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July 20

Thought experiment: compressibility of water

Thought experiment No. VIII. Imagine you have a magical, infinitely strong glass cylinder 300mm in diameter and as long as you like sticking up from the surface of the earth forever. (No hissy fits please. This is a thought experiment). Full of confidence that no idiot will scratch the glass, you relax on a sofa at the base and watch while somebody fills the tube with water and the pressure at the base goes up from thousands to millions to squillions of kilograms per square whazzername. We know that towards the end the material will collapse into a neutron soup and then, at the limit, into a black hole. Before this happens, what other stages would one observe? Captainbeefart (talk) 14:58, 20 July 2016 (UTC)

Um, I don't think that's going to work. I think you'd get nothing more than maybe some exotic ices though I doubt even that - I should recheck the phase diagram of water - because the water only accumulates in the cylinder below geostationary orbit, and with lower and lower gravity. (Well, OK, you can put it at the pole but the gravity still falls off fast, though not strictly to zero) I bet the total pressure would be less than inside a gas giant, but I'd have to do the math, and I'm feeling lazy. Wnt (talk) 15:56, 20 July 2016 (UTC)

There's pretty substantial pressure at the bottom of the world's oceans. ←Baseball Bugs carrots→ 15:58, 20 July 2016 (UTC)

Jupiter has an average density of 1.4 times water. Granted it doesn't reach water density till a bit in but the surface gravity is 240% Earth, it takes 11 Earth radii to drop off to zero and there's gas giants 13 times denser than Jupiter with the same size. Jupiter's maximum pressure is 91,000 times the ocean's and 13 times more stuff in the same size ball would make 13 times more gravity and 169 times the pressure if the density is simply 13 times higher everywhere. For 15,000,000 times maximum ocean pressure. This agrees with brown dwarf which says a pressure of 91,000,000 times the ocean for what is presumably a medium brown dwarf (they go from 13 to 65 Jupiter masses). Sagittarian Milky Way (talk) 17:15, 20 July 2016 (UTC)

• While we are dreaming, we can as well assume away any gravitational pull from other bodies, and more importantly the Earth's rotation (because otherwise, after some height, centrifugal forces would push it away more than gravity pulls it down).

Let us go by the standard hydrostatic pressure relation ${\displaystyle {\frac {dP}{dz}}=-\rho g}$ for which I cannot seem to find any good source for that right now (here is a bad one but with some details about the math). Let us also assume that water is incompressible (...yes, dreaming, but none wants to search the equation of state for liquid water for a large range of pressures), i.e. constant density (${\displaystyle \rho }$).

It would seem that as you integrate pressure on a higher and higher water column, it diverges, but that is not the case. ${\displaystyle g}$ is not constant with altitude; the gravitational pull of the Earth decreases as ${\displaystyle {\frac {1}{z^{2}}}}$.

So, defining ${\displaystyle g(z)=g_{0}\left({\frac {z_{0}}{z}}\right)^{2}}$ and we can integrate ${\displaystyle P(z_{0})-P(\infty )=\rho g_{0}z_{0}^{2}\int _{z_{0}}^{+\infty }{\frac {dz}{z}}^{2}=\rho g_{0}z_{0}}$. That is a finite value; with ${\displaystyle g_{0}=9.8\ m.s^{-2}}$ at ${\displaystyle z_{0}=6.4\cdot 10^{6}\ m}$ and ${\displaystyle \rho =10^{3}\ kg.m^{-3}}$, it comes to around ${\displaystyle 6.3\cdot 10^{10}Pa}$. 600 kbar is not something trivial, of course, but if you fancy a bit of shopping, this will get you 120 tons of pressure (which is 120 kbar, over a square meter). So, you can probably spare the glass and the dangerous job of filling it, if you have a specific experiment in mind.

Of course, if you insist that incompressible water is not realistic (ahem), then the final pressure would get higher - as the bottom layers squeeze, more mass gets in the stronger gravitational field. On the other hand, you can leave the Sun, Moon etc. in place, because the integral converges relatively quickly, so a mere 6,400km high glass gets you half the maximum pressure. Tigraan 17:02, 20 July 2016 (UTC)

120 tons per square meter is only 12 bars. 10 kbar is I believe the pressure of the 1993 World Trade Center bomb. Sagittarian Milky Way (talk) 17:31, 20 July 2016 (UTC)

At pressures in excess of 0.5 Mbar a superionic phase of water is predicted to be as hard as iron and glowing yellow, where hydrogen ions float within an oxygen lattice. It may exist in the ice giant planets Uranus and Neptune. See also Properties of water#Compressibility. We do not "know that the material will collapse into a neutron soup and then into a black hole". AllBestFaith (talk) 18:32, 20 July 2016 (UTC)

What an interesting substance! Apparently something is known of advanced superionic conductors and fast ion conductors and proton conductors already; I simply wasn't paying attention. So the hydrogen ions move freely and transmit current - I'm still not clear on whether their liquid-like state is simply like an electrolyte or something stranger... Wnt (talk) 17:52, 22 July 2016 (UTC)

Autism Cure

Why do so many people think Autism needs to be cured? Mage Resu (talk) 21:37, 20 July 2016 (UTC)

Name one. ←Baseball Bugs carrots→ 22:05, 20 July 2016 (UTC)

Define: Many; cure; autism. Some children diagnosed with autism are incapable of functioning on their own, being unable to communicate with other human beings. Some also exhibit self-harming behavior and have motor control difficulties. Most people would classify these as bad things. It's clear they need help, though that help can take many forms. But of course many autistics can function just fine, they just need to be taught and raised in a different manner from neurotypical children. Something that may be pushing the "cure" mind-set is the hoard of anti-vaccine advocates who insist that autism is some kind of brain damage that has hidden or destroyed their "real" child. Someguy1221 (talk) 22:54, 20 July 2016 (UTC)

ITYM horde --Trovatore (talk) 23:17, 20 July 2016 (UTC)

And for a more entertaining homophone, there's "whored". StuRat (talk) 04:40, 21 July 2016 (UTC)

Less interesting in meaning, but let's make it a quadruple with "hoared". DMacks (talk) 03:10, 22 July 2016 (UTC)

It does indeed seem like their child's personality has been stolen, in that in many cases their formerly outgoing toddler starts to regress socially. StuRat (talk) 04:40, 21 July 2016 (UTC)

There's an interesting essay on the subject here. -- BenRG (talk) 22:56, 20 July 2016 (UTC)

Neurodiversity advocates promote support systems (such as inclusion-focused services, accommodations, communication and assistive technologies, occupational training, and independent living support) that allow those who are neurodivergent to live their lives as they are, rather than being coerced or forced to adopt uncritically accepted ideas of normality, or to conform to a clinical ideal.

Many "curebies" believe that the neurodiversity movement does not believe in supporting autistic individuals in any way. Then they strike down that idea saying that it unethical. Why do they do this? Mage Resu (talk) 23:29, 20 July 2016 (UTC)

You have to be much more specific. Which groups, which curebies? What have they said? Someguy1221 (talk) 00:41, 21 July 2016 (UTC)

Mostly parents. The anti-vaccine movement loves that argument! It's just something I hear a lot! The question is, why are they assuming that Neurodiversity is something it isn't, even when corrected? Mage Resu (talk) 01:07, 21 July 2016 (UTC)

I highly recommed reading the llink the BenRG provides above. A lot of this might be caused by people talking past each other while they have different images of autism in their head. I don't think many people are advocating a cure for a child's being quirky in a group and not liking synthetic fabrics. But many people are advocating a cure for the child who tries to literally rip off his own face if you loosen his straight jacket. That is not hyperbole, such children exist. The desire for a cure is a desire to ease suffering, not to abolish a group of people who think differently. Someguy1221 (talk) 02:04, 21 July 2016 (UTC)

That said, I'm not sure why you're so convinced that a cure would be unethical. Perhaps we are talking past each other and have different ideas of the word "cure". Maybe you could enlighten us as to how you imagine a cure would be administered. Are you thinking of a pill that is freely offered to adult autistics, who can choose not to take it? Or are you imagining thugs holding down autistics and forcing them to become "normal"? This is why I asked for definitions at the beginning. We can't have a real conversation if our terms are left undefined. Someguy1221 (talk) 02:07, 21 July 2016 (UTC)

While I've found myself agreeing with pretty much everything you've said above, Someguy, the fact of the matter is, we shouldn't be indulging the OP's desire to have an ideological "conversation" here at all, as this is WP:NOTAFORUM. The reference desk is for providing reference; if the OP has a more specific inquiry which we can help address by providing sources, that's all well and good, but what he is doing so far is creating straw men and then asking us to engage in speculation about how people supposedly feel on this topic, in a manner that particularly invites defense or critique of those beliefs. This, unsurprisingly, is leading increasingly to expression of opinions, rather than the kind of reference services we are meant to be supplying here. There is no shortage of forums where an open-ended exchange on this topic would be appropriate, but this really isn't one of them. Snow 11:33, 21 July 2016 (UTC)

(edit conflict)Autism Speaks, for one. From their Mission Statement (emphasis added):

"We are dedicated to funding global biomedical research into the causes, prevention, treatments and a possible cure for autism." --2606:A000:4C0C:E200:60BC:894:7787:F31 (talk) 22:59, 20 July 2016 (UTC)

• See our Neurodiversity article for more information on the topic. --2606:A000:4C0C:E200:60BC:894:7787:F31 (talk) 23:14, 20 July 2016 (UTC)

Answer to this question can only be speculative. We can't really answer 'why many people think' type of questions. Hofhof (talk) 23:59, 20 July 2016 (UTC)

I'm not expecting a perfect answer, I'm just asking for possible explanations behind this behavior. Mage Resu (talk) 01:13, 21 July 2016 (UTC)

Are you opposed to finding a cure for autism, assuming such a thing could be done? ←Baseball Bugs carrots→ 01:28, 21 July 2016 (UTC)

A cure would be unethical. Mage Resu (talk) 02:02, 21 July 2016 (UTC)

I'm confused, Autism is defined as a spectrum disorder, just because SOME people with autism have a manageable manifestation and don't "want" to be cured because they are happy with their life, does NOT mean that there aren't lots of autistic people and parents of autistic children who face severe challenges and WOULD want to be "cured" if that was an option. How is that unethical? Is giving a deaf person a hearing implant unethical? Just because there exists some happy deaf people who do not want to be "cured"? Vespine (talk) 02:12, 21 July 2016 (UTC)

By "cure", I mean an intervention which somehow turns an autistic person into a neurotypical person. This is different from treatment which allows autistic people to function, but does not eliminate autism itself. Mage Resu (talk) 17:16, 21 July 2016 (UTC)

By "intervention", do you mean toward children or toward adults? ←Baseball Bugs carrots→ 20:59, 21 July 2016 (UTC)

Doesn't matter! People are people! Mage Resu (talk) 22:02, 21 July 2016 (UTC)

It DOES matter. Parents are responsible for their children. If a cure for something turned up, and the parents failed to provide it to their children, they would be derelict in their duties as parents. ←Baseball Bugs carrots→ 03:57, 22 July 2016 (UTC)

Thin ice, Bugs. That statement needs LOTS of qualifications. -- Jack of Oz 21:58, 22 July 2016 (UTC)

So if they found a cure for Down's Syndrome, parents should just say, "Well, we should just let little Johnny be what God made him"? ←Baseball Bugs carrots→ 23:52, 22 July 2016 (UTC)

This seems to me to be ultimately a question of "who has authority to decide". Here's where the idea of Non compos mentis comes into play. Clearly, children and people "not in their right mind" have a limited ability to make decisions based on informed consent, that includes decisions about their own welfare. So in those cases the law usually permits people like parents and guardians to make those decisions, but sometimes even those people can be demonstrate to NOT be making the decision in the best interest of the subject. Such as when blood transfusions are refused on religious grounds, or other cases of neglect, the law sometimes steps in and takes those decisions away from those people. But WHO gets to decide if autism means "non compos mentis"? Or if that person SHOULD be cured, even against their own will, or the will of their guardians? As in the case of blood transfusions. Well in the majority of those cases, the law sides with the medical profession, why? Because that's what the medical profession does. By definition, the consensus of the people who are most highly educated in the fields of health, including mental health, are the ones who we should defer our own judgement in cases of uncertainly. There is NO guarantee that they can't be wrong or make the wrong decision, but the chances they will be right are FAR higher than any individual or ideological group who have no demonstrable subjective authority beyond some ideology, such as this "neurodiversity" group. Vespine (talk) 02:29, 21 July 2016 (UTC)

Actually, jurisdictions vary wildly in just how they treat non compos mentis and what is called the "right to consent", including who is empowered to make those decisions and what manner of expert testimony (medical or otherwise) will be allowed. I'd also caution against making too direct a correlation between a "strictly" physiological treatment like a blood transfusion and anything that would profoundly affect the mental state of the patient, especially in a permanent fashion; in both legal and medical contexts, these are treated as distinct procedures for the purposes of capacity and informed consent. In any event, the OP's question, aside from riling the passions, is moot; the fact of the matter is, we can do little to nothing to "cure" autism; some behaviours and attention/perceptual difficulties can be managed with medication or behavioural therapy, but our fundamental understanding of the neurophysiology of autistic spectrum disorders is still incredibly limited, so notions of a radical "corrective" therapy--drug, genetic, or otherwise--are pretty much science fiction. Snow 11:52, 21 July 2016 (UTC)

Are there any advantages to being autistic? ←Baseball Bugs carrots→ 02:51, 21 July 2016 (UTC)

The intense focus that can accompany asperger syndrome can make a mildly autistic person very good at a specific job. There is also the know phenomenon of autistic savants. Someguy1221 (talk) 03:06, 21 July 2016 (UTC)

And it can be a social handicap. The OP is saying that if someone doesn't want to be autistic, or let's so "not as" autistic, then they have no right to want to "cure" it. That's extremely offensive. ←Baseball Bugs carrots→ 10:52, 21 July 2016 (UTC)

I think the OP's point is more that if someone autistic wants to stay so, or at least opposes any kind of treatment, then no cure should be imposed on them. It does raise an interesting ethical question (paternalism is the go-to article, methinks), and I defer to experts in the domain to say whether or not for a particular case the autistic patient can be deemed to have taken an informed decision about their well-being.

I could even imagine a stronger point that if a cure is somehow invented, it would plausibly work the same on those who want it, those who refuse it and those who are too crazy to consent either way. Searching for such a cure could be deemed unethical, because there is a risk that the cure is imposed by physicians/parents on some who do not want it. I disagree with that argument, which I see as an avatar of the neo-luddism argument that any technology with a risk of abuse (no matter how small or uncertain) should be opposed, regardless of the possible improvements it may bring. Tigraan 11:15, 21 July 2016 (UTC)

It's worse than neo-Luddism. If autism could be cured, then some people would be unemployed. It's in those people's vested interest to not find a cure. As for imposing on someone - would those who call it "unethical" likewise argue that a polio vaccine is unethical, and that if someone develops polio it is "God's will"? ←Baseball Bugs carrots→ 11:29, 21 July 2016 (UTC)

WP:NOTAFORUM. You're probably preaching to the choir for the majority of the science desk, Bugs, but this is really going way past the line into a protracted discussion of personal perspectives concerning what is ethical and appropriate, which is beyond our remit on the reference desks. Let's please confine discussion to referenceable facts, and leave ideological judgments and posturing to other forums where they are more appropriate. Snow 12:04, 21 July 2016 (UTC)

If you're going to play the "not a forum" card, lay it on the OP, who clearly came here with a personal agenda. ←Baseball Bugs carrots→ 14:02, 21 July 2016 (UTC)

Bugs, try replacing "autism" with "homosexuality" in this thread to see where the OP is coming from. Tevildo (talk) 20:46, 21 July 2016 (UTC)

Try replacing "autism" with "polio" to see where I'm coming from. ←Baseball Bugs carrots→ 20:57, 21 July 2016 (UTC)

Bad comparison. Mage Resu (talk) 22:00, 21 July 2016 (UTC)

Why? ←Baseball Bugs carrots→ 03:57, 22 July 2016 (UTC)

I wouldn't go with polio, but the homosexuality comparison is worse. The immediate "problems" with homosexuality all relate to interactions with other human beings, so we can blame other humans for the problems. (Some asshole will claim that not being able to reproduce is a problem, but that's only a problem in some existential sense that not everyone cares about, and ignores the fact that even a gay person could reproduce if they really really wanted to.) Polio is a bad analogy because polio doesn't have any obvious benefit to the people who get it (iron lung manufacturers benefit, but again, other people, screw their issues). Autism however, does have some benefits. There are professionals who have attributed their creativity or skills to their autistic condition, while at the same time very many people suffer as a result of autism (and unlike homosexuality, much of this suffering is entirely internal in nature). Many children with mild autism and their parents like the way they are. So we have a condition that is largely bad, but with some good, and now we're left with some big medical-ethical question about when/why/how/who is permitted to decide that it should be "cured", a question that can't be meaningfully discussed because there is no cure. Though none of this is really of interest to Mage Resu, our OP, who doesn't seem interested in actual discussion. He's probably just waiting for people to tell him that "cure" proponents are jerks who hate autistics or something. Oh, but this is a reference desk, so I should probably give references or something. Mage, if you are really interested in learning about this topic, go peruse a website of one of the major groups promoting a cure for autism, like here. Take a look around that site, see what they are researching and why. But of course no one can tell you why the specific people you have encountered want there to be a cure, because we are not mind readers. Someguy1221 (talk) 09:42, 22 July 2016 (UTC)

To address your implied question about whether, and when, an autistic person can be judged competent to consent to medical treatment, the answer is (and I'm sure this will not surprise), it depends. Needless to say, nations the world over vary immensely in how the view mental "defect" and how it affects capacity and other aspects of mental state. Even amongst nations from the western common law traditions, the standards, even the basic conceptions and assumptions they make about the mind for the purposes of the law, vary immensely. The U.S. in particular has a multiplicity of standards and perspectives in both statutory and common law, as varied as the states. The situation is made even more exponentially confused still by the fact that there is almost always a separate set of standards for mental states for each of a number of areas of law--criminal law, tort law, and medical intervention are just three of numerous areas where one might reasonably be asking whether a person can consent to treatment. So in reality you end up with many hundreds of distinct legal doctrines which may be of either mandatory or persuasive authority in a given jurisdiction. That being said, anyone with a form of autism severe enough that they cannot substantially communicate their desires will, of course, have most of their medical decisions made for them, whether that be a family member, a legal guardian, a court-appointed advocate or institution, or the court itself. Snow 12:31, 21 July 2016 (UTC)

Someguy, I know it's an innocent mistake, but that is a profoundly insulting comment, to conflate Asperger's and autism like that (and yes, I'm aware that the DSM-V has gone the same way). It also belies a significant lack of knowledge around savant syndrome, and just how far that is from Asperger's. Savants are incredibly rare (rarer than Nobel prizewinners) and are associated with generally low mental functioning in other aspects: those who are not are so rare that their existence is still seriously in doubt. The stereotypical "super-smart geek with Asperger's", perhaps in the Dirac mould, is a very long way from savant syndrome.Andy Dingley (talk) 11:39, 22 July 2016 (UTC)

And I thought I made it perfectly clear I was listing Aspergers and savant syndrome as utterly separate things, but maybe I did not. Sorry about the confusion of AS and autistic. I generally follow DSM for my definitions, and did not consider that "autistic" refers specifically to people diagnosed with autism, rather than any ASD syndrome. Someguy1221 (talk) 02:57, 23 July 2016 (UTC)

Perhaps a useful shift in perspective would be to take a step back and look at what can be done to help neurotypicals. Several years ago I remember reading about research to develop new drugs that would relieve humans of the burden of needing to sleep - unfortunately, I am drawing a blank on the name just now - and obviously this has wide applications in making more vigilant soldiers and better iPhone assemblers. Assuming that the laws of capitalism work as they have, the workers ought to be able to go twenty or more hours each day for the same pay they draw now for twelve, thus vastly improving worker productivity and market returns. Those who do not take the drugs would not be self-sufficient and would need to be cared for in some way ... perhaps by administering them the drugs. Or if you don't like cutting-edge technology, we could review the use of methamphetamine by the pilots and James Bonds and long-haul truck drivers of the world. Now I'm not sure where to go with this just yet; we're hampered by the problem that this is a Science discussion and scientists don't know jack about ethics; they just know more than ethicists that are generally in somebody's pocket. Wnt (talk) 13:04, 22 July 2016 (UTC)

@Wnt: You might be thinking of Modafinil? It had a lot of hype ~10 years ago. Cool stuff, very few side effects compared to traditional uppers. Not sure how much/in what context it is most used today, but our article has plenty of info. It is somewhat oddly classified as schedule IV in the USA, and by prescription only elsewhere. Of course there's then a black market for students and presumably there's also trucking industry and military usage. SemanticMantis (talk) 15:00, 22 July 2016 (UTC)

I think I must have read an overly optimistic early assessment of CRL40940 or CRL40941, but I'm not sure now; certainly what I see about them now does not match the initial breathless hype about reducing overall need for sleep long term. For which we can all breathe a sigh of relief before we go back to bed. Wnt (talk) 15:17, 22 July 2016 (UTC)

Anyway, the way I'd look at this personally would be to start from my particular notion of what a genetic disease is. To me, it seems like a gene that has been present in human populations for hundreds of thousands of years is part of the natural human variation and has withstood the test of selection, and therefore is not a disease to be cured. The problem is, that means that sickle cell trait is not a disease - yet, to be sure, the anemia is a disease when a patient complains of it and wants to be treated, but it would be a harmful deprivation of human diversity to remove the underlying trait from the gene pool, at least so long as a return of malaria is conceivable. Now autism of course is not entirely genetic, nor is it the result of harmful 'autism genes' of recent origin, so there's nothing to remove from the gene pool there either. But we can still ask - were there circumstances in the primitive environment where these people would survive and do well? Because if humanity's history holds a place where they were able to thrive, then our present potentially could offer the same, and it would be wrong to blunt their variation solely to make them fit a modern mold. But if the past outcome was always death and misery, then there is no idyllic state of nature to be returned to, and we can look at it as a disease state. This is not something readily measured, more of a simulation, but we'd do the same recreation if malaria were known to be absolutely and irrevocably extinct; we'd say sickle cell trait never would have been preserved by selection and the situation is so changed from nature that we should evaluate it in the context of a hypothetical history where the disease had never existed. Even so, we would have to be extraordinarily certain that there was no other benefit that is being lost! (I apologize for alternating between genotype and phenotype arguments, as they are similar but not the same and it is probably really confusing, but this is just how I'm thinking this through) The bottom line is that humanity has a long, established history that has defined it as a substance, and when we find ways to correct that substance in accordance with its history that is less shocking an intervention than when we shape it according to some new design. Yet the wishes of the individual largely override this - even so, we have to be careful that they are indeed the wishes of the individual and not a form of coercion, and when the condition makes it impossible to know those wishes, we should revert to a consideration of history. And I would guess, but do not know, that persons with severe or even moderate autism might have suffered terribly and died in ancient times. Wnt (talk) 13:27, 22 July 2016 (UTC)

Your solution to the problem introduces a new problem, one of paternalism and the ethics associated with it. If a cure existed that would revert the sickle cell allele, who has the right to decide that it cannot be used? (Of course keeping mind mind, this decision could be made for everyone, or left to individuals.) Unfortunately Misplaced Pages doesn't have much discussion of the philosophical/ethical aspects of this sort of question, but other places do . Someguy1221 (talk) 03:03, 23 July 2016 (UTC)

@Someguy1221: This is a valid concern. As I said, when the individual has a strong preference we largely defer to it, though as with other procedures like tongue splitting and genital bisection or indulging an amputee fetish, there is only so far that most of us want to ride that bus before we get off, and there is a point at which the lack of people willing to participate in a body modification becomes a significant limitation on its feasibility. But where paternalism matters most is when the person at issue is not what we regard as truly adult. In that situation, we reject that they can truly consent to so much as a tattoo when we view it as unnatural, yet we would routinely consent them to major surgery if we view it as repairing a trauma or defect. Paternalism is rightly reviled anywhere in the world outside of its proper role, which is to say, when exercised by someone acting as a parent. Wnt (talk) 03:37, 23 July 2016 (UTC)

• The user's question is a valid one. Those who are "functioning autistics" (to use my own term) are little different from "well-adjusted bi/homo-sexuals" (like myself, who discovered I was queer at 12, and started coming out at 14) or the deaf among the deaf as described brilliantly by Oliver Sacks. (I cannot recommend this book highly enough.)

Our nature is our nature, and we don't want to be "cured" of it, if we are able to be happy as we are. (There is a letter to the editor of this effect in the June 2016 Scientific American) Let me ask everyone reading this a question. If you were happy, would you be unhappy?' μηδείς (talk) 21:47, 22 July 2016 (UTC)

July 21

hyperferremia vs hemochromatosis

What is the distinction between the two? Can you have a hyperferremia that is not hemochromatosis? (you can find references where a patient is described having both hyperferremia and hemochromatosis, so they must not be synonyms). DTLHS (talk) 02:00, 21 July 2016 (UTC)

If I'm reading this article correctly, hyperferremia refers to hereditary hemochromatosis. Based on that (it certainly appears to be a reliable source), I've redirected the redlinked hyperferremia to iron overload, which is where hemochromatosis pointed. It should get noted on the target page somehow. I'll give it a shot if I get a few minutes. Matt Deres (talk) 03:24, 22 July 2016 (UTC)

Digging deeper, I'm not sure if I've redirected that appropriately; maybe HFE hereditary haemochromatosis would be better? I'm out of my depth here and neither page seems to have much activity on the talk pages. I've opened a ticket at WikiProject Medicine. Matt Deres (talk) 03:34, 22 July 2016 (UTC)

Quantum precognition and time reversibility

Suppose you have a system in which some electrons, nuclei or other objects can have spin up or spin down. Normally they are 50% each. You can transiently apply a magnetic field that makes either spin down or spin up the lower energy state, and the particles in the higher energy state emit particles to drop to the lower spin state. Eventually there is a strong disequilibrium. Then the field is removed, and for some period of time afterward, the formerly lower energy spin state continues to prevail if the state of these particles is "read".

In other words, the applied magnetic field over time (0 or 1 for various times) is 000000111000000, while what is presumed from ideas of causality is that the degree of spin polarization on a scale of 0 to 9 might perhaps be 000000369753211

Yet I have heard it said that quantum physics is time reversible, and it would seem like the times before and after the magnetic field is applied might be symmetrical. So it would seem plausible according to this way of thinking that among these particles the to-be lower energy spin state would be observed more often before the magnetic field is applied. In an extreme case, this would be 112357999753211, but conceivably it could be some compromise like 000001369753211, if for some reason the "decay" is faster, but not infinitely fast, when looking at past times than when looking at future times.

There are some issues here that would need to be looked at carefully, and doubtless I'm not looking at some of them carefully. For example, the time reversal of photons being emitted after the field is applied would seem to be for photons to be absorbed before the field is removed, and this seems to imply that the level of background photons is important. I assume no one has actually published a "quantum precognition" result or I'd have heard much about it, but has the experiment been done with any great precision? Wnt (talk) 02:31, 21 July 2016 (UTC)

I tried to read the article on T-symmetry, but I don't get it. The section on electric dipole moments seems similar to what you're talking about here, but that one class I took on quantum physics ten years ago has not prepared me for this material. Someguy1221 (talk) 03:12, 21 July 2016 (UTC)

You could make the same argument in classical electrodynamics. I think the resolution there is that either there is friction (which breaks time reversibility; it's an aspect of the second law of thermodynamics) or else there is no increase in the amount of magnetic dipole alignment. Whatever the answer is, it's not changed by quantization. -- BenRG (talk) 07:01, 21 July 2016 (UTC)

• As BenRG says, it is probably not a quantum question. The bottom question is "how can macroscopic equations be irreversible, when microscopic equations are". WP has a few articles on the subject, such as arrow of time, but they are not fantastic to be honest.

Notice also that the Curie principle is just that (a principle); in reality, symmetry breaking events happen. One of the implications is that, even though the equations of motion might respect some symmetry (e.g. time-reversal), their solutions might not. Now, whether this is a good argument for the defense of the causality principle, I do not know, but it certainly invalidates the "obvious" assumption that time-symmetric equations must lead to time-symmetric solutions. Tigraan 11:00, 21 July 2016 (UTC)

"All models are wrong; some models are useful". It is also important to remember that, philosophically, QM is still a model, it is a powerful and highly accurate model, but insofar as the model does not match observed phenomena, (and ALL Models have aspects that do not match observed phenomena, by their very nature). Macroscopic time reversal, FTL travel, "into the past" time travel, etc. are all examples of phenomena predicted by the equations of QM but which have never had any evidence of any sort to support. With all of the caveats around "absence of evidence is not the evidence of absence", it is most important to maintain a strict adherence to the null hypothesis regarding the reality of such phenomena. QM is powerful in the way it aligns with observable phenomena. That doesn't mean we need to accept, on faith, the veracity of predictions it makes that do not align with observation. --Jayron32 11:14, 21 July 2016 (UTC)

Well we know there's some problems with modern physics, but this is not related to anything like that. No problem in Quantum mechanics is being talked about. All that's being talked about is our expectations. As to the question what is the meaning in talking about observations that might have been made but weren't? Dmcq (talk) 12:06, 21 July 2016 (UTC)

• Again, this is not a QM question, at least historically it came about thermodynamics.

In any case... At any moment, there are three kinds of predictions made by any model: those that are verified experimentally, those that are falsified experimentally, and those that have not been tested (for any reason - it could be impossible to test, or just really hard, or it just had not been done yet). The heart of the experimental part of the scientific method is to transfer predictions from the latter to any of the first two categories, and while doing so one should indeed be "unbiaised", to validly put the theories to test.

However, when one is not testing the models, it is completely reasonable to "believe" the predictions of models that are successful. That is just Bayesian inference: there is a priori no reason that the ratio of model predictions that would come true if tested among the untested ones is any lower (or higher) than among those that have been tested. This is an outrageous simplification of Bayesian principles, of course - notably, the a priori probability of any given model is not independent of that model. "Leprechauns did it" is less convincing than serious alternatives, even before we begin to search for leprechauns. There is indeed the leap of faith (it could be that hardest-to-test predictions are also more likely to falsify the model), but it is faith in the method rather than in a particular model (you do not expect gravity to just stop at the 300th anniversary of Isaac Newton's death, even if none has made experiments after this date yet). Tigraan 12:30, 21 July 2016 (UTC)

It's not that the model is necessarily wrong, I should probably say, it is that out inferences and interpretations of the model are not necessarily consistent with observable behavior. The classic example of this is that of the gravitational singularity; the model predicts regions of infinitesimal volume and thus infinite density; such mathematical singularities, when mapped onto reality, usually are interpreted to mean a breakdown of the theory rather than a prediction of expected behavior. No one really thinks that infinite density exists, as noted in the gravitational singularity article, the prediction of such a singularity at the Big Bang is assumed to be a breakdown of the predictive power of the model rather than the existence of such a literal singularity. To varying degrees, other such fantastical predictions of the QM model (functionally the leprechauns of the theory) involving reverse time travel and other violations of causality, should be similarly understood. In the same way that the prediction of a gravitational singularity should be interpreted not as an expectation of its existance, but as a limitation of the theory, similarly time reversal should also be thought of in the same way. "The model predicts that time reversal is possible" is not the same thing as saying "time reversal is possible". --Jayron32 16:14, 21 July 2016 (UTC)

Everyone knows leprechauns are extinct. InedibleHulk (talk) 15:01, July 21, 2016 (UTC)

Yes, but has anyone told the leprechauns? {The poster formerly known as 87.81.230.195} 2.123.26.60 (talk) 19:35, 21 July 2016 (UTC)

The article Delayed choice quantum eraser discusses these type problems and shows what you might consider as 'precognition' in action. Dmcq (talk) 14:51, 21 July 2016 (UTC)

This is a fascinating phenomenon, but does not actually reach that standard. The issue is that the entangled photon is measured at one of the four mirrors, not put there; so it's not possible for a decision made at the future time point to affect that in the past. I think... though there are many possible permutations of the idea. My interest here isn't on a fancy entanglement scheme, but just a very basic brute-force measurement to see if there's even the slightest increase in possibility of seeing a 1 or a 0 in a formerly indeterminate bit of data on some sort of storage medium if it is going to be set in the future. I feel like somebody ought to have done this experiment, and I'm just wondering how well - people check all kinds of things, whether the gravitational law is right, whether constants change, do they check this? All the talk about leprechauns misses the point that causality (physics) is nothing more than a religion that contradicts millennia of popular belief - it's not even a theory, as far as I know; at least, not unless many careful experiments of this sort have actually been done. Wnt (talk) 23:12, 21 July 2016 (UTC)

I wonder if anyone's done that experiment too. Methinks it wouldn't magnetize before you write because that would either give you an unstoppable urge to magnetize it or it would be a source of free energy if you can convince someone to not magnetize before he does it. And the laws of physics don't care what a sentient being wants. Sagittarian Milky Way (talk) 23:34, 21 July 2016 (UTC)

I would go with the first model. It is true that trying to paradox the situation here would be problematic... my guess is such efforts might be defeated if they simply generate small amounts of noise in the experimental apparatus to foul the result, though I suspect that weird macroscopic phenomena, like one of the experimenters going mad and shooting up the place, might be even lower in energy than such noise. I also admit to having the personal opinion that certain configurations of such an apparatus with looped causal characteristics could actually assume sentience in their own right... I am not sure what sentience without intelligence looks like. Wnt (talk) 00:13, 22 July 2016 (UTC)

The Aspect experiment (and its successors) is probably the best-known example of this sort of thing. Tevildo (talk) 00:30, 22 July 2016 (UTC)

That links to Bell test experiments where, as far as I know, there is no observable difference in measuring the 'future' or the 'past' of the entangled particle; only the fact that you're going to measure it matters. I think the entanglement issue may simply be something different. Wnt (talk) 00:47, 22 July 2016 (UTC)

All this talk about particles and "entanglement" is still discussions of the model; when you look at all of these experiments that start with such precepts as "whatever we're looking at is either a wave or a particle at some point in its path" and even the fairly common interpretation such as superposition assumes that it should be one or the other and that it somehow "chooses" (as though it has agency) or is "chosen" as one or the other by act of observation itself; all that still starts with the presumption that "particle" and "wave" are binary choices. Light is light; the properties that light displays depends on the nature of the measurement. That's the Occam's razor interpretation of all QM experiments; it makes a minimal number of presumptions based on available evidence. When we pile expectations upon the phenomenon (by asking questions like "Is it a particle or a wave?" or even "What makes it behave like a particle or a wave?") we're bringing assumptions into the model. Statements like " If the experimental apparatus is changed while the photon is in mid‑flight, then the photon should reverse its original "decision" as to whether to be a wave or a particle" presumes that light was either or both or some combination or superposition of both. It was light. All the experiment proves is that the properties we measure are dependent on the way we measure them. The interpretation of the data says more about the psychology of the interpreter than it does about the nature of light. --Jayron32 11:11, 22 July 2016 (UTC)

The delayed choice quantum eraser has nothing to do with backward causation. The only people who think it does are people who don't understand the difference between correlation and causation. See this answer. I'll quote the key bit here:

You have a bag containing 4 balls, 2 red and 2 black. You draw a ball. There's a 1/2 chance it will be red. If it is red, there's a 1/3 chance that the second ball you draw will be red.

But if you don't look at the first ball, there's a 1/2 chance that the second ball you draw will be red, and if it is, there's a 1/3 chance that the first ball you drew was red. If you collect data over many trials, conditioned on the second ball being red, you'll find that indeed about 1/3 of the first balls you drew were red.

Backward causation??1? Of course not. If X is correlated with Y, then Y is correlated with X. It doesn't matter whether Y happened after X.

The argument for backward causation in the delayed-choice quantum eraser experiment is exactly the same as the argument for backward causation in this classical experiment.

-- BenRG (talk) 17:37, 22 July 2016 (UTC)

As always Ben, a most relevant, accessible, and well-written answer. --Jayron32 17:42, 22 July 2016 (UTC)

What's the reverse of a debris field turning into a tornado turning into a charcoalized forest turning into fire which shrinks to a broken glass field which becomes a Molotov cocktail which rockets up till it slows into a hand in an airplane and transfers its fire to a match which is scratched by a dude and unlights itself? The equations are time reversible so this is totally possible. Sagittarian Milky Way (talk) 23:18, 21 July 2016 (UTC)

Well, I didn't think I was suggesting exceptions to the second law of thermodynamics here. I suppose that a trace of magnetization in advance would indeed need to become steadily stronger until the bit is written, which suggests a reversal of entropy, but that decrease in entropy is eventually paid for by an increase in entropy somewhere else when the bit actually is written, and of course we know that bits can indeed be written this way, it's just a question of precisely when. Wnt (talk) 00:03, 22 July 2016 (UTC)

http://arxiv.org/abs/quant-ph/0105101 Count Iblis (talk) 00:13, 22 July 2016 (UTC)

Fascinating, and it would be more so if I understood the other 2/3. Nonetheless, even in describing their 'time machine' (of sorts) the authors dismiss signalling to the past because it 'contradicts causality'. Wnt (talk) 00:44, 22 July 2016 (UTC)

There is an apparent time asymmetry in the usual formulation of quantum mechanics: wave functions collapse, but don't uncollapse. I think the point of this paper is to show that it's an artifact of the formalism, not a real asymmetry. The only relevance of this to your experiment is that you could try to argue that the time symmetry in your experiment comes from wavefunction collapse. This paper (if you believe it) says that that's wrong. But in the classical case, you could never make that argument in the first place, because there's no analogue of physical wavefunction collapse and everyone agrees that the laws are time symmetric. So the classical version of your experiment is stronger than the quantum version, in this respect. -- BenRG (talk) 17:37, 22 July 2016 (UTC)

@BenRG: Is it really true that wave functions don't uncollapse? For example, in a quantum eraser scenario where a particle has two possible pasts and now you don't know which. I would think that just as any observed particle has multiple futures, so it could have multiple pasts. Wnt (talk) 01:05, 23 July 2016 (UTC)

In traditional quantum mechanics (which was taught to me in college, and may be what people mean when they say "Copenhagen interpretation"), wavefunctions collapse after measurement, and never uncollapse, by fiat. It's an explicitly asymmetric rule.

The modern view is that the "measurement effect" that was traditionally attributed to the collapse is really due to quantum decoherence, which is irreversible because of the second law of thermodynamics. The wavefunction collapse then has no observable consequence, and I suppose there's there's no reason it couldn't uncollapse too. (This is like saying "maybe other realities that we can never detect are appearing or disappearing all the time".)

In the DCQE experiment, detection is irreversible. The photon heats up the detector, the heat spreads, the detector emits slightly more blackbody radiation, etc. The reverse process never happens because of the second law. If it did happen, a reverse collapse model would correctly describe it. -- BenRG (talk) 18:29, 23 July 2016 (UTC)

Advanced potential may be relevant. Unfortunately Misplaced Pages doesn't seem to have an article on it (that link redirects to "retarded potential"). There is an article on Wheeler–Feynman absorber theory but it's not very readable. In short, it's an open question why oscillating particles emit radiation in the future but not in the past. But again, this problem isn't specific to quantum mechanics; it was recognized in the 1800s. -- BenRG (talk) 17:46, 22 July 2016 (UTC)

The way I read that article is that there is no need to consider backward in time ('advanced') transmission of EM waves because there is no "free EM" going off to infinity; every wave that is emitted 'advanced' is matched with some other wave that is absorbed (as a normal retarded wave). In this thought problem, if some kind of advanced spin polarization develops before the bit is written, it means that something interacted with those spins to set them in one direction, which can be looked at as a "writing" process in forward time. (This is why I suggested there needed to be some sort of background of thermal photons at the beginning) But can the sign of that writing process be dependent on what signal will subsequently be sent to align the spins all one way, whether or not it occurred first? Wnt (talk) 19:05, 22 July 2016 (UTC)

July 22

Physiological signs

I stumbled across our article at dermatoglyphics and found it very interesting. Do we have similar kinds of pages for signs at other areas of the body, such as eyes, nails, and so on? There's a cat associated with that article that lists a few more isolated articles, but maybe there's something more comprehensive? Non-WP links would also be appreciated. Matt Deres (talk) 03:14, 22 July 2016 (UTC)

The broader version of this would seem to be anthropometry, our article on which lists a lot of specialties within, such as dermatoglyphics. Someguy1221 (talk) 09:50, 22 July 2016 (UTC)

Cool - thank you! Matt Deres (talk) 10:53, 22 July 2016 (UTC)

While you are discovering interesting articles related to this, double check to see if they are in the appropriate cat(s) and add them as appropriate. That way the next person won't have trouble finding them. --Guy Macon (talk) 15:38, 22 July 2016 (UTC)

Lapidary

Suppose you're trying to make a very thin (so thin as to be translucent), flat, mirror-smooth slice of an opaque gemstone with Mohs hardness between 5 and 6, and further suppose that you can't afford a professional-grade faceting machine. Given these conditions, which machine would give better results -- a power sander or a grinder? 2601:646:8E01:7E0B:7D92:4B92:BDBC:ACFB (talk) 08:20, 22 July 2016 (UTC)

I'm not sure any such machine will give reasonable results, as the tolerances involved are outside of what you need to perform the task. If I'm trying to figure out if the machine will work, I'd try to think a) what is the thicknes and b) what is the smoothness of the final product. Since sanders and grinders would both have a huge variance in their vibrational motion, you'd not be able to control how they grind your surface to such a precision as to get satisfactory results. In simple terms, you're using an axe to do a scalpel's job, and just as you can't reliable cut a 5 mm incision in a specific location by swinging an axe at full force, you likewise can't expect woodworking tools to do the fine cutting and polishing you're expecting. --Jayron32 11:00, 22 July 2016 (UTC)

Neither of these could give you a mirror finish as they are much too coarse. They could probably cut off the bulk, but then you would need to go very carefully, perhaps with hand held sharpening block. Then you will need finer and finer polish dusts to get to mirror smooth with imperfections under 1μm. Graeme Bartlett (talk) 11:26, 22 July 2016 (UTC)

That might work -- just tell me, how smooth a finish will I need to get a refraction index? 2601:646:8E01:7E0B:7D92:4B92:BDBC:ACFB (talk) 03:46, 23 July 2016 (UTC)

It seems like you could learn much by reading that faceting machine article and other articles on the device you want. Even though you can't afford it, it represents the technology you aspire to. Note, for example, the mention of pulmonary disease (from silicosis and the like, I assume) from breathing mineral dust, and the use of a drip to prevent this and to also keep heat from the grinding from cracking the stone. I'd say get an understanding of all such little technical points before you think about improvising, unless you want to run through multiple stones and/or lungs on your learning curve. Wnt (talk) 19:11, 22 July 2016 (UTC)

Are you kidding? I'm fully aware of the dust hazards -- I plan to wet down the rock before each pass and to wear a dust mask! 2601:646:8E01:7E0B:7D92:4B92:BDBC:ACFB (talk) 03:46, 23 July 2016 (UTC)

The OP does not state what type of grinder he has access to. If it is a surface grinder then the way I would tackle it would be to embed the lower part of the stone in epoxy putty upon a parallel plate. Then grind down to just above the putty. The putty itself will clog grinding wheel -so stop, before reaching that point. Also, clean the stone (with a suitable solvent, and even consider etching it with a quick dip in hydrofluoric acid in order for the epoxy to get a good bond). Then, with stone still embedded, hand-lap the the surface to a glass like finish on a lapping stone. Then release polished stone with an epoxy solvent and remount on parallel plate with epoxy glue with the polished face down. Grind down to within just a gnat's whisker on one's desired thickness. Then, hand-lap the wafer of stone on a lapping plate one again. Once a glass finish has been archived, release prepared and polished wafer by using an epoxy solvent once more. This gives a thin and transparent wafer. If it is a big and valuable stone, consider first using a thin abrasive paper disc to cut it into thin sections and repeat above process. With a power sander it is very difficult the achieve a flat surface (on a large specimens) . Try as one might, the edges get warn down the most. --Aspro (talk) 12:12, 23 July 2016 (UTC)

Well, I don't need the whole stone (and I can't use the whole stone, anyway, on account of it's opaque) -- it will be a synthetic and will probably come out of the reactor as a cylindrical slug, so I'll just need to cut a thin slice off the end and then grind it down to where it's translucent (which means grinding it down to a very thin slice indeed). Thanks for the advice, it sounds like a workable plan! 2601:646:8E01:7E0B:D5B2:91C:A132:E02D (talk) 00:36, 24 July 2016 (UTC)

Since you want to identify the mineral, there are also other ways. Consider hardness test, streak test, specific gravity, borax bead test. And the refractive index can be estimated from a small particle in those liquids with different refractive indexes. You can also measure the Brewster angle from a polarised light reflection. Graeme Bartlett (talk) 12:54, 23 July 2016 (UTC)

I'm actually not trying to identify an unknown stone -- I'm trying to check whether my synthetic stone (which I haven't actually synthesized yet -- I'm just putting the plumbing together at this point) is as close as possible to the real thing in terms of physical properties (which means I have to do all these tests, or at least as many of them as I can). (The best way, of course, would be by FTIR, but I can't afford that machine either and also have no room for it even if I could.) So you're saying that I might not need a perfectly smooth finish in order to measure the refractive index with a refractometer? Oh, and did I mention that the stone is opaque except in very thin sections? 2601:646:8E01:7E0B:D5B2:91C:A132:E02D (talk) 00:04, 24 July 2016 (UTC)

A very small crumb / piece of dust should also be thin enough to transmit light. You can use Optical relief or the Becke line test to get an estimate. Another idea is to find a lapidary club and ask someone for help. Perhaps you can borrow their equipment. You may be able to hire some machines too. TO measure reflection you will only need a smooth finish on a surface, and not cut it so thin that it becomes transparent. And that surface does not have to be too big, a square millimeter may be enough. Also an optical spectrogram may be useful. X ray crystallography can tell if you have the right mineral structure. Graeme Bartlett (talk) 01:43, 24 July 2016 (UTC)

Right, I plan to take an optical spectrum with a spectroscope -- for this I will need a piece which is translucent but not necessarily smooth, whereas for the refraction index I will need one which is smooth but not necessarily translucent. Of course, if the piece is both smooth AND thin, I can use it for both things (optical spectrum first, then refraction index). Did I understand you correctly? 2601:646:8E01:7E0B:D5B2:91C:A132:E02D (talk) 03:28, 24 July 2016 (UTC)

Digging Earth

Peeps Earthlings,

I can’t recall if I asked this before, so I’m asking now, I would like to know if Earth diggers can reach the Earth’s core or not…

Regards.

Apostle (talk) 09:24, 22 July 2016 (UTC)

Not even close. The deepest hole ever drilled is the Kola Superdeep Borehole at a bit over 12 km. The deepest mine is the Mponeng Gold Mine at a little over 4 km. The outer core starts about 2,890 km below the surface. As you go deeper the temperature and pressure gets larger which limits the range of traditional digging / drilling technology. Dragons flight (talk) 09:36, 22 July 2016 (UTC)

Googling deepest hole on earth into Google would have answered that for you quickly regardless of how many times you've asked us. Matt Deres (talk) 10:52, 22 July 2016 (UTC)

Perhaps, but we have no rule that requires prior googling. And unlike google, we presumably can limit our responses to reliable sources. Google is not some magic sage, and often search results yield incorrect and misleading "answers". If you don't like to answer questions that are easy for you to answer, you are allowed to refrain from doing so ;) SemanticMantis (talk) 14:55, 22 July 2016 (UTC)

And now a word from our sponsor: Misplaced Pages, a friendly non-profit encyclopedia project, offers a Search field at the top of this screen that returns a fine selection of articles when one enters deepest hole on earth that compare favorably with anything a bloated profit-hungry advertising company might offer. AllBestFaith (talk) 16:15, 22 July 2016 (UTC)

One potential application of deep holes are Gravity trains, but these will likely remain theoretical thought experiments. SemanticMantis (talk) 14:57, 22 July 2016 (UTC)

Diggers encounter problems after only a few feet never mind thousands of miles deep Law of holes. Dmcq (talk) 16:57, 22 July 2016 (UTC)

Okay, thank you all for the information. I have to learn it some other time...

If you guys don't mind, could you please give it to me in miles, kilomiles (I'm guessing, given for all kinds of digging, above), metre, feet/foot and any other known mathematics i.e. applicable, that diggers are using while digging, please? -- Apostle (talk) 05:23, 23 July 2016 (UTC)

If you have a problem like that just stick a line into Google search like "2,890 km in miles" (quotes not needed) and our AI overlord will condescend to enlighten you using an attofraction of its power. Dmcq (talk) 08:46, 23 July 2016 (UTC)

It comes on the first page! -- Apostle (talk) 03:58, 24 July 2016 (UTC)

Thanks all. Regards. -- Apostle (talk) 03:58, 24 July 2016 (UTC)

Civil engineering projects

In civil engineering projects, does the principal contractor and its site management staff (construction managers, project engineers) etc still have overall responsibility for the site when all the civils work is done and interior fitout/electrical wiring/IT etc starts? In other words, by the time the site is handed over to the client, is the finished product, in a usable state for whatever it's intended purpose is or does it still require some work? 2A02:C7D:B945:6400:2897:1BD0:7DBA:B99D (talk) 09:38, 22 July 2016 (UTC)

• It looks more like a law question to me. Are you sure you would not move your question to Misplaced Pages:Reference_desk/Humanities? Tigraan 10:45, 22 July 2016 (UTC)
• You also seem to be asking more generally about management and organizational structure. I'm not sure of the answer, but those will provide you some additional reading. I also agree with Tigraan that this isn't a Science question, and is more suited for the Humanities or Miscellaneous desk. --Jayron32 10:50, 22 July 2016 (UTC)

Misplaced Pages has an extensive article about contracts. A major Civil engineering contract usually defines various phases of construction, that may follow a Design–bid–build or Design–build delivery sequence. Good Project planning will ensure that actual progress is compared with the baseline schedule (possibly drawn on a Gantt chart) throughout the project such that responsibilities for any deviation or incompletion are identified. Payments should be tied to clearly defined acceptance criteria, and the contract may specify "penalty" deductions for delays. Legal disputes often arise after delivery if the concept "suitability for its (not it's) intended purpose" was not quantified at the outset in measurable, objective terms. AllBestFaith (talk) 12:23, 22 July 2016 (UTC)

QuestionEnergy efficiency of batteries

Is it more energy efficient to charge AA batteries and put them into device, or use 3 volt transformer plug to power device directly off mains socket? — Preceding unsigned comment added by 111.249.153.69 (talk) 12:28, 22 July 2016 (UTC)

The use of batteries involves energy losses in 1) manufacturing the batteries, 2) the battery charger circuit, and 3) the energy return loss (including self-discharge) of the batteries themselves. Using an AC adapter eliminates 1) and 3) above and the only remaining energy loss is likely similar to 2). Most of the energy losses mentioned can be felt as heat. The overall energy inefficiency of using batteries is the price you pay for portability. I corrected the header to identify the topic. AllBestFaith (talk) 12:43, 22 July 2016 (UTC)

Genetics and inheritance

when sexual partners have sex, unprotected is it true that they exchange some pf their genetical material? — Preceding unsigned comment added by Kaymcluke (talk • contribs) 13:10, 22 July 2016 (UTC)

When sexaul partners have sex, unprotected, do they exchange their gebetical material? — Preceding unsigned comment added by Kaymcluke (talk • contribs) 13:12, 22 July 2016 (UTC)

They don't exactly exchange, as there is no change in their genetics. However, their genetic material is combined to form a new organism (a zygote). Is this what you are asking? --T H F S W (T · C · E) 14:30, 22 July 2016 (UTC)

Well, more precisely, a sex act could result in the combination of genetic material to form a zygote, but it isn't guaranteed to do so. Sperm is released during sex (assuming a healthy, fully-functional male), but whether or not a viable ovum is present is more a matter of chance and/or planning as the egg is not released due to the sex act itself. Dragons flight (talk) 15:29, 22 July 2016 (UTC)

If I wanted to learn more about this topic, I'd start reading at Human embryogenesis and Fertilisation and follow further links to articles that discuss various aspects thereof in more detail. --Jayron32 15:19, 22 July 2016 (UTC)

If you are asking whether genetic material from the male partner is permanently incorporated into the genome of the female partner, and vice versa, then the answer is no. The emotional and physical consequences of sex may change people's lives in many ways, including the possibility of pregnancy and sexually transmitted infections; however, the only transfer of genes is from parents to child. There is no incorporation of genetic material from one partner into the other partner. Dragons flight (talk) 15:29, 22 July 2016 (UTC)

Presumably the OP is not speaking of microbes such as STD's. ←Baseball Bugs carrots→ 16:26, 22 July 2016 (UTC)

(edit conflict) All of that also applies for a same-sex couple, of course - though no zygote can be formed, except maybe in extraordinary circumstances such as those listed at Disorders_of_sex_development. Tigraan 16:27, 22 July 2016 (UTC)

• The "inheritance" in the thread title suggests that the questioner wants to know about incorporation of the sex partner's DNA in the genome of the individual, and the answer would seem to be "No" from the above answers. But in another sense of "exchange" I wish to point out Locard's Principle. Misplaced Pages's article is Locard's exchange principle.which says that after any encounter each person will leave some trace evidence and take away some trace evidence. In this instance each participant might well retain some DNA from the other participant, until time and bathing remove it. This could include DNA from semen or vaginal fluids, skin cells, blood or the roots of hairs. Tests are now so sensitive that ridiculously small traces are found. In one recent case, DNA was turning up at many and varied crime scenes, and it turned out to be from a technician at the factory where the swabs used in testing were made. In another case, trace DNA was found under the fingernail of a millionaire murdered in a mansion and matched to a homeless man. It turned out to behave been transferred inadvertently a paramedic who had been at the death scenes and who had earlier treated the homeless man and picked up his dna on a medical device.. (I read this in some reliable online news article in the last 2 weeks but do not have a handy link. The point is that DNA detection is very sensitive and perhaps so sensitive as to provide false leads). Edison (talk) 16:56, 22 July 2016 (UTC)
  • Found the article about the false positives from DNA trace analysis:"The false promise of DNA testing," The Atlantic, June 2016. Techs in the past have made huge errors and botched basic DNA tests, sending innocent people to prison. Now they are delivering analyses of trace DNA from a fingerprint or a microscopic drop of sweat or saliva, even when in a mixture of DNA contributions.Edison (talk) 17:09, 22 July 2016 (UTC)
    • Here is a good article from 2015 that discusses secondary DNA transfer. Which probably takes us far afield of the OP's question, but given the direction of the tangent, I thought it an interesting article. --Jayron32 17:37, 22 July 2016 (UTC)
• Possibly - at least male to female when a fetus is involved. See fetomaternal microchimerism where children's cells can be detected in many mothers even years later and so will contain some of the father's DNA. Rmhermen (talk) 19:20, 22 July 2016 (UTC)

Radioactive heat from radium

If I had a gram of radium metal, how much would it heat the environment around it? Would anything much happen if I put it on a wooden table? (Assuming for the purpose of this question that I am well-protected from the radiation.) Double sharp (talk) 15:26, 22 July 2016 (UTC)

${\displaystyle 1\,{\text{gram}}{1\,{\text{mole}} \over 226\,{\text{gram}}}{6.02\times 10^{26}{\text{atoms}} \over 1\,{\text{mole}}}{ln(2) \over 1600\,{\text{years}}}{4.87\,{\text{MeV}} \over 1\,{\text{atom}}}=28.5\,{\text{W}}}$

Warm, but less hot than a typical incandescent light bulb. Dragons flight (talk) 15:41, 22 July 2016 (UTC)

Thank you! Double sharp (talk) 15:57, 22 July 2016 (UTC)

• Minor nitpicks to Dragons flight's math: this is assuming one gram of pure radium (it tends to be diluted in other stuff), of the 226 isotope (the usual one), and I suspect the 4.87MeV figure refers to the whole radiation, which may or may not dissipate as heat as it meets the table (but going by the WP article, most of the radiation is alpha decay, which does get stopped shortly). Tigraan 16:18, 22 July 2016 (UTC)

Radium is a reactive so-called alkali earth metal, and will oxidize rapidly in ordinary air. You will have to keep the radium either in a vacuum jar or a jar containing a non-reactive gas (nitrogen, argon, etc.) or in a hydrocarbon liquid. Robert McClenon (talk) 17:46, 22 July 2016 (UTC)

• Bear in mind 1 gram is a very small amount of metal (it would be a cube about 5 mm on each side, roughly the size of a small piece of gravel) pressed right up against the table. Let's assume that 1/6th of the energy is absorbed by the wood (since we're dealing with a cube), in a thin layer immediately under the cube (I read that alpha particles are stopped by a sheet of paper, so presumably they don't go much further in wood. Let's be generous and say the bulk of the flux is absorbed by a volume 5mm * 5mm * 1mm). If you ignore heat flow, that bit of wood is going to heat up by about 700 C per second. In reality, you'll get a fair bit of conduction and air cooling, but I built a simple model in a thermal simulator, and it calculated that the wood would reach its burning point - and the radium would reach melting point - very quickly (within a few seconds). Presumably this is why there are no pictures of pure radium on the internet - it's not a thing that can actually exist in a stable state. Think about it this way: what would happen if you were to take the coil out of a lightbulb and press it right against a wooden table? Smurrayinchester 18:36, 22 July 2016 (UTC)

You're right. I wasn't very careful in thinking about the volume being heated. If it is really a pure gram that would get very hot. If it is 1 gram mixed in a base of 99% some other metals (rather more likely), then the resulting temperature would be less. One would need to know more about how the radium is distributed. Dragons flight (talk) 21:53, 22 July 2016 (UTC)

You mean they never found that mine? --Trovatore (talk) 21:07, 22 July 2016 (UTC)

Plenty (ok, a few) pictures of radium are on the internet. On wiki(p|m)edia, we even have File:Radium-226.jpg of the isotope in question. DMacks (talk) 19:44, 22 July 2016 (UTC)

The Wikimedia photo is poorly labelled. The image is (purportedly) of a "check source" for a CD V-700 Geiger counter. It's a little bit of radioactive material attached to the instrument that you can use to verify that the probe is working when you're in the field. Its actual radium content is quite low; the measured activity of the source is on the order of 8 nanocuries, meaning that the vast majority of the metal present is non-radioactive filler. I suspect that something similar is true of most other photos you will find of "radium-226" on the internet. TenOfAllTrades(talk) 20:05, 22 July 2016 (UTC)

File:Radium226.jpg is a more clearly described image. Not a chunk, but a possibly pure-ish surface layer (though unknown how thick the layer is or how completely covered the substrate is). DMacks (talk) 21:41, 22 July 2016 (UTC)

It looks like an extremely thin and spotty film (although admittedly, radium does go yellow-brown when exposed to air). Certainly nowhere near 1 gram. Smurrayinchester 21:50, 22 July 2016 (UTC)

Hot humid weather and joints

I asked a similar question some time ago and got the answer "nobody knows". Here's hoping for an answer to this one! And this is definitely not a request for medical advice. I know what to do thank you.

I have noticed that when the temperature reaches above about 24 degC and the relative humidity over 70, my arthritic joints are in a worse condition than when the temperature is lower and the humidity is lower. Why would this be? --TammyMoet (talk) 18:11, 22 July 2016 (UTC)

Take a look at the results of this Google Scholar search and take your pick. Rheumatoid arthritis patients show weather sensitivity in daily life, but the relationship is not clinically significant from 1999 seems to sum up most of the results. Alansplodge (talk) 18:24, 22 July 2016 (UTC)

See Weather pains. Loraof (talk) 22:07, 22 July 2016 (UTC)

Blimey we do have an article on everything! Thank you!--TammyMoet (talk) 09:40, 23 July 2016 (UTC)

July 23

Why is there so much broken pottery buried in every garden in Great Britain?

Take a spade and start digging in any back garden in Great Britain and you are sure to find loads of broken pottery. Why did people bury their pottery? How old is it? Is it Roman earra? — Preceding unsigned comment added by TTshojo (talk • contribs) 09:15, 23 July 2016 (UTC)

Not in my back garden there isn't. It was ancient woodland and common land going back to the Doomsday Book until 1945. --TammyMoet (talk) 09:37, 23 July 2016 (UTC)

Until fairly recently all rubbish was simply dumped outside the house, or in a hole in the garden - rubbish collection is a recent invention. Pottery has the distinction, when compared with other rubbish, of being almost indestructible. It is also something which cannot easily be repaired or re-used (unlike metals). It has also always been quite cheap, and easily replaced. If you happen to live somewhere which has been inhabited for a long time, people will have been chucking out their broken pots for many centuries. They chucked out a lot of other rubbish as well - but the pottery is what survives best (which is why archaeologists get so excited about it). Wymspen (talk) 11:20, 23 July 2016 (UTC)

See potsherd for the archaeological significance of this throughout history.

Not just "pottery", it's predominantly Victorian blue and white. It's the product of four things, all of which peaked in the Victorian age: pottery availability (factory potteries made it cheaply available to everyone), pottery fragility (Victorian china will break on a quarry-tiled floor when 17th century heavy slipware on a beaten earth floor will just bounce), refuse handling (greater volumes of middens near the houses) and also the development of the towns themselves and the denser packing of housing. This effect reduces from around 1900, mostly as refuse handling becomes more centralised.

In some towns, like Bristol, it's not pottery but some industrial waste product instead. Dig a garden in South Bristol and it's not long before you find some zinc smelter slag from the Keynsham side of town. That stuff gets everywhere. Andy Dingley (talk) 12:16, 23 July 2016 (UTC)

Here in the TMZ, if you dig anywhere you will find pieces of the broken hopes and dreams of people who moved here hoping to make it in show business... --Guy Macon (talk) 19:19, 23 July 2016 (UTC)

If the OP considers the dates of all that pottery (and he didn't mention clay pipe stems) most will probably date to before hyper-consumerism. The only thing collected by the authorities in those periods would have been night soil. People, did not have TV sets to depose of nor washing machines nor plastic packaging and tin cans. Any glass bottles and jars where reused. If one wanted (say) vinegar, one took the old jar back to grocer to get it refilled from his cask etc. Household supplies where bought loose and not in little packets. Metal was still expensive so any unwanted metal tools, implements were traded in for scrape and recycled so was broken glass. What was left was a small amount of broken pottery that had little recyclable value and thus, was simply dumped in one's back yard. This was also before the time of cigarettes, one could buy a clay pipe of tobacco and then throw the pipe away after smoking it, so this is why you should also find short lengths of small diameter white tubes amongst the stuff you dig up. Around the 1900's local authorities started generating electricity to light the streets. The power-stations were fueled buy rubbish and so dust-bin-men started to collect not just dust (victorian euphemism for nigh soil) but anything dumped in the bin to fuel the boilers. So the mass of 'blue and white' your finding is probably mostly restricted to the period where 'blue & white' became affordable and cheap in an area which was already developed and limited by date to the introduction of the dust-bin-men which signaled the end of having to dump broken pottery in ones own yard. Dig up a garden in a new town such as Milton Keynes and you won't find any.--Aspro (talk) 19:20, 23 July 2016 (UTC)

Victorian dustbinmen (at least in Britain) didn't collect night soil. They were two separate trades, and turf was fought over. Particularly in South Bristol, where night soil was something of a local specialty trade (Night soil from the whole city went out through Bedminster, towards the market gardening areas beyond.) Andy Dingley (talk) 00:16, 24 July 2016 (UTC)

I wonder if some part of this issue involves the practicality of moving an outhouse. Every so often those who use them dig another hole and move the thing over it. Over the course of hundreds of years, that's a lot of holes. Wnt (talk) 23:55, 23 July 2016 (UTC)

Finasteride and Estradiol

Do Aromatase inhibitors (which inhibit estrogen) counteract the sexual side effects of Finasteride? They say that Finasteride increases the production of Estradiol! https://www.baldingbeards.com/how-to-avoid-propecia-side-effects/ — Preceding unsigned comment added by 182.18.177.78 (talk) 12:41, 23 July 2016 (UTC)

That sounds like a request for medical advice, disguised as a general question. --Hofhof (talk) 13:29, 23 July 2016 (UTC)

The funny thing is, it doesn't matter. All we have to do is refrain from giving medical advice, which does not preclude helping OP find medical information. For an example of this, see my response and references below. SemanticMantis (talk) 16:26, 23 July 2016 (UTC)

Here are few scholarly articles about the effects and side effects of Finasteride. They seem to touch upon some of your questions, and you also look through their references, as well as use google scholar to see what papers cite these and search within those papers, like so: . SemanticMantis (talk) 16:25, 23 July 2016 (UTC)

Quartary consumers

Using African animals, what is the most popular quartary consumer?? Given that lions eat cheetahs as well as plant-eaters, they can be either secondary or tertiary. What is the most common quartary consumer when it comes to African animals?? Georgia guy (talk) 14:56, 23 July 2016 (UTC)

You'll never get a clear answer to this, it all depends on your perspective and definitions, which you basically get at in your question.

That being said, we can still offer candidates that might be interesting. One way to get at quaternary consumers is to find a tertiary and see what eats it (searching for "quaternary consumer" is more standard terminology, and may help you find more relevant material ). So if you think a lion is tertiary, what eats lions? Lots of things, but the botfly and other parasites are the easy answer, and they tend to be fairly high density in Africa. Here's a nice scholarly survey of the primary eaters of lions. The top eaters-of-lions in terms of incidence are Isospora felix, a protozoan (infecting 48% of sampled lions). The top animal lion eater is a trematode. There are also of course many blood-sucking insects that feed on "top" mammal predators like lions and cheetahs. SemanticMantis (talk) 16:47, 23 July 2016 (UTC)

The other place to get large/long food chains is in aquatic systems, and these then chain into the bird world. I am not that familiar with the freshwater ecology of African, but you can easily see certain raptors that eat insectivore birds as quaternary consumers - so a Bateleur may eat a pratincole, an insectivore bird, the pratincole eats a dragonfly, dragonfly eats another bug, which may or may not eat bugs. Since the dragonflies themselves can be order 4-5 within the aquatic realm, this could put the bateleur up to level 6 or so if you like. Then there's the African_fish_eagle, and again, lots of depth is available in fish-fish-insect-insect food chains. So certain birds of prey will be good candidates, but I'm pretty sure there are many parasites of predatory mammals that are far more numerous :) SemanticMantis (talk) 16:47, 23 July 2016 (UTC)

Here are a few scholarly articles on large African mammals and their prey. While they will not specifically answer your question, they will give you good context and further reference. SemanticMantis (talk) 16:47, 23 July 2016 (UTC)

Water poisoning is not caused by inadequate salt intake?

We can read here that the Yanomami indians have a sodium intake of 0.9 mmol/day, which is about 50 mg of salt per day. This is so small compared to even the most salt restrictive diets that you can implement in practice, that it seems to contradict the guidelines that I've read for exercise about drinking and salt intake to prevent water poisoning. Clearly, something is not right about the whole idea to make sure we get in enough salts when this refers to quantities of the orders of grams of salts when the Yanomami indians survive in a tropic conditions doing hard work, drinking a few liters of water per day and getting in hardly any salt at all.

Should drinking a lot of water and taking in salt to prevent water poisoning be compared to doping, similar to injecting yourself with insulin and taking in a large amount of glucose? If an athlete would collapse into a hypoglycemic coma, would we say that this happened because he didn't take in enough glucose, or would be say that insulin doping is the cause? Count Iblis (talk) 18:35, 23 July 2016 (UTC)

Your link is talking about the salt content of their urine. For people in modern countries with air conditioning and the ability to avoid hard labor, the salt content of urine may be fairly similar to the salt content of one's food. However, if one is sweating frequently, the salt losses via sweat can exceed the losses due to urine by a large factor (>100 in some cases). Without a clearer source, I would assume their salt intake is actually much larger than 50 mg/day, but that most of it comes out as sweat rather than urine. Dragons flight (talk) 19:07, 23 July 2016 (UTC)

It is well known that you can kill yourself by drinking too much water. I wonder whether drinking too much Pedialyte or Suero Oral would have the same effect? --Guy Macon (talk) 03:35, 24 July 2016 (UTC)

Is appearance of white hair in early age belongs to psychological troubles?

Question moved from Language desk Tevildo (talk) 23:04, 23 July 2016 (UTC)

Is appearance of white hair in early age belongs to psychological troubles or it's a result of genetics only or combining of the two? 213.57.115.202 (talk) 19:39, 23 July 2016 (UTC)

See Human_hair_color#Stress. Rojomoke (talk) 20:21, 23 July 2016 (UTC)

July 24

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