophist bharadwaja concieved ideas about flyinh machines which could carry people.this was about 5000 yrs ago (supposition).many of his own designs as in the text,was later found to be in resonanace with,latest aviation theories.as science advances ,how his ideas can be dealt with,on grounds of modern engineering principles? | |||
:Many ancients thought of flying. ] was known for his engineering drawings of flying machines, among other things. The ancient Greek myth of ] and ] also featured a flying machine. The idea that if birds can fly, then people should be able to fly if they just strap on a pair of wings is just wrong, though. People would need a completely different body design, with half our muscles in our arms, minimal legs, and lightweight, hole-filled bones, for that to work. The first concept needed for flying is the ], which provides lift by moving forward without flapping the wings. The next concept is that ], or some other means of control (like a ]) are needed. These things could have been discovered by the ancients, and could get you a decent glider using, say, a balsa wood frame with silk fabric. However, the development of internal combustion engines was necessary to make machines capable of true flight. ] 17:30, 7 January 2006 (UTC) | |||
== misleading websites == | |||
I keep coming across websites that are not what their name suggests they are, e.g. they might link to a competitor's website (like www.national-express.co.uk links to a rail site instead of a coach site), or all the useful-looking links from a fansite turn out to link to commercial sites or attempt to upload files to my computer. Is there a name for such sites? I am trying to remove them from Misplaced Pages but would like to know how to describe them. They don't necessarily seem to be ]. --] 16:21, 7 January 2006 (UTC) | |||
:Yes, and I've also noticed misspellings of common websites, like http://www.gookle.com/, are packed with ads. The level of deception online is quite amazing, mainly due to a lack of laws and law enforcement actions. ] 17:15, 7 January 2006 (UTC) | |||
::A you suggesting there needs to be more control of the Internet? By who? The problem is not a lack of laws, it is people who are willfully ignorant. If people don't make the effort to educate themselves about how it works and don't learn to do a little bit of critical thinking they are going to be flimflammed regardless of how many laws get passed. I'm not talking about fraud--that is and should be illegal--I'm advising a bit of caution and '']''.--]] 07:13, 8 January 2006 (UTC) | |||
:The terms you are looking for are ] and ]. ] ] 18:18, 7 January 2006 (UTC) | |||
==Adams apple== | |||
What signifince do larger Adam's apples have? What causes protuding adams apples, and what does this mean in terms of the body? | |||
:A protruding Adam's Apple could be a sign of an enlarged thyroid gland. My brother had that and had thyroid cancer. So, go to a doctor and have it checked out. ] 20:38, 7 January 2006 (UTC) | |||
:The Adam's Apple is the protrusion of the ]s of the ]. The larynx is essentially a semi-rigid box that facilitates ] from the ]s. The significance is that its owner may posess a deep voice. There are several factors contributing to the normal variation of degree of protrusion, including, but not limited to: | |||
:#Gender (male>female) | |||
:#Developmental stage (prepubescent<adult) | |||
:#Body fat (fat neck hides it) | |||
:#Individual anatomic variation | |||
:There are also pathologic reasons for enlargement of the Adam's Apple, however, these usually result in an observable increase in size of the structure over time, that cannot be readily explained by normal causes, such as onset of puberty. Thyroid cancer can cause swellings in the neck, and these usually occur first at the front of the base of the neck, below the Adam's Apple. Thyroid cancers are also (usually) not as firm to the touch as the Adam's Apple is, and are often asymetric in appearance. Any concern about cancer is best addressed by your doctor - if you have any new swelling or mass or spot or whatever, anywhere, get it checked out. Far better to be told its normal than sit on something deadly. --] 01:25, 8 January 2006 (UTC) | |||
== scientific method == | |||
i am a student doing some studying for midterms, and i am desperate to find the answer to this question: | |||
Knowledge and application of the scientific method: | |||
*question | |||
*hypothesis | |||
*design/perform experiment | |||
*collection/ analysis of data | |||
*conclusion | |||
*communication | |||
i'm only in the 6th grade and i need some help. if you end up spelling something wrong i probably will correct you because i am the number one speller in my county. thank you! sorry if i sounded like i was showing off. | |||
from, | |||
#1speller | |||
*You don't actually have a question there. The sure tip-off is the lack of a question mark. Also, you might want to extend your spelling skills to the proper capitalization of words.] 18:42, 7 January 2006 (UTC) | |||
well typically i'd need to know the application of the scientific method to those, hey i'm only 11. | |||
:*I don't think 11 is too young to capitalize. In some cases, I don't even think it's too young for capital punishment. ] 02:25, 8 January 2006 (UTC) | |||
*Hi there chum! I've formatted your post a little better so hopefully it will be more readable. What you have described is generally what is taught as "the scientific method". We have an article on the ] which might be somewhat useful, but it is probably more complicated than what you can use. The basic point of the scientific method is to ask questions about ''nature'' which can be checked to be right or wrong. What your midterms are probably requiring you to know is how each of those steps participate in doing this. Try looking at our article and see if it makes sense to you, if not maybe others can help out. --] 19:32, 7 January 2006 (UTC) | |||
::Wow, whoever wrote ] really has a thing for elevated vocabulary. ] 23:38, 7 January 2006 (UTC) | |||
:::I hate when people write in unnecessarily complex terms. Please feel free to simplify it, to make it readable by a general audience. ] 01:05, 8 January 2006 (UTC) | |||
::::I agree. I mentioned it on the ] so maybe they'll attempt to rewrite it. To #1speller you really need to work on punctuation. No capitals at all looks quite lazy. I assume you don't wish to give this impression? ] ] 01:10, 8 January 2006 (UTC) | |||
*Good luck: There is a small entry on the scientific method in our , which is designed to be more easy to understand than our other entry. Perhaps it will be useful. --] 00:36, 8 January 2006 (UTC) | |||
:Your what? ] 02:05, 8 January 2006 (UTC) | |||
::Argg, I tried to link to the simple Misplaced Pages but I did it incorrectly, obviously. Anyway I fixed it now. --] 17:18, 8 January 2006 (UTC) | |||
Holy cow! That article is unreadable. It's way beyond my assumed audience of 'National Geographic' (or grades 10-12). How could one tackle this? --] 15:15, 8 January 2006 (UTC) | |||
:ps. I take this all back. I read the discussion, and I wouldn't touch it with a 10' monotone soliloquy. --] 15:30, 8 January 2006 (UTC) | |||
Is it possible to provide a link from the main Scientific Method page to the simple one? ] 19:57, 8 January 2006 (UTC) | |||
== verizon == | |||
:What do you want to know about it ? ] 03:35, 8 January 2006 (UTC) | |||
== Router for large network == | |||
Is there a limit to how many computers a router can handle? Should a standard 4-port router such as the be enough to serve IP addresses to a network of 30 or more computers via various switches, hubs and wireless access points? If not, what kind of a router is needed? Thank you, ] 19:06, 7 January 2006 (UTC) | |||
:Routers don't specifically "serve IP addresses" (unless the router is also doing something else, or unless this is what you are meaning by NAT). What is the router actually doing in your network? ] 19:08, 7 January 2006 (UTC) | |||
Jebums, that was fast. My router serves as a gateway between the LAN and the cable modem, and also as the network's DHCP server, hence the serving of IP addresses. --] 19:17, 7 January 2006 (UTC) | |||
:Well, there are two things to worry about: limitations – for example I have seen a firewall that will only allow 50 IP addresses; and performance. From a performance point of view, cable internet connections are incredibly slow, compared to the potential network speed, so even the cheapest router isn't likely to be fazed. Routers are able to be used to connect two full speed wired networks. Limits you'd need to check the documentation for your specific router. It also needs a sufficient supply of addresses for DHCP of course, but that's under your control. DHCP itself puts a trivial load on its server. ] 19:31, 7 January 2006 (UTC) | |||
Here's why I wonder: When I asked the Comcast guy if the new service would be sufficient to support 30 computers, he said that would be fine, all I'd need is a router that can handle all those computers. I can't find anything in the router's documentation about it. Searching for answers on the internet, I found that says, "On an eight-port wireless router, you may only use a total of eight connections, not eight wireless and eight wired." However, now I've found that seems to contradict the first one. By the way, when you say cable internet is incredibly slow, do you mean relative to ethernet networks (obvious) or relative to DSL? --] 19:57, 7 January 2006 (UTC) | |||
:Just relative to a 100 mbps wired ethernet. Is this router also a wireless access point? ] 20:29, 7 January 2006 (UTC) | |||
No, we have a high-powered antenna (AirPoint PRO Outdoor) attached via ethernet. Why? --] 20:40, 7 January 2006 (UTC) | |||
:I think we are talking pure dedicated routers here without wireless or multiple ports. I have an old Netgear RT311 and it chokes with the multiple IP connections that gtk-gnutella generates. I have to knock that value way down. I can't find specs on general router processor speed, and #IP connections, but I am sure this is important for 30 computer connections. --] 23:04, 7 January 2006 (UTC) | |||
== Do hippos have enemies? == | |||
Someone inserted the following passage: | |||
* The only animal of any danger to the hippo is the rhino, which is a lethal enemy to our friend the ]. | |||
Don't worry, it got of course deleted. But the question remains: Do hippos have enemies? ] 19:11, 7 January 2006 (UTC) | |||
*I can think of ]... (I don't think full-grown hippos have a natural enemies, but I don't know for sure) --] 19:21, 7 January 2006 (UTC) | |||
:: Yes, sadly there are two types of human enemies: ]s and ] according to ]. ] 19:31, 7 January 2006 (UTC) | |||
::: yeah, human beings, in short. Even those who don't directly kill them but indirectly destroy their habitat by wasteful consumption. ] (]) 21:08, 7 January 2006 (UTC) | |||
::::Anything other than people? ] 02:07, 8 January 2006 (UTC) | |||
:::::Crocodiles. There was a documentary on television last month about hippos. It showed a young hippo swimming around and then killed and eaten by a croc. As for the human/hippo relation, the hippo kills more humans in Africa each year than any animal other than other humans. --] <small><sup>]</sup></small> 02:25, 8 January 2006 (UTC) | |||
::::::I'm sure from the hippos' point of view we've got it coming to us.--]] 06:41, 8 January 2006 (UTC) | |||
== PS3 GPU RSX == | |||
There is a rumor going on on the internet that say that the PS3's GPU codenamed RSX developed by Sony and Nvidia is less powerful then Nvidia's upcoming GEFORCE 7800 GTX? Is this true? If it is true then that would mean that the PS3's graphics are going to be obselete compared to computers that would use the 7800GTX. | |||
The "RSX" that the PS3 uses is basically a copy of the 7800GTX except the "RSX" may be a little faster. As with all consoles and the PS3 is no exception, every console is obsolete as soon as they are released because high end gaming computers catch up and eventually surpass console hardware technology in a couple of months. | |||
:Having said that, console graphics have an advantage in that programmers learn to get the most out of the hardware over time, so console graphics (I think) do improve slightly despite the actual hardware being the same. --] 20:27, 7 January 2006 (UTC) | |||
::To say the same thing with different words, PC game developers must cater for the widest range of videocards, cpu and ram configurations, so any features that are are harder to implement and less likely to work on common hardware won't make it into the product. But I think it's plain to see the relationship between graphics and gameplay is now not 1:1 at all, it is necessary to pump exponentionally(?) more effort into graphics capability to increase the enjoyability levels linearly. ] 03:20, 8 January 2006 (UTC) | |||
== What causes the magnetic dipole moment of an atom? == | |||
I've read our articles on ] and ], which say that ]s are caused by the motion of charges, but then add that electrons in atoms don't actually move. What electrons actually do in atoms, apparently, is (i) to sit around in ]s and (ii) to possess a property called ], but they neither orbit nor spin in the mechanical sense. How does this mysterious behaviour create a magnetic dipole? I'd like to add the answer to this question to our articles, even if it's just that "nobody knows". --] 20:49, 7 January 2006 (UTC) | |||
:Well, quantum spin isn't exactly like mechanical rotation, but they do share many properties. I think every particle with both charge and spin has a magnetic moment, including the proton and the electron. Even the neutron has a magnetic moment, because it is made of spinning, charged quarks. —] 22:46, 7 January 2006 (UTC) | |||
:There is two direct contributions to an atomic magnetic moment: Electron spin and spin-orbit coupling. Electron spin is the biggest contribution, and basically comes from the fact that each electron has a magnetic moment, and therefore the magnetic moment of an atom is equal to the difference between the number of spin up and spin down electrons. If you like, each electron is a tiny dipole, and an atom gets the net sum of those. | |||
:Spin orbit coupling is more involved, and arises from relativity - Diracs equations describe this. It's not possible to give a non-relativistic analogy directly. The 'spin-only' approximation is close enough for many purposes, however. ] 23:07, 7 January 2006 (UTC) | |||
Thanks. I'll revisit the magnetism-related articles. There were some contradictory statements, about electrons moving/not moving, that I was unhappy with. By the way, can you give me an idea of the accuracy of the 'spin-only' approximation? A few per cent, or a few parts per million? --] 12:36, 8 January 2006 (UTC) | |||
:It's around 10% out. That is, however, enough to clearly identify the net spin of a atom. See for some example numbers. Note that, as that page is aimed for chemists, it's talking in terms of moles of ions, not individual atoms. Also, on the electrons moving / not moving thing - note that there are multiple equivilent ways of describing the same phenomena. You can describe electrons as moving but not emmiting EM radiation, or as static but generating a magnetic moment, and you ends up with the same sort of descriptions; both of these are approximations to the real situation. ] 14:47, 8 January 2006 (UTC) | |||
I was thinking about differences in ] between atoms, but then I realise that is the cause of dipole momenets in molecules, not atoms. But I'd thought I mention it anyway. ] (]) 15:43, 8 January 2006 (UTC) | |||
=January 8= | |||
== Circulatory System == | |||
'''== How long does it take for a drop of blood to travel through your entire body? ==''' | |||
Could a link please by supplied to a reliable source... thanks --] 01:18, 8 January 2006 (UTC) | |||
:Well, you're going to have a hard time finding a straight answer, because blood doesn't travel in drops, and some paths back to the heart are short while others are very long (going through mazes of ]). —] 02:41, 8 January 2006 (UTC) | |||
:Keenan's right. Any given drop of blood will travel along random pathways throughout the circulatory system, and during that journey the fluid and cellular components of blood are continually exchanged. So the answer to your question is : "it depends". | |||
:Of more use to you may be that there is a way of averaging this, which doctors use, based on a person's ]. The link, & its links, give some reasonably detailed information, but in short: | |||
* Average ] =70 beats/minute, average ] (amount pumped in a single beat from the left ventricle) = 70mL. | |||
* Cardiac output = Heart rate x stroke volume, so cardiac output = ~4.9L/min. <s>(A gallon is about 4.5L if you're in the US & don't do metric).</s> -- Clearly I don't do antiquated and unnecessarily complex measurement systems. A gallon is 3.785L according to ]. --] 08:37, 8 January 2006 (UTC) | |||
* Average blood volume is about 8% bodyweight in kg. So for the "average" 70kg man, blood volume is about 5.6L. | |||
* So, the heart pumps the equivalent of total blood volume about every 68 seconds. | |||
: Any human physiology text can give you these details. To check my numbers, I used Guyton & Hall (1996), Textbook of Physiology (9th Ed). Hope that helps. ] 05:47, 8 January 2006 (UTC) | |||
== how does an oil derrick function == | |||
Have you looked at ]? ] 06:38, 8 January 2006 (UTC) | |||
== When was the first offshore oil drilling rig in the US built? == | |||
: in 1894, "Summerland, the first offshore oil field to be developed in the United States, had been discovered near Santa Barbara, California." In 1903, a "wooden pier that rested on stilt-like piles stretched out into the ocean at Summerland and a number of rigs drilled from it." - ] 03:49, 8 January 2006 (UTC) | |||
== Black Holes == | |||
I am a tad confused about the concept of, what is described in our article on ] as "narrow jets of particles at relativistic speeds." I was wondering how this works, because I was under the impression that the gravity in a black hole was strong enough such that no matter can escape its gravitational pull. So how is it possible that the black hole can "eject" particles outwards and away from it's über strong gravity? Thank you. - ] 03:42, 8 January 2006 (UTC) | |||
:The particles are not coming from inside the black hole, but from the ] of matter around it. The particles can still escape from the black hole's gravity as long as they have not passed the ]. —] 06:03, 8 January 2006 (UTC) | |||
:: In fact, this allow ]s that form at the edge of the event horizon but not past it, to separate from each other before they annihilate, then being ejected, resulting in ]. ] (]) 09:50, 8 January 2006 (UTC) | |||
:Thanks for the responses. - ] 19:20, 8 January 2006 (UTC) | |||
== Jews == | |||
Are Jews (the people group, not the religion) smarter as a race? Because there seems to be alot of famous Jewish people, for exanple 22% percebt of Nobel Prize winners are Jews. So, do the Jews have a genetic or ethnic advantage in mental intellengence? | |||
:I don't think so, but i do think that Jewish people are extreeeemely cool :D --] 04:00, 8 January 2006 (UTC) | |||
:Misplaced Pages has an article on ]. - ] 04:34, 8 January 2006 (UTC) | |||
::The typical explanation is that Jewish culture values education and study more than other cultures. ] 07:25, 8 January 2006 (UTC) | |||
== Speed of light == | |||
If nothing can reach the speed of light, why can light or electrons reach it? | |||
:Nothing can ''exceed'' the speed of light, and from what I gather, electrons cannot ''reach'' the speed of light anyway. - ] 04:25, 8 January 2006 (UTC) | |||
:And light, by definition, travels at the speed of light in a vacuum. - ] 04:30, 8 January 2006 (UTC) | |||
:: If the light is ''not'' in a ], it gets slowed down and other things (such as electrons) can travel faster than it. --]]] 04:37, 8 January 2006 (UTC) | |||
::(edit conflict) It is not exactly true that nothing can reach the speed of light. To be more precise, although still not very precise, it is, according to current physics, impossible to accelerate matter up to or beyond the speed of light; that is, the speed of electromagnetic radiation in a vacuum. It is theoretically possible to have particles that have an ] rest mass and so ''always'' travel faster than light (]s), and I believe that ]s (the particle associated with light), being massless, must travel at the "speed of light". Also note that the relevant limit is ''c'', the speed of light ''in a vacuum''. Electrons can be accelerated to very close to ''c''. If they are traveling in something like glass or water, they can actually travel faster than light can travel in that medium, without ever exceeding ''c''. This produces ], approximately similar to a sonic boom. This explanation is oversimplified and others more knowledgeable than I should feel free to correct me. — ] ] 04:45, 8 January 2006 (UTC) | |||
:It's a common misconception that electrons go the speed of light in a wire. The electric current as a whole does go the speed of light, but the individual electrons don't go anywhere near that speed. The average speed of the electrons (the ]) is about a millimeter per second, depending on the thickness of the wire and other factors. A good analogy is a water faucet. When you turn the faucet on, water instantly comes out, but that doesn't mean it came all the way from the water tower in that amount of time. The water was waiting in the pipe. When you turn on a light switch, the electrons going through the light bulb were already there waiting in the wires. They just get "pushed out" by the electrons coming from the power plant, so to speak. —] 06:14, 8 January 2006 (UTC) | |||
:: And to further clarify to other readers, the speed of light of an electric current comes in if say, that power plant was two light seconds away (and ignoring what would be massive amount of electric resistance in the wire, let's just assume it's a mile thick :p), then it would take two seconds for the electrons in the filament of the light bulb to start moving the moment the switch is flicked. The electrons from the power station electrons 600,000 km away (roughly) will take two seconds to push all the electrons between them and the electrons in the filament in order to get the electrons in the filament going. This is a necessary consequence, because otherwise you could transmit ] (which represents order, something covered by the laws of ] faster than ''c''. ] (]) 09:58, 8 January 2006 (UTC) | |||
== is breaking the sound barrier as easy as snapping your fingers? == | |||
is breaking the sound barrier as easy as snapping your fingers? | |||
if you snap your fingers, is the resulting sound due to breaking the sound barrier, the subsequent impact, or simply the loss of force due to friction? | |||
:The sound comes from your fingertip hitting the base of your thumb. No ]s involved. —] <small>(])</small> 05:58, 8 January 2006 (UTC) | |||
:::I agree there's no sonic boom, however I think your statement isn't completely true. When you click your fingers, what causes the sound is that you lean your ring finger to the base of your thumb and you snap your middle finger to it. If you do not put your ring finger there, and snap your middle finger that way, you don't get a click, only a much weaker thump sound, because the pad at base of the thumb is much softer than your ring finger which has a bone close to the surface. (It it, however, possible to use different fingers instead of the middle and ring finger and still produce the clicking sound, but this combination is the best. You can even use a finger of your other hand instead of your ring finger.) I am not sure, but I think that the vedge-shaped gap formed between the ring finger and base of the thumb might also take part in producing the sound. | |||
:::For a sonic boom, you need an object moving with at least 300 m/s, and I don't suppose your finger would move with more than 0.5 m/s in a simple finger clicking. – ] 14:09, 8 January 2006 (UTC) | |||
::Snapping a whip is the easiest way to create a sonic boom. ] 07:09, 8 January 2006 (UTC) | |||
== Light in orbit == | |||
Given that light can be pulled inwards by gravity(by something as massive as a black hole), and that it has a reliable velocity, and that those are the only two characteristics necessary for something to move into orbit around a celestial body, it there light endlessly orbiting black holes? Is there a distance out from a black hole at which, if you weren't pulled apart by the gravity or something like that, you would see a ring of light all around you? Because that would be pretty cool. It'd be fun to imagine something so absolutely black(except radiation) being encased by a sphere of pure light. If so, would that be near the event horizon? One problem I've found with this is that black holes are constantly expanding, so the orbital distance would be increasing as well, meaning any light currently in perfect orbit would eventually get pulled in, but maybe that's not a problem. --] 06:52, 8 January 2006 (UTC) | |||
:I believe the orbital distance would be the ]. You are right that those orbits would be unstable due to the increasing size of the black hole. Therefore, I would expect you would find some, but not much, light in orbit at any given time. ] 07:13, 8 January 2006 (UTC) | |||
::Yes, as I understand it, the event horizon would be defined by the distance at which light almost escapes but not quite, and would therefore presumably contain some light "orbiting" the black hole. However, it would not appear as a sphere of light as you describe. If you are at a distance from the black hole, the light is on the event horizon and therefore unable to reach your eyes. Remember, for you to see a photon, it must reach your eyes. It doesn't shine in all directions. If it's orbiting, it will be invisible unless it breaks free somehow and travels toward you instead. Note that you may be able to see black-hole–related phenomena, including light trapped near the event horizon, but orbiting light shouldn't be one of them, as far as I can tell. — ] ] 07:36, 8 January 2006 (UTC) | |||
:::If a black hole had a constant mass and a photon would be in orbit at that distance (I'll assume that that's the event horizon) then it would stay there, I presume. But how would it get there? As soon as it's within the event horizon it's lost. So it has to approach from the outside. The only way for it to do that would be to spiral in. But because it has to stabilise at exactly that distance that would only happen after an infinite amount of time. So I imagine there might be a halo of spiralling (not orbiting) photons just outside the event horizon, but none exactly ''at'' the event horizon. But even if the black hole were to expand a bit, then I don't think any photons would fall into place in that orbit, but that's just gut feeling. ] 10:09, 8 January 2006 (UTC) | |||
::::The photons could also come in along a tangent to the event horizon, or what works out as a tangent, taking into account the bending of the ray, as it approaches the black hole. Also note that objects falling into the black hole would tend to dislodge photons from orbit as they pass the event horizon. ] 11:08, 8 January 2006 (UTC) | |||
:I am not an expert from this, but I'll try to give some answers. You can find some interesting discussion on these effects on . | |||
:From what I understand, there is indeed such a sphere where light could circle endlessly, and this can happen not only for black holes but other very dense stars that are not dense enough to form a blackhole but aren't far from it. However, this light orbit is not stable: light circling on that sphere will eventually either fall in or escape outwards, so there will be no glowing "sphere of pure light". However, this sphere can cause odd visual effects, namely you can see distorted images of the sky around that are from photons that have circled near this sphere a few times. | |||
:Also I think this sphere is not the event horizon, but it is outside of it, but I am not sure of this (I think I don't even understand what the event horizon is exactly). – ] 13:16, 8 January 2006 (UTC) | |||
::You're correct. At the distance where light moving in a circle around the hole stays in orbit, light moving away from the black hole can still escape. If you could stand there, the black hole would appear to cover exactly half of the sky. At the event horizon, on the other hand, no light can escape. A hypothetical observer standing motionless at the event horizon would see the black hole cover the ''entire'' sky, with the possible exception of a single point of light straight above. —] <small>(])</small> 16:06, 8 January 2006 (UTC) | |||
:::(Well, that is, if a) it was possible to stay motionless at the event horizon, and b) we could ignore all this weird stuff about space and time being relative. But you get the idea.) —] <small>(])</small> 16:11, 8 January 2006 (UTC) | |||
::::What I don't understand is that the page I linked above claims that this sphere has a radius that's a constant multiply of the radius of the event horizon. But it also claims that dense neutron stars that aren't black holes could also have such a sphere. Don't these two claims contradict? – ] 21:18, 8 January 2006 (UTC) | |||
== Security vulnerability == | |||
In a typical software company (like Microsoft, Apple, Sun Microsystems, etc.), did the programmer(s) responsible for a security vulnerability (wrote the code that caused the vulnerability, that is) got punished or disciplined in some way? --] 07:28, 8 January 2006 (UTC) | |||
:There is an assumption in your question that all vulnerabilities are due to either malicious or unintentional errors by programmers. On the contrary, I think many vulnerabilities are inherent in the high-level design of a program. If programmers are asked to make an operating system that will execute programs on your computer which are downloaded off the internet, without your permission, this is an inherent vulnerability. Think of it as if you left your house key under the door mat in case somebody needed access to your house, like a firefighter. Obviously, anyone can find the key and gain access. You can add a supplemental security system that denies access to people it regonizes as bad, but that still lets lots of bad people in which aren't recognized. Similarly, a virus-check program can only stop those viruses it recognizes. A more practical approach to security would be to ban all access to your computer to everyone you haven't specifically authorized to have access. ] 08:23, 8 January 2006 (UTC) | |||
::Uh, I think I should be more specific. Actually, what I mean is security vulnerability caused by programming mistakes (e.g., incorrect authentication routines, unchecked buffer, etc.), not security risks in general. To be more specific, do someone in the company get punished for making mistakes in program code that turned into a security vulnerability? ] 08:55, 8 January 2006 (UTC) | |||
:::As a general rule, there are computer companies that flood us with vulnerabilities that should never have been there in the first place, and there are computer companies you never hear in the news about vulnerabilities because we go 10 years or more between them having a flaw (] for example). This is because the latter have systems to catch vulnerabilities in development before the product goes to the customers, This requires extensive testing of the software, which adds to the cost of the product. Because the market demands cheapest possible products, the market gets what it pays for, products that have not been properly tested to make sure they have no security vulnerabilities. If the programmers that did the poor programming are no longer working at the place where they did the bad code, it is unlikely that the company will go after them, if it even knows who done it. The industry, that has won the market share war, has a dismal record of security standards, compared to in computer historical standards where quality was mission critical. ]|] 09:10, 8 January 2006 (UTC) | |||
::::Also, note that when you open any software package you agree that the company will not be held responsible for any damage caused to you or your business even as a direct result of defects in their product. If car makers could be assured that they would not be sued, the car defect rate would be as high as the software defect rate. The lack of responsibility leads to, well, irresponsibility. ] 09:39, 8 January 2006 (UTC) | |||
:In any company, employees can make mistakes, sometimes very expensive or embarrassing ones. How companies deal with this is rightly a secret: between themselves and the employee, and generally dealt with case by case. Some companies punish those who make mistakes, but others have learned that this only encourages ingenuity in hiding them until they become more serious. In some companies, corporate embarrassment is severely punished, by sacking a senior person in charge. Software companies generally learn that if you sack every programmer who makes a mistake, then you won't have any programmers. ] 11:14, 8 January 2006 (UTC) | |||
::As a computer programmer myself, I can tell you most of us would very much want to thouroughly test and fix our software, but management budgets and schedules don't allow this. So, blaming the programmers is a bit like blaming a homebuilder who you told to build you a mansion in a week for a thousand dollars. ] 11:50, 8 January 2006 (UTC) | |||
== How do solar sails work ? == | |||
I understand that light hits the sail and is reflected back off the sail. My question is how masslesss photons can exert any pressure on the sail. When I use F = ma to calculate the force, even if the acceleration is from the speed of light in one direction to the speed of light in the reverse direction, I still get a force of zero for a massless particle. What am I missing ? | |||
There is a device with a similar function, a "fan" inside an evacuated glass container with one side of each blade painted black and the other white. The difference in reflectivity causes the fan to rotate when in the light. This might be a purer example of the effect I'm asking about, since solar sails will also catch particles in the solar wind which do have mass. ] 08:03, 8 January 2006 (UTC) | |||
: The "fan" (]) seems to work on something completely different from the solar sail. The light mill needs gas particles to work (i.e. a partial vacuum, not a total vacuum). --]]] 08:27, 8 January 2006 (UTC) | |||
:: According to ], the pressure comes from ]. Have a look at that article; it explains how it works. ] (]) 08:39, 8 January 2006 (UTC) | |||
I've read that article, and it really didn't explain it, just gave a formula to find the strength: | |||
:It may be shown by electromagnetic theory, by ], or by ], making no assumptions as to the nature of the radiation, that the pressure against a surface exposed in a space traversed by radiation uniformly in all directions is equal to 1/3 the total radiant energy per unit volume within that space<!--- e.g. http://scienceworld.wolfram.com/physics/RadiationPressure.html --->. | |||
:For ] radiation, in ] with the exposed surface, the energy density is, in accordance with the ], equal to ''σT''<sup>4</sup>/3''c''; in which ''σ'' is the ], ''c'' is the ], and ''T'' is the absolute ] of the space. One third of this energy is equal to 6.305×10<sup>−17</sup>''T''<sup>4</sup> J/m<sup>3</sup>K<sup>4</sup>, which is therefore equal to the pressure in ]s. | |||
I'm really looking for an intuitive explanation. I suppose if it involves ] or something else inherently non-intuitive, I will just have to accept it without understanding it. ] 09:09, 8 January 2006 (UTC) | |||
]. It's not really the same context as a solar sail, but it ends up ejecting electrons (which bear mass) - so it is ultimately the same principle. F=ma is an incomplete formula: it is incompatible with quantum mechanics. I myself am searching for a better formula (I have a hunch that one exists) that will account for the force a photon exerts on a mass, but also compatible with classical mechanical situations. (ie. breaking down the "mass" into different components). ] (]) 10:02, 8 January 2006 (UTC) | |||
:Energy is mass in a different form. So if mass can propell something, energy should also be able to do that. But mass can only propell something when it has energy (which it then transfers to the object being moved). So energy is the only thing that is needed, I'd say. Which makes sense of course. What happens to a photon that hits a sail (or anything else for that matter)? Does it lose its energy=mass and thus get transformed into something else? I understand from photoelectric effect that photons (being electromagnetic radiation) knock electrons out of the material they hit. But then the sail would be 'eaten away'. ] 10:17, 8 January 2006 (UTC) | |||
:::Having electron constantly leaving the material does seem like a problem, unless they are somehow created by the photons which hit. I didn't think the photon lost any energy, but just changed it's direction, like a perfectly elastic ball bouncing off a wall. Also, I don't see energy as equal to mass but rather as something that can theoretically be converted into mass. As far as I know, this doesn't happen in a solar sail, however. ] 10:22, 8 January 2006 (UTC) | |||
:::I thought about it a bit more, and I suppose losing electrons at a sizable portion of the speed of light would accelerate the object to a similar portion of the speed of light (although this might take thousands of years). A large positive charge would seem to build up on the solar sail, however, as it becomes deficient in electrons. I would think this charge would build to a point where it would suck any ejected electrons right back down. ] 10:43, 8 January 2006 (UTC) | |||
:::: It'll probably generate current and the electrons simply go to another part of the sail (which then the current replaces the electrons the metal atoms lost). The energy would then probably eventually contribute to the driving force on the sail anyway. ] (]) 15:40, 8 January 2006 (UTC) | |||
:::::I don't see how this solves the problem of the sail taking on a net positive charge and thus a huge attraction for any electrons which manage to get free. ] 20:51, 8 January 2006 (UTC) | |||
:: The problem is that I think the relationship between mass and energy in correspondence to force isn't e=mc^2, but something entirely different, based on the entire premise that say, a body that isn't moving doesn't bear any force anyhow, but of course, holds energy. ] (]) 10:23, 8 January 2006 (UTC) | |||
:::It is true that photons have zero mass (zero ''rest mass'', to be precise), but they do have ]. This allows you to use ] to calculate the radiation pressure. You may think that momentum implies mass, but physicists say that this is not true (see on ''Physics FAQ''). --] 12:03, 8 January 2006 (UTC) | |||
I'm just a lowly engineering science-type guy, but this just F=Ma with the solar particles, and perhaps radiation (the wave-particle thingie). Solar sails are a thing of the past, I think good old ion engines with nuclear power are way better! --] 17:10, 8 January 2006 (UTC) | |||
:Obsolete before they have even been made to work yet ? ] 20:51, 8 January 2006 (UTC) | |||
== hEARing == | |||
I believe we have body activity patterns we have subconsiously learned to ignore. | |||
What causes me to intermittently hear my ]ing out of my right ear? (I am assuming that is what I am hearing.) Is that a symptom of some ] problem? | |||
I went for months without this distraction, then had it on and off a couple days, typically hald a dozen short sessions of perhaps 1/4 hour worth, then a rest for a while, then another session, and now I have peace and quiet again. I not remember my left ear hearing this in ages. | |||
I will be age 62 this Feb 8 and fear that as our bodies grow older, they develop new aliments. I sure hope this nuisance is not going to be another of those new ailments, I will have to learn to live with. ]|] 09:17, 8 January 2006 (UTC) | |||
:Just about everyone could hear their own heartbeat in complete silence. Hearing your heartbeat at normal background sound levels may be a sign of high blood pressure, however. I suggest you get a BP cuff and take your BP the next time this happens. Also take some "baseline" readings when you don't hear this sound, to see what your normal reading is. Spikes in BP may be caused by certain conditions, such as sodium sensitive hypertension. It would be a good idea to consult a physician, as untreated high BP can be quite dangerous. ] 09:32, 8 January 2006 (UTC) | |||
::I'm no expert at this at all, but isn't high blood pressure a symptom rather than an ailment? For example for blood clots? To continue with this thought, I can imagine that if a tiny clot would end up in a small blood vessel near the inner ear that could have such an effect. A remedy might then be taking aspirin (an anticoagulant). Or alcohol, for a happier alternative :) . ] 10:29, 8 January 2006 (UTC) | |||
:::No, I think ], AKA, high blood pressure, may be considered an ailment by itself. It could also be viewed as a result of bad diet, obesity, age, etc., and a cause of things like stroke. ] 10:47, 8 January 2006 (UTC) | |||
== spiders : how do they build some nets? == | |||
I need to make a question to a spiders expert because I need information on how some spiders build their nets, everybody speaks about nets and spiders but nobody actually explain how some extraordinary patterns are made! | |||
I saw 9 metres nets long in orizontal direction with nothing in between!!! How can they build it???We use elicopters but they do not! | |||
waiting for answer | |||
Raffaele Serafini | |||
Veneto-Europe | |||
raffaeleserafini@tiscali.it | |||
:I think you mean '''webs'''. There are also some spiders which make portable '''nets''', but I don't think that's what you're asking. Each species has a different technique, but here's a general overview of web design: | |||
:1) First they drop from the highest point and leave a non-sticky line behind. They then anchor this at the lowest point, too. | |||
:2) They then climb back up the line and repeat another line but anchor it at the center of the orignal line as well as at the top and bottom. This new line might be rotated, say 30 degrees, about the center from the first line. | |||
:3) They repeat this until they have all the axial lines in non-sticky silk. | |||
:4) They then connect some cross supports with non-sticky thread, maybe 2 or 3 concentric sets. | |||
:5) Now it's time to add the sticky silk in a radial pattern between the supports. | |||
:6) Depending on the spider, they might go to the center or to the edge to wait for a victim. Once they feel vibrations on the non-sticky lines, the follow them out to the prey and kill it. | |||
:] 11:41, 8 January 2006 (UTC) | |||
==Caves== | |||
<small>Section title added</small><br/> | |||
WHICH IS THE OLDEST CAVE IN THE WORLD````````` | |||
:Please don't use all CAPITAL LETTERS; it looks you are shouting. I don't think that there is any 'oldest' ]; many caves have existed since prehistoric times. <font style="color:#00BB55"><u><b>s</b>murray</u></font><font style="color:#00AA77"><u>inch</u></font>]<font style="color:#00AA77"><u>ster</u></font><font style="color:#00AA77"><sup>(]), (])</sup></font> 14:11, 8 January 2006 (UTC) | |||
:: Probably since the Earth was formed too. ] (]) 14:49, 8 January 2006 (UTC) | |||
:::It's possible he means the oldest cave that's used as a tourist attraction. ] 20:11, 8 January 2006 (UTC) | |||
== sound == | |||
if all objects create sounds by vibration then what is doing the vibrations? | |||
:Not a true assumption. Could you clarify? --] 15:17, 8 January 2006 (UTC) | |||
::Please see ]. -- ] <small>(])</small> 18:51, 8 January 2006 (UTC) | |||
:::Any part of an object can vibrate. That vibration pushes on the air/water/etc, which makes that vibrate. The vibration of the air makes your ear drum vibrate, which is how you hear. ] 20:15, 8 January 2006 (UTC) | |||
Some other form of energy creates the vibrations initially. For example, during an explosion chemical potential energy is changed into various other forms of energy, including sound vibrations. ] 20:41, 8 January 2006 (UTC) | |||
== HTML tag for verdana text? == | |||
I'd like to make the text on a HTML page appear in Verdana (obviously only when installed on the PC of the viewer). '<font face="verdana">' and '<font family="verdana">' don't work, and a Google search yields nothing. Can anyone help me? | |||
: It's been many years since I last touched the <code><font></code> tag but the first should work, although you might like to capitalise the V in Verdana. It is now better to use the <code><span></code> tag as follows: <code><span style="font-family:Verdana">Text</span></code>. ] (]) 15:53, 8 January 2006 (UTC) | |||
: <small>(After edit conflict...)</small> There's no HTML tag for Verdana, but you could use ]: | |||
<nowiki><span style="font-family:verdana">Your text</span></nowiki> | |||
: Putting in an alternate font for users without Verdana would be a good idea too: | |||
<nowiki><span style="font-family:verdana,sans-serif">Your text</span></nowiki> | |||
: Or if you plan to use Verdana in a couple places, e.g. in the title of the page and in each paragraph of content, you'd be better of using straight CSS without the <tt>style</tt> tag. In the <tt><head></tt> of your HTML page:e | |||
<nowiki> <style type="text/css"><!-- | |||
h1 { font-family:verdana } | |||
p { font-family: verdana } | |||
//--></style></nowiki> | |||
: and then code the body of your HTML page as usual: | |||
<nowiki> <h1>Page title</h1> | |||
<p>This is some text that will appear in Verdana.</p> | |||
<p>Here is some more text also in Verdana.</p></nowiki> | |||
: Hope that helps, ] (]) 16:01, 8 January 2006 (UTC) | |||
Thanks for your response, but none of those seem to help; I should have mentioned that the text I want to Verdana-ise is in a table -- meaning I want the whole table to be in verdana. FONT FACE works if I start it during a cell, ie <nowiki>''<td><font face="verdana">Red motorcar</td>''</nowiki>, but when I write /TD it automatically closes the FONT FACE tag, too (meaning I'd have to type it around 250-300 times). | |||
:Then wrap the whole table on a div: | |||
<nowiki><div style="font-family: Verdana, sans-serif"><table> | |||
... | |||
</table></div></nowiki> | |||
:Don't forget the "sans-serif" part, which is used when the Verdana font is not installed. --] 16:38, 8 January 2006 (UTC) | |||
:: Or define the <code><td></code> tag as Verdana: | |||
<style type="text/css"> | |||
td { font-family:verdana } | |||
</style> | |||
:: ] (]) 17:07, 8 January 2006 (UTC) | |||
*I think the answer you are looking for is: there isn't a reliable way to set all of a table's font faces with one tag using just HTML. I believe in Internet Explorer you can put the entire TABLE element inside of a FONT tag, but I don't think this works in most browsers. Instead you have to either set the FONT for each bit of text in the table or you have to use CSS. --] 17:16, 8 January 2006 (UTC) | |||
==What?!== | |||
What kind of a sick freak would deface a nativity? Do they have no respect for christ at all? Is this a treatable mental illness? Or are some people just beyond hope?--] 17:33, 8 January 2006 (UTC) | |||
:Maybe. --] 19:32, 8 January 2006 (UTC) | |||
::Could you be more specific? Who defaced what nativity when, and how? Most likely, it is not a ], and as such does not require treatment. If they defaced a display, it seems reasonable to suppose that no, they don't respect the person being honored by it. And I suspect many people don't define 'hope' the way you're using it here. --] 20:21, 8 January 2006 (UTC) | |||
:We live in a world of people with a wide range of impaired judgement, like kids who turn over gravestones in cemetary of some sob-group of society they not like, for reasons they cannot explain to anyone who not share their dislike. Often this is a problem of a lack of education, or an unwillingness to be educated on ] topics. Start off with the assumption, that for some people, nothing is sacred. It then follows that they see nothing wrong with terrorism, hijacking airliners, murder, drug abuse, respect for other people's religious icons. ]|] 20:47, 8 January 2006 (UTC) | |||
::Not intending to start anything here, and I agree that it's a shame and disrepsectful, but knocking over some mannequins is a very common form of youthful vandalism, can be hilarious, and is not on a par with any of the things you mentioned. And drug abuse? I live in a town with some very socially conscious hippies who would take exception to being lumped into a category with terrorists, or even nativity-defilers. Point is, this is not the place to debate morality. The questions asked are not answerable, and this whole part ought to be deleted. Just the facts, ma'am. ] 1418, 8.1.06 | |||
There are some who feel the use of public dollars to display items in support of any one religion is wrong, and might vandalize it for that reason. I think it's wrong, but wouldn't go that far. ] 21:22, 8 January 2006 (UTC) | |||
== Weather == | |||
Why does summer in Ontario on Lake Superior feel hotter than in the prairies even though the temperature is not as low?--] 18:42, 8 January 2006 (UTC) | |||
:Humidity and/or wind speed ? ] 20:32, 8 January 2006 (UTC) | |||
== Hydrated to anhydrous == | |||
What are some ways to change a hydrated salt anhydrous? | |||
Heat it. Don't heat it too much though, as that will cause the salt to decompose. --] 19:24, 8 January 2006 (UTC) | |||
:Some salts have greater affinity for water than others. I think that if you stored the hydrated salt together with anhydrous, high affinity salt, eventually most of your original salt would be anhydrous. ] 20:16, 8 January 2006 (UTC) | |||
==Miscellaneous Questions== | |||
I have several science related Miscellaneous questions: | |||
1) Bullets travel faster than sound, right? So why don't we experiance a sonic boom, something like two bangs one for the gunpowder and another shortly after for breaking the sound barrier? | |||
:The bullet breaks the sound barrier while still inside the gun barrel. ] 20:25, 8 January 2006 (UTC) | |||
:I don't know a lot about ], but believe you only hear one as the object passes you. So, if there was one, the person firing the gun wouldn't hear it. As the bullet passes someone, if there was an audible sonic boom, it would be heard before the gun firing. The boom reaches you when the bullet reaches you, and the bullet is traveling faster than the sound of the gun. But would there be enough of a time delay between them to hear the difference? --] 20:43, 8 January 2006 (UTC) | |||
2) Would there be a light barrier eg. in theory if an object of some sort exceeds the speed of light (although not possible) would there be some kind of explosion of light as it build up aroung the object, this is all merely theoretical. | |||
3) Is 100% insulation of an object possible? eg. a means of an object forever retaining constant temperature? and on the other extreme is 100% heat conductivity possible? | |||
4) What are quarks made of? And then what is that made of and then that, etc? | |||
:I think quarks are made of strings, according to current theory. I don't think current theory goes any deeper than that. ] 20:25, 8 January 2006 (UTC) | |||
5) What effect does the combinations of quarks have on a particle eg. rather than 2 down and 1 up two bottom and a top, and if i had a rod of iron one made of the first type of neutrons and then another with the second kind would there be a visual, chemical or physical difference? | |||
] 19:55, 8 January 2006 (UTC) | |||
:In answer to question 2. When you are talking about the sound barrier, its the speed of sound in a particular media. When talking about light, the speed of light in material media is of course much lesser than that in vaccum. This lesser value can be crossed. ] is electromagnetic radiation emitted when a charged particle passes through an insulator at a speed greater than that of light in the medium. The characteristic "blue glow" of nuclear reactors is due to Cherenkov radiation. It is named after Pavel Alekseyevich Cherenkov, the 1958 Nobel Prize winner who was the first to rigorously characterize it. --] 20:22, 8 January 2006 (UTC) | |||
:In answer to question 3, 100% insulation of an object isn't possible. Energy can be conveyed through matter by conduction, and through vacuum carried by photons (radiative transfer). 100% heat conductivity is possible, depending on exactly what is meant by the term. ]s like liquid helium are perfect conductors of heat; in their superfluid state it is impossible to set up a temperature gradient within the fluid. ](]) 20:31, 8 January 2006 (UTC) | |||
:To answer question 5, the combination of quarks ''defines'' the type of particle. By definition, a neutron contains one up and two down quarks. A particle made up of one top and two bottom quarks–while still being of neutral charge–would be a very different beast. (Much more massive, and very short-lived.) ](]) 20:31, 8 January 2006 (UTC) | |||
== tornados == | |||
What makes the sky change to a yellow-green hue often when a tornado is in the area? | |||
I can't seem to find any information on this . Is it a change in the electrical charges ? | |||
thank you. | |||
*It's the water vapor, does the same thing during a plain thunderstorm, just acts like a filter for the sunlight--] 21:18, 8 January 2006 (UTC) | |||
::After searching both Google and HowStuffWorks for the terms 'tornado green sky', I'm prepared to answer this question in full: Nobody knows. There are quite a few theories floating around, including | |||
::*It's just like an extreme sunset(which can have a green layer), the water-heavy air combined with the right time of day refract light farther than usual. | |||
::*It's the vegetation that's been pulled up by the tornados (made up by some guy on a message board) | |||
::*It's a sign of heavy hail. The hail refracts the light differently from most other things, and so gives different signs, namely a green tint to the clouds and sky. | |||
::*Something indistinct about electricity. | |||
::There seems to be some agreement, however, on under what circumstances it shows up. It shows up with heavy storms. Some claim it shows up with tornados, some say it shows up with hail, but everyone agrees it is connected in some way to especially dangerous storms. For myself, I've only ever experienced it once (luckily, my dad recognized it and got us inside), and then, it came with everything. --] 21:38, 8 January 2006 (UTC) |
Latest revision as of 00:51, 27 December 2024
Welcome to the science sectionof the Misplaced Pages reference desk. skip to bottom Select a section: Shortcut Want a faster answer?
Main page: Help searching Misplaced Pages
How can I get my question answered?
- Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
- Post your question to only one section, providing a short header that gives the topic of your question.
- Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
- Don't post personal contact information – it will be removed. Any answers will be provided here.
- Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
- Note:
- We don't answer (and may remove) questions that require medical diagnosis or legal advice.
- We don't answer requests for opinions, predictions or debate.
- We don't do your homework for you, though we'll help you past the stuck point.
- We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.
How do I answer a question?
Main page: Misplaced Pages:Reference desk/Guidelines
- The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
December 13
What is the most iconic tornado photo
Request for opinions |
---|
The following discussion has been closed. Please do not modify it. |
What photo of a tornado would you say is the most iconic? I'm researching the history of tornado photography for an eventual article on it and I've seen several specific tornadoes pop up over and over again, particularly the Elie, Manitoba F5 and the "dead man walking" shot of the Jarrel, Texas F5. Which would be considered more iconic? ApteryxRainWing🐉 | Roar with me!!! | My contributions 17:21, 13 December 2024 (UTC)
|
December 15
help to identify File:Possible Polygala myrtifolia in New South Wales Australia.jpg
Did I get species right? Thanks. Gryllida (talk, e-mail) 06:56, 15 December 2024 (UTC)
- related: https://species.wikimedia.org/Wikispecies:Village_Pump#help_to_identify_species Gryllida (talk, e-mail) 06:57, 15 December 2024 (UTC)
- FWIW, I can't detect any visible differences between the plant in this photo and the ones illustrated in the species and the genus articles. However, the latter makes it clear that Polygala is a large genus, and is cultivated, with hybrids, so it's possible that this one could be a close relative that differs in ways not visible here, such as in the bark or roots. That may or may not matter for your purposes. {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 10:11, 15 December 2024 (UTC)
How to address changes to taxonomy
Hi all,
I am a biology student brand new to wiki editing who is interested in cleaning up small articles/stubs for less known taxa. One that I've encountered is a mushroom that occurs in the pacific northwest (Fomitopsis ochracea). The article mentions that this fungus is occasionally mistaken for another fungus, Fomitopsis pinicola.
However, the issue I've run into is that F. pinicola used to be considered a single species found around the world, but relatively recently was split into a few different species. The original name was given to the one that occurs in Europe, and the one in the pacific northwest (and thus could be mistaken for F. ochracea) was given the name Fomitopsis mounceae.
The wiki page says
Historically, this fungus has been misidentified as F. pinicola. When both species are immature, they can look very similar, but can be distinguished by lighting a match next to the surface of the fungus. F. pinicola will boil and melt in heat, while F. ochracea will not.
Since the source says pinicola (as likely do most/all other sources of this info given the change was so recent), and since technically it's true that they used to be mistaken for it... what would be the most appropriate way to modernize that section?
My questions are:
Should I replace F. pinicola with F. mounceae? Or is that wrong because the source doesn't refer to it by that name? Would it be better to write something like (now known as/considered F. mounceae) next to the first mention of the species? Or is that a poor choice because it implies all the members of F. pinicola were renamed F. mounceae?
Any advice on how to go about updating this section is incredibly appreciated
TheCoccomycesGang (talk) 10:21, 15 December 2024 (UTC)
- First, take these sorts of questions to the relevant Wikiproject, in this case Misplaced Pages talk:WikiProject Fungi. I am not as familiar with the consensus at WP:FUNGI, but it seems like they defer to Species Fungorium/Index Fungorium and Mycobank to decide. Those sources presently seem to consider Fomitopsis pinicola a good species. Also, be careful about "replacing", there are rules to ensure the continuity of the article history. By the way, there is a hilarious but unencyclopedic/copyvio recipe appended to the Fomitopsis mounceae article. Abductive (reasoning) 11:09, 15 December 2024 (UTC)
- Thanks for the tips, I didn't know about projects so I'll go read up on that. And thanks for the warnings about replacing things. I've been reading a lot of help pages, but I'm still in the process of learning the all conventions and what mechanics break if you do things the wrong way.
- I actually saw the recipe ages ago before I made my account and completely forgot about it... it was one of many things that prompted me to get into wiki editing. TheCoccomycesGang (talk) 23:12, 15 December 2024 (UTC)
- First, take these sorts of questions to the relevant Wikiproject, in this case Misplaced Pages talk:WikiProject Fungi. I am not as familiar with the consensus at WP:FUNGI, but it seems like they defer to Species Fungorium/Index Fungorium and Mycobank to decide. Those sources presently seem to consider Fomitopsis pinicola a good species. Also, be careful about "replacing", there are rules to ensure the continuity of the article history. By the way, there is a hilarious but unencyclopedic/copyvio recipe appended to the Fomitopsis mounceae article. Abductive (reasoning) 11:09, 15 December 2024 (UTC)
Does stopping masturbation lead to sperm DNA damage?
I'm looking for information on the potential link between the frequency of ejaculation (specifically through masturbation) and sperm DNA damage. I've come across some conflicting information and would appreciate it if someone could point me towards reliable scientific studies or reviews that address this topic.
Specifically, I'm interested in whether prolonged periods of abstinence from ejaculation might have any negative effects on sperm DNA integrity. Any insights or links to relevant research would be greatly appreciated. HarryOrange (talk) 17:08, 15 December 2024 (UTC)
- Only males may abstain from sperm-releasing Masturbation that serves to flush the genital tract of old sperm that in any case will eventually dissipate. No causal relationship between masturbation and any form of mental or physical disorder has been found but abstinence may be thought or taught to increase the chance of wanted conception during subsequent intercourse. Philvoids (talk) 00:51, 16 December 2024 (UTC)
- There's many rumors about that topic. One is that not ejaculating frequently increases the risk of developing prostate cancer. Abductive (reasoning) 01:02, 16 December 2024 (UTC)
- Nothing really conclusive but there's some evidence that short periods are associated with lower DNA fragmentation, see
- Du, Chengchao; Li, Yi; Yin, Chongyang; Luo, Xuefeng; Pan, Xiangcheng (10 January 2024). "Association of abstinence time with semen quality and fertility outcomes: a systematic review and dose–response meta‐analysis". Andrology. 12 (6): 1224–1235. doi:10.1111/andr.13583. ISSN 2047-2919.
- Hanson, Brent M.; Aston, Kenneth I.; Jenkins, Tim G.; Carrell, Douglas T.; Hotaling, James M. (16 November 2017). "The impact of ejaculatory abstinence on semen analysis parameters: a systematic review". Journal of Assisted Reproduction and Genetics. 35 (2): 213. doi:10.1007/s10815-017-1086-0. ISSN 2047-2919. PMC 5845044. PMID 29143943.
- Ayad, Bashir M.; Horst, Gerhard Van der; Plessis, Stefan S. Du; Carrell, Douglas T.; Hotaling, James M. (14 October 2017). "Revisiting The Relationship between The Ejaculatory Abstinence Period and Semen Characteristics". International Journal of Fertility & Sterility. 11 (4): 238. doi:10.22074/ijfs.2018.5192. ISSN 2047-2919. PMC 5641453. PMID 29043697.
- for example. Alpha3031 (t • c) 02:12, 16 December 2024 (UTC)
- Mature sperm cells do not have DNA repair capability. Inevitably, as sperm cells get older, they will naturally and unavoidably be subject to more and more DNA damage. Obviously, freshly produced spermatozoa will, on average, have less DNA damage. It is reasonable to assume that the expected amount of damage is proportional to the age of the cells, which is consistent with what studies appear to find. Also, obviously, the more the damage is to a spermatozoon fertilizing an oocyte, the larger the likelihood that the DNA repair in the resulting zygote, which does have DNA repair capability, will be incomplete. The studies I've looked at did not allow me to assess how much this is of practical significance. --Lambiam 09:40, 16 December 2024 (UTC)
December 16
Abelian sandpile model
Thanks to those who answered my last question, I think it should be added to a disambiguation page. If anyone wants to help me write that, reach out.
A sandpile seems disorganized and inert, but these are critically self-organizing. Do the frequency and size of disturbances on sand dunes and snowy peaks follow power law distribution? Gongula Spring (talk) 01:18, 16 December 2024 (UTC)
- Shouldn't this be at the Math Desk? Abductive (reasoning) 05:12, 16 December 2024 (UTC)
- If the question is not about the model mentioned in the heading but about the physical properties of sand dunes and snowy peaks, this here is the right section of the Reference desk. --Lambiam 08:51, 16 December 2024 (UTC)
- I await a non-mathematical answer. Abductive (reasoning) 09:23, 16 December 2024 (UTC)
- It depends is probably a fairly reasonable non-mathematical answer for these kinds of systems. For sand dunes anyway, sometimes avalanche frequency is irregular and the size distribution follows a power law, and sometimes it's close to periodic and the avalanches span the whole system. It seems there are multiple regimes, and these kinds of systems switch between them. Sean.hoyland (talk) 09:35, 16 December 2024 (UTC)
- Thank you! I'm impressed this seems so casual, but surely you read this somewhere that might have a URL?
- Gongula Spring (talk) 22:29, 19 December 2024 (UTC)
- It depends is probably a fairly reasonable non-mathematical answer for these kinds of systems. For sand dunes anyway, sometimes avalanche frequency is irregular and the size distribution follows a power law, and sometimes it's close to periodic and the avalanches span the whole system. It seems there are multiple regimes, and these kinds of systems switch between them. Sean.hoyland (talk) 09:35, 16 December 2024 (UTC)
- I await a non-mathematical answer. Abductive (reasoning) 09:23, 16 December 2024 (UTC)
- If the question is not about the model mentioned in the heading but about the physical properties of sand dunes and snowy peaks, this here is the right section of the Reference desk. --Lambiam 08:51, 16 December 2024 (UTC)
- Hi, this is an interesting and somewhat open question! A lot of work is done on these models but much less on careful analyses of real dunes. I did find this dissertation that is freely accessible and describes some physical experiments and how well they fit various models. The general answer seems to be that the power law models are highly idealized, and determining the degree to which any real system's behavior is predicted by the model ahead of time is very difficult. Update: This is one of the earlier important works on the topic and it does include discussion of how well the model fits experiments.SemanticMantis (talk) 17:21, 16 December 2024 (UTC)
- That dissertation is great!
- Gongula Spring (talk) 22:30, 19 December 2024 (UTC)
Polar night
Are there any common or scientific names for types of polar night? The types that I use are:
- polar night - meaning a day when sun's altitude remains below horizon entire day (there is no daylight at solar noon, only civil twilight), occurring poleward from 67°24′ north or south
- civil polar night - meaning a day when sun's altitude remains below -6° entire day (there is no civil twilight at solar noon, only nautical twilight), occurring poleward from 72°34′ north or south
- nautical polar night - meaning a day when sun's altitude remains below -12° entire day (there is no nautical twilight at solar noon, only astronomical twilight), occurring poleward from 78°34′ north or south
- astronomical polar night - meaning a day when sun's altitude remains below -18° entire day (there is no astronomical twilight at solar noon, only night), occurring poleward from 84°34′ north or south
These names were changed on Polar night article, and I wnat to know whether these named I listed are in use in any scientific papers, or in common language. (And I posted that question here and not in language desk because I think that this is not related to language very tightly.) --40bus (talk) 18:56, 16 December 2024 (UTC)
- Some definitions at The Polar Night (1996) from the Aurora Research Institute. Alansplodge (talk) 22:55, 16 December 2024 (UTC)
- These seem to be generalizable as: X polar night is a period, lasting not less than 24 hours, during which the sun remains below the horizon and there is no X twilight. The specific definitions depend then on the specific definitions of civil/nautical/astronomical twilight. These can be defined with a subjective observational standard or with an (originally experimentally determined) objective standard. --Lambiam 10:36, 17 December 2024 (UTC)
- FWIW, I as a former amateur astronomer have never previously thought about the question of Polar twilight and night nomenclatures, but immediately and completely understood what the (previously unencountered) terms used in the query must mean without having to read the attached descriptions. {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 16:34, 17 December 2024 (UTC)
- These seem to be generalizable as: X polar night is a period, lasting not less than 24 hours, during which the sun remains below the horizon and there is no X twilight. The specific definitions depend then on the specific definitions of civil/nautical/astronomical twilight. These can be defined with a subjective observational standard or with an (originally experimentally determined) objective standard. --Lambiam 10:36, 17 December 2024 (UTC)
December 17
differential equations with complex coefficients
In an intro ODE class one basically studies the equation where x is a real vector and A is a real matrix. A typically has complex eigenvalues, giving a periodic or oscillating solution to the equation. That is very important in physics, which has various sorts of harmonic oscillators everywhere. If A and x are complex instead of real, mathematically the ODE theory works out about the same way. I don't know what happens with PDE's since I haven't really studied them.
My question is whether the complex case is important in physics the way the real case is. Can one arrive at it through straightforward coordinate transformations? Do the complex eigenvalues "output" from one equation find their way into the "input" of some other equation? Does the distance metric matter? I.e. in math and old-fashioned physics we use the Euclidean metric, but in realtivity one uses the Minkowski metric, so I'm wondering if that leads to complex numbers. This is all motivated partly by wondering where all the complex numbers in quantum mechanics come from. Thanks. 2601:644:8581:75B0:0:0:0:DA2D (talk) 22:54, 17 December 2024 (UTC)
- Perhaps I don't understand what you are getting at but simple harmonic motion is xdot=j*w*x where w is angular frequency and j is i Greglocock (talk) 00:35, 18 December 2024 (UTC)
- If PDEs count, the Schrödinger equation and the Dirac equation are examples of differential equations in the complex domain. A linear differential equation of the form on the complex vector space can be turned into one on the real vector space . For a very simple example, using the equation can be replaced by
- --Lambiam 01:11, 18 December 2024 (UTC)
- Shouldn't this be at the Math Desk? It almost seems like the IP could be trolling, given the same question just above. Abductive (reasoning) 14:49, 18 December 2024 (UTC)
- The question whether the complex case is important in physics the way the real case is, is not a maths issue. IMO the Science section is the best choice. I do not see another post that asks the same or even a related question. --Lambiam 21:51, 18 December 2024 (UTC)
- Just as above, I await a non-mathematical answer to this question. Abductive (reasoning) 07:01, 19 December 2024 (UTC)
- The question whether the complex case is important in physics the way the real case is, is not a maths issue. IMO the Science section is the best choice. I do not see another post that asks the same or even a related question. --Lambiam 21:51, 18 December 2024 (UTC)
- Shouldn't this be at the Math Desk? It almost seems like the IP could be trolling, given the same question just above. Abductive (reasoning) 14:49, 18 December 2024 (UTC)
Thanks all. Greglocock, your SHO example is 1-dimensional but of course you can have a periodic oscillator (such as a planetary orbit) in any orientation in space, you can have damped or forced harmonic oscillators, etc. Those are all described by the same matrix equation. The periodic case means that the matrix eigenvalues are purely imaginary. The damped and forced cases are where there is a real part that is negative or positive respectively. Abductive, of course plenty of science questions (say about how to calculate an electron's trajectory using Maxwell's equations) will have mathematical answers, and the science desk is clearly still the right place for them, as they are things you would study in science class rather than math class. Lambiam, thanks, yes, PDE's are fine, and of course quantum mechanics uses complex PDE's. What I was hoping to see was a situation where you start out with real-valued DEs in some complicated system, and then through some coupling or something, you end up with complex-valued DEs due to real matrices having complex eigenvalues. Also I think the Minkowski metric can be treated like the Euclidean one where the time coordinate is imaginary. But I don't know how this really works, and Misplaced Pages's articles about such topics always make me first want to go learn more math (Lie algebras in this case). Maybe someday. 2601:644:8581:75B0:0:0:0:DA2D (talk) 07:25, 19 December 2024 (UTC)
December 18
Why don't all mast radiators have top hats?
Our mast radiator article describes a device called a "top hat" which increases the range for mast radiators that can't be built tall enough.
So, why would you bother building a mast radiator without a top hat? Couldn't you just build it shorter with the top hat, and save steel? Marnanel (talk) 15:00, 18 December 2024 (UTC)
- The main source cited in our article states, "
Top loading is less desirable than increased tower height but is useful where towers must be electrically short due to either extremely low carrier frequencies or to aeronautical limitations. Top loading increases the base resistance and lowers the capacitive base reactance, thus reducing the Q and improving the bandwidth of towers less than 90° high.
" If "reducing the Q" is an undesirable effect, this is a trade-off design issue in which height seems to be favoured if circumstances permit. --Lambiam 21:41, 18 December 2024 (UTC)
Name of our solar system
Is our star system officially called "Sol", or is that just something that came from science fiction and then became ubiquitous? 146.90.140.99 (talk) 22:06, 18 December 2024 (UTC)
- It's called the Solar System, and its star is called Sol, from Latin via French. Hence terms like "solstice", which means "sun stands still" in its apparent annual "sine wave" shaped path through the sky. ←Baseball Bugs carrots→ 23:31, 18 December 2024 (UTC)
- Via French? According to the OED, it came direct from Latin. --Lambiam 11:45, 19 December 2024 (UTC)}}
- Old French plus Latin. ←Baseball Bugs carrots→ 14:25, 19 December 2024 (UTC)
- Also in Old French, the word meaning "sun" was soleil. --Lambiam 23:42, 19 December 2024 (UTC)
- Old French plus Latin. ←Baseball Bugs carrots→ 14:25, 19 December 2024 (UTC)
- Via French? According to the OED, it came direct from Latin. --Lambiam 11:45, 19 December 2024 (UTC)}}
- Let's say to that claim. The star is indeed called Sol if you're speaking Latin, but in English it's the Sun (or sun). Of course words like "solar" and "solstice" derive from the Latin name, but using "Sol" to mean "the Sun" does seem to be something from science fiction. --142.112.149.206 (talk) 06:04, 19 December 2024 (UTC)
- "Sol" is occasionally used to mean the Sun by astronomers. I feel like it is used in contexts where it is necessary to distinguish our experience with the Sun here on Earth, such as sunsets, from more "sterile" aspects of the Sun one might experience off the Earth. Abductive (reasoning) 08:56, 19 December 2024 (UTC)
- Being an astronomer myself, I don't think I've ever heard anyone use "Sol" outside of a science fiction context. --Wrongfilter (talk) 09:06, 19 December 2024 (UTC)
- Scientific articles that use the term Sol; Development of the HeliosX mission analysis code for advanced ICF space propulsion and Swarming Proxima Centauri: Optical Communication Over Interstellar Distances. These are rather speculative but as I mentioned, the usage is for off-planet situations. Abductive (reasoning) 13:05, 19 December 2024 (UTC)
- Using Sol, Terra and Luna to refer to the Sun, Earth and Moon only happens if you write your entire article in Latin and in science fiction, not in regular science articles. They are capitalised though. Just as people write about a galaxy (one of many) or the Galaxy (the Milky Way Galaxy, that's our galaxy). The Solar System is also capitalised. PiusImpavidus (talk) 10:38, 19 December 2024 (UTC)
- The article says "Sol" is the "personification" of the sun. Google Image the term "old Sol" and you'll see plenty of images of the sun with a face, not just Sci-Fi stuff. And "Luna" is obviously the basis for a number of words not connected with Sci-Fi. Lunar orbit, lunar module, etc. And the term "terra firma" has often been used in everyday usage. ←Baseball Bugs carrots→ 11:34, 19 December 2024 (UTC)
- And yet, if you ask 1,000 people "What's that big yellow thing up in the sky called?", you'll get 1,000 "the Sun"s and zero "Sol"s. Yes, in specialised contexts, Sol is used; but that doesn't justify saying our solar system's star "is called Sol" without any qualification, as if that were the normal, default term. It's not. -- Jack of Oz 12:16, 19 December 2024 (UTC)
- And after you've gotten that response, ask them why it isn't the "Sunner System". And why a sun room attached to a house isn't called a "sunarium". And why those energy-gathering plates on some roofs are not called "sunner panels". ←Baseball Bugs carrots→ 14:22, 19 December 2024 (UTC)
- What does that have to do with anything? The question was 'Is our star system officially called "Sol"?' (my emphasis). The answer is it is not. And that does not preclude other terms being derived from Latin sol (or, often enough, from Greek helios), nobody denies that, it is irrelevant to the question. --Wrongfilter (talk) 14:52, 19 December 2024 (UTC)
- The problem is that the OP's question contains false premises. One is the question of what the "official" name is. There is no "official" name. It's the "conventional" name. And the second part, claiming that "Sol" comes from Sci-fi, is demonstrably false. ←Baseball Bugs carrots→ 15:05, 19 December 2024 (UTC)
- Then demonstrate (that the usage of "Sol" as a name for the Sun, in English, not its use to derive adjectives, originated outside of SF), with references. The original question does not even include any premises, with maybe the exception of "ubiquitous". --Wrongfilter (talk) 15:18, 19 December 2024 (UTC)
- "Is our star system officially called "Sol" , or is that just something that came from science fiction and then became ubiquitous? ". And the wording of your own question, just above, does not make sense. ←Baseball Bugs carrots→ 15:24, 19 December 2024 (UTC)
- Looking at Newspapers.com (pay site), I'm seeing colloquial references to "old Sol" (meaning the sun) as far back as the 1820s. No hint of sci-fi derivation. ←Baseball Bugs carrots→ 15:32, 19 December 2024 (UTC)
- Great! Well done. --Wrongfilter (talk) 15:41, 19 December 2024 (UTC)
- Feel free to box up this section. ←Baseball Bugs carrots→ 15:52, 19 December 2024 (UTC)
- Great! Well done. --Wrongfilter (talk) 15:41, 19 December 2024 (UTC)
- Looking at Newspapers.com (pay site), I'm seeing colloquial references to "old Sol" (meaning the sun) as far back as the 1820s. No hint of sci-fi derivation. ←Baseball Bugs carrots→ 15:32, 19 December 2024 (UTC)
- The 1933 OED entry for Sol, linked to above, gives several pre-SF uses, the earliest from 1450. --Lambiam 23:48, 19 December 2024 (UTC)
- Yes, of course, but that's not surprising, is it? 15th century humanists, astrologers and pre-Victorian poets liked to sprinkle their texts with Latin words. But I don't think this is what the question is about. It's a matter of context, but it should be up to OP to clarify that. --Wrongfilter (talk) 08:48, 20 December 2024 (UTC)
- It's not surprising, but the discussion was not whether the use of Sol in English texts is surprising, but whether it originated outside of SF. --Lambiam 10:52, 20 December 2024 (UTC)
- In my view, the question has a clear scifi bent, and that particular usage ("Where shall we go for our vacation? Alpha Centauri or Sol?") does not originate in the 15th century. The word is much older, of course it is, but the usage is not. In the 15th century people didn't even know that the Sun is just an ordinary star and could do with a particular name to distinguish it from the others. The connotations of sol were vastly different from what they are today and from what is implied in OP's question. Incidentally, the IAU doesn't even define a name , although they recommend using capitalised "Sun". Certainly no "Sol" anywhere. --Wrongfilter (talk) 12:04, 20 December 2024 (UTC)
- It's not surprising, but the discussion was not whether the use of Sol in English texts is surprising, but whether it originated outside of SF. --Lambiam 10:52, 20 December 2024 (UTC)
- Yes, of course, but that's not surprising, is it? 15th century humanists, astrologers and pre-Victorian poets liked to sprinkle their texts with Latin words. But I don't think this is what the question is about. It's a matter of context, but it should be up to OP to clarify that. --Wrongfilter (talk) 08:48, 20 December 2024 (UTC)
- "Is our star system officially called "Sol" , or is that just something that came from science fiction and then became ubiquitous? ". And the wording of your own question, just above, does not make sense. ←Baseball Bugs carrots→ 15:24, 19 December 2024 (UTC)
- Then demonstrate (that the usage of "Sol" as a name for the Sun, in English, not its use to derive adjectives, originated outside of SF), with references. The original question does not even include any premises, with maybe the exception of "ubiquitous". --Wrongfilter (talk) 15:18, 19 December 2024 (UTC)
- The problem is that the OP's question contains false premises. One is the question of what the "official" name is. There is no "official" name. It's the "conventional" name. And the second part, claiming that "Sol" comes from Sci-fi, is demonstrably false. ←Baseball Bugs carrots→ 15:05, 19 December 2024 (UTC)
- What does that have to do with anything? The question was 'Is our star system officially called "Sol"?' (my emphasis). The answer is it is not. And that does not preclude other terms being derived from Latin sol (or, often enough, from Greek helios), nobody denies that, it is irrelevant to the question. --Wrongfilter (talk) 14:52, 19 December 2024 (UTC)
- And after you've gotten that response, ask them why it isn't the "Sunner System". And why a sun room attached to a house isn't called a "sunarium". And why those energy-gathering plates on some roofs are not called "sunner panels". ←Baseball Bugs carrots→ 14:22, 19 December 2024 (UTC)
- Does that make it a Sol-ecism? Clarityfiend (talk) 12:19, 19 December 2024 (UTC)
- More like a Sol-ips-ism. Meaning a factory where suns are made. From Sol = sun, and ipso = facto. Thus endeth the entymogology lesson for today. Go in peace to love and serve whomsoever. -- Jack of Oz 19:37, 19 December 2024 (UTC)
- And yet, if you ask 1,000 people "What's that big yellow thing up in the sky called?", you'll get 1,000 "the Sun"s and zero "Sol"s. Yes, in specialised contexts, Sol is used; but that doesn't justify saying our solar system's star "is called Sol" without any qualification, as if that were the normal, default term. It's not. -- Jack of Oz 12:16, 19 December 2024 (UTC)
- The article says "Sol" is the "personification" of the sun. Google Image the term "old Sol" and you'll see plenty of images of the sun with a face, not just Sci-Fi stuff. And "Luna" is obviously the basis for a number of words not connected with Sci-Fi. Lunar orbit, lunar module, etc. And the term "terra firma" has often been used in everyday usage. ←Baseball Bugs carrots→ 11:34, 19 December 2024 (UTC)
- Being an astronomer myself, I don't think I've ever heard anyone use "Sol" outside of a science fiction context. --Wrongfilter (talk) 09:06, 19 December 2024 (UTC)
- "Sol" is occasionally used to mean the Sun by astronomers. I feel like it is used in contexts where it is necessary to distinguish our experience with the Sun here on Earth, such as sunsets, from more "sterile" aspects of the Sun one might experience off the Earth. Abductive (reasoning) 08:56, 19 December 2024 (UTC)
Mountains
Why there are no mountains on Earth with a height above 10,000 m? As the death zone is about at 8,000 m, and above 19,000 m, there is an Armstrong limit, where water boils at normal human body temperature, it is good that there are no more mountains higher than 8,000 km than just 14, but if there were hundreds of mountains above 9,000 m, then these were bad to climb. If there were different limits for death zone and Armstrong limit, would then there be possible to have higher mountains? I have just thought that, it is not a homework? --40bus (talk) 22:29, 18 December 2024 (UTC)
- There are mountains elsewhere in the solar system that are over 20km high. Given that some of those are on airless worlds, I don't think the air pressure has any bearing on it. 146.90.140.99 (talk) 22:57, 18 December 2024 (UTC)
- Multiple sources from web searching suggest the theoretical maximum height for mountains on Earth is around 15,000 m – the limiting factor is Isostasy; the higher (therefore more voluminous) a mountain is, the more its weight causes the crust beneath it to sink. The actual heights of mountains are a trade-off between how fast tectonic movements can raise them versus isostatic sinking and how quickly they are eroded, and tectonic movements do not last for ever. See also Orogeny. {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 00:25, 19 December 2024 (UTC)
- And erosion goes faster as the mountain gets higher, in particular when it's high enough to support glaciers – one reason why mountains can get higher on an airless world. Now it gets interesting for a mountain high enough to reach into the stratosphere, as it would be too dry to have anything but bare rock. I suppose it would locally raise the tropopause, preventing that. PiusImpavidus (talk) 11:13, 19 December 2024 (UTC)
December 19
Does human DNA become weaker with each generation?
As with photocopying something over and over, the text becomes less clear each time.
Does human DNA become weaker with each generation? HarryOrange (talk) 21:22, 19 December 2024 (UTC)
- Sure, DNA replication is not perfect, although proofreading reduces the error rate to about 1 mistake per 10 nucleotides (see our article on DNA Replication). But that is per generation of cells, not of the whole organisms. Many mutations will be neutral in effect (because much of our DNA is redundant), some will be deleterious, and a few might be advantageous. It is the process of natural selection that hinders the spread of deleterious mutations: sometimes this aspect is called purifying selection. One thus usually expects a stable mutation–selection balance over time rather than that "DNA becomes weaker with each generation". Medical science is reducing the selection pressure against some mutations, which consequently may become more common. One of the problems for asexual organisms is referred to as Muller's ratchet; assuming that reverse mutations are rare, each generation has at least the mutational load of its predecessor. In contrast, in sexual organisms genetic recombination generates the variation that, combined with selection, can repair the situation. Sexual organisms consequently have a lighter genetic load. JMCHutchinson (talk) 22:42, 19 December 2024 (UTC)
- So purifying selection won't work properly in case of Inbreeding ? HarryOrange (talk) 23:16, 19 December 2024 (UTC)
- The larger the degree of inbreeding, the larger the chance that deleterious traits are expressed. But this very expression of traits leading to decreased biological fitness of their bearers is what actually enables purifying selection in the longer term. --Lambiam 23:36, 19 December 2024 (UTC)
- @Lambiam so DNA repair won't stop these deleterious traits to get expressed? HarryOrange (talk) 14:11, 20 December 2024 (UTC)
- No, this is not an issue of damage to the DNA. The genes involved are faithfully reproduced and passed on from generation to generation. --Lambiam 15:53, 20 December 2024 (UTC)
- @Lambiam so DNA repair won't stop these deleterious traits to get expressed? HarryOrange (talk) 14:11, 20 December 2024 (UTC)
- The larger the degree of inbreeding, the larger the chance that deleterious traits are expressed. But this very expression of traits leading to decreased biological fitness of their bearers is what actually enables purifying selection in the longer term. --Lambiam 23:36, 19 December 2024 (UTC)
- So purifying selection won't work properly in case of Inbreeding ? HarryOrange (talk) 23:16, 19 December 2024 (UTC)
- Or stronger e.g. "...we found that genes specifically duplicated in the Greenland shark form a functionally connected network enriched for DNA repair function", and those guys live for centuries and have much more DNA than us. Sean.hoyland (talk) 15:21, 20 December 2024 (UTC)
- @Lambiam If not due to DNA damage, why do babies from inbreeding appear like DNA-damaged species? HarryOrange (talk) 17:29, 20 December 2024 (UTC)
- Inbred offspring of species that normally outcross may show abnormalities because they are more likely than outcrossed offspring to be homozygous for recessive alleles that are deleterious. In individuals that are heterozygous at these loci, the recessive alleles will not be expressed (because the other wild-type dominant allele is sufficient to do their job adequately). See our article on inbreeding depression. JMCHutchinson (talk) 19:26, 20 December 2024 (UTC)
- @Lambiam If not due to DNA damage, why do babies from inbreeding appear like DNA-damaged species? HarryOrange (talk) 17:29, 20 December 2024 (UTC)
Larvae going south
In a novel I've just finished (The Chemistry of Death by Simon Beckett) he writes:
- leave the body in an orderly fashion, following each other in a neat procession that always heads south. South-east or south-west sometimes, but never north. No-one knows why.
The author has done considerable international research on the science of forensic identification of decayed bodies and I assume his details can be trusted.
I've looked online for any verification of this surprising statement, but found only this, which seems to debunk it.
Is there any truth to this? -- Jack of Oz 23:38, 19 December 2024 (UTC)
- Can't speak to its truth, but . . .
- Does Beckett state this in his own auctorial voice (i.e. as an omniscient narrator)? If so, he might be genuinely mistaken.
- The book was published nearly 20 years ago, what was the accepted wisdom then?
- What specific species (if any) is the book describing? – your linked Quora discussion refers only to "maggots" (which can be of numerous species and are a kind of larva, but there are many others, including for example Processionary caterpillars).
- Alternatively, if the statement is made by a character in the book, is that character meant to be infallible, or is he portrayed as less than omniscient, or an 'unreliable narrator'?
- Regarding the statement, in the Northern hemisphere the arc of South-east to South-west is predominently where the Sun is found well above the horizon, the North never, so the larvae involved might simply be seeking maximum warmth or light. {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 02:18, 20 December 2024 (UTC)
- This appears in the very first paragraph of Chapter I, which starts out:
- A human body starts to decompose four minutes after death. Once the encapsulation of life, it now undergoes its final metamorphoses. It begins to digest itself. Cells dissolve from the inside out. Tissue turns to liquid, then to gas. No longer animate, the body becomes an immovable feast for other organisms. Bacteria first, then insects. Flies. Eggs are laid, then hatched. The larvae feed on the nutrient-rich broth, and then migrate. They leave the body in an orderly fashion ... (then the quote above completes the paragraph).
- It's not until para 2 that he starts talking about any human characters, and not until para 4 that he invokes the first person.
- That's as much as I know. But I find it hard to believe he'd just make up a detail and put it in such a prominent place if it could so easily be debunked if it were not true. -- Jack of Oz 02:39, 20 December 2024 (UTC)
- I wonder how they would measure the migratory path of maggots within a sealed coffin. ←Baseball Bugs carrots→ 02:51, 20 December 2024 (UTC)
- The context of the novel is about finding decaying corpses that have been dumped in a forest. No coffins involved. -- Jack of Oz 06:08, 20 December 2024 (UTC)
- Baseball Bugs, see also body farm research facilities. Alansplodge (talk) 13:44, 20 December 2024 (UTC)
- Could it be that the larvae are setting off in search of another corpse? The prevailing wind in the UK is from the south-west, so by heading into the wind they won't be distracted by the frangrance of the one they've just left. Shantavira| 09:30, 20 December 2024 (UTC)
- The context of the novel is about finding decaying corpses that have been dumped in a forest. No coffins involved. -- Jack of Oz 06:08, 20 December 2024 (UTC)
- I wonder how they would measure the migratory path of maggots within a sealed coffin. ←Baseball Bugs carrots→ 02:51, 20 December 2024 (UTC)
- This appears in the very first paragraph of Chapter I, which starts out:
If you can, have a look at 'Heinrich, Bernd. “Coordinated Mass Movements of Blow Fly Larvae (Diptera: Calliphoridae).” Northeastern Naturalist, vol. 20, no. 4, 2013, pp. N23–27. JSTOR, http://www.jstor.org/stable/43288173.' Here are some extracts
- On the fourth day, after a cooling night with dew on the grass, a stream of tens of thousands of larvae exited from beneath the carcass within 1 h after sunrise, and proceeded in a single 1-2-cm-wide column directly toward the rising sun...
- However, in this case, the larvae left at night, within 1 h after a cloudburst (at 21 :00 hours). But, unlike before, this nocturnal larval exodus in the rain was diffuse; thousands of larvae spread out in virtually all directions over an 8 m2area. Apparently, the sudden moisture had cued and facilitated the mass exodus, but the absence of sun had prevented a unidirectional, en masse movement.
- However, on the following morning as the sun was starting to illuminate the carcass on the dewy grass, masses of larvae gathered at the east end of the carcass at 07:00 hours. In one half hour later, they started streaming in a column directly (within one degree) toward the rising sun, and the carcass was then nearly vacated.
It goes on. Maggot migration appears to be a bit more complicated than the novel suggests. Sean.hoyland (talk) 09:39, 20 December 2024 (UTC) I suppose you could try to address it from the other direction and look at the technology your average maggot has access to in terms of light detection, heat detection, olfactory systems, orientation in magnetic fields (like many arthropods) etc. They presumably have quite a lot of tools. Sean.hoyland (talk) 10:13, 20 December 2024 (UTC)
- If orderly migrating maggots tend to move towards the sun, they should display a northward tendency in Oztralia. --Lambiam 10:31, 20 December 2024 (UTC)
- Maybe, but the novel is set in England.
- I must say, as soon as I read the quoted para for the first time, my immediate thought was that it might have something to do with the magnetic field of the earth. -- Jack of Oz 10:42, 20 December 2024 (UTC)
- Prime suspect might be the Bolwig organ, the photoreceptor cluster many fly larvae have. Sean.hoyland (talk) 10:49, 20 December 2024 (UTC)
- Obviously, Jack, you need to create a corpse, place it in a nearby forest, and carefully observe which way the maggots go. For Science! And Literary Criticism! {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 21:01, 20 December 2024 (UTC)
December 20
Winter solstice and time of sunrise?
How is it that despite December 21st supposedly being the shortest day of the year, sunrise here happens later and later until December 26 and only on January 05 starts to turn around to occur earlier and earlier. On December 25 it takes place at about 08:44, between December 26 and January 04 it takes place at about 08:45, and on January 05 it takes place again at about 08:44. (Google rounds out the seconds). Is it Google's fault? Is it everywhere the same? Confused in Brussels, Belgium. 178.51.16.158 (talk) 12:06, 20 December 2024 (UTC)
- The pertinent article is Analemma, start with the section Earliest and latest sunrise and sunset. The details are not that simple to understand, but it's basically due to the ellipticity of Earth's orbit and its axial tilt. --Wrongfilter (talk) 12:22, 20 December 2024 (UTC)
- Also note that sunset begins to be later on 22 December so that the time between sunrise and sunset is a few seconds longer than on 21 December (3 seconds longer on 22/12/24 in Brussels according to this). Alansplodge (talk) 13:33, 20 December 2024 (UTC)
- Also see Equation of time#Major components. The obliquity of the ecliptic (that is, the Earth's axial tilt) is the main component and hardest to understand. But the idea is that the time when the Sun is exactly south (that is, the true noon) moves some minutes back and forth throughout the year and it moves quite rapidly to later times in late December. PiusImpavidus (talk) 19:05, 20 December 2024 (UTC)
Three unit questions
- Why territorial waters are defined by nautical miles instead of kilometers?
- Why GDP is usually measured in US dollars rather than euros? Euro would be better because it is not tied into any country.
- Are there any laws in United States that are defined by metric units?
--40bus (talk) 23:30, 20 December 2024 (UTC)
- There were nautical miles in use before there were kilometers.
- There were US dollars in use before there were Euros.
- Yes.
- The questions all reduce to Why can't millions of people make a change of historically widely accepted units that continue to serve their purpose, and convert to different units that would have no substantive difference, because someone has an opinion. Philvoids (talk) 00:52, 21 December 2024 (UTC)
- Do any people use metric units in marine and air navigation like "The ship is 10 kilometers from the port", "The plane is 10 kilometers from the destination? And is there any European country with metric flight levels? --40bus (talk) 07:22, 21 December 2024 (UTC)
- Inland shipping (rivers, canals and lakes) in Europe (except the UK) is fully metric. Ships going for example Tilbury – Duisburg may have to switch units along the way. Gliders and ultralight aircraft in Europe often use metric instruments and airport dimensions are also metric (including runway length). Countries are free to define their territorial waters in whatever way they deem fit, so with nautical miles having no legal status in a fully metric country, they may define their territorial waters as extending 22224 metres. PiusImpavidus (talk) 11:23, 21 December 2024 (UTC)
- Our nautical mile article says: "In 1929 the international nautical mile was defined by the First International Extraordinary Hydrographic Conference in Monaco as exactly 1,852 metres (which is 6,076.12 ft). The United States did not adopt the international nautical mile until 1954. Britain adopted it in 1970..."
- Inland shipping (rivers, canals and lakes) in Europe (except the UK) is fully metric. Ships going for example Tilbury – Duisburg may have to switch units along the way. Gliders and ultralight aircraft in Europe often use metric instruments and airport dimensions are also metric (including runway length). Countries are free to define their territorial waters in whatever way they deem fit, so with nautical miles having no legal status in a fully metric country, they may define their territorial waters as extending 22224 metres. PiusImpavidus (talk) 11:23, 21 December 2024 (UTC)
- As the US customary units are actually defined in terms that relate them to metric units, any US law based on measurements is technically defined by metric units.--User:Khajidha (talk) (contributions) 01:55, 21 December 2024 (UTC)
- The US dollar has been the world's dominant reserve currency for about 75 years. As for the metric system in the US, it is standard in scientific, medical, electronics, auto manufacturing and other highly technical industries. By law, all packaged foods and beverages have metric quantities as well as customary quantities. See Metrication in the United States. Cullen328 (talk) 02:28, 21 December 2024 (UTC)
- Do any people use metric units in marine and air navigation like "The ship is 10 kilometers from the port", "The plane is 10 kilometers from the destination? And is there any European country with metric flight levels? --40bus (talk) 07:22, 21 December 2024 (UTC)
The Wikipaedia article on the Nautical Mile talks about how the term originated, it was originally defined in terms of latitude not as a number of meters 114.75.48.128 (talk) 10:03, 24 December 2024 (UTC)
The euro is tied to multiple specific countries is it not? If you use euros you're just changing from one "dependency" to a "dependency" on the eurozone countries. A statement of the problem or problems intended to be addressed would be useful. Currency values are interconvertible in any case. Economics does sometimes use the "international dollar" for certain things, which is intended to adjust for differences in purchasing power between countries and over time. But since it's not an actual "real" currency it's not something one can easily "visualize" in their heads, which is likely why it's not used more. --Slowking Man (talk) 05:41, 26 December 2024 (UTC)
December 24
Unknown species of insect
Am I correct in inferring that this guy is an oriental beetle? I was off-put by the green head at first, but the antennae seem to match. JayCubby 03:00, 24 December 2024 (UTC)
(reference: https://www.genesdigest.com/macro/image.php?imageid=168&apage=0&ipage=1)
It looks like one of the invasive Japanese beetles that happens to like my blackberries in the summer.Modocc (talk) 13:11, 24 December 2024 (UTC)
- I would say not necessarily a Japanese beetle, but almost certainly one of the other Scarab beetles, though with 35,000 species that doesn't help a lot. Looking at the infobox illustration in that article, 16. & 17., "Anisoplia segetum" looks very similar, but evidently we either don't have an article or (if our Anisoplia article is a complete list) it's been renamed. {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 14:18, 24 December 2024 (UTC)
- Yes, it's not the Japanese beetle for this beetle appears to lack its white-dotted fringe although its condition is deteriorated. Its shape is also more or less more slender; and not as round. Modocc (talk) 15:02, 24 December 2024 (UTC)
- Perhaps it is the shining leaf chafer Strigoderma pimalis. Shown here. Modocc (talk) 16:09, 24 December 2024 (UTC)
- That looks like easily the best match I've seen so far, and likely correct. {The poster formerly known as 87.81.230.195} 94.1.223.204 (talk) 17:09, 24 December 2024 (UTC)
December 25
Mass of oscillating neutrino
From the conservation of energy and momentum it follows that a particle that is not subject to external forces must have constancy of mass.
If I am right, this means that the mass of the neutrino cannot change during the neutrino oscillation, although its flavoring may. Is this written down somewhere? Thank you. Hevesli (talk) 19:24, 25 December 2024 (UTC)
- Any (flavored) neutrino that is really observed is a superposition of two or three mass eigenstates. This is actually the cause of neutrino oscillations. So, the answer to your question is complicated. Ruslik_Zero 19:40, 25 December 2024 (UTC)
- Important note: particle physicists today generally only ever use "mass" to mean "invariant mass" and never anything else: . Like the term says, invariant mass is well, invariant, it never changes ever, no matter what "external forces" may or may not be involved. Being proper particle-icans and following the standard practice in the field, then, the three neutrino masses are constant values. ..."Wait, three?" Yeah sure, turns out neutrinos come in three "flavors" but each flavor is a mixture of the three possible mass "states". As mentioned, due to Quantum Weirdness we aren't able to get these different states "alone by themselves" to measure each by itself, so we only know the differences of the squares of the masses. Yeah welcome to quantum mechanics.
- Richard Feynman: "Quantum mechanics describes nature as absurd from the point of view of common sense. And yet it fully agrees with experiment. So I hope you can accept nature as She is – absurd." --Slowking Man (talk) 06:06, 26 December 2024 (UTC)
- The equation uses invariant mass m0 which is constant if E and p are constant. The traveling neutrino has a varying mass mixture of different flavors with different masses. If a mixture of different masses changes, you would expect the resulting mass to change with it. But somehow this does not happen as the neutrino mass mixture changes. These mixture changes cannot be any changes. The changes must be such that the resulting mass of the traveling neutrino remains constant. My question is whether this is described somewhere. Hevesli (talk) 11:16, 26 December 2024 (UTC)
- I freely confess I'm uncertain exactly what's being "asked for" or "gotten at" here. Have you looked at the neutrino oscillation article? From it:
That is, the three neutrino states that interact with the charged leptons in weak interactions are each a different superposition of the three (propagating) neutrino states of definite mass. Neutrinos are emitted and absorbed in weak processes in flavor eigenstates but travel as mass eigenstates.
- What is it that we're "doing" with the energy–momentum relation here? For the neutrino, we don't have a single value of "mass" to plug in for , because we can't "see" the individual mass eigenstates, only some linear combination of them. What you want for describing neutrino interactions is quantum field theory, which is special relativity + QM. (Remember, relativity is a "classical" theory, which presumes everything always has single well-defined values of everything. Which isn't true in quantum-world.) --Slowking Man (talk) 18:41, 26 December 2024 (UTC)
- Not all potential evolutions of a linear combination of unequal values produce constant results. Constancy can only be guaranteed by a constraint on the evolutions. Does the fact that this constraint is satisfied in the case of neutrino oscillation follow from the mathematical formulation of the Standard Model, or does this formulation allow evolutions of the mass mixture for which the combination is not constant? If the unequal values are unknown, I have no idea of how such a constraint might be formulated. I think the OP is asking whether this constraint is described somewhere. --Lambiam 00:51, 27 December 2024 (UTC)
- I freely confess I'm uncertain exactly what's being "asked for" or "gotten at" here. Have you looked at the neutrino oscillation article? From it:
- The equation uses invariant mass m0 which is constant if E and p are constant. The traveling neutrino has a varying mass mixture of different flavors with different masses. If a mixture of different masses changes, you would expect the resulting mass to change with it. But somehow this does not happen as the neutrino mass mixture changes. These mixture changes cannot be any changes. The changes must be such that the resulting mass of the traveling neutrino remains constant. My question is whether this is described somewhere. Hevesli (talk) 11:16, 26 December 2024 (UTC)