Wikipedia:Reference desk/Archives/Science/2012 October 9

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

October 9

Yearly hours of sunlight at different latitudes

Do I understand rightly that all locations worldwide receive an equal number of hours of sunlight in a year? I'm ignoring clouds for the moment, along with shade from mountains and other factors that vary from place to place at the same latitude. I found this discussion, but (1) I can only read part of the page; and (2) the guy who drew the diagram seems to be saying that night and day are also equal, and I know that's wrong because the Sun is a disc, not a point. Nyttend (talk) 02:46, 9 October 2012 (UTC)

It's almost true. If the Earth's orbit around the sun was a perfect circle, every point on Earth would see the sun exactly 50% of the time, averaged over the whole year. But the Earth's orbit is actually slightly elliptical, so there are small differences. I am ignoring the disk-shape of the sun -- that's a very small factor, along with some others such as the curvature of the Earth. Looie496 (talk) 04:11, 9 October 2012 (UTC)

Also note that this doesn't mean every place on Earth receives the same magnitude of sunlight, as, near the poles, the Sun is always low on the horizon, and hits at a shallow angle, after going through more atmosphere. So, a solar panel at the poles is not very useful, compared with the equator. StuRat (talk) 04:16, 9 October 2012 (UTC)

lightning

Does lightning go through closed windows? Is it safe to be on a computer during lightning? If lightning strikes a body of water, how far away does it travel? — Preceding unsigned comment added by 173.22.168.103 (talk) 02:49, 9 October 2012 (UTC)

Our Lightning strike article may be of help here. Regarding your particular questions, though glass is a good insulator, the window frame and surrounding structure will probably not be, I doubt that shutting the window will reduce the risk, but you are almost certainly safer inside a building than outside. As for computers, anything connected to the electricity mains or to a phone line has a chance of being zapped by a strike outside being conducted through the wires - though it is probably more likely to damage the computer than the user. As for lightning strikes onto water, I'm not sure. In any case, though lightning is dangerous, there are precautions that can be taken, and fatalities are relatively rare. AndyTheGrump (talk) 03:50, 9 October 2012 (UTC)

The danger of being on a computer is mainly to the computer. If your computer is plugged into a power strip with a surge protector, there shouldn't be much risk, though. If your computer isn't plugged into a power strip, it ought to be, if you value your computer.

I don't think a urge surge protector would do much good if your house was struck by lightning, but that's rare, as was previously said. StuRat (talk) 04:17, 9 October 2012 (UTC)

Lightning could strike a pole-mounted transformer that leads to your house. A while ago, some contractors were working near such a transformer. An accident caused the transformer to short out, sending a surge down the line and into my friend's house. It fused the switchboard and power outlets, and basically destroyed everything that was plugged into a power outlet, regardless of whether it was switched on or off. I don't think that a surge protector would have made a hair breadth's difference in this case. Plasmic Physics (talk) 11:23, 9 October 2012 (UTC)

"Urge protector"? Isn't that one of these? AndrewWTaylor (talk) 21:03, 9 October 2012 (UTC)

While a serge protector prevents you from sewing your hand. StuRat (talk) 00:51, 10 October 2012 (UTC)

The one thing that people should avoid seems to be the old landline telephone. According to this, on average one American dies each year from a lighting strike on his telephone line. Non-lethal effects include ruptured ear drums and electric burns. Running the telephone wires on utility poles instead of under the ground may be a risk factor. Ssscienccce (talk) 14:02, 10 October 2012 (UTC)

While it is in the sense that the pole is more likely to be struck directly, underground lines are at just as much of a risk in the same way that underground plumbing can transmit lightning (it's also best to avoid taking showers/baths during thunderstorms). Ks0stm ^{(T•C•G•E)} 03:34, 11 October 2012 (UTC)

I was thinking that once it went underground, the voltage would be lowered considerably, making it less likely to travel through the air again from phone to person. With plumbing people can be in direct contact with both drain and water pipe. Mains voltage would be enough to kill them. Ssscienccce (talk) 04:15, 13 October 2012 (UTC)

Ball lightning does form indoors. Thankfully, it's pretty rare. A recent scientific paper. Zoonoses (talk) 03:18, 13 October 2012 (UTC)

Not in a microwave oven.

Mine made a ball lightning once. It was an almost perfectly clear, orange sphere ~3" in diameter. When I saw it, I opened the door (stupid move, i know) and it flew out at my face and bounced off, and disappeared.

(Speculation ahead) Or then I thought it bounced off my face. Today I would rather speculate that a stable ball lightning tends to avoid(in the sense of being repelled by) conductors like the oven and its door, and humans, and when I opened the door, it could get out of the oven until I was in the way, so it stopped some inches short of me and changed direction. I did not feel anything, so there was probably no contact at all.

After that, the ball moved around a bit and disappeared after 2 or 3 seconds, about 1 foot below the ceiling. I think it didn't touch anything, it just faded.

And I was unable to reproduce the ball lightning in over 100 attempts. It must have been the perfect mix of a dodgy microwave oven, too small a food portion for near-full power, and who knows what. - ¡Ouch! (^{hurt me} / _{more pain}) 07:22, 15 October 2012 (UTC)

It's fun to make microwave plasma. I have a setup which works every time, which usually produces a white-violet vortex of plasma accompanied by a sound that sounds like a vocalised razz.

The setup consisted of an inverted spherical glass vase covering a spark gap, a saucer with water on the side to protect the magnetron. The spark gap consisted of florist's sponge inserted into a bottle screw cap. Two lengths of graphite pencil leads were inserted at an accute angle, ~5 mm appart at the top, into the sponge base. An unused match was inserted between the leads, pointing up. I tried using bentonite clay as a base, but it melted into glass. Plasmic Physics (talk) 08:42, 16 October 2012 (UTC)

Relative speed and position

If I am here and I am then being on the Earth I'm traveling +- 1000mph. Traveling around the Sun I'm traveling +- (way fast) On through the Milky Way and so forth to the outer limits. Then where are we? Where are we going and how fast? Shalom, Tim Jagoe — Preceding unsigned comment added by 108.249.61.251 (talk) 02:52, 9 October 2012 (UTC)

"where are we?" Relative to where? Neither position or speed have any absolute value. They can only be expressed in relation to something else. AndyTheGrump (talk) 03:35, 9 October 2012 (UTC)

Andy's point is the entire point of the various "Theories of Relativity", especially Special relativity, but even it's predecessors Galilean invariance and Newton's third law or its sequel General relativity. All of these theories basically have the same principle: there is no privileged frame of reference. That is, there is no point in the universe which can be considered to be "standing still" against which we measure the motion of other objects, except in a purely arbitrary sense: we define "still" generally from where we, as an observer, is standing, but that choice is arbitrary, and the laws of motion are the same if another frame were to be chosen. Or to put it simply, if I say that I am standing still and you are moving, that is completely identical to claiming that you are standing still and I am moving. --Jayron32 04:18, 9 October 2012 (UTC)

We are moving at approximately 370km/s relative to CMB. manya (talk) 04:37, 9 October 2012 (UTC)

domestic cats like killing

Since cats have traditionally been useful for keeping down rode.t numbers it seems likely that we would have encouraged wanton killing. But what'a with them leaving dead animals on the doorstep or similar place for us to find. Are they giving us the food, or simply frequently happen to drop it there by coincidence.

Is it possible that we have encouraged the trait of bringing us food much the way it would bring its own kittens food? Its the only way I can see that they would get anything out of it — Preceding unsigned comment added by 149.135.146.109 (talk) 03:17, 9 October 2012 (UTC)

If you read Cat#Hunting_and_feeding it has some good information on "presentation of dead animals to owners" as you describe. There's also some links, via the footnotes, to other sources on the behavior, but I think the salient point made in the Wikipedia article is "One poorly understood element of cat hunting behavior is the presentation of prey to human owners." (bold mine) In other words, science hasn't got a firm grasp on explaining the behavior in a conclusive way. I'm sure a dozen people after me will present some unreferenced folky explanation on what cats are doing when they do this, but perhaps someone will come along with some solid references that contradict the Wikipedia article to say that this is "poorly understood". --Jayron32 03:27, 9 October 2012 (UTC)

Jackson Galaxy might know. For the rest of us, it's pretty obvious that the cat is bringing a present to its owner. Cats aren't pack animals like dogs are, but they do have a sense of a "pecking order". ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:48, 9 October 2012 (UTC)

And in steps Bugs with an unsourced 'explanation' ;-) Actually, I've heard another, entirely contradictory 'unverifiable explanation' - that cats, having never seen humans catch mice, assume that they are kittens in this respect, and need to be taught how to do it - hence their predilection for bringing home live specimens for us to practice on. The truth is though, that we don't know. If I remember correctly Wittgenstein said that 'if lions could speak, we couldn't understand them' or something to that effect. Felines are different from us, and trying to understand their behaviour in terms of 'why' rather than 'what' may be a futile endeavour... AndyTheGrump (talk) 03:58, 9 October 2012 (UTC)

Unless you own a cat yourself and watch Jackson Galaxy's TV series, keep your grumpy trap shut. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:30, 10 October 2012 (UTC)

I wonder if we selected for it, it if wild cats will do it inately. I wasn't aware that wild cats are very sociable. Even if they are more social creatures than I realised, presenting an alpha with food is quite an advanced social tool! The idea that cats see their owners as a mixture of mother and kitten seemed mire plausible but I was merely hypothesized with no evidence. — Preceding unsigned comment added by 149.135.146.89 (talk) 04:03, 9 October 2012 (UTC)

I'll go with Bugs here. Specifically, cats exhibit behavioral neoteny, meaning we have selected for cats which maintain kitten-like qualities into adulthood. This is even more true when we have them neutered. Their owners take the role of mother (regardless of gender), unlike with dogs, where the owner is the pack leader. As such, bringing home caught prey to their mother is a way to demonstrate their value and gain approval. I also suspect that people, in the past, have been more wiling to allow a successful hunter to live with them, as that shows the cat is "doing it's job" to keep down the rodent population (very important for those with grain stores). StuRat (talk) 04:11, 9 October 2012 (UTC)

I'd agree with neoteny being a factor in the domestication of most animals - I'm not entirely sure how true it is of cats though, in that their 'domestication' as pets seems to be relatively recent, and there may have been little selective pressure to change behaviour beyond a willingness to hang around where the humans are - because that is where the mice are to be found. AndyTheGrump (talk) 04:19, 9 October 2012 (UTC)

But "adult" cat behaviors, which we've now largely bred out of them, would involve them hissing and scratching and biting us, and would get them thrown out into the cold quite fast, if not outright killed. Domestic cats have been around for thousands of generations, which is enough for selection pressures to work their magic. StuRat (talk) 04:27, 9 October 2012 (UTC)

I haven't tried to work out the answer yet, but I should point out that the African wildcat is what will display evolutionarily sensible behavior; the actions of domestic cats, as pointed out above, may be different. Wildly speculating (which I shouldn't do because there's probably an answer to this one) I'm prone to compare this to the various sorts of gun dogs, pointers and setters and retrievers, which I've seen explained plausibly as caused by a defect in the natural hunting instinct at various points in the process, from the moment the prey is first sighted to the point where it is about to be devoured. Wnt (talk) 06:03, 9 October 2012 (UTC)

As a long time cat owner (40+ yrs), I suspect that the cats leave the dead animals not as a gift, or as food but the place we find the animal is where the cat got bored of playing with it or eating it and wandered off. 217.158.236.14 (talk) 09:22, 9 October 2012 (UTC)

Weirdly enough, I just received this in my email: a comic from The Oatmeal. Anyway, it sources a National Geographic and University of Georgia project, called Kitty Cams Project, which studies domestic cats when they're away from the prying eyes of their human owners. I can't vouch for its legitimacy, but there we go. – Kerαunoςcopia^◁_galaxies 09:37, 9 October 2012 (UTC)

On a somewhat similar point, I would say you're somewhat lucky when all you find is half of a dead animal (or whatever), far worse when your cat brings in a bird, gets feathers and possibly blood everywhere while playing with it for many minutes while it (the bird) screeches only to get bored of it and leave the half dead bird somewhere and you have to decide whether to kill the half dead bird or let it die naturally. You can of course try to save the bird but unless you're either willing to play the vet bills everytime it happens or continually bother volunteer bird rescue groups there's a fair chance the bird will die anyway, particularly once the cat learns you'll take the bird off it. Worse still when your cat brings in a live mouse or rat, only to find 10 minutes later the cat desperately searching for the mouse or rat. Anyway to get back to the original question, I think this sort of thing highlights why we need to be careful with evolutionary explanations, logically playing with your food to the extent you may lose it is not advantageous particularly when your primary benefit to humans was in catching vermin. Even if this behavior has increased in recent times as catching vermin has become less important and neutering more common, is the fact this behavior still exists reflective of the fact it's not easy to breed out without either negatively affecting learning, other desirable behaviours, or simply suggestive as with most cases, it's likely fairly complicated? Nil Einne (talk) 12:48, 9 October 2012 (UTC)

Never, never, attempt to rescue a bird from a cat: http://www.cbsnews.com/2100-500202_162-20088063.html μηδείς (talk) 18:04, 9 October 2012 (UTC)

That seems of questionable relevence if you don't live in the US. Nil Einne (talk) 03:38, 10 October 2012 (UTC)

What would be the evolutionary pressure which would breed this behavior out of cats ? How many people would neuter or kill their cat because it did that ? StuRat (talk) 21:49, 9 October 2012 (UTC)

If I had to take a wild guess (a flagrant Just-so story) I would speculate that a cat that efficiently catches and eats the mouse will get filled up and stop bothering them, but one which plays with it and forgets it will keep going after more. And such a cat, maybe, would get a reputation as a "good mouser" and be preferentially bred. (Leaving the remains where the owners could see probably wouldn't have hurt either) Wnt (talk) 22:56, 9 October 2012 (UTC)

Another possibility, equally unreferenced but in my opinion more plausible: Cats that "practice" hunting when game is plentiful are more likely to be able to feed themselves when it's not. So if they're not particularly hungry, they "play" with the mousie to hone their reflexes (and may not even eat it at the end).

This one is even somewhat testable — see if hungry cats are less likely to play with their food, and whether cats that engage in this sort of practice become more skilled. --Trovatore (talk) 08:33, 10 October 2012 (UTC)

This may indeed be more convincing than my scenario, especially when I remember that carnivores tend to be scavengers as well - in the wild, a rotten mouse stashed in a "safe" place might still be food in the future. Wnt (talk) 16:13, 10 October 2012 (UTC)

As Jackson Galaxy often explains, cats are hard-wired to hunt and kill. That basic fact explains a lot about their behavior. I saw a story recently where some outdoors cats were equipped with small cameras so that observers could see what they were up to. It turns out they were killing a lot more prey than people generally assumed. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:30, 10 October 2012 (UTC)

I think it's quite likely in the past when cats were not really seen as pets as such, a cat which keeps losing vermin (particularly if it brings them from further away) rather then killing them would find itself out of favour of any humans it tries to live near them. Whether it would be killed or simply thrown out or have to leave because of the human reaction is largely a moot point; it's very unlikely neutering comes in to it much, remember we are talking about hundreds or thousands of years in the past and when cats weren't seen as pets much. Wnt does have a point that it's not clear whether what the cat was doing would have been appreciated as such. Although it's also worth considering from a results POV, while no one was doing scientific experiments, if humans found the vermin level has not decreased much or perhaps even increased they're far less likely to see a reason to keep cats around then if they found them significantly decreased. And if the neighbours cat (or an old cat) seems to have been far more effective this could also affect the chance of the cat being kept. Of course even lost vermin may die from the injuries, but they generally have a more effective immune system then birds. In fact, it's even possible there would be greater evolutionary pressure on this sort of behaviour for quite a while then stuff like biting. If a cat is helping with the vermin population even if it doesn't really let humans handle it this could easily be more successful then on which does not help with the vermin population but lets humans handle it. In any case, it does demonstrate the point you need to take care when considering evolutionary explainations. Nil Einne (talk) 03:23, 10 October 2012 (UTC)

Yeah, I don't think we'll get to any real answer unless we come up with more observations on the behavior of Felis silvestris lybica. Wnt (talk) 16:13, 10 October 2012 (UTC) -- hmm, while I didn't see anything naturalistic about it on NCBI, I did stumble across a commercial photo stock image of European Felis silvestris playing with prey. Unfortunately the author isn't credited that I see, so asking him would be a paper chase ... still, there must be people contactable somewhere who have observed these cats in the wild or in zoo-like conditions who can tell us if they play with prey like domestic cats. (though we should be careful of assumptions based on little evidence but presumed resemblance) Wnt (talk) 16:22, 10 October 2012 (UTC)

• I am not quite sure what the mystery is here. Domestic cats are usually not starving. So if they do catch prey, why wouldn't they bring it back to the den just like wild cats do, either to eat later or share with the family? I am allergic to cats. So perhaps I am missing out on their being some other behavior that needs explaining, like the cat pawing you with a bird in his mouth, or doing a little end-zone dance to get your attention? μηδείς (talk) 17:14, 10 October 2012 (UTC)

• They do a strange twitching thing when stalking prey. I attribute this to the effects of adrenaline flooding their system as they try to keep still. StuRat (talk) 15:47, 11 October 2012 (UTC)

• Yes. Cats are instinctive hunters. It doesn't much matter if they're hungry or not. They do what they do because it's programmed in them. ←Baseball Bugs ^{What's up, Doc?} carrots→ 05:12, 11 October 2012 (UTC)

Scale of eyes

Our eyes detect light and we can determine size and scale. If there were beings whose heads were as big as the sun would their eyes be able to see as detailed as ours? The same amount of photons would be shining on them?GeeBIGS (talk) 05:21, 9 October 2012 (UTC)

They probably could not see things as small as we can. We can't make out items as finely as a spider can. I think the issue is that larger lenses cause larger distortions, making it more difficult to focus on smaller objects. Now, what I'm unsure of is if our eyes could be much better for viewing small objects, if there was evolutionary pressure for them to be so. I'm quite nearsighted myself, and, without contact lenses, I can make out very tiny objects, like the individual dots on a printed picture, but only if my eye is within a few inches (that's too close for binocular vision to work). So, perhaps a nearsighted Sun-sized creature could see more detail at very close range, but not at the distances of planets. StuRat (talk) 06:55, 9 October 2012 (UTC)

I'll second Stu's experience regarding distortion. I as well can make out small details without my contacts; they distort my close vision for the sake of giving me decent distance vision. Optical aberration has some details which may help as well. --Jayron32 18:18, 9 October 2012 (UTC)

I don't really understand the question. Is it asking whether a head exactly like ours except scaled up to the size of the sun would be able to see things a fraction of an inch in size? Or whether it would be able to see things that are scaled up to an equal degree? Looie496 (talk) 18:50, 9 October 2012 (UTC)

I took it the first way. StuRat (talk) 21:41, 9 October 2012 (UTC)

The first way. Stu you seem to contradict yourself, could you please clarify?GeeBIGS (talk) 00:09, 10 October 2012 (UTC)

That is, "whether a head exactly like ours except scaled up to the size of the Sun would be able to see things a fraction of an inch in size". To that I say no, although they could see smaller things close up (but not that small), than if focused on distant planets. StuRat (talk) 00:44, 10 October 2012 (UTC)

If you simply scale up everything in the eye, there's no way it could detect tiny things, because scaling up the photoreceptor cells in the retina would mean they would have vastly larger receptive fields. Looie496 (talk) 02:05, 10 October 2012 (UTC)

Is it possible to wire to a spiders brain and see through its eyes like a spy camera?GeeBIGS (talk) 04:30, 10 October 2012 (UTC)

I don't know, but it would be simpler to mount a camera on the spider. We have cameras that fit into the human bloodstream, so a large spider would easily be able to carry one. Nyttend (talk) 20:08, 10 October 2012 (UTC)

I suspect that a spider is extremely nearsighted, as they need to see their prey when they approach it, not things on the other side of the room. So, it would be useless as a spy camera. StuRat (talk) 15:43, 11 October 2012 (UTC)

Can anyone do this?

Does anyone know how to put his little toe on the second toe?

http://www.youtube.com/watch?v=adxiafRNmTo — Preceding unsigned comment added by 192.117.235.33 (talk) 07:07, 9 October 2012 (UTC)

I can't, at present, but perhaps could if I exercised those muscles. StuRat (talk) 07:17, 9 October 2012 (UTC)

Ha, what a neat trick! but aren't you counting from the wrong end, it crosses the 4th toe surely. I'm off to practice that. Richard Avery (talk) 14:00, 9 October 2012 (UTC)

I couldn't, but I have small, stubby toes. My wife could do what's in that video easily. She's got toes she could play piano with. People have different feet. --Jayron32 16:52, 9 October 2012 (UTC)

My toes are quite long, but they don't move like that, at least not on their own. Presumably this is because the muscles needed to do such movements aren't well developed in my little toes. StuRat (talk) 21:40, 9 October 2012 (UTC)

Some muscular control is also innate and not that trainable. Some people can curl their tongue and others cannot; some people can wiggle their ears and others cannot. I don't know that there's an explanation or mechanism as to why not, but tongue rolling or tongue curling (two different tongue movements) is one of those "you can do it or you can't" things, and I'm not sure it is trainable. Our article on tongue rollings states that it is an "intrinsic" property of the musculature of the tongue, but also says that it has no demonstrated genetic component. I'm not sure how to resolve that in my mind (if something is inborn, but not genetic, what does that mean?!?) but it isn't a trainable skill. --Jayron32 21:58, 9 October 2012 (UTC)

You'll want to apply to study prana-bindu muscle technique which allows one "to bend the last joint in her little toe while remaining otherwise motionless" at a Bene Gesserit school. μηδείς (talk) 02:27, 10 October 2012 (UTC)

Nah, I'm already the Kwisatz-Haderach, so it's pretty pointless messing around with amateur stuff like that. --Jayron32 04:29, 10 October 2012 (UTC)

I am pleased to note that not merely do we have an article on Kwisatz Haderach, but it leads me to the actual basis of this in the Kefitzat Haderech. (Though it fails to connect this with the story of Al-Buraq, which would be more appropriate to the novel's Islamic theme) Wnt (talk) 16:33, 10 October 2012 (UTC)

Oh, that's brilliant. I knew that Bene Gesserits were the daughters of the Jesuits (under whom Herbert studied) but didn't know this too had a real-world antecedent. The novel is far more ecumenical (Orange Catholic, Zen-Sunni) than just Muslim. There are even real live Jews in Heretics and/or Chapterhouse. μηδείς (talk) 02:20, 11 October 2012 (UTC)

Real image?

What is this substance? The image is in a science section, so I'm guessing it something real but would like to know what. Thanks. Dismas|^(talk) 11:03, 9 October 2012 (UTC)

That link takes me to a mosaic of 24 images. Which one are you talking about? Rojomoke (talk) 12:39, 9 October 2012 (UTC)

if you mean the first image, with the animation, I believe I've seen it before in videos of a Japanese guy making miniature, fake food. It came in a kit that you had to mix all the bits together, then form the food. It's called "Konapun". — Preceding unsigned comment added by 217.158.236.14 (talk) 12:59, 9 October 2012 (UTC)

Sorry. I thought it would be a direct link. I'm talking about the 14th image. I get a grid of images four across. In which case I'm talking about the second column, fourth image down. The two hemispheres. Dismas|^(talk) 14:08, 9 October 2012 (UTC)

It is a computer animation. I believe it to be made with Autodesk 3ds Max. I don't know what it is supposed to be achieving.217.158.236.14 (talk) 14:13, 9 October 2012 (UTC)

Okay, thanks. I wasn't sure what with the poor quality of the image. Dismas|^(talk) 20:56, 9 October 2012 (UTC)

Resolved

Microwave oven question

At my place of work, our (very old) microwave oven is acting strange recently. Sometimes, the turntable will begin turning and the microwave sound like it is running when the door is opened (after having stopped/not been in use). Some of my coworkers are wondering: Could a microwave oven that's on while the door is open be dangerous, perhaps leaking radiation? If so, is it an amount of radiation to be worried about? Thanks! -- 143.85.199.242 (talk) 19:34, 9 October 2012 (UTC)

Here's what Wikipedia has on the subject: Microwave burn#Adults_and_microwave_ovens 209.131.76.183 (talk) 19:37, 9 October 2012 (UTC)

Don't even think about it any further, just trash the oven immediately. Roger (talk) 20:03, 9 October 2012 (UTC)

And unplug it until you can have it serviced or disposed of. On the plus side, if it's just an issue of the door switch sticking closed, that ought to be easy and cheap to fix. Just cleaning the switch might do it. StuRat (talk) 20:27, 9 October 2012 (UTC)

Ugn, not even worth considering, bin it and get a replacement, it's a potential health hazard. Tell them either buy a new unit for $150 or risk a law suit.Vespine (talk) 23:12, 9 October 2012 (UTC)

$150? Sounds rather a lot. They start at £32 in the UK. Alansplodge (talk) 00:53, 10 October 2012 (UTC)

$150 would be a premium version. The cheap one you linked to runs $30-$40 in the US. I actually prefer the cheap ones, though, as it's much quicker to turn two dials than to navigate through menus to try to get the darned thing to turn on. One thing I'd prefer, though, is if they don't have those levers you have to hit to get them to open. Those can stop working if they get dirty. I prefer a big handle you can yank open. StuRat (talk) 01:14, 10 October 2012 (UTC)

Most decent microwaves with digital controls have a 1 minute or similar button meaning there's no need to navigate any menus. In fact most don't have menus for normal usage, even if you don't want to use the 1 minute button, simply push the buttons for the time and push start. One big advantage with fancier microwaves is you can get one with an inverter meaning you have less problems when using it at non full power. Nil Einne (talk) 03:44, 10 October 2012 (UTC)

You've hit on a pet peeve of mine. To get the quality item, I often have to accept unwanted electronics. For example, I'm fine with manual adjustments on my car seat, except that I'm often limited to just forward/back and maybe tilt. If I want additional degrees of freedom, like an up/down control, then I not only must accept those additional features being controlled by motors, but the basic features, as well. StuRat (talk) 06:56, 10 October 2012 (UTC)

I have to admit i had NO idea about the prices of microwave ovens, I chose $150 after doing a shopping search in australian google! After that, $150 seemed conservative! There are $200, $300 and even $400 models!! $30-$40?!? Forget foxconn! You gotta wonder about the conditions of the places where that kind of stuff is made.. Vespine (talk) 00:13, 15 October 2012 (UTC)

Can human nature evolve, and if it does evolve, can humans understand earlier humans thoughts millions of years from now?

Can human nature evolve, and if it can and does evolve, can humans understand earlier humans thoughts and motives and desires millions of years from now? 140.254.226.212 (talk) 19:38, 9 October 2012 (UTC)

Please see the top of the page where it states "The reference desk does not answer requests for opinions or predictions about future events. Do not start a debate; please seek an internet forum instead." This isn't the correct venue. --Jayron32 19:41, 9 October 2012 (UTC)

I'm not sure what Jayron's problem with this Q is, looks perfectly valid to me:

1) Can human nature evolve ? Yes, personalities, willingness to cooperate with others, tendency towards violence, etc., are all aspects of human nature with genetic components. As such, they can evolve just like any other attribute, provided there is sufficient evolutionary selection pressure for them to do so. This means that the ability of people to survive and reproduce must be affected by these attributes.

2) As far as future human's understanding us, I don't see a problem there, as long as we leave behind records of our motivations. It's a bit harder when archeologists look at ancient humans, who lacked writing. You can get some clues, though, such as whether they buried the dead with important items or just tossed them into a hole. StuRat (talk) 20:26, 9 October 2012 (UTC)

Yes, all we need to do is preserve Wikipedia, including all of the historic versions of the pages. There is then a continuous link from the present to the far future, making it easy to decipher ancient texts. Count Iblis (talk) 20:43, 9 October 2012 (UTC)

• The second question is indeed unanswerable. To illustrate, it is possible that future humans will be exactly like present humans, by accident or design, in which case they can understand. But it is also possible that future humans will live in a dictatorship so appalling that the mere conception of being "free" causes one of them to immediately fall over dead by genetic design, in which case they cannot understand. Wnt (talk) 23:20, 9 October 2012 (UTC)

To give a less ridiculous scenario, humans and chimps are separated by "millions of years". Can you understand a chimp's thoughts and desires, and do you think a chimp could understand ours? The Aztecs are separated from us by 600 years; they considered it an honor for their living, beating hearts to be ripped out of their chests and sacrificed to the gods. Do you understand them? The Taliban are living in our own time, and they think shooting a 14-year-old girl in the head is OK. Do you understand them? (I do understand the Taliban's motivations, but many people don't; they resort to idiotic cop-outs like "they're just evil", "they're just crazy", or "the devil made them do it", which is essentially equivalent to saying "I can't understand X; therefore, nobody alive today can understand X, and nobody who will ever be born will understand X") --140.180.242.9 (talk) 22:30, 10 October 2012 (UTC)

I understand the Taliban's motivation as far as wanting everyone who disagrees with them to be afraid to speak up. However, they don't seem to have considered the negative PR implications of murdering children. Not the way to broaden their base of support. StuRat (talk) 15:39, 11 October 2012 (UTC)

I believe humans and chimpanzees are not in fact "separated by millions of years"; rather, they co-exist and are each separated from a common ancestor. 82.31.133.165 (talk) 21:43, 15 October 2012 (UTC)

Genetic bottleneck from the KT and Permian mass extinctions

Can one calculate that there were mass extinctions about 65 and 250 million years ago using only the data from genomes of modern animals? Count Iblis (talk) 20:36, 9 October 2012 (UTC)

I think in principle it should be possible: the signature would show up as large numbers of species-pairs having their last common ancestor around 65 or 250 million years ago. To make it work, though, techniques for genetic dating would have to be improved, and the genomes of a lot more species would need to be sequenced. Note that this not the sort of bottleneck that is normally discussed -- the normal kind is where the number of individuals in a species becomes very low for some period of time. The technique for detecting that is quite different from the one I just gave. Looie496 (talk) 21:50, 9 October 2012 (UTC)

The method you are referring to is the molecular clock. The problem you'd run into, besides its general inaccuracy, is that few lineages date to the boundary itself. The Galloanserae date to well before the KT boundary, and songbirds to maybe 15 million years after. This paper shows most placental orders predating KT.[1] And there is no common protein or gene that evolved at, was selected by, or which links all the survivors of those events. I'd be surprised, if you knew what you were looking for, and had huge resources, if some statistical correlations couldn't be teased out of the data. But the chances of stumbling across such an event unless you already knew what you were looking for based on other evidence? μηδείς (talk) 02:24, 10 October 2012 (UTC)

DermaWand®

I've watched an informercial selling a dermatological device which claims to do all sorts of wonderful things for your skin, including reversing signs of ageing. Not that I'm in the least interested in using this device, but it does raise some questions. In the informercial, it was noted that during opperation, the device produces a scent associated with an electical storm, which can only mean ozone. Ozone is highly oxidising, which has the opposite effect of rejuvenation. What is really going on, is the effect of skin exposure to ozone negligible, is it cummulative, is it longterm. This reminds me of Venetian ceruse, on account it it causing a positive feedback loop: using it damages your skin, the more your skin was damaged, the more you used it to cover up the damaged skin. Plasmic Physics (talk) 00:28, 10 October 2012 (UTC)

I wouldn't expect ozone to have much effect on your skin, since it's covered with a layer of dead skin. An exception would be for someone who just had a seriously chemical peel. Your lungs, on the other hand, could be damaged by a high concentration of ozone. StuRat (talk) 00:41, 10 October 2012 (UTC)

Hmmm, let's begin by trying to find out what it is. "DermaWand is a condensed version of the exact same technology found in large commercial high frequency machines used by skin care specialists all over the world for 40 years ... stimulates and rejuvenates by sending out a gentle stream of low level micro-current impulses up to 168,000 cycles per second, imitating hundreds of tiny fingers that massage your skin ... helps improve circulation bringing oxygen and vital nutrients to your skin's surface. The gentle micro current also has a thermal effect on the skin s surface, helping the skin look more toned and tight, smoothing out the appearance of fine lines and wrinkles. Plus DermaWand oxygenates by giving off enriched oxygen that cleanses and purifies, helping breathe new life into your skin's surface. "[2]

Hunting for "high-frequency" "skin" "dermatologist" on Google yielded [www.scirp.org/Journal/PaperInformation.aspx?paperID=20115] "investigated the skin rejuvenation effect of dual-frequency ultrasound, with frequencies of 3 and 10 MHz, which has the ability to modulate both MMPs and HSPs. It was shown that such waves can significantly improve different visual appearances of ageing skin. This safe, non-invasive method yields results that are not as marked as those shown by injecting of fillers, but can be successfully used by subjects with a broad spectrum of visual skin ageing problems, which have to be treated simultaneously." This in the open access but never heard of before by me Journal of Cosmetics, Dermatological Sciences and Applications, so I'll present this more as a statement of their POV than as fact until I know more. The most applicable source from their introduction is something from Med Hypotheses [3] which... is less than persuasive. But the way the data is presented, measuring skin a week after the last of 8-12 biweekly treatments, and the data they present, suggesting at least a short-term improvement, doesn't look unreasonable. Now the question is whether we can find enough evidence to inform us about this treatment's effect in any longer term... Wnt (talk) 00:43, 10 October 2012 (UTC)

To my surprise, there's more about this at NCBI: [4], PMID 21332912, PMID 21284234, PMID 21283035, PMID 20115948, PMID 19204844. Some of the references later on the list (older) sound more serious. I'm mixing two different high-frequency treatments - radio frequency and ultrasound - because I'm still not sure which the "wand" is, if either. The gist appears to be to heat the skin, damage collagen fibers, have larger new filaments reform to produce a tighter/less wrinkled look. There might be something to this; there's not much of a theoretical reason why you can't rejuvenate wrinkled skin because there's probably only recent cultural selection against it. Wnt (talk) 00:54, 10 October 2012 (UTC)

"micro current impulses" sounds like a static discharge, which would explain the presence of ozone. Vespine (talk) 02:49, 10 October 2012 (UTC)

There's an "Ozone Cleansing Beauty Device (personal high frequency)" marketed with all kinds of claims "a versatile handheld esthetic tool that uses ozone / o3 which has three oxygen atoms that is power to sterilize, detoxify, deodorize and whiten your skin.Ozone Cleansing Beauty Device gives you a refreshed feeling and has a powerful function for reducing inflammation, reducing pain, balancing the pH of the skin. Moist importantly, Ozone Cleansing Beauty Device's high frequency current has an antiseptic effect on the skin that will detoxify bacteria caused by acne breakouts". Maybe the same circuit inside but aimed at a different audience? Ssscienccce (talk) 14:58, 10 October 2012 (UTC)

Shelf life for sealed lead-acid battery

About what shelf life should be expected for a sealed lead-acid battery? Bubba73 ^{You talkin' to me?} 00:55, 10 October 2012 (UTC)

Depends what you mean by shelf life. If you leave one on the shelf for 3 years it'll be flat as tack, but roughly 80% of them will survive and will be usable after recharging. Greglocock (talk) 01:06, 10 October 2012 (UTC)

...provided they don't freeze and split open. StuRat (talk) 01:08, 10 October 2012 (UTC)

The shelf life is strongly dependent on temperature. It's hard to get good data, but there are two mechanisms that lead to reduced performance while on the shelf: gradual deterioration and self discharge. When any lead acid battery is substantially discharged, it's capacity sharply drops from then on. The general rule of thumb is that both gradual deterioration and self discharge double in rate for each 10 degrees C increase in temperature. The impact of self discharge can be eliminated by recharging - once each 3 months is the recommedation. If this is not done, expect the battery to be ruined within a year at ordinary sorts of mediteranian climate temperatures. However, there is another life-affecting mechanism - batteries will only last a certain number of charge-discharge cycles.

How long the battery will last does indeed depend on just what you mean by shelf life. My comments above are applicable to defining end of service life as the capacity reduced to 80% of rated value.

Wickwack60.230.227.185 (talk) 07:52, 10 October 2012 (UTC)

Debate about the weather in Detroit
The following discussion has been closed. Please do not modify it.
(All this discussion really belongs on a talk page, not here, but you have no screen name and a dynamic I/P, so you have no talk page to post to. You should have posted any criticism of me on my talk page, not here, so this discussion could take place off the Ref Desk. I've moved it there now: User_talk:StuRat#Detroit_weather.) StuRat (talk) 19:09, 10 October 2012 (UTC)

The shelf-life will vary depending on the battery and the conditions it is exposed to. If your bettery is well-marked (some cheap ones aren't) you should be able to look up the manufacturer, and they may have a data sheet available. It will outline things like discharge rate over time, effects of different charging voltages and cycles, and expected lifetime under different conditions. 209.131.76.183 (talk) 13:52, 10 October 2012 (UTC)

They are by Werker. I don't have a way to recharge them, at present. Bubba73 ^{You talkin' to me?} 01:26, 11 October 2012 (UTC)

Amphetamine good for children, bad for adults?

According to a recent NYT article, doctors are now considering amphetamines as good for all kids in low-income, poorly funded school districts, not just some special group who show the "reverse effect" or whatever. [5] But although I still remember it as the new drug that some kids at college used to stay up on finals week, methamphetamine is more demonized than ever, an addictive scourge that leaves people batshit crazy, worn out and used up, missing teeth. Is there any way to make sense out of this, to say whether amphetamines are good or bad, or explain when they're good and when they're bad? Is it age of the user, impurities in the preparation, or is the explanation actual, literal transsubstantiation at the tip of a Licensed Doctor's pen? Wnt (talk) 01:10, 10 October 2012 (UTC)

Yes, there is a way to make sense of it. The brains of children are neurochemically different in some ways from the brains of adults -- in particular the dopamine system, which is targeted by drugs like amphetamine and Adderall, seems to be more active in children. Basically if you see an adult who is addicted to amphetamine or another dopamine agonist, that adult will act in a number of ways like a five-year-old: impulsive, hyperactive, etc. So it is plausible that drugs that act on the dopamine system will have different effects on children than on adults. I'm not asserting that it is true, just that it is plausible. Looie496 (talk) 01:59, 10 October 2012 (UTC)

(edit conflic with above) I don't think we need to theorize about differences between child and adult brains. There are plenty of adults who are prescribed amphetamines too. The issue's very similar to the recreational abuse of other prescription drugs (vicodin, etc.). A trained medical professional can decide when it is likely that the benefits of a given drug will outweigh the potential costs, and can proscribe the dosing. When taken recreationally, people often take more than a doctor would proscribe, on a less regular schedule, and don't monitor for potential side effects. Though demonized as a recreational drug, Methamphetamine can be prescribed. As I understand it there are some issues with dependence, but the side effects aren't particularly bad when taken in a controlled manner. As you suggest, it probably helps that it's being made by drug companies instead of gangsters (residual hydroiodic acid isn't particularly good for you). The infamous meth mouth, while probably partly due to the drug itself (similar effects are seen to a much lesser extent in people prescribed amphetamines), is probably more a result of the poor diet and dental hygiene of most meth addicts. Buddy431 (talk) 02:10, 10 October 2012 (UTC)

And that's not to say that there aren't side effects that can occur when amphetamines are taken under a doctor's supervision: cardiac problems, possible psychosis, etc. There are some countries where amphetamines are illegal under all circumstances. Canada briefly banned Adderall in 2005 due to possible risk of sudden death from cardiac events. But again, when taken at therapeutic doses, especially under the eye of a doctor, these side effects can be monitored, and at least in theory, the benefits of the drug will outweigh the risks. Canada later allowed it to be prescribed again, figuring that the benefits to many people with ADHD outweighed the slight cardiac risks. Buddy431 (talk) 02:32, 10 October 2012 (UTC)

Wouldn't kids be more at risk of addiction than adults, precisely because their dopamine system is more active? 24.23.196.85 (talk) 03:19, 10 October 2012 (UTC)

See paradoxical reactions, they are not uncommon in children. μηδείς (talk) 03:32, 10 October 2012 (UTC)

Most amphetamines - including methamphetamine in many of its common forms - are Schedule II Controlled Substances in the United States. This means that, according to 21 USC § 812 [6], "The drug or other substance has a currently accepted medical use in treatment in the United States or a currently accepted medical use with severe restrictions." This specific legislation has been in effect for several decades, and the classification of methamphetamine has not changed in a very long time (1970, and 1971 in other forms). So, there's nothing to be confused about: methamphetamine is widely recognized as a very seriously potentially harmful controlled substance that also has certain useful medical properties. There's no conundrum. In fact, if you read any of the literature promoted by the Department of Justice's Drug Enforcement Agency, it's actually fairly progressive in its stance: these drugs are controlled because they have potential to do harm. The Methamphetamine fact-sheet states clearly: "it has a high potential for abuse and limited medical use. It is available only through a prescription that cannot be refilled. Today there is only one legal meth product, Desoxyn®. It is currently marketed in 5-milligram tablets and has very limited use in the treatment of obesity and attention deficit hyperactivity disorder (ADHD)." Note the critical distinction between illegal and controlled. And even these two descriptions have absolutely nothing to do with whether the substance is good or bad. If you need help differentiating good from bad, chances are very high that you will never get an answer from the DEA, or from a doctor, or from the reference desk. Perhaps you should consult our article on the philosophical analysis of good and evil. Nimur (talk) 03:37, 10 October 2012 (UTC)

This is a well-written and respectable answer ... except that it conflicts with the initial article saying that it is now being used on kids without ADHD. Wnt (talk) 16:26, 10 October 2012 (UTC)

The article Attention Disorder or Not, Pills to Help in School, mentions Adderall. Adderall is not methamphetamine. According to the United States Food and Drug Administration's Adderall (R) CII fact-sheet, "ADDERALL® is indicated for the treatment of Attention Deficit Hyperactivity Disorder (ADHD) and Narcolepsy." In other words, it may apply to medical treatment for "kids without ADHD." In fact, only a qualified medical professional would know whether it is applicable; and only a qualified legal professional would know whether it is legal; but you can peruse the many pages of public information made available by the FDA and by the drug vendor to inform your own opinion about it. Now, whether I would personally trust a doctor who prescribes this medication is a moot point; (I wouldn't); but again, despite a bit of journalistic sensationalism, there's no clear indication that the medication is being used or marketed in a way contrary to applicable regulations or medical need. We have articles on Risperdal and Clonidine, the other medications mentioned in the New York Times article; and the FDA provides fact-sheets for each, as well. Nimur (talk) 17:29, 10 October 2012 (UTC)

I'm not asking a sophisticated medical or legal question here. What I'm thinking is that, except for very heavy users, recreational users of methamphetamine or amphetamine (I haven't seen any indication they work differently, though there's another possibility) are not consuming more overall than those prescribed the drug on a daily basis. The kids often are free not to take the drug as prescribed, but to grind it up and snort it, possibly in binges for tests or for recreation. [7] So I don't see any difference, except in a religious sense, between the use of the drug as purchased illegally on the street and as used by at least a significant fraction of the kids to which it is medically prescribed. So to put it bluntly I would expect that, if half the stories about meth heads are true, that we would have kids on the prescription setting up guns and tripwires in their school lockers to guard against CIA agents pilfering their stash. There's something about all this that just doesn't fit, unless there's some important but unaccounted factor like an impurity in the street drug, or somebody is seriously lying about some aspect of how the drug is affecting some group of people, or if it's only dangerous when used at more than a critical (large) dosage, etc. Wnt (talk) 19:22, 10 October 2012 (UTC)

Why do you believe that someone recreationally taking meth or amphetamine is not taking more than prescribed? The term "Meth Head" indicates someone who is addicted, has built up a tolerance, who might be taking 60+ mg a pop (typical prescribed does is in the range of 20 mg/day, probably taken in two doses, or before meals if for weight control). A recreational user is also more likely to inject it, smoke it, or snort it, whereas someone prescribed an amphetamine will be taking it orally (and thus getting more of it in the system quickly). If they inject it, they are often doing so with a used needle, giving themselves HIV, Hep. C, etc. Street drugs are notorious for being cut with fillers, which are often not harmless. The production of street meth is often not done very carefully, and might have leftover byproducts, which certainly aren't harmless (Phosphorus, Hydroiodic acid, etc.) Buddy431 (talk) 20:09, 10 October 2012 (UTC)

Both of you are essentially stating your estimation of a descriptive point, namely how much meth is typically consumed by a recreational user, as fact. How about some real facts? I would be curious to know whether there is such a thing as a controlled recreational user, someone who knows his limit and stops, and if so how common such a thing is. Are there any reliable data on that? (I concede that there might very well not be any good data on it; such people, if they exist, presumably stay under the radar of law enforcement and of addiction treatment facilities.) --Trovatore (talk) 20:13, 10 October 2012 (UTC)

I estimated my typical "street dose" from this probably unreliable source. If we look at the slightly more reliable PBS FAQ, it suggests a "hit" of about a quarter gram, which, if it's 50-70% pure, is quite a bit higher than my estimation. The point remains that it's significantly higher than what a doctor would prescribe. Buddy431 (talk) 20:37, 10 October 2012 (UTC)

Uncle Fester (not the most reliable source) recommends a maximum dose of 50mg a day, maximum 5 days a week in one of his books; but if a topic about daily dosage on a drug forum can be trusted, most meth heads would be taking 200 to 500 mg. If used to enhance productivity the Erdős way, 10 to 30mg would be sufficient.

Given the mechanism of action, tolerance will build up rapidly, at least for the stimulant effects. Hallucinations and psychosis are likely to develop, in experiments they were able to induce hallucinations in all test subjects by increasing the dosage. The difference between the effects of small and large doses could be related to the type of vesicles involved; at low doses, the large vesicles release dopamine, at large doses also the small vesicles start releasing.

Phosphorus and hydroiodic acid are unlikely adulterants, especially HI would never survive the acid/base extraction. Iodine salts may be present, and chloro-ephedrine has been found in street meth. Red phosphorus isn't especially toxic, otherwise match boxes and matchbooks would come with health warnings, the striking surface is 50% phosphorus.

Most of this comes from sources that aren't necessarily WP:RSMED, so... Ssscienccce (talk) 00:47, 12 October 2012 (UTC)

Hmmmm, this source [8] says that "an average dose of meth is about a quarter of a gram. Because of ice’s intensity, smaller doses provide bigger highs; a gram of ice can provide 10 to 25 hits (doses) of meth. Heavy meth users take three or more grams of meth at a time." Apparently purity is a really major factor in trying to understand what the dose is... Wnt (talk) 03:35, 12 October 2012 (UTC)