Wikipedia:Reference desk/Archives/Science/2012 February 23

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February 23

Mpemba effect

Ok, guys, I need a favour. I have just lost a pub quiz and been made to perform a humiliating forfeit involving a Manchester United shirt. The question that swung it was "Which freezes first, water at 20C or water at 80C?". I answered 80C, due to the Mpemba effect. The quizmasters said the answer was 20C and that it was a common misconception that hotter water freezes faster. What I need from you is a long list of reliable sources (ideally academic papers) that say the Mpemba effect is real. There are a few references in our article, but they are mostly scientists trying to explain the effect rather than saying they have actually tried it. If you have sources or arguments saying that I'm wrong, then I don't want to hear them - this isn't about the truth, this is about proving me right! Thanks in advance for your help! --Tango (talk) 00:47, 23 February 2012 (UTC)

There's this one from the American Journal of Physics. Someguy1221 (talk) 01:01, 23 February 2012 (UTC)

I'm looking for more, and the general conclusion (including the one taken in the above article) is that the effect is not always present, which is also reflected in our own article. I also just noticed that that article is also linked in mpemba effect. Anyway, the question is bad. There are variables (known and unknown) that can change the answer, which means you deserve at least half a point. Someguy1221 (talk) 01:05, 23 February 2012 (UTC)

Unfortunately, half points weren't an option - it was the final round and the rule was that you get 2 points very every correct answer, but get nothing at all for the round if you get an answer wrong (you could leave questions blank with no penalty)... --Tango (talk) 01:43, 23 February 2012 (UTC)

As stated, the question is ambiguous. Water doesn't freeze at 20C or 80C! The question needs to be more explicit.

• Are they going to start the stopwatch, submerge both samples in a sub-zero cryostat ethanol bath, and clock which sample freeze first? If so, unfortunately for Tango, the initially-20C sample will freeze first.
• Are they going to carefully cool the 80C sample to 20C; start the stop-watch, and then submerge both samples in a sub-zero cryostat ethanol bath? If so, Tango may be correct; the initially-80C sample may freeze first, [depending on the temperature of the bath. In fact, the initially-20C sample may not freeze at all, even if brought to -10 C!

The Mpemba effect isn't something I'd want to get into a debate about in a bar. It's a purely empirical result. We have very handwavey ways to explain it theoretically, but it's not exactly a simple effect. It doesn't have a clean answer. The linked paper is really the nail in the coffin: they have a hard time even defining what it means to freeze! (Sometimes, only the water in contact with the walls froze!) The effect is real, repeatable, and measurable, but it's complicated. I'd say it's too complicated to give a binary "yes/no" binary answer to this sort of trivia question. As evidence, the linked paper provides a matrix of starting temperatures, times, experimental conditions, and qualitative results. It's not even monotonic! In different cold-bath temperatures, the susceptibility to freezing for the initially-warm water is either greater or less than the initially-cold sample! All we can say is, when you're poking around in the noise-floor of experimental science, (like trying to determine exactly when water will freeze), the facts aren't very pretty. Nimur (talk) 02:02, 23 February 2012 (UTC)

To be pedantic, water will probably freeze at 20 and 80 degrees C. Just not at standard/atmospheric pressure. If I haven't completely forgotten my physics/chemistry understand File:Phase diagram of water.svg properly and there's not something complicated at such extremes that I'm missing, water has the potential to freeze at something under 1 GPa at 20 degrees C and at something over 2 Gpa at 80 degrees C. If you have water at 20 degrees C and 80 degrees C and slowly raise the pressure without affecting the temperature the 20 degrees C water will probably freeze first. (By freezing I'm of course meaning forming any crystalline/solid phase of water i.e. any variety of ice.) Nil Einne (talk) 23:15, 23 February 2012 (UTC)

• Just to clarify a bit, the Mpemba effect is a very real, and very misunderstood, effect. The problem with the OPs question is that, as asked, the answer is that the 20 degrees celcius water will freeze first. The word "first" is not a synonym of "faster". The second issue is the way in which the Mpemba effect shows itself requires a very specific set up; in some cases with some particular experimental set ups, you can get a result which shows that the liquid-solid transition in water occurs faster when starting from a higher temperature water. Such an effect is small, and requires a very specific set of circumstances; it does not mean that of any two arbitrary temperature water samples, the warmer one always freezes faster. In fact, without any other stipulations, if all you know is that the two samples are at different temperatures, always assume the cooler water will freeze sooner. Especially for a large temperature difference like 60 degrees!!! --Jayron32 14:24, 23 February 2012 (UTC)

The real problem here is that Tango is taking a pub quiz too seriously. Count Iblis (talk) 15:22, 23 February 2012 (UTC)

The real real problem is that Tango is going to pubs where Manchester United shirts are tolerated... --Stephan Schulz (talk) 20:45, 23 February 2012 (UTC)

Sheep Shearing? Surely!

I've looked around and can't seem to find the answer to this burning question, I need a source to settle an argument--

When is a sheep's first shearing? That is, is a lamb sheared? Is there a substantive difference between sheep wool and lamb wool so the shearers wait until the lamb pubesces into a sheep?199.94.94.20 (talk) 01:53, 23 February 2012 (UTC)

The implication in Sheep shearing is that it's first done whenever it's practical. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:43, 23 February 2012 (UTC)

• Lambs are first sheared when they are between three and 11 months old. This wool is called lamb's wool, and it is fine and soft.
• Lamb's wool is generally softer than that of the sheep of the same flock; and as it has the felting quality in a high degree, is much used in the hat manufacture.

Have you never seen those poor little lambies shivering on a cold day after their first shearing? SpinningSpark 09:09, 23 February 2012 (UTC)

Thanks Sparky! This is the OP, terrific source, I appreciate it (even though I was wrong)66.30.10.71 (talk) 12:55, 23 February 2012 (UTC)

We do have a very brief article: Lambswool. I suppose that not many editors are shepherds! Alansplodge (talk) 22:32, 23 February 2012 (UTC)

Well I'm not a shepherd, but where I live, sheep are not sheared until they are at least 14 months old, and usually older. I expect the answer varies according to the breed of sheep and the climate. Dbfirs 16:35, 24 February 2012 (UTC)

Fasting blood glucose

Directions for preparing for this test generally say not to eat or drink anything other than water for 8 to 12 hours before the test. I know why the 8-hour minimum, but why is there a maximum? What happens after 12 hours that affects the reading? Bielle (talk) 04:14, 23 February 2012 (UTC)

Your blood sugar drops dangerously low, I imagine. This certainly should be avoided by diabetics, but possibly also hypoglycemics. StuRat (talk) 06:03, 23 February 2012 (UTC)

Actually I don't think it's a maximum as such. It's more like just giving you a time range for how long to fast, in that it should be at least (but doesn't have to be exactly) eight hours, but on the other hand you don't have to starve yourself for a whole day say. --jjron (talk) 13:56, 23 February 2012 (UTC)

What is left out of these instructions is that the time of the test also matters. See Dawn phenomenon. Wnt (talk) 18:40, 23 February 2012 (UTC)

dark matter is a time gap

do you agree my scenario such this about "Dark matter"?dark matter is a time gap--Akbarmohammadzade (talk) 11:03, 23 February 2012 (UTC) — Preceding unsigned comment added by Akbarmohammadzade (talk • contribs) 10:55, 23 February 2012 (UTC) what is crab nebula for example right now ?!! may be nothing ,disappeared plasma ,etcetera, where is Andromeda then ?in different place and condition User:Akbarmohammadzade|Akbarmohammadzade]] (talk) 11:16, 23 February 2012 (UTC)

Wikipedia is not a publisher of original research, but you may be interested in our articles on the Crab Nebula and the Andromeda Galaxy. Apart from both being astronomical objects, they have virtually nothing in common. — Lomn 14:10, 23 February 2012 (UTC)

The OP raises an interesting question in general. I don't know what he means by "dark matter is a time gap". But it's interesting to imagine what something that's extremely distant from us looks like "now". For example, theoretically we're seeing the Andromeda Galaxy as it looked 2.6 million years ago. However, unless something catastrophic happened to it in the last 2.6 million years, it's reasonable to assume that on the large scale it looks pretty much the same, as 2.6 million years is a fairly short time, geologically speaking. And the Crab Nebula is much closer, only 6,500 light years. It's reasonable to suppose it might have changed in the interim. If there are reasonably clear photographs of it from 50 to 100 years ago, it might be possible to do some kind of computer analysis on it to extrapolate its possible evolution. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:10, 24 February 2012 (UTC)

Such studies of nebulae and star clusters are indeed routinely done, and were routinely done even before the application of computers (as I recall from my 1st-year University Astronomy course 36 years ago). See para 2 here, for example, and also the section 'Distance' further down. {The poster formerly known as 87.81.230.195} 90.197.66.196 (talk) 14:29, 24 February 2012 (UTC)

 what we are seeing now is the condition of crab nebula has been happened
6500~7000years ago.If it does expand some parsecs in duiration of 950 years .so
it is expanded 6times further ,and may diapeared.Akbarmohammadzade--78.38.28.3 (talk) 11:16, 25 February 2012 (UTC)

What is highly substituted double bond?

Hi

I was reading Zaitsev's rule [[1]] and it says " In general, the compound that has a more highly substituted C=C double bond is more stable." I can compare stability of alkenes but what do we mean by highly substituted double bond? I am not able to get it. A picture comparison would be nice..

Thanks— Preceding unsigned comment added by Devvaibhav (talk • contribs) 12:08, 23 February 2012 (UTC)

It has mystified me, but perhaps you could email Ian Hunt at University of Calgary - he wrote it. His website is given as one of the references. Ratbone121.221.43.214 (talk) 13:09, 23 February 2012 (UTC)

Zaitsev's rule says that, during E2 elimination, the more substituted alkane is favored. Thus, the product on the right is the major product of E2 elimination; since the alkene contains more bonds from sp2-hybridized carbons to other carbon atoms.

"More highly substituted" in this case means more bonds to carbon. For example, ethene is as unsubstituted as you can get, as each of the four possible bonds from the sp2 carbons in the double bond is a bond to H. The most substituted (for the purpose of the Zaitsev rule) would be 2,3-dimethyl-2-butene, which would have all four bonds to carbon. The whole point of the Zaitsev rule is when you have a choice between which product to produce via an E2 elimination mechanism, you always choose the choice that gives you the double bond with more bonds to carbon (more substituted). I have uploaded and attached a picture. I hope this makes sense. If you don't understand, let me know, and I'll try to explain it a different way. --Jayron32 14:13, 23 February 2012 (UTC)

Thanks @Jayron23 I got it but as far as i know this rule is not applicable to all the cases. Exceptions are always there. So i decided to go what the mechanism says. Right or not? And again thanks for reply... — Preceding unsigned comment added by Devvaibhav (talk • contribs) 14:10, 25 February 2012 (UTC)

Safety of Ground Zero After A Nuclear Blast

Let's suppose a 'standard' cold war era hydrogen bomb was detonated in a city. How soon after the blast would it be safe to visit (for a few minutes, to a maximum of one hour) Ground Zero with only a moderate chance of long term health effects, assuming all reasonable precautions are taken (e.g. NBC suit worn)? What about if the visitor was willing to risk long term effects, so long as they are not immediately debilitating?--87.113.49.152 (talk) 13:40, 23 February 2012 (UTC)

Our (uncited) article says 3 - 5 weeks before the ground would be considered relatively safe. It also implies that in the immediate aftermath, you'd absorb a lethal dose of radiation in about seven minutes (see Nuclear_fallout#Short_term). I assume there are government recommendations on what to do, but I haven't found anything with explicit times given, possibly because it's so variable based on the yield of the bomb, the type of the bomb, and whether it was exploded in the air or on the ground. Someguy1221 (talk) 21:51, 23 February 2012 (UTC)

Relation between government deficit and debt

In the chapter "Primary deficit, total deficit, and debt" of the Wikipedia article "Government budget deficit" there are simple equations that connect deficit and debt. To me it appears they are too simple! If you look e.g. at Eurostat document "Provision of deficit and debt data for 2010 - first notification" http://epp.eurostat.ec.europa.eu/cache/ITY_PUBLIC/2-26042011-AP/EN/2-26042011-AP-EN.PDF it is easy to see (see e.g. the latest figures for United Kingdom and Germany) that the simple equation doesn't hold. Something missing? I cannot explain or understand this. Hope there are some economists online! ;)

(I have in fact already asked about this in http://en.wikipedia.org/wiki/Talk:Government_budget_deficit but haven't got any answer or comment there) --Sivullinen (talk) 14:31, 23 February 2012 (UTC)

Well, now I see finance and economics belong to 'Humanities' section, feel free to move if you can --Sivullinen (talk) 18:23, 23 February 2012 (UTC)

This is indeed the wrong desk, but I think I can probably answer the question. The important point is that the measure of government spending in the equations does not include spending that is used to pay off the existing debt. If that spending is included (as it typically is in a government's budget), a more complex formula is necessary. Looie496 (talk) 19:31, 23 February 2012 (UTC)

That is not an explanation, that is just what the 'simple equation' tells: deficit/surplus = change of debt. But it doesn't hold. --Sivullinen (talk) 20:52, 23 February 2012 (UTC)

Governments tend not to pay off existing debt, they just roll it over (ie. they pay it off by borrowing an equal amount of new debt). When doing these kind of calculations, you can generally ignore issues about when debt matures since it will just get rolled over anyway. You should just be able to look at the overall deficit/surplus, since any deficit will be funded by extra borrowing and any surplus will go towards paying off debt (ie. not rolling over all of it). I can't understand the numbers in that document either. The footnotes suggest the expenditure includes interest payments, but even it they don't the numbers would imply an interest rate for the UK government of 14% in 2007, which is far too high. --Tango (talk) 20:23, 23 February 2012 (UTC)

I'm not sure what the debt figures include. If they include cash in issue, then the increase could be due partially due to quantitative easing which involved buying securities other than government bonds. If the debt figure is net, then these assets would be counted against the debt and the transaction would be (broadly) neutral. Eurostat also reports changing the debt and deficit figures in relation to the Northern Rock, Bradford and Bingley affairs. This too is obscure to me. The document also reports "imapaired assets" and difficulties accounting for military spending on an annualised basis. Rich Farmbrough, 18:22, 24 February 2012 (UTC).

Do parrot view their cages as prisons?

The reason I ask, is that from what I've seen, it doesn't seem that they do.

I know that some people say things like 'parrots want to fly free' and claim that caging a parrot is like putting it in jail - however, from my own observations of pet parrots (my own and those of others) over the years, it seems that given the choice, they return willingly to their cage when they've had enough time outside, or will sit inside their cage playing with their toys even when the door is open, or will actively resist their owner trying to remove them from their cage if they don't want to go out (e.g. if you're trying to get them to fly around a bit more for exercise) - and as far as I'm aware, none of these were parrots that had been caged and never allowed out for years and thus 'screwed up' and 'institutionalized'. It would seem to me that they see a cage more as a home than anything else. Just curious as to if anyone else has researched and written on this matter, or if anyone has any thoughts?

FWIW, I do believe that it's cruel to keep a parrot in a cage and never allow it out - and in recent years, I've actually gone from being a total 'parrot guy' to becoming more and more opposed to keeping parrots singly, or maybe with only one more of their own kind for company - as housepets, like so many people do (if you see them in a big flock and take the time to look at how they interact and socialize, it makes you stop and think, I guess). --Kurt Shaped Box (talk) 17:35, 23 February 2012 (UTC)

Well, a parrot isn't going to have a concept of "prison" to compare it to, so the question doesn't really make sense. There has been a lot of research into the effects of keeping animals in captivity. The important things seem to be to make sure they have enough space that they aren't physically harmed (eg. they can get some exercise, they aren't forced to stay in one position all the time) and that they have suitable stimulation. I've never heard anything about a desire for freedom in animals. Google will find you lots of discussion on this subject. --Tango (talk) 17:51, 23 February 2012 (UTC)

The problem with the question is that it anthropomorphizes parrots by presuming that they have human value systems, or human perceptions, or human understandings of the world. We really need to be careful in evaluating animal behavior and/or views of the world by using our human-based value systems. The same thing happened here a few days ago when someone called the mating behavior of large cats like lions "rape". It is a bad idea to place human values on animal behavoirs in this way; which is not to answer the question of how parrots "feel" about their cages, but we do need to take care, when answering, to not try to answer "how a human would feel if it were in the parrot's place", and terms like "prison", for which there is no equivalent in the parrot world, make no sense in this regard. --Jayron32 23:42, 23 February 2012 (UTC)

I was trying to touch on that with my OP, as it goes, in that perhaps we do assign a human mindset to parrots. Something that seems to be overlooked by the 'parrots were meant to fly free for miles each day' people whenever that argument is made is that one of the main reasons that parrots fly for miles each day in all weathers is because they and their young are always on the edge of starvation in the wild. If they didn't have to constantly search for food, would they still desire to range far and wide like that (with the risk of encountering Harpy Eagles and suchlike)? Do they take pleasure in feeling the wind in their faces, or is it just routine drudgery to them, etc.? --Kurt Shaped Box (talk) 00:37, 24 February 2012 (UTC)

I was the person who used the term "rape" a few days ago in connection to whether cats enjoy sex, and I used domestic cats as a key example. Have you not ever seen domestic cats have sex? I hve seen it a few times: first, the male and female have a moderately violent fight ("moderate" is a relative term, domestic cats are extremely violent animals), eventuallly the female adopts the standard cat submissive pose, with the male over her, then he does the job in a few quick jabs, sometimes followed by body language that suggests he doesn't quite know why he did it. There's obviously nothing pleasurable it for the female, unless she enjoys being real scared, and it is DEFINATELY against her will. Surely that is rape. Presumably if the male is unable to subjue the female, he won't get any, but I've not witnessed that. It's risky to assign human values to animal behavior, but not invalid. The more researchers look into animal behavior, the more they establish that human behavior is merely an evolved form of animal behavior, just like physical aspects of humans eg legs. Re parrots, another aspect to consider is the behavior of long term prisoners. Often, after decades in gaol, they don't want to leave - fear of the unknown perhaps, or just a matter of comfort zone. In my city, the main gaol was an old Victorian era stone dungeon - cold, damp, & smelly. Cells had no toilets - prisoners used buckets. A few years ago, the Govt built a brand new prison along modern lines. Very secure, video survelance & electrified perimeter fences etc, but the cells are like small furnished flats with a proper toilet. And good common rooms. Now, were the lifers happy to be moved from the old prsion to the new - not a bit! They made a big fuss. But after they had been in the new prison for a few months, they were quite happy. So maybe those parrots in their cages are like lifers. Ratbone60.230.200.142 (talk) 02:01, 24 February 2012 (UTC)

I just want to say I completely disagree with the above post for precisely the reasons Kurt Shaped Box describes. it's purely an exercise in anthropormization. The breeding patterns of cats preceed the concepts of free will and consent, let alone "rape", It's pure nonsense to frame it in those terms. Vespine (talk) 03:53, 24 February 2012 (UTC)

Your reasoning seems strikingly similar to the Cartesian view of animals, which justified the most horrific cruelties based on the assumption that animals are machines without a soul, and therefore do not have "human" feelings. You argue against anthropormization (sic), yet cats and humans share similar biochemistry, a similar nervous system, and a similar brain structure. There's a reason that mammals are often used in neuroscience experiments--because their bodies and brains are very much like ours.

You also claim that the breeding patterns of cats preceed concepts of free will and consent, which seems to suggest that if a father has sex with his 5-year-old daughter against her will (and without explaining concepts like free will or consent), it wouldn't be rape. You also have not demonstrated that cats have no concept of free will and consent, whereas I would interpret a female cat trying to resist her male counterpart as a very clear indication of free will. Furthermore, if I agree that cats don't have the concept of free will, you still have to demonstrate that the breeding patterns of humans did not preceed the development of such a concept in humans. Considering that sexual reproduction predates the first multicellular organism, I don't think you'll convince anyone that this is the case. --140.180.9.36 (talk) 04:31, 24 February 2012 (UTC)

This isn't the place for taking this further, but I just have to add that I completely disagree with pretty much every point you raise ;) If you're interested in discussing this further, drop me a note on my talk page. Vespine (talk) 23:09, 26 February 2012 (UTC)

As the owner of several cats, and having watched a female cat in heat, I would have to disagree that the female cat doesn't want to have sex. It's obvious that she does. The yowl she lets out at the end is because the male cat's penis is barbed, so withdrawal is painful for her. The reason for this seems to have something to do with stimulation of ovulation. See this site Please don't anthropomorphise natural things. --TammyMoet (talk) 10:22, 24 February 2012 (UTC)

I'm not a cat person (my mother owns one - which doesn't like me and runs away and hides when I call round), but TBH - having seen how cats fight and the fuss they make (not to mention how quick and flexible they are), I'm struggling to imagine a scenario in which a male cat could force sex upon a totally unwilling female cat without suffering great pain and blood loss from bite wounds and scratches.

I know that there's a behaviour in Mallard ducks that could be considered rape (and is often described thus). That's far less ambiguous though - when a large group of males pile on a single female and forcibly mate with her, sometimes to the point that she's forced under the water and drowns (in effect, they fucked her to death), it's difficult to think of that as anything other than 'rape'. Well, IMO anyway. --Kurt Shaped Box (talk) 11:49, 24 February 2012 (UTC)

Just because the female cat has the right hormones flowing to put her in heat, and she displays typical "on heat" behaviour, it doesn't mean its not just pre-programmed instinct - it doesn't mean she necessarily understands what is going on, anticipates sex, or actually wants sex. As to whether male cats can force a totally unwilling female - I think that's an unknown, as I said before, perhaps if the male cannot subdue her, maybe he doesn't get any - that makes evolutionary sense (weak males would not produce offspring), but I personally have not seen a female not submit. I did say the fights are violent but not as violent as cats can be (eg territorial fights - they can be a fight to death) - maybe some instinct kicks in for the female not to fight too hard - that doesn't mean she likes it or wants it, any more than a human female becoming submissive during a rape means it is not rape. Having said that, I reckon the average cat sex fight leaves both of them pretty sore. I've read of whales joining in to assist one male to rape an unwilling female too, by preventing her from surfacing to breath. Ratbone121.215.16.6 (talk) 13:44, 24 February 2012 (UTC)

Back to the OP's question:Parrots are well known territorial creatures. It probably sees its cage as its own 'private space' or Personal space in the same way that a teenager sees his/her/its bedroom, and a place to retreat to when dad/mom/big sister/little sister etc., throws a wobbly. Of course, if you and the family are in the habit of frequently climbing to its cage to sit on one of the perches with it, then bang goes my theory. --Aspro (talk) 19:39, 24 February 2012 (UTC)

I was asked to comment here as the resident animal rights person. :) The AR perspective on parrots in cages can be found here on the PETA website. The idea that parrots see their cages as a safe place is probably true, but that's not inconsistent with the idea of it as a prison; even in prisons, people might retreat to the safety of their cells. The question is whether any of us would want to be taken captive, flown to another climate against our wills, have bits of our bodies clipped off so we couldn't flee, and placed in a cage for the rest of our lives, probably alone. If we wouldn't like it, why do we imagine that parrots might? Would we get used to it, and make the best of it? Possibly, and so might they.

For a very different perspective on animals in zoos, however (so long as they are good zoos), see Yann Martel's Life of Pi. He argues that the last thing animals want is to be released back into the wild, because the one thing animals hate is change. Bit like us. :) SlimVirgin ^{TALK|CONTRIBS} 01:32, 25 February 2012 (UTC)

I think that asking whether parrots see their cages as prisons is really asking the wrong question. The real problem is that parrots (at least the ones I'm familiar with - Amazons and macaws) are intensely social. And this works both ways - wild parrots will come and visit a caged parrot, hang out on the outside of the cage. The problem with a caged parrot is that it's likely to be alone, and that's really a terrible thing to do to a parrot.

Obviously if you give a caged parrot more space, it will use it. Give a parrot with clipped or pinioned wings the chance and it will probably leave its cage, and come join the 'family'. Again, my guess is that their seeking company more than space. Of course, if you let a caged bird fly, it will fly, and it will probably appear to "enjoy" the experience immensely (though, of course, calling it "enjoyment" is an anthropomorphism...if anything, it's probably more akin to the experience of running - your body knows that's what it was meant to do, it just feels right, and you're likely to say you "enjoy" running, but that's really not the right word because, to an inexperienced or out-of-shape runner, it's actually an exhausting and painful experience...but one that feels right).

If you let a caged parrot out of its cage, odds are it will hang around "its people", since they at least someone (probably) fulfill its need to be gregarious. But if there are wild parrots, the need to be gregarious with parrots will almost certainly outweigh its desire to be with people. But neither of these is a response to the cage as such. Rather, it's most likely a response to what the cage prevents (socialisation, not 'freedom'). Guettarda (talk) 06:46, 25 February 2012 (UTC)

@ SlimVirgin ”why do we imagine that parrots might?” These creatures are endowed with with instinct. An instinct to preserve them in the tree canopy of the jungle. A jungle is a place where one either eats or gets eaten. A human home provides them with a habituate that may not be _{'NATRUAL' JUNGLE} but is free of the stress of jungle warfare and other stresses like periods during which there is a lack of food. Parrots thus live for longer in captivity than in the wild. If the 'wild' is so fantastic- why aren’t Homo sapiens not leaving their centrally heated/ air conditioned cities with its plentiful supplies of food and safe drinking water, and getting back to the good life of living off the land in their droves? After all didn't many suffer the trauma of being sent off as young children to become school 'captives'? Why didn't their ancient ancestors shun the unnatural activity of rubbing two sticks together when it gets cold. Parrots may not have the intellectual capacity to achieve what we have (?) but that doesn't mean to say they can't choose prefer it. --Aspro (talk) 19:41, 25 February 2012 (UTC)

It should probably also be mentioned that parrots are increasingly being bred in captivity nowadays (not that I'm saying that there aren't debatable moral/ethical issues with that) - in fact the situation sometimes arises where animal shelters actually have a surplus of parrot species that are endangered in the wild (because people who get new parrots usually want new fledglings). I couldn't honestly say whether the majority of pet parrots are captive bred or not, as I don't have the figures in front of me - but certainly a significant percentage of pet birds will never have even seen their species's natural habitat. --Kurt Shaped Box (talk) 21:08, 25 February 2012 (UTC)

Aspro, Yann Martel agrees with you (Life of Pi, pp. 22–24):

"A biologically sound zoo enclosure ... is just another territory, peculiar only in its size and in its proximity to human territory. That it is so much smaller than what it would be in nature stands to reason. Territories in the wild are large not as a matter of taste but of necessity. In a zoo, we do for animals what we have done for ourselves with houses: we bring together in a small space what in the wild is spread about. ... Finding within it all the places it needs -- a lookout, a place for resting, for eating and drinking, for bathing, for grooming, etc -- and finding there is no need to go hunting, food appearing six days a week, an animal will take possession of its zoo space in the same way it would lay claim to a new space in the wild, exploring it and marking it out in the normal way of its species, with sprays of urine perhaps. Once this moving-in ritual is done and the animal is settled, it will not feel like a nervous tenant, and even less like a prisoner, but rather like a landholder ... Such an enclosure is subjectively neither better nor worse for an animal than its condition in the wild; so long as it fulfills the animals' needs, a territory, natural or constructed, simply is, without judgement, a given, like spots on a leopard. Think about it yourself. Would you rather be put up at the Ritz with free room service and unlimited access to a doctor or be homeless without a soul in the world to care for you? ...

"A good zoo is a place of carefully worked-out coincidence: exactly where an animal says to us, 'Stay out!' with its urine or other secretion, we say to it 'Stay in!' with our barriers. Under such conditions of diplomatic peace, all animals are content and we can relax and have a look at each other. ...

"I know zoos are no longer in people's good graces. Religion faces the same problem. Certain illusions about freedom plague them both."

SlimVirgin ^{TALK|CONTRIBS}

Plumbane and other metal hydrides

Would plumbane be a more stable molecule, if all the hydrogen atoms are switched out for deuterium or tritium, ignoring tritium's radioactivity? Would this effect extend to other other metal hydrides, or would it have the opposite effect on some? Plasmic Physics (talk) 21:27, 23 February 2012 (UTC)

There certainly is likely to be a stability difference based on different isotopes. The underlying concept of heavier isotopes generally forming stronger bonds is the basis for the kinetic isotope effect. That article has some discussion of the stability issues themselves. The section about inverse KIE gives transition-metal hydrides as its example (again with the same "heavier==stabler" but is focused on the C–D(H) of the product rather than the M–D(H) of the reactant. But it might be a starting-point if you want actual studies involving the metal species (I'm sure someone has done the stability by calculation and/or experiment). I don't know of specific data for lead, but again it's fairly easy to run some simplistic calculations of such a rigid molecule on a home computer. DMacks (talk) 21:54, 23 February 2012 (UTC)

OK. Plasmic Physics (talk) 00:00, 24 February 2012 (UTC)