Although light sensitive cells, which eventually lead to the evolution of eyes, are so advantagious that when they do randomly develop they tend to stick around. Which is why the eye has seemingly evolved independently many times. See convergent evolution --Majts 02:53, 20 October 2005 (UTC)

Life can exist in a much broader range of environments than we're usually taught in secondary school biology; see extremophile. And those are just organisms evolved on earth. The evolution of life on Earth itself was not terribly predictable and involved a great deal of chance- there's a book about this by Stephen Jay Gould called Full House.--Pharos 10:13, 19 October 2005 (UTC)

Organisms could even develop resistance to UV-rays if they were situated on a planet orbiting a dwarf star. But then again, it depends on the heavenly lottery, where life is going to evolve. Intelligent life, on the other hand, could already possibly exist, although either they are to shy to communicate with us, have tried to remove all traces of their existence so as not to be bothered by stubborn Earthlings, or have not yet developed the technology to communicate with other alien beings. If intelligent life other than our own races existed, I'd dare say that they don't want (or need) visitors from beyond. Don Diego 10:18, 19 October 2005 (UTC)

No, it won't take the same form, for the same reasons the dolphins can't mate with sharks. Even on earth, the role of chance in evolution is overwhelming, and even where organisms of different origins have evolved similar traits to fit similar ecological niches, they are still very radically different. Alien organisms should be even more different. I think this is one of the stronger arguments against the existence of intelligent alien life - I think that it is as wrong to imagine aliens being intelligent in the way humans are as it is to imagine sharks to act like dolphins, and I have yet to see a convincing definition of intelligence that doesn't boil down too "seems to be like humans". --Diderot 10:53, 19 October 2005 (UTC)

I would say dolphins are rather similar to sharks (at least the smaller sharks that eat fish). They have similar skin and fins, no hair or fur or feathers, no visible ears, etc. These similarities are remarkable considering how different the evolutionary paths are that led to those creatures. Another example of parallel evolution is bees and hummingbirds, which both independently devloped the ability to hover in flight in order to feed off flowers. StuRat 23:08, 21 October 2005 (UTC)

I assume that we are talking about life as we know it....Capitan. :-) --Eye 22:15, 19 October 2005 (UTC)

There are some interesting speculations about additional conditions for life at the Fermi paradox article. --JWSchmidt 00:08, 20 October 2005 (UTC)

Who says life can't be silicon-based? --65.188.159.140 02:57, 20 October 2005 (UTC)

• Of course, even most mainstream scientists will admit that there's no evidence of any life sustaining planets, anywhere else in the galaxy, and that man is most likely a unique creation--WwJd 04:20, 20 October 2005 (UTC)

• Keep in mind, "life" is only a word; a literal metaphor used to express an idea. This would require us to define what life is. Some suggest fire is alive. It is born in a sense, and it dies in a sense. Fire consumes, and it also reproduces. In this case, if we are to suppose that our definition of life must in some way or another involve DNA, then yes, there are very specific requirements (carbon, oxygen, nitrogen, and hydrogen, as well as a number of other spacial requirements), but as suggested above, why can life not be silicon based? Or an as yet to be discovered form? What I'm getting too is that with this perspective in mind, the universe itself can be seen as alive, and we (being carbon-based lifeforms) are only one of a potentially countless array of possible configurations. - Cobra Ky (talk, contribs) 04:55, 20 October 2005 (UTC)

Might I suggest an article to open your minds?

• Alternative biochemistry- Cobra Ky (talk, contribs) 04:36, 20 October 2005 (UTC)

The idea that everything is alive sits well with me even if it is only in the spritual sense. --Eye 22:06, 20 October 2005 (UTC)

Life exists many places on our planet where we humans cannot, although perhaps not sentient life.

• North and South Poles
• Bottom of Ocean
• Inside caves and caverns where there is never any light
• Underground (what do worms eat?)
• High in our atmosphere
  • Around Hot gas vents called Black Smokers
  • Around Hot water springs Mud Pots Artoftransformation 09:14, 31 October 2005 (UTC)

Consider a system with 2 or more stars orbiting each other, or a black hole, or whatever, there's enough radiation there for planets to be further away and sustain life.

Our moon is humogous relative to our planet by average standards, so we evolved with significant tides, very rare as averages in our known universe goes, although telescopes not yet telling us a whole lot about planets around other stars. How come our moon is so large? Well I buy the arguement that once upon a time there was a planet between Mars and Jupiter that broke apart, and a lot of the pieces did not stay where the asteroid belt now is, they flew outwards and inwards, and some were captured by gravity of other planets, one of which being our moon. I recognize that is not the most popular theory of astronomy.

Meteors have been found with fossils inside. How did they get there? Most plausible to me is that when our planet was hit with a really large rock from space that made a crater like Hudson's Bay in Canada, the rock that killed off the dinosaurs, etc. that some of our planet splashed into space, and those chunks of rock had life that became fossilized, but there is an argument, that I cannot follow, that says some of that came from Mars. Assuming these rocks carry simple life that can come off them and thrive again, when given moisture and light, then contamination can travel from planet to planet. AlMac| 01:33, 26 October 2005 (UTC)

See Drakes Equation Artoftransformation 09:14, 31 October 2005 (UTC)

Brain hyperactivity

Throughout my entire life, I had a problem with "thinking". I always thought way too much about things, all sorts. I can't control it at all, and in several occasions I got headaches and sick because of it. It's physically PAINFUL sometimes (I get tense and my throat, face, neck and guts hurt). I've tried learning relaxation techniques and all, seen psychologists, and even got to a few doctors who offered me some medication (fluoxetine). It didn't work. Recently I had an issue with a friend, partially because of this. I, of course, am feeling terrible about it. The problem is, this led to a major impulse in this thinking pace, and I can barely sleep now. I'm hardly hungry (but I got more thirsty for some reason). And this all scares me. I'm beginning to think there's something neurological behind this. So I set an appointment with a neurologist. I'm not sure if this is the best thing to do, but can't be any harm, eh?

My question is this: are there any sort of neurological conditions that cause this sort of problems? If so, what sort of medical solutions can be taken? If not, what could I possibly do, I've ran out of ideas here.

Attention-deficit hyperactivity disorder, Obsessive-compulsive disorder, and Amphetamine use come to mind. (I'm not a doctor -- you should wait to see your neurologist before jumping to any conclusions.) --Quasipalm 14:28, 19 October 2005 (UTC)

OCD, perhaps, but the rest? I don't think so. I don't have problems with ADHD, I can focus on things and everything, I just can't control thinking about everything else while I'm at it at the same time. This is what bothers me.

Have you considered meditation? Also I can't help wondering whether you need to get more exercise. Your diet might also be a factor. Shantavira 19:10, 19 October 2005 (UTC)

Yes I have, along with the relaxation and all... Tried it 15 minutes/day for about a month, and I just couldn't stop these "streams". Also, this triggered some sort of double personality, so I started arguing with myself, inside my head, while I was with this. It's like some other part of me was trying to disturb me. Now, excercise and diet seem more likely to be an issue. I'm very sedentary and my diet is poor (i'm underweight and my diet is not very rich, indeed)...

Proper diet and exercise might well be the cure. Even if they aren't, getting healthier can't exactly hurt, can it ? I particularly think the balance of electrolytes is critical. I have noticed I get muscle spasms when I haven't eaten well, maybe it affects your brain. If, and only if, proper diet and exercise fail to fix the problem, should you consider going to psychoactive meds. They could mess you up, so don't risk it unless you've used up all other options. StuRat 22:57, 21 October 2005 (UTC)

The symptoms you describe could means lots of things, including a little bit too much anxiety and self-analysis. None of us have any business diagnosing you with anything definite. However, I will offer guidance to the right kind of doctor. Your symptoms undoubtedly fall on the mind side of the old cartesian mind:brain divide. Whether you need reassurance and insight, constructive suggestions, or diagnosis and treatment, you will get more help, more sympathy for the symptoms, and a more experienced perspective from a mind doctor than a brain doctor. I promise I am saving you a step. Good luck. alteripse 23:09, 19 October 2005 (UTC)

Yes, but I've seen psychologists and they all said the same thing: that I had some self-esteem issue so I was constantly judging myself, and that I'm too anxious with things, so I judge them too often. They sent me to this other guy who gave me the fluoxetine, which, like I have stated, didn't help. BTW, I'm 19.

I would be careful. I was diagnosed with OCD and put on medication. Nothing worked. I had 4 different kinds over 4 years. By then I was a wreck. Finally I found out I did not have OCD. It has taken me years to recover. If the problem is just thinking, then that is not really a problem. If the problem is thinking about the same things over and over without any resolution, that is an anxiety disorder. You are probably very smart and like to think about things, like quantum physics. Arguing with yourself might just be a very pronounced way of resolving inner issues, trying to make decisions. Alteripse is right, though, when saying none of us has any business diagnosing you by 'remote control' this way. Find a good counsellor and get some help, it may be you just have an active imagination. Top priority is to find a counsellor you trust.

I have a similar problem, though nowhere near as serious. I just can't get to sleep because I'm constantly thinking of things. A 'solution' that has worked for me for 25 years is to smoke some marijuana before sleeping. Just a bit works wonders. A big advantage is that if it doesn't help it won't hurt any either. A potential major problem is that it can land you in prison in many countries (I have the good fortune to live in the Netherlands). Although even in the US it's accepted as a legal drug these days, I believe. You'd just need a doctor to prescribe it to you. DirkvdM 15:07, 24 October 2005 (UTC)

The body is designed to breathe, move (exersize), eat, excrete, socialize and have sex. Your brain will continue to nag you until you give it what it wants. Stop repressing yourself. WAS 4.250 00:58, 26 October 2005 (UTC)

Define gravitation

Please remember to search before asking questions; see our article on gravitation.

Take a look at gravitation. — Laura Scudder | Talk 16:36, 19 October 2005 (UTC)

It's also a huuuuge book by John Wheeler, but Laura's link will probably be more helpful. -- SCZenz 16:39, 19 October 2005 (UTC)

Basic binary sum circuit

I had to create a basic binary sum circuit for my computing class, where three single-digit inputs would be summed to obtain two outputs, one for each digit of the sum (e.g.: if I had 1, 1 and 1 as input, I would get 1 and 1 as output; if I had 1, 1 and 0 I would get 0 and 1, and so on). I can do the first digit no problem - (A xor b) xor C - but I'm having some trouble doing the second digit. So far I have succeded in summing the first two inputs - A and B - but I don't know how to sum the third. Any help? :) Sorry if this explaination is somewhat incoherent, but English is not my native language -- Whitetigah 16:39, 19 October 2005 (UTC)

Try looking at the adder article. --cesarb 16:49, 19 October 2005 (UTC)

Thank you, that was exactly what I was looking for :) -- Whitetigah 17:41, 19 October 2005 (UTC)

astrophysics

why are almost all planets in the solar system coplanar i.e all their orbits lie on a single plane?is it specific only tothe solar system or is it found in other planetery systems?

They are not exactly coplanar. You may read the Protoplanetary disc article for some insight. There is also the issue of outer planets acting like large vaccuums, and removing smaller planetoids, and other bodies with odd orbits. Dominick 17:13, 19 October 2005 (UTC)

You might be interested in the discussion on this question elsewhere at the Ref Desk. Note that Pluto's radical inclination is widely believed to result from Pluto's post-creation capture as opposed to the co-formation of the other planets. 199.209.144.218 17:28, 19 October 2005 (UTC)

Sand bags

Considering the relatively higher permeability of sand compared to clay, shouldn't we ideally be using "clay bags" rather than "sand bags" in a flood?--Commander Keane 17:46, 19 October 2005 (UTC)

• My guess, which is only my guess, is that clay is a lot harder to move around than sand. --jpgordon∇∆∇∆ 18:02, 19 October 2005 (UTC)

Sand can be removed later, clay sets and sits in one place. Sandbags collect garbage from the floodwaters and do a surprizingly good job at damming a flood, from my personal FL experience. (Turn Wilma turn!) Dominick 18:08, 19 October 2005 (UTC)

That's the great thing about sandbags: even if some water gets through the sand it's clean, so you just have water damage, rather than mud/gunk everywhere on top of water damage. I'd also think that the fact that sandbags naturally reshape themselves to fit their neighbors is a big advantage over clay. — Laura Scudder | Talk 18:35, 19 October 2005 (UTC)

Sandbags are particularly useful as secondary supports. An unsupported concrete wall can easily be pushed over in a flood, due to the pressure differential between water on one side and air on the other. If sandbags are piled up against the air side, that will substantially eliminate the pressure differential and prevent collapse. StuRat 22:46, 21 October 2005 (UTC)

A few questions about Hybrid vehicles like Prius

I have a few questions about hybrid vehicles like Toyota Prius. What I want to know is- 1) How much more hybrid vehicles like Prius cost (in %) more than gasoline powered vehicles with similar power and capacity? 2) How many times mileage does Prius or other hybrid vehicles give compared to similar gasoline vehicles? 3) Should we charge the battery that runs the car similar to electric cars? 4) Are all hybrid vehicles automatic geared?

Many of your questions can be answered at hybrid vehicle, or by surfing the web sites of car manufacturers. But here's some quick and dirty answers:

1. According to Toyota's web site, the Prius starts at US$21,275, whereas the Matrix, which seems to be of a similar size, starts at $15,110. So it's about 35% more expensive. But I'd bet you'd make up the cost in gas savings fairly quickly.
2. Toyota's site says the Matrix gets up to 30 city MPG, whereas the Prius gets 60 city MPG. Of course, numbers straight from the company like this are always wishful thinking…
3. No. The battery is actually charged by the gas engine.
4. That one I'm not sure of.

Garrett Albright 18:51, 19 October 2005 (UTC)

RE: #3 -- Some people have actually hacked their cars to be able to plug them in overnight at home. See here. They reported that the Prius was able "to reach between 100 and 180 MPG in a typical commute" after the change. So, why don't hybrid cars ship with the ability to plug-in? Reportedly, because car companies were so afraid that people would think that cars that plug in would be annoying or weak, they didn't even build them with the option. Dumb, eh?

RE: #4 -- The Honda Insight has a manual / hybrid version.

--Quasipalm 19:06, 19 October 2005 (UTC)

The matrix is significantly larger than the Prius, the Prius is more similar in size to the Echo. A better comparison would be the Honda Civic ($14,650) vs. the Honda Civic Hybrid ($21,850), that's a 50% difference in price and averages 15mpg better. That means at 10000 miles/year and gas at $3/gal, The Civic would use 285 gallons of gas a year and the Hybrid would use 200 gallons of gas a year. That means you save a whopping $255 a year, which means you would have to own the hybrid for over 28 YEARS for you to come out ahead. Despite the manufacturer's marketting, Hybrids are still nowhere CLOSE to economically feasible. Even with gas at $5 a gallon, it would take almost 17 years, with gas at an absurd $10/gallon, it would take 8 and a half years. -Drdisque 22:21, 19 October 2005 (UTC)

Here's a great site, Garrett, fueleconomy.gov. --Quasipalm 23:15, 19 October 2005 (UTC)

Avian influenza

Is VIRA 38 snake oil or actually capable of reducing the risk of catching avian influenza should it begin to spread amongst humans? Also, is Tamiflu available anywhere via mail-order without a prescription? I'm not freaking out or anything, but Science Friday freaked me out a little last week. (Perhaps it's a good time to re-read The Stand ;-) --Quasipalm 18:56, 19 October 2005 (UTC)

I'm having trouble finding published research on "VIRA 38". As far as I know, the neuraminidase inhibitors such as Tamiflu have only been tested in short-term experiments. It is not clear to me that they are the solution to a flu pandemic. The idea that the world should stock pile these drugs in order to limit a pandemic seems to be a good way for a few drug companies to make a lot of money. It may be that the money would be better spent on ways to limit exposure of humans to the avian flu virus and development of vaccines. --JWSchmidt 23:53, 19 October 2005 (UTC)

A vaccine cannot be developed until the virus mutates into a form that can cause the pandemic. There is a delay of 4 - 6 month before enough vaccine can be produced. So the idea is, that antivirals will reduce the death toll in the meantime. Theresa Knott (a tenth stroke) 23:57, 19 October 2005 (UTC)

A human vaccine for the avian flu virus has already been reported ("AVIAN INFLUENZA: 'Pandemic Vaccine' Appears to Protect Only at High Doses" by Martin Enserink was in Science, Vol 309, Issue 5737, 996 , 12 August 2005 doi:10.1126/science.309.5737.996b). If actions (such as vaccination) were taken to protect against infection of humans by existing avian flu virus, then there would be a reduced chance of a mutant form evolving that would easily transfer between humans. There can be some protection from antibodies to a type of flu (like H5N1), even if the antibodies are made against a different variant of the type. If humans were vaccinated against the existing H5N1 type bird flu, there would be some protective antibodies that would cross-react with new mutant strains. I'm not saying that the neuraminidase inhibitors are useless, but I'm not sure that they are the best way to throw money at the problem, particularly if it just turns into a matter of those few who can afford the inhibitors getting them via mail-order. --JWSchmidt 00:33, 20 October 2005 (UTC)

Pulseless Electrical Activity PEA (EMD)

Hello, I hope you can help with this enquiry, I am currently on a medical course and have just failed a practical assesment. I was following the protocol as I understood it in that I shocked my PVT patient four times until their rhythm changed. What I saw was a sinus rhythm and checked the carotid pulse and was told that there was a weak palpable pulse. I interprited this as sinus rhythm and gave AV for one minute and re analysed patient. On completion I was told that the patient had been in PEA and should have commenced CPR. Am I way off the mark or can you as was explained to me by the assessor a palpable carotid pulse in PEA?

Many thanks Alastair Palmer --62.189.84.170 18:57, 19 October 2005 (UTC)

A Google yielded our Pulse article, the baseline Emergency Medicine guideline to palpate for carotid pulse for 10 or more seconds as a preliminary for CPR, and some additional guidelines for performing immediate surgery. It looks like the technique is fundamental for physicians. But a further Google using the exact wording on your question also indicates this is a pre-terminal condition with a 5% survival rate, so it is unclear to me why CPR for PEA (EMD) is more than a stopgap; a 3rd Google shows that the CPR responder should also be requesting Advanced cardiac life support (ACLS) at the same time. Thanks for posting the question. But the Google hits make me wonder whether the symptom lack of carotid pulse=>CPR is consistent with weak palpable pulse. What did the assessor mean by this? Ancheta Wis 10:31, 21 October 2005 (UTC)

Infinity

Many years ago I remember my maths teacher saying that mathematicians didnt use infinity in equations. Something to do with things not adding up. I was never interested in maths but that has always stuck in my head. Is this true? If it is true how then does science deal with infinity when the language of science is maths and infinity in terms of the universe is ..well .a distinct possibility.--Eye 22:12, 19 October 2005 (UTC)

You can't use infinity as some form of quantity, because when you try and do tricky things with it, things break down. Sure, inf + inf = inf, 2*inf = inf, but what is inf/inf? (Suppose inf/inf = a, then inf = a inf. You can choose any such a and the equation will still work). There are other cases like this.

However, infinity can be a useful symbolism. If you want to express the sum 1/2+1/4+1/8+..., you can write it as

${\displaystyle \sum _{i=1}^{\infty }{1 \over 2^{i}}}$

but really, this is the same as saying

${\displaystyle \lim _{n\rightarrow \infty }\sum _{i=1}^{n}{1 \over 2^{i}}}$

where the "lim" means the limit as you let n get larger and larger.

So infinity is more like a concept than a quantity. Lots seem to get entranced by the idea of infinity, so you should get a large response here... Dysprosia 22:35, 19 October 2005 (UTC)

(Added after edit-conflict so might be parroting Dysprosia a bit).

The thing with infinity is that it really makes no sense. Take for instance the classical example of divison by zero. Lets try dividing 5 by zero:

${\displaystyle {\frac {5}{0}}=\infty }$

Ok, so far, so good. Well, that must mean.....

${\displaystyle {\frac {5}{\infty }}=0}$

Sure, sure, ok, good.....

${\displaystyle {\frac {5*\infty }{\infty }}=0*\infty }$

Hmm, where are you going????

${\displaystyle 5=\infty *0}$

What???? Infinity times zero equals 5!!! Cool!! Anyway, the point is, when you treat infinity like a normal number (ie you put it in formulas and subject it too normal algebraic operations like cancelling out factors from a divison), ridiculus stuff happens. When math has to deal with infinity (and infinitismals), such as in calculus we replace them with limits. A limit is basically a number that goes "very, very close" to a certain point (such as infinity or zero). For instance, to find the derivative of the function x^2 (if you don't know what a derivative is, don't worry, it doesn't really matter) you have to simplify this equation:

${\displaystyle {\frac {x^{2}-(x+h)^{2}}{h}}}$

Where h is a number that is an infinitismal (ie an "infinitly small number", a number as small as possible). Normally, this would break the division by zero-rule, but if we impose limits we can work with it.

${\displaystyle \lim _{h\to 0^{+}}{\frac {x^{2}-(x+h)^{2}}{h}}}$

${\displaystyle \lim _{h\to 0^{+}}{\frac {x^{2}-(x^{2}+2hx+h^{2})}{h}}}$

${\displaystyle \lim _{h\to 0^{+}}{\frac {2hx-h^{2}}{h}}}$

${\displaystyle \lim _{h\to 0^{+}}{2x-h}}$

Now, since h is so tiny that it really doesn't change the result anymore (since it's basically 0), we can safely remove it and the limit and get the answer, 2x. This is a bit (alot) simplified since you are a non-mathematician (so am I btw, I'm a serious dilettante), but that's the gist of it. gkhan 22:54, 19 October 2005 (UTC)

Mathematicians definitely do use infinity, although for reasons the above posters mention, you must use care, or you'll end up in trouble. There are in fact several different numbers which could be called infinity. There is the infinity in the extended real line, which satsifies a bunch of things like infinity + any number = infinity. The expression infinity*0 is left undefined (no one claims that infinity*0=5). Other infinities include omega and aleph nought, and many more. -Lethe | Talk 01:06, 20 October 2005 (UTC)

Of course any discussion of infinity (you have at least skimmed that article right?) would be lacking without a mention of cardinality of infinity. That is something that blows most peoples minds when they first learn of it because they are used to the conventional wisdom of infinity being the biggest thing out there. How could there possibly be different sizes of infinity? Well at least in set theory there is. - Taxman 18:17, 20 October 2005 (UTC)

I think you people are deliberately trying to confuse me. :-) --Eye 20:14, 20 October 2005 (UTC)

If ${\displaystyle 1/\infty =0}$ then one might assume that the infinity being referred to is countable. However, if one accepts the existence of countable infinity, then by set theory (see Cantor's diagonal argument), one must also accept the existence of uncountable infinity. If the reciprocal of countable infinity is zero, then surely the reciprocal of uncountable infinity is also zero? Of course. But then what is the reciprocal of zero? Is it countable or uncountable? It cannot be both, because if 1/0 is equal to both infinities, then the two infinites are equal to each other, which they are not, by definition. So paradoxes such as these blow up in one's face, and one must conclude that infinity is somewhat beyond ordinary grasp.

It depends on what field of numbers one is dealing with. The field of real numbers does not include infinity even though its cardinality is uncountable infinity. So when one asks "how many real numbers are there?" the answer is not a real number. Real numbers are good enough for practical purposes: infinities being dealt with as limits. However, it is possible to define other mathematical structures which include things which are called "infinities". For arithmetic, see surreal numbers. For geometry, see projective geometry.

Physics is based on the ability to take measurements of physical quantities, such as mass, distance, and time. When an experimental physicist makes a measurement, the instrument which makes the measurement is finite, and the number resulting from that measurement is finite. Physical theories are confirmed by being tied down to experiment (see empiricism) and physical experiments always give finite answers. Physics deals with infinities by getting rid of them, by hook or by crook: see regularization and renormalization.

Mathematics, on the other hand, is rationalistic and not empirical. Mathematical structures are tested by self-consistency: if it is not self-consistent, it does not exist. Each mathematical structure is self-contained and independent of other structures, so Euclidean geometry and Riemannian geometry each have their own separate existences, even though they would contradict each other. (Likewise, the theory of infinity has two branches, one which accepts the continuum hypothesis, another which rejects it: but each branch capable of being self-consistent.) Moreover, mathematical structures do not have physical existence. The number five does not physically exist. One might have five finger's on one's hand, but the five fingers are not the number five. One might draw a red number 5 on a paper, but that five is not the concept of number five. The symbol ${\displaystyle \infty }$ for infinity is not itself infinite. The symbols which mathematicians manipulate on paper are all finite. Infinites are known only indirectly, through logical inference, and inhabit a non-physical realm. So when one says "There are a countable infinity of natural numbers", those numbers do not really exist physically. Besides, if mathematics only dealt with infinities, it would be impractical and rather useless and mathematicians would not gain their bread, whose quantity is finite, positive, and non-zero, which they eat regularly in order to obtain a finite, positive, non-zero amount of energy (see pragmatism). On the other hand, mathematics does have a corner of its realm permanently reserved for infinities: as Hilbert said: "No one can drive us from the heaven which Cantor created for us." —Anonymous, 20 October 2005

What's infinity + -infinity? Jazz1979 10:58, 30 October 2005 (UTC)

+ (inverse )is a arthmatic operation, and might not be valid on non-numbers. The algebra of infinity is a subset of mathamatics called Non-Standard Analysis.

See this link: to Summarize: infinity + a constant = infinity .: infinity + - infinity = a constant.

For a more precise definition:

October 20

Computer science and math skills

I'd like to know just how skilled one would have to be at mathematics in order to go into the field of computer science. After reading some articles on the subject here on Wikpedia (which I could barely understand, if at all) it seems like a fascinating field. Impaciente 01:09, 20 October 2005 (UTC)

Computer science is broken into several branches, including computer engineering/architecture which requires some technical skills to learn what component functions are, computer programming, which is oriented towards learning languages and a form of qualitative logic that is needed to understand the workings of the code of the program, and then, computer networking and information technology, which is concerned with computer services and networks. In computer programming, generally very little math is required, but that is only in my experience. Pick out books or articles about certain regions of comp-sci and find your way through the subject.--Screwball23 02:02, 20 October 2005 (UTC)

My experience has been that computer science doesn't require a complex mathematical background. In completing my Bachelor's degree, I would have only encountered complicated mathematical formulas once or twice (in case you are wondering, Data Communications and a subject on Artificial Intelligence). Apart from these two instances, I think a sound knowledge of algebra and problem solving will probably get you through (bear in mind I am Australian, so maybe your education system is a bit different). Ranglin 02:56, 20 October 2005 (UTC)

However, if you want to become an computer science researcher, as distinct from a practising programmer/software engineer, mathematics skills become a lot more important. A friend of mine did a PhD in the computer science department at Princeton University; he didn't write a single computer program during that period. His work was entirely mathematical. Much of theoretical computer science is essentially a branch of discrete mathematics, there may be a lot of statistics in some areas, and many topic areas (such as computer vision) require a fair bit of mathematics.

In any case, while higher mathematics may not be strictly necessary to become a computer programmer, the mindset that it teaches you is a very valuable skill in becoming a good one. Maths is good for you :)--Robert Merkel 03:08, 20 October 2005 (UTC)

While this is generally true, it is possibly to get even a PhD in CS if you are not so good at math (although it is hard in practice). There are some areas within CS that require less math, notably systems. Having said this, it really really helps if you are good at math. First, because fundamentally programming is logic (i.e. math), and you have to be good at programming to get a CS degree. There are, however, people who are bad at math and good at programming, although this is not common. Second, to be a good programmer, you really need to understand certain concepts which are mathematical in nature (e.g. computational complexity). One thing to remember is that the kind of math one needs for CS is different from the sort of math one is used to in high school or math college courses. In particular, calculus is not especially important. Ornil 05:05, 20 October 2005 (UTC)

I first went to university hoping to score a degree in computer science. However, my high school had an experimental math program known as College Preparatory Mathematics that sure as hell didn't prepare me for college math, and I scraped by with a D- in pre-calculus, a class that didn't count toward the degree anyway. I gave up and switched to English literature. However, I know how to program; I've been writing programs of various degrees of complexity since I was twelve or so, and the most complex thing I've run into is parabolic equations. So really, even though higher math isn't seen so much in programming in the real world, you do need to have a knack for math to get a degree in computer science. Garrett Albright 14:04, 20 October 2005 (UTC)

I'm an application programmer speciallizing in CAD and database apps. While I have used advanced math up to calculus in some of the applications (calculating component masses for center of gravity analysis), this is just my case, not typical. I would say a typically programmer won't have to deal with more than basic math, perhaps time math and percentages being the limit (used for benchmarking how much faster one version of a program is than another). Knowing how to extrapolate a graph is also quite useful..."If the program can process 10 items in one second and 100 items in ten seconds, it should take how long to process 1000 items ?". If you work with graphics, some knowledge of geometry is also needed, such as the formulae for distance and a circle. StuRat 22:22, 21 October 2005 (UTC)

I majored in math in college because it was my favorite and best subject in high school, then discovered to my dismay that college math is a totally different subject than high school math, then was pleased to discover that college physics is very similar to high school math, so I switched majors. Out of college, I discovered that what I had learned in college had no correlation with what the job market was looking for, talk about not planning ahead, but most everyone that way. I went into computing because of an illusion that there was some relationship between computers and math, and found that from perspective of the end user, and the worker in the field, computers have as much to to with knowing math, as driving an auto has to do with knowing how the auto works inside the engine. About the only mathematical stuff I have needed in a multi-decade computer career has been decent estimating skills. I mean write a program to get certain answers. How do you know it is getting right answers? How do you know you not have a rounding error? Well in my brain I can get ball park answers to compare with computer answers. AlMac| 01:44, 26 October 2005 (UTC)

Excel column headings

I'm using Excel 2003. Every worksheet comes up with numeric headings at the top of columns. How can I change this to alphabetical headings? I've searched the Excel section of the Microsoft Office 2003 All In One manual but without finding a solution. I have a feeling I'm missing something pretty basic, but what?

Erasmus 02:12, 20 October 2005 (UTC)

Go to Tools/Options/General and deselect "R1C1 reference style".-gadfium 02:48, 20 October 2005 (UTC)

Thanks, Gadfium, it works beautifully. You've saved me hours of thrashing around. Erasmus.

Who manufactures the buses of the so-called "Wiki Wiki" shuttle line at Honolulu International Airport?

The buses are owned by the State of Hawaii and operated by Airport Group International. Who is the manufacturer?

Example photo: http://www.futureofthebook.org/blog/archives/wikiwikibus.jpg .

I don't recognise the badge logo, and the picture is too low-resolution to zoom in and tell that way.

Why not contact the operators and ask? --Robert Merkel 03:32, 20 October 2005 (UTC)

What are the interrelationships between science and technology?

What are the interrelationships between science and technology?

Our Technology article states: "The lines between science and technology are not always clear. Generally, science is the reasoned investigation or study of nature, aimed at finding out the truth, generally according to the scientific method. Technology is the application of knowledge (scientific, engineering, and/or otherwise) to achieve a practical result (Roussel, et.al.)." Capitalistroadster 08:09, 20 October 2005 (UTC)

• It's a very big and complex question. Scientists create technology in order to do science (think of Galileo and the telescope), but it is also often a case of a solution looking for a problem (nobody was enthusiastic about PCR when it was invented, for example, because they were worried about different problems than the one it would eventually solve). Sometimes technologies in a broader sense are derived from scientific understanding (the nuclear reactor from nuclear fission, for example), though the conversion is in no means usually simple ("reduction to practice" is often quite difficult, because no technology is reliant on elementary scientific notions alone). On the other hand, there are technologies which were created without any reference to scientific knowledge — in many cases the technology comes first and is understood by the science later.
• In short, they are very interrelated activities, and the forms of causality (what causes what) goes both ways at different times, and at times they have nothing to do with each other at all. Hopefully that answer gives you some food for thought. If you want to read an interesting book about the relationship between invention and science, I recommend Thomas Hughes, American Genesis: A Century of Invention and Enthusiasm. --Fastfission 16:54, 20 October 2005 (UTC)

CCE

What does "CCE" in various Atari 2600 games stand for? (some exposition or exhibition?) Thanks.

CCE was the (unlicensed) company that used to sell some Atari 2600 games and other stuff here in Brazil (and apparently in the rest of South America too). I suppose that ROMs with the CCE text were ripped from Brazilian\South American cartridges. EDIT: take a look at this page I found too ☢ Ҡieff | Talk 06:00, 20 October 2005 (UTC)

On another note, the company still exists and its products are worthless than junk. ☢ Ҡieff | Talk 07:43, 20 October 2005 (UTC)

Opening Matlab

I currently have Matlab installed on my computer. But when I open the program it gets to the initalising stage and then closes again. So far I have tried reinstalling windows and also resinstalling the service packs. But it still wont work. Does anyone have any ideas on the cause or solution to this problem, would be of great assistance.

• I don't use Matlab myself, so I'm probably of little help in that regard, but I'd like to tell you to be careful about reinstalling Windows. It may break settings you've had or if there's a problem, kill your computer altogether. Only try reinstalling Windows as a last resort in the future. - 131.211.51.34 07:22, 20 October 2005 (UTC)
  • Matlab seems to do a lot of thing on startup, so a diagnosis will be interesting. It may check to see how many concurrent licences are running on the network etc. Try searching Mathworks support for some help. I dug up Problems Starting Matlab which might be of some use. Good luck!--Commander Keane 11:16, 20 October 2005 (UTC)

Breakdown of a trillion dollars in ways people can easily understand.

Hello, all. I have a question/favor to ask. This question may be in a wrong column for asking, but here it is. Long time ago, I saw in a newspaper with a columnist showing and explaining just how much a trillion dollar is, in a sense of talking about national debt, and to make it easier for everyday folks to understand, there was a breakdown of a trillion dollars on this column. A broad general example would be that a trillion dollars is enough money to buy 30 NFL football stadiums, 100 3-carat diamond rings, 100 Corvettes, and still have a lot of money to buy or do other things. For some reason, a columnist's name Dave Barry comes to mind. I may be totally wrong on who this columnist was back then, but if anyone out there has any positive feedback or information or the article on it, I would really appreciate the information. Thanks.

Porc

Which trillion you're talking about? I don't know which is used in USA. ☢ Ҡieff | Talk 07:53, 20 October 2005 (UTC)

It would be the US trillion, as the British trillion is far more money than exists on Earth. StuRat 22:03, 21 October 2005 (UTC)

• According to Wordnet on answers.com, the US usage is one followed by 12 zeros see . Everywhere else, it is one followed by 18 zeros. As to your question, I don't know but Dave Barry sounds plausible see . Capitalistroadster 08:18, 20 October 2005 (UTC)

Everywhere else is not true. ☢ Ҡieff | Talk 09:22, 20 October 2005 (UTC)

Not to miss the point, but that sounds like kind of a crappy explanation of a trillion (american i guess) dollars. By my count, you could buy 97 $10B stadiums, 100,000 $200k Ferrari F1 Spiders, and 100,000 5 carat diamond rings (for $80k ea.), and still have money ($2 billion dollars) left. You know, for what its worth. (edited for more casual numbers). --Jmeden2000 21:45, 20 October 2005 (UTC)

I do remember a picture-based representation of how big a stack of bills you would need to represent a certain very large amount in cash, but I don't remember where I saw it (it was very impressive though). But I found this via a quick search (see second paragraph). Tzarius 10:03, 21 October 2005 (UTC)

A trillion dollars is enough to give everyone on Earth a color TV. WAS 4.250 01:10, 26 October 2005 (UTC)

"Unit" means "Mols"?

Hi all, a quick question. I'm doing some calculations on drug dosage, and I often come across statements like "This formulation contains 10 units of Pitocin per mL". My question is, when they say "units", do they mean "Mols"? Or is it some arbitrary unit that they've come up with? I suspect they do mean "Mols" (or "Moles"), but I want to be sure, and I can't find anything on Google. Can anyone help? For an example of the usage I'm referring to, see--inks 09:16, 20 October 2005 (UTC)

• I'm not sure if it matters. Just ensure that your final answers are in terms of units e.g. "he should be fed 5 units every 24 hours." Charlie123 (Talk) 10:09, 20 October 2005 (UTC)

The use of 'units' or 'international units' for pharmaceuticals is in many ways a relic of the age before really high quality analytical chemistry. For a given drug or preparation, one 'unit' was the quantity of drug that produced a specific biological effect. (One unit of antibiotic X would inhibit the growth of a specific number of bacteria, for example.)

By measuring the potency of a drug through a biological effect, manufacturers didn't have to know the concentration of active ingredient (if the active ingredient was known), the concentration of different enantiomers, or the effect of different related active molecules. They just had to test each batch for biological potency and then slap a label on the jar. There's no specific conversion factor to go from 'units' to 'milligrams'; since international units are defined in terms of a biological effect, the conversion factor is different for each drug. (You can look up the conversion factor for most drugs, however.)

Now that we've gotten better at pharmaceutical chemistry, we can do two things that are gradually making measurement in 'units' obsolete:

1. We can produce very pure drugs with a single active chemical ingredient, and
2. We can measure the amount of active ingredient very precisely.

Hope that helps. TenOfAllTrades(talk) 11:49, 20 October 2005 (UTC)

• Have a look at International unit -- Rune Welsh | ταλκ | Esperanza 14:32, 23 October 2005 (UTC)

• According to Goodman and Gilman's textbook, the potency of Pitocin was originally determined by its ability to cause changes in vascular smooth muscle contraction. One unit is about 2 micrograms of oxytocin. --JWSchmidt 03:12, 24 October 2005 (UTC)

Computer upgrade

We have a set of pentium 20 computers and we would like to upgrade all our computers to pentium 4 confuguration.We had been suggested to upgrade the same by using a node concept which means to insert a card for each computer in a common server ,from where all the computers would be upgraded. We would like to have your opinion for the same.

By

shubhada

(formatting fixed --David Wahler (talk) 13:09, 20 October 2005 (UTC))

What are you trying to upgrade? Disk space? -- Ec5618 13:13, 20 October 2005 (UTC)

Maybe he wants a network-boot (PXE) setup? Tzarius 09:53, 21 October 2005 (UTC)

Instead of a single server, perhaps 2 servers would be better, allowing you to backup half at a time and still keep the others operational, for example. Also, if one server goes down you would still have half of your computers able to communicate with one another. StuRat 21:58, 21 October 2005 (UTC)

This is a Brilliant solution for some types of networks Artoftransformation 10:03, 31 October 2005 (UTC)

It depends completely on the current and planned usage of the computers. If your doing websurfing ONLY, then this might work, but you'll need a fast server.Artoftransformation 10:03, 31 October 2005 (UTC)

Similar Question: Id like to paint a small room, but faster than Michelangelo(11+ Years), but with higher quality? I dont mean to demean your question, but more information is definatly needed.

Liquid Leaking out of my hard disk

I have a clear liquid leaking out of an external hard disk - any ideas what it could be? Oil for the motor perhaps?After a shave 15:42, 20 October 2005 (UTC)

What ever it is, you should back up all the data off the disk pronto! Wierd behavior from disks is a sign of imminent failure. smurrayinchester 17:02, 20 October 2005 (UTC)