The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
What's the test called in Psychology where you give a group of people the same sheet of paper where there is a character description. People are supposed to rate on the scale of 1 to 10 how much it applies to them, but the point is that everybody gives it a really high rating because it includes such generic qualities (like being lazy sometimes, wanting to do good, being pretty smart in relations to some things etc.)? I went to a lecture at the local university when I was around 13 and they performed this test on all the audience and I've been trying to find out what it's called ever since. --BiT (talk) 00:50, 13 March 2009 (UTC)[reply]
It's the basis of most palm-reading, tarot card readings and astrology predictions. Cold reading, the Forer effect (also called the "Barnum Effect"), Subjective validation, Cognitive bias...these are all related to this effect. I don't know which particular term psychologists use. SteveBaker (talk) 01:06, 13 March 2009 (UTC)[reply]
No, it's not related to palm reading or tarot cards. What you're talking about is the Myer-Briggs test. The test is dependent on how self-aware or honest the test-taker is so some people argue the validity of the results, but the theories independent of that are pretty interesting. --75.34.179.39 (talk) 18:39, 17 March 2009 (UTC)[reply]
Bloody hell. It looks like all the guy's whiteheads are trying to crawl out of his face and escape. One of the comments on the video suggests that this condition may be related to eating parasite-ridden seafood - and several others suggest that it is best treated by rubbing cockroach juice into the skin. I'd really like to know more about this myself. There's just something incredibly compelling about videos of other people having parasites removed, isn't there? --Kurt Shaped Box (talk) 02:28, 13 March 2009 (UTC)[reply]
My dad knew someone with untreated worms, which he would occasionally pull out of his arm as a form of entertainment. For some reason, that man didn't have a wife or girlfriend. StuRat (talk) 05:19, 13 March 2009 (UTC)[reply]
Really? I would have thought the man would have had plenty of bait for catching women... —Cyclonenim (talk · contribs · email) 07:43, 13 March 2009 (UTC)[reply]
Stuff like that makes my skin crawl.91.111.85.208 (talk) 13:36, 13 March 2009 (UTC)[reply]
The skin does not look inflamed, and the "worms" (and I do think that is what they are) do not seem to be erupting in any consistent way with regard to pores or lesions. The way the gloved hand keeps rubbing the skin just before the worms appear makes me suspect the worms are being applied rather than being brought out from deeper tissue. I'm not familiar with any human parasite that would appear in this way, nor would I expect one to affect the face so diffusely without skin changes. I think it's being misinterpreted. Just my sense of it, not enough info to be dogmatic, but I think Worms on face would be a more accurate heading. --Scray (talk) 00:51, 14 March 2009 (UTC)[reply]
I decline to view that video, but aren't there some sorts of flies that lay their eggs on an animal's skin that burrow under the surface, and the maggots feast on the fresh flesh when they hatch? -- Deborahjay (talk) 22:19, 21 March 2009 (UTC)[reply]
Pressure ridges in ice
Reading about pressure ridges, I was curious: does this involve strictly cracks, or does it include other phenomena also? The picture to the side I took yesterday at a lake that exhibited pressure ridges (see another picture for what I mean), but it also had an extremely bumpy surface at one edge. Could this be related to the pressure ridges? Nyttend (talk) 01:36, 13 March 2009 (UTC)[reply]
I would think that bumpy ice is formed when water leaks up through cracks out onto the smooth ice surface and freezes there. StuRat (talk) 05:10, 13 March 2009 (UTC)[reply]
Yes, I've seen that before. Also, especially on the edges while the ice is still forming there tends to be a layer of water on top of the ice, and the movement of the water from wind and currents can cause the ice to form in less than perfect sheets. 219.102.220.90 (talk) 06:35, 13 March 2009 (UTC)[reply]
I added to the Pressure ridge article that they are also found on sea ice, probably more common due to the larger expanse of ice, added an image and a link to Commons. Google has some good pictures as well. The effect in the picture is probably created in the way that StuRat and 219.102.220.90 describe. It could also be caused by an stream where the inflow is going over the top of the ice and then freezing as per 219. Strangely enough the effect in the picture is not that common up here. Enter CambridgeBayWeather,waits for audience applause,not a sausage 16:23, 13 March 2009 (UTC)[reply]
Perhaps because the freezing process occurs quicker? I'd love to time researching the languages up there some day. 219.102.220.90 (talk) 23:36, 13 March 2009 (UTC)[reply]
Formula Unit vs Empirical Formula (Ionic Compounds)
Hello. What is the difference between the formula unit and the empirical formula for ionic compounds? Thanks in advance. --Mayfare (talk) 01:59, 13 March 2009 (UTC)[reply]
Aren't they the same? Formula unit and empirical formula seem to be the relevant articles. I think there might be some pathological chemicals which are exceptions, where the ratio of atoms does not seem to make sense based on electronegativities or "expected" ionization states; in those cases, the empircal formula would be the measured ratio of atoms as determined by elemental analysis (e.g. by mass). Nimur (talk) 04:30, 13 March 2009 (UTC)[reply]
So, is there actually any sort of upper limit to how large we can make a handgun? --90.240.240.251 (talk) 05:20, 13 March 2009 (UTC)[reply]
Well, how much can you lift with one hand? It's mostly a question of weight and recoil, I would think. The gun has to be capable of being aimed and fired without knocking the wielder off his feet. This would be affected by both the size of the projectile and the amount of propellant. A related factor would be capacity - how many rounds should it carry? More rounds, more weight. Hm. Turns out I have more questions for you than answers! - EronTalk 05:27, 13 March 2009 (UTC)[reply]
Yes. The limiting factor would probably be human lift strength. If you dispense with niceties like ammo and reloading, and focus on projectile diameter, you could theoretically launch a light-weight bullet the size of a dinner plate. Such a bullet would be of negligible actual use, being severely limited in range, accuracy, and damage, but hey, you'd have the biggest gun. As far as practical guns are concerned, you'll probably find the upper limit already available for purchase in one form or another, depending on your particular value of "practical" (0 = dinner plate). In handgun size, like many other things, bigger is not necessarily better. – 74 07:53, 13 March 2009 (UTC)[reply]
Yeah, with these 'big guns' it sounds as though we're already getting into the realms of pistols that could only really be fired repeatedly with any accuracy by a Terminator. Sure, if you needed to take down a fully-grown, angry African Elephant or Rhino at close range before it flattened you, then something like the above might be useful - but a pistol that weighs six kilos is a heck of a lot to lug around in the wilds, on a 'just in case' basis (I think that the standard, tried-and-tested elephant rifles are actually lighter than this!). --Kurt Shaped Box (talk) 19:44, 13 March 2009 (UTC)[reply]
According to The Rifle and Hound in Ceylon, which is a bit outdated of course, the obvious solution is to exploit some natives as the carriers for each British man's armament:
4 Double-barrled No. 10 bore, "of such power in metal that they weigh fifteen pounds each"
A No. 10 twelve-grooved rifle (rifled preferred for elephant shooting over smooth-bores, though much disputed)
A four-ounce single-barrel rifle weighing 21 pounds
One long two-ounce (bullet) rifle weighing sixteen pounds
Several smooth bores and fowling pieces (which do not count toward the total armament count)
It's hardly a fair fight for the elephant, with that armament. But a fair fight - "this is a foreigner's notion of the chase; he hunts for the pot; and by Englishmen alone is the glorious feeling shared of true, fair, and manly sport." Nimur (talk) 20:26, 13 March 2009 (UTC) [reply]
Hey, it sounds a heck of a lot more sporting than one of those canned hunt jobs. Yep, you can now go to South Africa and shoot semi-tame elephants at point-blank range from the comfort of a Jeep or your favourite hunting chair without having to hump the heavy ordnance around (five shot .600 Nitro revolver - five elephants for the bag?). I can't help but feel that we've lost something along the way. --Kurt Shaped Box (talk) 21:07, 13 March 2009 (UTC)[reply]
Funnily enough, that quote reminded me of something one of the S.African canned hunt operators said when interviewed by a disapproving Louis Theroux. Basically, he said that this (canned hunting) was something that worked in a South African context, stating that the proliferation of CH ranches in the last decade has been beneficial from a conservation standpoint in the country - as the hunters' considerable incoming funds have allowed tens of thousands of acres of natural habitat to be purchased and protected (by armed guards and 50ft fences!), in a pristine state (as opposed to say, being razed for intensive farming) and also, that by breeding endangered species to be put to the foreign gun and (literally) putting a high price on their heads, a tangible financial interest in ensuring the proliferation of the various species has been created (yaknow, give something a value and The People Will Take An Interest). It's an interesting argument, at least. --Kurt Shaped Box (talk) 03:47, 14 March 2009 (UTC)[reply]
I'd think the recoil would be the bigger issue. It would depend on both the caliber and "load". Firing too much bullet would cause a recoil which would make the gun move out of position for the next shot. This would make such a gun less effective than one with a more reasonable size. StuRat (talk) 14:50, 13 March 2009 (UTC)[reply]
There are widely varying theories of lethality for various calibers (it seems to amount mostly to situational needs and personal preference). I would posit that the mainstream available guns are manufactured in sort of a "bell curve" of available calibers because those dimensions are best-suited for their lethality. For example, although a Desert Eagle may pack a punch with a single round, as a weapon overall it is probably less "effective" than, say, a Beretta 92 (with a dramatically smaller bullet). As such, few organizations use Desert Eagles (and those who do very likely use it for intimidation-factor, rather than combat effectiveness). This is of course a judgment call based on a lot of estimated factors; but the US Army seems to agree - when it comes to caliber, smaller is better. Nimur (talk) 15:30, 13 March 2009 (UTC)[reply]
When it comes to a (non sniper) battlefield situation, the difference in tactical terms between killing and merely wounding the enemy is not particularly great. Either way, you've just shot a man, who has fallen over in the mud and now has two or three of his comrades kneeling around him, trying to plug the holes and stop him from leaking (and also not pointing their guns at you). If he lives, he won't be up and fighting again for a while, if ever again. So, if you don't strictly *need* to kill your enemy with one shot to take him and his cohorts out of the fight, then why not use a smaller, lighter round and benefit from the decreased recoil and increased capacity? --Kurt Shaped Box (talk) 20:01, 13 March 2009 (UTC)[reply]
That sounds like a reasonable analysis of conventional warfare, but I'm not sure if it applies as well to the modern terrorist. That is, if they are able to move, a suicide bomber will likely still detonate his explosives, and nobody is likely to attempt a rescue of a suicide bomber, in any case. StuRat (talk) 23:41, 13 March 2009 (UTC)[reply]
Kurt: I would expect that armies want more stopping power from a more powerful round. bibliomaniac15 04:00, 14 March 2009 (UTC)[reply]
Take a look at the articles on Punt guns and on recoilless guns. Especially the latter, as it explains how to deal with the recoil problem. --Dr Dima (talk) 22:37, 13 March 2009 (UTC)[reply]
Traditional "recoilless" techniques are of very limited use in a handgun, where discharging anything behind the gun would prove rather hazardous for the wielder. Still, recoil can be managed by trading off against a different parameter: increasing gun mass, reducing powder load, reducing bullet mass, etc. – 74 02:11, 16 March 2009 (UTC)[reply]
The Gyrojet of Man from UNCLE fame fired a rocket propelled slug. It came out of the barrel at quite low velocity, so no recoil to speak of. At least in the Man from UNCLE version, the gun itself was very lightweight (didn't need much strength) and could be mistaken for a toy. 75.62.6.87 (talk) 22:10, 14 March 2009 (UTC)[reply]
Toilet seat warmers
Sorry, two questions! The first is about the toilets we have here with seat warmers on them. I've heard in the past about bacteria and parasites that can survive x amount of time after initial contact on places like toilet seats (but probably more often on door handles and the like), and I'm just wondering if seat warmers wouldn't have a significant effect on that, possibly keeping these things alive until the next guy comes. 219.102.220.90 (talk) 06:27, 13 March 2009 (UTC)
I've taken the liberty of splitting your double-question into two separate questions because otherwise the answer thread(s) will be horribly confusing! SteveBaker (talk) 10:47, 13 March 2009 (UTC)[reply]
Bacteria on things like a toilet seat probably don't die through lack of warmth over a period of hours. But what the warm seat MIGHT do is allow them to multiply - which might be more serious. However, there is unlikely to be much in the way of nutrients - so I suspect there is no great risk. At any rate - as careful (and a little obsessed) as the Japanese are about safety in general - and about toilets (we British would NOT want our toilets to talk to us!) - I'm sure they've tested these things for safety. SteveBaker (talk) 10:47, 13 March 2009 (UTC)[reply]
Don't worry; my toilet doesn't talk to me. It has a power freshener, makes a waterfall sound when I sit on it, and sprinkles my anus with warm fluid. 219.102.220.90 (talk)
On a dry, nonporous surface, I suspect that warming will have little effect — and may actually shorten the viable lifespan of any pathogens by hastening evaporation. As well, in addition to warmth and moisture, growth of pathogenic organisms will require a food source — and there's very little for a bacterium to eat on a toilet seat.
In practice, the bacterial counts on a toilet seat are usually quite low, and most pathogens aren't capable of entering your body through the firm barrier of your intact posterior. Surfaces in your home that generally host more bacteria than your toilet seat include: your refrigerator door; kitchen countertop; sinks and faucets throughout the home; kitchen sponge or cloth; dish towels; the typical child's toy...[2]. TenOfAllTrades(talk) 13:44, 13 March 2009 (UTC)[reply]
This is slightly tangential, but it's worth saying. In this supposed "era" of energy-awareness and conservation, while everyone is converting incandescent lightbulbs to cold-cathodes to save thirty or fifty watts, people are still finding amazing ways to spend fifty or a hundred (or fifty-thousand) extra watts "warming" toilets and roadways. This reflects dismally on our prospects for energy conservation. Nimur (talk) 15:37, 13 March 2009 (UTC)[reply]
Yeah, it's pretty sad, I know. There is a button for "energy conservance mode", but it doesn't seem to change the temperature of the seat at all, so I can't imagine how much energy it saves. Maybe it just turns it off during the wee hours. *cough*. 219.102.220.90 (talk)
Nothing feels more refreshing than sitting on a toilet seat that is actually cold. A warm seat just serves to remind you that other people use the bathroom too. Livewireo (talk) 15:58, 13 March 2009 (UTC)[reply]
But it's not quite as refreshing a second later, when you realize that it only feels cold because it's wet. :-) StuRat (talk) 01:43, 14 March 2009 (UTC)[reply]
Ah - I understand - so you heat the seat so you can be sitting in a puddle of someone else's pee without noticing that it's wet. Got it. Thanks! SteveBaker (talk) 02:33, 14 March 2009 (UTC) [reply]
The second question is about body donation. I assume that the laws vary a lot depending on where you live; as you can probably tell from my IP I'm in Japan, but I'm Canadian. I have no idea if they have a body donation program in Japan, but I'm pretty sure they do in Canada. Most of the information on the web is about American medical schools so I'm not even sure about that. Also, if I were to want to donate my body to an institution that was outside of my country of citizenship (assuming I was Canadian, or American if there's no information), would that be possible? Thanks! 219.102.220.90 (talk) 06:27, 13 March 2009 (UTC)[reply]
Many countries won't even allow you to donate blood if you have lived overseas in the last (say) 10 years - so there is no doubt that organ donation for medical purposes is going to be impossible in some places. However if you are donating it for research, then I don't see why that would be a problem. You're going to have to find out what the laws are where you live because it's highly unlikely that they'll be the same everwhere. SteveBaker (talk) 10:47, 13 March 2009 (UTC)[reply]
Donating your body to science may be possible, but expect to pay for the transport yourself. The University of Tennessee Body Farm has such a clause.[3] - Mgm|(talk) 11:30, 13 March 2009 (UTC)[reply]
The body farm issue has came up before Wikipedia:Reference desk/Archives/Science/2008 October_22#UK BOD. If you just want to donate your body to science (be it for research or practice) I'm quite sure there will be progrms available in Japan. If you wan't find anything you may want to check with universities particularly those involved in medical research and attached to teaching hospitals. Nil Einne (talk) 11:36, 13 March 2009 (UTC)[reply]
Are psychological illnesses contagious?
If you spend too much time with aggressive people, for example, does this make you aggressive?--80.58.205.37 (talk) 12:17, 13 March 2009 (UTC)[reply]
Well, aggressiveness isn't technically a psychological illness, so the answer to your question below is that it depends on the personality. The human mind has a tendency to mimic others and try to fit in with its situation. OTOH, there are people whose personalities are such that they can at least minimize the aggressiveness of some. (Take, for instance, a good counselor who helps violent youth to try to get turned around all day.)
Psychological illnesses, OTOH, aren't contagious int he sense you can actually catch bipolar disorder, for instance. Being around poeple who are totally bipolar all day can wear one down and cause anxiety-related disorders, though.
But then,t here's also the joke that someone will repeat, so it may as well be me - "Insanity is hereditary - you get it from your children." :-)172.131.176.22 (talk) 12:54, 13 March 2009 (UTC)[reply]
Depending how one reads your questions, there are a couple of answers. To the general are psychological illnesses contagious?, I suppose one could point to something like mass hysteria for an instance of a bona fidepsychological condition.
The second question – on aggressiveness – could be rephrased as, are modes of social interaction learned? The biggest part of that answer is almost certainly yes. We tend to pick up and internalize cues for appropriate interpersonal conduct from those around us. TenOfAllTrades(talk) 13:28, 13 March 2009 (UTC)[reply]
Yes, I expressed myself poorly. I mean both - are some illnesses - like depression or anxiety - 'contagious'? And are character or behavior traits 'contagious'? —Preceding unsigned comment added by 80.58.205.37 (talk) 13:34, 13 March 2009 (UTC)[reply]
I would expect that the more common effect would be that people would attempt to keep their mental illness hidden if they receive negative feedback and not keep it hidden if it is "accepted". This wouldn't apply to severe psychoses, but only to those conditions which are somewhat controllable. For example, someone with OCD who needed to repeat some phrase every time a door is opened could probably repeat it in their mind if they were laughed at whenever they said it out loud. On the other hand, if they were around others with OCD or others who were more accepting of OCD, they might say the phrase out loud. This could give the appearance of "OCD being contagious". StuRat (talk) 14:14, 13 March 2009 (UTC)[reply]
I haven't read any research on your question, but it would not surprise me. I have worked in psychiatric hospitals and it was really tough for me to spend so much time every working day with people who feel really bad, who suffer from deep depression or deep anxiety. I think it would have been detrimental for my own mental health if I would have stayed there. Of course, this only goes for those of us who are vulnerable in that way, but that is usually the case with contagious diseases. Lova Falk (talk) 17:11, 13 March 2009 (UTC)[reply]
The following article might be helpful, you might not be able to read the whole thing if you aren't a new scientist subscriber, but I seemed to be able to get most of it even when I was logged off.
Well, I suppose that psychological conditions could be passed via power of suggestion, but contagious implies that there is a contagion, i.e. a substance which could carry the dissease with it. I mean, if you get depressed being around depressed people all day, that doesn't mean that there was a germ or virus or something that carries the depression, it just means that the emotional state of the people you hang around with can effect your own emotional state... --Jayron32.talk.contribs 00:06, 14 March 2009 (UTC)[reply]
I've heard the word "contagious" used in a more general way quite often, as in "laughter is contagious". Then there are a small percentage of mental disorders which may be directly caused by a contagion. On the other hand, general diseases, some of which are contagious, may also cause some mental problems, such as depression, in some people. StuRat (talk) 00:56, 14 March 2009 (UTC)[reply]
Two part question:
-Use of UV light to highlight body fluids on surfaces as seen in crime dramas: Is there a name for this and do we have an article on it? If not, is there any trick to it, or do you just need a UV lamp and dark conditions?
-Would this technique work to highlight "cat spray" (not urine, but the oily, stinky stuff they use to mark territory)?
Maybe you can guess -- a cat sprayed in my basement, and I can't find the exact spot, so I can't do much to clean it up!
ike9898 (talk) 14:07, 13 March 2009 (UTC)[reply]
That's photoluminescence, and specifically fluorescence, although I didn't locate an article specifically about your application of finding bodily fluids. Another way to find the cat pee is to bring a cat or dog down there, which will immediately locate it for you. Just make sure you don't bring an intact male, or he will feel the need to add his own contribution to the spot. And, while we're at it, why not get the cat in question neutered to prevent a repeat ? StuRat (talk) 14:24, 13 March 2009 (UTC)[reply]
Using a dog is a great idea, which I think I'll try tomorrow! As to the neutering, this is what everyone I talk to brings up. Both my cats (males) are neutered and have been since they were adopted as kittens. I have caught one of them spraying a few times over the years. So I don't think it's impossible for a neutered male to spray, just a lot less likely. ike9898 (talk) 14:58, 13 March 2009 (UTC)[reply]
A quick skim of some fairly reliable sources supports the notion that neutered males can spray. ike9898 (talk) 21:38, 13 March 2009 (UTC)[reply]
Yea, I guess that happens if they are too old when neutered. Another factor in animal spraying is that they all feel the need to spray whenever they smell the spray from another animal. Having two males makes them particularly likely to try to best one another. If you can get all the smell out and use a powerful deodorizer, you might stop a recurrence. StuRat (talk) 23:36, 13 March 2009 (UTC)[reply]
Cat urine definitely fluoresces under a blacklight. No luminol needed, no special tricks: just turn the lights out and the blacklight on, and make a basement sweep. I'm pretty sure that "spray" is just a special case of urine. The lights are fairly cheap, so I would definitely give it a try. - Nunh-huh 16:45, 13 March 2009 (UTC)[reply]
Does the urine fluoresce after drying? And, does that happen with dog or human urine as well? -hydnjo (talk) 19:48, 14 March 2009 (UTC)[reply]
Yes and yes. The components which fluoresce aren't liquid, so can't evaporate. StuRat (talk) 04:23, 15 March 2009 (UTC)[reply]
Update I tried two different UV lamps. Both effectively revealed the location of the urine spots, but one of the lamps made the spots glow much brighter (at least one of these two lamps emits UV in a different range that a "Blacklight" does). Anyway, I cleaned the spots, the smell went away, and then two days later the cat did it again! ike9898 (talk) 21:39, 16 March 2009 (UTC)[reply]
That's a cat for you.... Try it one more time: clean it, then crinkle up some tin foil and spread it over the previously affected area. Apparently peeing on tin foil isn't quite so much fun for kitty. Some folk also put double-sided tape on the floor near the area (cats don't like to walk on it) and use citrus scented spray, which cats tend to avoid. - Nunh-huh 21:45, 16 March 2009 (UTC)[reply]
I've ordered some pheromone diffusers that supposedly have a calming effect on cats. And some enzyme based cleaner. Wish me luck. ike9898 (talk) 13:50, 17 March 2009 (UTC)[reply]
Uranian axis tilt > 90 degrees?
The axis of the planet Uranus is said to be tilted about 98 degrees, i.e., it is essentially on its side and "rolling" through its orbit. Cute simplistic imagery aside, why is it that this value is not rather given as about 82 degrees, that is, less than a right angle? As a somewhat absurd analogy, the axis of the Earth is not said to be tilted at 157 degrees.
I thought it might be because the pole found on the south side of the ecliptic was actually closer to the planet's North magnetic pole, but the diagram in the article suggests otherwise, if I read it correctly.
Why is this convention held? Baccyak4H (Yak!) 15:01, 13 March 2009 (UTC)[reply]
I'm wondering if it has anything to do with the polarity of the rotation ("clockwise vs. counterclockwise"). I have to think about this for a while to see whether this actually makes any sense (as the planet revolves around the sun); but it may be a greater-than-90-degree tilt to preserve the correct rotation direction as most of the other planets. Nimur (talk) 15:42, 13 March 2009 (UTC)[reply]
Also see IAU/IAG Working Group on cartographic coordinates and rotational elements[4], which explicitly lays out the justification for picking which pole is "north", while acknowledging that this is a matter of preference. "The north pole is that pole of rotation that lies on the north side of the invariable plane of the solar system. The direction of the north pole is specified by the value of its right ascension α0 and declination δ0." They do not seem to give the "97.77°" number. Note that the description of Uranian rotation is sometimes given as "retrograde" and sometimes not - so it seems like there is not a total consensus on which pole is "north." Nimur (talk) 15:50, 13 March 2009 (UTC)[reply]
In other words, the issue is whether you view the direction of rotation as defining which end of the axis is north. In my opinion that is the sensible thing to do and it means that the axis is inclined by 98°. The IAU/IAG group has the opposite opinion. In that case the axis itself does not carry an orientation so it is natural to refer to it as inclined by an angle less than 90°, i.e. by 82°. You then have to add that the rotation is retrograde. By the way, the same issue arises for Venus and Pluto. --Anonymous, 19:38 UTC, March 13, 2009.
Nimur and Anonymous explanations are correct. I just want to point out that the description of Uranus motion as "rolling through its orbit" doesn't make sense and should be avoided. Dauto (talk) 19:45, 13 March 2009 (UTC)[reply]
Looking southward onto Uranus from the north side of the ecliptic, the planet would look more like it's rotating in retrograde motion than not. Venus has an axial tilt of nearly 360 degrees, due to its retrograde motion, but that likely depends on the convention used. ~AH1(TCU) 22:34, 13 March 2009 (UTC)[reply]
I think you were turned the wrong way when you said 360°; it should be 180°, right ? StuRat (talk) 23:29, 13 March 2009 (UTC)[reply]
Likewise, many sources list the axial tilt of Venus as a more absurd 177 degrees. The convention seems to be that the "north pole" is that pole which, if you call it north, will present a planet that rotates the same direction as Earth. So basically, depending on your perspective, Venus is either spinning "backwards" (if you accept that it's north pole is the one closest to the orientation of the Earth's north pole) or "upside down" (if you accept that north is defined by the direction of spin). The same logic applies to Uranus, and it really doesn't matter which you pick. Either Uranus has an 82 degree tilt, and turns backwards (i.e. retrograde) or it has a 98 degree tilt, turning in the same direction as Earth... --Jayron32.talk.contribs 00:00, 14 March 2009 (UTC)[reply]
Many thanks for the replies. The parity of the rotation makes sense. Baccyak4H (Yak!) 03:56, 14 March 2009 (UTC)[reply]
Any difference between brush with a dry or wet toothbrush?
I've noticed a few habits when people brush their teeth. Some put toothpaste on a dry toothbrush and proceed to brush. Others put toothpaste on, then wet the toothbrush with water. And still others wet the toothbrush, put toothpaste on, then wet it again. Is any method "better" than others? I would tend to think the dry brush would have a more abrasive effect since it's not being diluted by water (at least initially before its mixed with saliva). --70.167.58.6 (talk) 16:27, 13 March 2009 (UTC)[reply]
A clinical comparison of three powered toothbrushes found that the toothbrush filaments on some toothbrush models may bend slightly when wet. There did not seem to be any effective change in the resulting cleaning capability. Nimur (talk) 16:44, 13 March 2009 (UTC)[reply]
Keep in mind that, as our toothbrush article indicates, abrasive is not really what you want while brushing your teeth, as it can damage the enamel. --140.247.250.160 (talk) 19:59, 13 March 2009 (UTC)[reply]
I'm one of the wet-brushers (I wet it after, but I'll attribute that to laziness), and there is a clear reason for that, or at least there is to me. Putting a dry toothbrush into your mouth instantly lowers the average saliva level in your mouth (because loose saliva will attach to the brush head) and since most gel toothpastes foam better when mixed with water (as with soaps) wetting the brush keeps the inside of the mouth salivized and facilitates the toothpaste foaming process. I find brushing with a dry brush makes it difficult to distribute the toothpaste evenly among my teeth, as it clumps up and gets pushed to the side when it should be getting mixed into the bristles. 219.102.220.90 (talk) 23:51, 13 March 2009 (UTC)[reply]
Volunteering extra information: I have in my possession books published about thirty or forty years ago that were against brushing teeth with toothpaste. Using a dry brush was recommended, and for tough cases, brushing your teeth with salt was deemed the best solution. --Ouro (blah blah) 17:26, 14 March 2009 (UTC)[reply]
Breathing dust from cat litter, unhealthy?
When I clean my cat litter, it produces an awful amount of dust. I'm wandering whether it can be unhealthy to breath that dust? --Phenylalanine (talk) 16:48, 13 March 2009 (UTC)[reply]
Yes. Don't you know we have an article on everything? See here and also here. Matt Deres (talk) 20:04, 13 March 2009 (UTC)[reply]
Virtually any type of dust can cause pneumoconiosis. Certain chemicals (notably asbestos and coal soot) are so problematic that they have special medical terminology just for them. However, the sorts of occupational exposures are usually daily interactions over many years. Short-term exposure to small quantities of dust is probably not harmful, but if you find it aggravating, you can consider wearing a disposable dust mask (our article focuses mostly on respirators, but I'm thinking of simpler cloth or fiber masks like this). They are very cheap, and you can get a lot of uses out of them. Nimur (talk) 20:07, 13 March 2009 (UTC)[reply]
It may not be unhealthy but it's definitely smelly!!--TammyMoet (talk) 21:09, 13 March 2009 (UTC)[reply]
Thanks to all for the useful information! --Phenylalanine (talk) 22:44, 13 March 2009 (UTC)[reply]
Wait, wait! There's more about the smell. -hydnjo (talk) 23:41, 13 March 2009 (UTC)[reply]
Adding on to what that article notes, the pine-based cat litter is, unlike the silica or clay, nearly dust-free. It alone has earned the Nunh-huh seal of approval. -Nunh-huh 01:35, 14 March 2009 (UTC)[reply]
So how do they get rid of the formaldehyde? Or do they? AFIK pine naturally emits formaldehyde. It's part of the "piney" smell. I googled but there seems to be no mention of that. BTW> There's also recycled paper litter and wheat based litter if you don't want to go with clay. Printing ink has some very nasty chemicals in it, so the ink free varieties should be better. Baking soda helps against the smell. 76.97.245.5 (talk) 08:18, 14 March 2009 (UTC)[reply]
Baking soda also fizzes when urine is sprayed on it, and the result of that is that kitty point blank refuses to use the litter tray and pees elsewhere! --TammyMoet (talk) 14:27, 14 March 2009 (UTC)[reply]
Re the formaldehyde question: From this site"According to the manufacturers, pine-based varieties are made from recycled shavings, which are kiln dried to remove aromatic oils, and then compressed into pellets." And from the Feline Pine site"Feline Pine® is 100% natural, biodegradable pine that has been heated and pressurized to remove any harmful wood oils." -hydnjo (talk) 19:27, 14 March 2009 (UTC)[reply]
Thanks, that explains it. Re.: Baking soda Tammy, cats have preferences. We had one who insisted on a particular brand of cat litter and you can imagine what happened when we moved to a place where that wasn't available! If you mix it in with the litter and don't use too much I haven't had one yet who refused to use the box then, but you never know. 76.97.245.5 (talk) 09:39, 15 March 2009 (UTC)[reply]
I'm new to protein expression, and I could use a little starting out advice. I have a human gene that has already been cloned into a pCMV-SPORT6 mammalian expression vector under a CMV promoter; the vector also contains an AmpR selectable marker. The protein involved is a very hydrophobic ER membrane protein that is also post-translationally modified, so bacterial expression isn't really an option. My questions are:
Since the vector has AmpR, is there some mammalian (or other eukaryotic) selection agent I can use, or do I have to subclone the gene into another vector that can be used for selection?
What types of cell lines are usually used for expression of intracellular membrane proteins?
Are there any particular pitfalls, gotchas, or other horror stories that I should know about before I begin? —Preceding unsigned comment added by 69.127.231.186 (talk) 16:54, 13 March 2009 (UTC)[reply]
Ampicillin resistance will only be useful for bacterial selection (i.e. propagating your clone). For selection in mammalian cells you'll need something like G418 selection, which will require you to subclone into another vector. You could also try expression using baculovirus-infected insect cells. Choice of cell line probably depends on what's available at your institution (it's usually easy for someone to split some cells for you to start growing) but you may want to find the most physiologically relevant cell type. Lots of people just use chinese hamster ovary (CHO) cells, but if you know what cell type your protein is expressed in, you could try to pick a cell line from that tissue. The ATCC website has tons of info about different cell lines (http://www.atcc.org/Portals/1/Pdf/CellCatalog/Tools_Models.pdf) that you can sift through. The major "gotchas" are going to come in the protein purification step, especially if you have an integral membrane protein that is hydrophobic and post-translationally modified. Good luck! --- Medical geneticist (talk) 18:54, 13 March 2009 (UTC)[reply]
M.g.'s response is excellent as always, but I'd add that this answer illustrates the utility of being able to move your gene from one vector to another until you find the right system, and the Gateway system can be your best friend in this situation (no conflict of interest to report!). The "destination" vectors they offer (for a wide variety of host cells) include N- and C-terminal extensions that increase solubility and/or offer tags (like 6His, myc, etc) for purification. Of course, they offer all sorts of selectable markers. Transfers among vectors are isothermal and nearly 100% efficient. Getting it into the Gateway system can be tricky but their tech support is helpful. Hope this helps. --Scray (talk) 00:30, 14 March 2009 (UTC)[reply]
It looks like a great system, but the costs are... prohibitive. Unfortunately, we're limping along financially as it is. 69.127.231.186 (talk) 03:18, 14 March 2009 (UTC)[reply]
Understood, but don't underestimate the savings one realizes when an experiment works. --Scray (talk) 03:27, 14 March 2009 (UTC)[reply]
Need information from an Icarus article
I'm hoping someone here has access to this journal article:
Zellner, B (March 1985). "The eight-color asteroid survey: Results for 589 minor planets". Icarus. 61 (3): 355–416. doi:10.1016/0019-1035(85)90133-2. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
If you do, I'd like to know if it provides a classification of asteroid 243 Ida, when the spectroscopic measurements were taken, and what pages of the article the information appears on. Thank you. Wronkiew (talk) 17:55, 13 March 2009 (UTC)[reply]
Thanks for the tip. I posted this request at WRE as well, maybe someone has access to the paper there. Wronkiew (talk) 17:13, 14 March 2009 (UTC)[reply]
If I have a solution of about 50% methanol in water (plus salts etc), is it possible to differentially evaporate only the methanol, leaving only water? For a bit of background, we're trying to remove this from a frozen cell culture pellet in a lypholyser/freeze drier.
Any physical chemists or anyone know anything about this topic?
Since ethanolmethanol has a boiling point of 78.4 64.7°C and water has a boiling point of 100°C, heating it to a temp between those two should cause the ethanol methanol to boil off and leave most of the water. This assumes that nothing else is present, but you said some salts are present, which could alter the boiling point of the water. Also, be careful when boiling off ethanol methanol, as it is flammable. That is, don't let it vent into a lab where there are open flames, but rather do this under an exhaust fan. You did ask about evaporation, though, not boiling. This would work, too, but could take a very long time. The colder the sample, the longer it will take. StuRat (talk) 23:19, 13 March 2009 (UTC)[reply]
The OP is asking about methanol, not ethanol. As far as ethanol/water, nuh-uh, it forms an azeotrope. Franamax (talk) 23:30, 13 March 2009 (UTC)[reply]
Thanks for the correction, I've updated my post accordingly. As for the azeotrope issue, the next poster seems to have addressed that. StuRat (talk) 00:52, 14 March 2009 (UTC)[reply]
Azeotropes generally only occur at certain concentrations and pressures, for example with ethanol-water mixture, the azeotrope forms at a 95% ethanol/5% water mixture (hence, the maximum proof of liquor is usually 190 proof). We do have an article on Azeotropic distillation which discusses special techniques for seperating azeotropes. However, this forum post: [5] indicates that methanol and water do not form azeotropes at atmospheric pressure, which means that you should be able to get pure seperation using simple distillation techniques. this data table of azeotropic data indicates the same; that methanol forms no azeotrope with water. So if you heat the mixture to above the boiling point of methanol, which at atmospheric pressure is about 65 deg C, then you will be able to drive off all of the methanol and leave all of the water (as an aside, due to the fact that water still has a sizable vapor pressure at those temperatures, meaning that while you can leave behind pure water, if you cool and collect the methanol vapor, you will still have water in it... --Jayron32.talk.contribs 23:52, 13 March 2009 (UTC)[reply]
There's also membrane separation from what I looked ar earlier trying to find a solution. I think the problem here though is that the OP wants to keep the cell culture frozen, so 65 degC wouldn't do it. If the pellet can be thawed, then wouldn't dilution be simplest? Put the pellet on a filter and pour water on it, eventually there will be cells and water, with all the methanol flushed through the filter. (Just don't shake it at the same time, the methanol will get stronger!! :)
To do it in a frozen state, I think you would need something like a getter for methanol, i.e. some substance that would adsorb or fix the methanol and give it a lower vapour pressure. Perhaps enclosing the pellet in a separation membrane, with a drying agent on the other side? Then the methanol would sublimate and pass through the membrane, while the water stayed in vapour equilibrium on the pellet side. Franamax (talk) 03:35, 14 March 2009 (UTC)[reply]
banded krait bite
If bitten on hand by a banded krait snake, would it save life if hand was cut off soon after bite? —Preceding unsigned comment added by 72.160.181.221 (talk • contribs) 18:50, 13 March 2009
Let's hope this is not a medical advice question. If the venom has already entered the bloodstream, it will spread within a few seconds, so amputation is useless. If the krait venom is only in the tissues, it will spread diffusely, and so it's possible that an amputation may actually help. Field Manual 21-76 states clearly that in snakebite situations, amputation is commonly a result of too-late treatment, but it does not mention it as a precaution, in the event of snakebite.
“
The primary concern in the treatment of snakebite is to limit the amount of eventual tissue destruction around the bite area.
A bite wound, regardless of the type of animal that inflicted it, can become infected from bacteria in the animal's mouth. With nonpoisonous as well as poisonous snakebites, this local infection is responsible for a large part of the residual damage that results.
Snake venoms not only contain poisons that attack the victim's central nervous system (neurotoxins) and blood circulation (hemotoxins), but also digestive enzymes (cytotoxins) to aid in digesting their prey. These poisons can cause a very large area of tissue death, leaving a large open wound. This condition could lead to the need for eventual amputation if not treated.
Shock and panic in a person bitten by a snake can also affect the person's recovery. Excitement, hysteria, and panic can speed up the circulation, causing the body to absorb the toxin quickly. Signs of shock occur within the first 30 minutes after the bite.
”
I can find no references to "preventative" amputation. Amputation is not to be taken lightly, and should certainly not be performed by an amateur; this may cause collateral damage far worse than the original injury. Nimur (talk) 19:12, 13 March 2009 (UTC)[reply]
Well it certainly helped Hannibal at his time of need ;-) -hydnjo (talk) 22:59, 13 March 2009 (UTC)
I don't know about preventative amputation for snakebites, but preventative amputation is sometimes used in other cases, such as cancer. StuRat (talk) 23:12, 13 March 2009 (UTC)[reply]
In that case, a trained surgeon is present and has a little time to prepare - a krait bite's neurotoxin can kill a bull in under half an hour. A human, weighing an order of magnitude less than a bull, probably has an order of magnitude less time. That's not a lot of time to prep an OR! Nimur (talk) 23:44, 13 March 2009 (UTC)[reply]
Our article states that, "There are no authenticated records of human beings having been bitten." Not sure this is the snake one should worry about most. --Scray (talk) 02:05, 14 March 2009 (UTC)[reply]
Corneal diseases of less severity than Fuch's Dystrophy
Is there a corneal disease of less severity than Fuch's Dystrophy which has the similar effect of poorly regulating fluid transfer in the endothelium and can result in a reduced cell count in the endothelial layer? I heard of something like "Haltata" but could not find anything on the web or in Wikipedia. For symptomatic relief, I understand this condition can be aided by lubricative moisturizing drops as opposed to actually drying out the eyes with a hair dryer as suggested by Wikipedia's article on Fuch's Dystrophy. —Preceding unsigned comment added by Jaysfive (talk • contribs) 19:55, 13 March 2009 (UTC)[reply]
Why the location of the new Russian spaceport?
Russia is planning to construct Vostochny Cosmodrome in the Russian Far East, to reduce its dependence on the Baikonur Cosmodrome for low inclination or geostationary launches. They're planning on locating it in the Amur Oblast (although they don't decide as to where until next year). You would think that the primary criterion for a Baikonur-replacement site would be as low a latitude as possible (Baikonur is at 45°N). The Amur Oblast ranges only as far south as 49°N. On looking at the Russian Far East, there seem to be some rather nicer places to put such a facility: somewhere like Khabarovsk (which is at 48°N and which is near Komsomolsk-on-Amur, Russia's capital of aviation) or the flatlands north of Vladivostok (at about 44°N). Both are well connected to Russia's mainline railway network, and seem to be better situated with regard to weather, power, and supporting industry. The launch tracks from either would still largely pass over water, Sakhalin, and maybe the sparsely inhabited parts of northern Hokkaido. Surely every degree south would save fuel or afford more orbital flexibility. So my question is - what technical characteristic favours the inland Amur basin over these two maritime options? (or is there a political angle I've not considered?) 87.115.143.223 (talk) 20:25, 13 March 2009 (UTC)[reply]
Far be it from me to speculate, but there may be some ugly politics associated with launching spacecraft eastbound into the Pacific? Nimur (talk) 20:35, 13 March 2009 (UTC)[reply]
That's true, but missile/launcher capable powers are very careful to tell each other when they launch anything even slightly suborbital. No-one is going to mistake a Russian sat launch for a missile. Plesetsk is a former ICBM base (firing over the pole at the US) and no-one gets upset when they see a planned launch (often in a polar orbit) from there. 87.115.143.223 (talk) 20:47, 13 March 2009 (UTC)[reply]
I guess my point is not about true operational problems (as you describe, it is easy to avoid those). Most civilians have very little trouble cooperating internationally and making sure that their expensive rockets don't accidentally land where they are not supposed to. However, any civilian space-program always carries an implicit, public declaration of military missile capability for the nation it represents - and so there is a subtle, ugly undertone to any civilian launch (even if it carries the most benign and friendly scientific satellite). The act of launching the rocket is sort of a reminder to everyone: "We can launch something (wink wink nudge nudge) and fly it near/over your territory. By the way, this one is harmless." So, even though the construction of a civilian cosmodrome may truly have no sinister intent (conspiracy theories aside, and ignoring military-civilian collaboration projects) - there can still be political thunderclouds associated with it. Nimur (talk) 22:08, 13 March 2009 (UTC)[reply]
(Take a look at Poker Flat. A lot of awesome science is done there. It's about as far from "military" as I've seen, and I've been through my fair share of missile ranges). "The whole idea of tipping a rocket on its side was brand new," said Geophysical Institute Assistant Professor and HEX Principal Investigator Mark Conde. An 800 mile-long horizontal rocket-track on a civilian range which points northward from Alaska? Sure it was, Dr. Conde, sure it was. Nimur (talk) 22:13, 13 March 2009 (UTC)[reply]
And (as it's surely scarier to be on the receiving end) there wasn't a tizzy when they fired a Bulova missile from the White Sea at central Kamchatka [6] in November. 87.115.143.223 (talk) 20:59, 13 March 2009 (UTC)[reply]
Incidentally I think I've discounted some political issues:
invasion from China: both Vladivostok and Khabarovsk are of huge military significance to Russia: they'll defend them long after a dump like Amur has fallen
proximity to China (wherein countries get unnerved when rockets get launched very near their borders): the same is true for southern Amur - to get a decent distance from China in Amur they'll have to be at about 51°N - it doesn't seem worthwhile to build so far north, when they have Plesetsk.
flooding of the upper Ussuri River (for the Vladivostok option) - well, they're not cheap british housebuilders, so they're smart enough to find a big flat hill :)
When governments build big things in the middle-of-nowhere provinces, it's often to create jobs where they're badly needed. So that's my guess --Pykk (talk) 20:51, 13 March 2009 (UTC)[reply]
Pykk's idea is reasonable. However, I'd think that a priority would be to ensure that no launch tracks passed over any other country, even "sparsely-populated" areas. Rockets leave toxic residue from the fuel downrange; Hokkaido is home to the minority Ainu people of Japan, so sparse population doesn't necessarily count; Russia and Japan are still arguing about those four islands from WWII; and I'm not a launch expert, but wouldn't the launch track tend to head a bit southwards anyway? I'd imagine the priority would be to ensure that you can get the payload into orbit entirely over your own territory and international waters. If that takes a little more boost, so be it. The Russians already have pretty powerful boosters anyway, the biggest in the world I do believe. Franamax (talk) 23:50, 13 March 2009 (UTC)[reply]
Rockets don't always go where you want them to either, and not hitting people when a booster fails is an important consideration. SDY (talk) 00:08, 14 March 2009 (UTC)[reply]
Thanks everyone; I think Franamax has it. Frankly I really doubt the Russians care very much about the nerves of South Korean and Japanese air defence officials, or the feelings of the people of Hokkaido, but I think they don't want to have to fly through Japanese airspace (and thus have to ask permission, rather than just give notice). As our airspace article notes, there's no real definition of how high a country's airspace goes, but I bet they're factoring in some possible future international agreement that puts it at the Karman line, and they need a few hundred miles of setback to make sure they're above that before they pass over Japan. That's essentially the arrangement at Baikonur; they'd still be ascending when they passed over China and Mongolia, but clearly high enough to be (or to claim to be) out of those countries airspaces. 87.115.143.223 (talk) 12:34, 15 March 2009 (UTC)[reply]
X-Z motorized stage
I am looking to buy or build a small motorized stage that can move a small, light weight object vertically ~3 cm and horizontally ~6 cm. This will be part of a micro imaging system. An interface for computer control would be a big plus, but manual toggle switches might work too. I have $1000+ budget, but a short time frame, so it needs to be something that can be bought or assembled off-the-shelf in a hurry. Anyone have any ideas of suppliers for this sort of thing? In the absence of something commercial, I've also been considering hobby items and toys that might be repurposed (e.g. Lego Mindstorms), so that kind of suggestion might work too. Dragons flight (talk) 23:52, 13 March 2009 (UTC)[reply]
Lego Mindstorms could EASILY do that - and at a couple of hundred bucks would be well within your budget. If you need to move in X, Y and Z then you'll need three motors (I forget how many you get with the standard set - so you may need to buy an extra. The motors come with 'rotation sensors' so you can figure out how far they've moved. There are also 'bump sensors' that you could place at one end of each 'track' so the computer can wind the motors in that direction until the sensor triggers so it knows where they are at the start of the run. There are 'rack and pinion' gears to translate rotary motion into linear motion.
The biggest issue is going to be precision. You have not said how precise or how smooth it has to move...and that's a HUGE deal. You can gear the system WAY down so it moves very slowly - but there is a limit to precision because Lego gears do not mesh particularly tightly - and there is a certain amount of backlash. There are a few tricks to help that - which we can discuss if you'd like. But if you are expecting (say) 1/10th millimeter precision - then it's going to be hard. 1mm precision is more do-able...but that's the critical factor here. There are HUGE numbers of online resources for Lego enthusiasts (they call themselves "AFOL's" - Adult Fans Of Lego) and there are a lot who have much mechanical/robotics expertise.
Interfacing to the Lego computer is very easy - there are lots of libraries out there to help you do that. It has a bluetooth interface should you want to interface things like keyboards - you can drive it with the keypad on any bluetooth cellphone! It can be hooked to the computer with a USB cable. The programming "language" it comes with is a graphical thing where you essentially draw a flow-chart of sorts. However, the AFOL's have written a C-like programming language called "NQC" (Not Quite C) that enables experienced programmers to work with it and feel right at home.
You'll probably find that the kit you get will be missing some parts you'll need for this project (although you might get lucky). If so then I strongly suggest you go to the http://www.bricklink.com/ site - where AFOL's will sell you any number of super-rare and specialised parts for pretty low $$$. That's MUCH less frustrating than scanning the shelves of Toys'R'Us hoping to find a kit with just the right gear wheel - and then finding you need to buy 20 sets to get the number you need!
I have a target speed of ~0.5 cm/s horizontal and discrete steps of 0.5 mm vertically. Bricklink seems quite helpful. I was concerned that the parts in the default set didn't go all that far towards covering my needs. Dragons flight (talk) 04:04, 14 March 2009 (UTC)[reply]
I would probably take too long for you, but using a printer or scanner might work neatly. I haven't tried to control a modern printer precisely, but the older dot matrix epsom printers could be sent commands to nudge the roller or print head a bit at a time. Polypipe Wrangler (talk) 21:25, 14 March 2009 (UTC)[reply]
This is one of those problems that you can solve quickly or solve cheaply - but quickly AND cheaply is harder. I agree that you could certainly do a MUCH better job by repurposing other mechanism or having custom parts made...but that's either expensive or time-consuming. With Lego, you get cheap AND fast - but at the price of not being able to make a really powerful or really precise mechanism. However, you'll certainly be able to gear down a gear train so where you can reach the horizontal speed and the vertical 'step' size - but the problems will come if (for example) you command the system to go 2cm up and then 1cm down - and if you then expect to be 1cm up from where you started to a precision of within 0.5mm - that's tough because of gear backlash. However, if you've driven 1cm up and now you want to drive another 0.5mm up - I don't think that's a problem because you're going in the same direction.
Because the teeth don't mesh precisely - there are little gaps between the teeth of one gear and that of the next. When you keep driving in one direction, this isn't a problem because everything stays in contact. But when you reverse the motor, it has to revolve a little bit to move the first gear tooth backwards across that little gap. This is 'backlash'. If you have to use a 'train' of (say) six gearwheels to get the speed low enough - each pair of wheels has to move across that gap. Worse still, with really low gearing you have to turn the motor much more in order to cross the gap in the last set of gears. So the computer can't naively just assume that if it turns the motor 100 revolutions in one direction then 100 revolutions in the other - that the output will actually move at all.
Backlash is present in all geared systems - but it's worse with lego because the manufacturing tolerances of plastic wheels isn't very good to start with - and the nature of the geometry of lego (with fixed spacing for the 'studs' that is different from the vertical spacing of the 'bricks'), it's necessary to allow for very loose gearing in order that little kids can make things that actually work! Using a nice set of brass gears would get you much better precision - but making it all work on-time and in-budget would be much harder.
There are some tricks (both hardware and software) to get around the problems to some degree.
Re-purposing some other mechanism is possible - but the effort to integrate it into a system is vastly harder. Sure, the positioning mechanisms on old-style printers is pretty good - but you have to figure out (without documentation) how to drive the motors - and you have to machine custom brackets and stuff. You could even use things like the head positioning motors from an old CD drive - which will get you SPECTACULAR precision - but you'll need to fritz around experimenting because they can't move much of a load. (Incidentally - you didn't tell us how much weight you want this gizmo to move...that's important too!) But the beauty of Lego is that it's all there...the parts all fit together - you can build any geometry you want - and you can have something working in a couple of hours. If there is a problem with it - you can tear it apart and do it again some other way and be done in another hour.
Lego has a lot of parts that you'd find hard to get other ways - things like a clutch gear that slips if it's asked to deliver too much torque - very handy to avoid wrecking things if you're trying to drive something against a hard end-stop - there are pulleys with rubberbands for drive belts - drive chains (like a bicycle chain with plastic chain links that you can snap in and out to change the length) - rack & pinion gears, etc. Lego also has pneumatic cylinders, valves, pumps and reservoirs. There are 3rd party Lego-compatible temperature, pH, pressure and ultrasonic ranging sensors.
How do soundwaves travel from a radio or TV? —Preceding unsigned comment added by 71.31.106.65 (talk) 01:59, 14 March 2009 (UTC)[reply]
The same way they do when you speak or make any other sound. The electrical signals inside the radio (or whatever) cause an electromagnet coil to pull or push a small magnet that's glued onto the back of the loudspeaker cone - when the cone moves forwards, it pushes a higher pressure "wave" of air ahead of it - and when it moves backwards it creates a region of lower pressure. It does this hundreds or thousands or even tens of thousands of times per second depending on the pitch of the sound it's producing. The waves travel outwards through the air like ripples when you toss a pebble into a pond (well, kinda) and those ripples eventually reach your ears where the waves of high and low pressure alternately push and pull your eardrum. That in turn causes pressure waves through fluid inside your ear - which wiggles some tiny hairs that are connected to nerve cells that turn those vibrations into electrical signals for your brain. SOund waves are a little bit different from waves in a pond because they push and pull at the air rather than moving it up and down like the water waves. That allows them to travel in three dimensions instead of just along the surface as water waves do. Hence the sound 'ripples' move outwards in spherical patterns instead of circles as water waves do. Sound waves move at somewhere around 700 miles per hour - so the sound waves seem to travel pretty much instantaneously. SteveBaker (talk) 02:09, 14 March 2009 (UTC)[reply]
Were you asking how they travel from the radio or TV to your ear, or how they get to the radio or TV in the first place, 71.31.106.65? --ChetvornoTALK 06:25, 14 March 2009 (UTC)[reply]
In what year in firearms history was antimony first added to lead in the manufacture of bullets?
I would like to know in what year in the developmen of firearms was antimony first added to
lead in bullet manufacture to cut down on lead deposits in the bore. —Preceding unsigned comment added by 76.29.75.202 (talk) 05:53, 14 March 2009 (UTC)[reply]
This page says: "Antimony has been used in shot since the 1800s, but did the Spanish use it in musket balls in the 16th century? I don't know." Given that antimony-lead alloys have been known about since ancient times ["The Elements of Murder: A History of Poison" by John Emsley], it's likely that antimony-lead was used right from the beginning of firearms. --Heron (talk) 14:19, 14 March 2009 (UTC)[reply]
Orbits of moons
As far as I know, all the planets orbit the sun in (almost) the same plane. Do the moons orbit their planets in the same plane ? Are there moons whose orbital plane makes a wide angle (say > 45 deg) to the plane in which the planets orbit the sun ? WikiCheng | Talk 06:05, 14 March 2009 (UTC)[reply]
All of the planets orbit the Sun in roughly the same plane (now that we don't count Pluto as a planet). And most of the planets have moons (and maybe rings) which orbit in approximately the same plane. However, the "moon planes" are often different from the "planet plane". StuRat (talk) 06:50, 14 March 2009 (UTC)[reply]
It depends on how the moon is formed. If it is a body that originally orbited the Sun and which was later by captured by the planet (such an event must involve the influence of a fourth body), then its orbit can be inclined at any angle. According to the articles on these irregular moons and the Kozai mechanism, inclinations above about 55° are unstable in the long term. One moon with an inclination above 45° is Margaret.
Larger moons that are formed with the planet or broken off it by a giant impact will be regular moons, with low orbital inclination (with respect to the planet's equator, not the ecliptic).
--Anonymous, 06:59 UTC, March 14, 2009.
Take a look at Uranus. The whole planet, rings and moons are tilted at about 98° to the plane of Uranus' orbit round the Sun. Astronaut (talk) 11:06, 14 March 2009 (UTC)[reply]
Which is why I said "with respect to the planet's equator". See also the item above about whether that description is appropriate. --Anonymous, 20:04 UTC, March 14, 2009.
Solutions
What do you get if you mix a liter and a quarter of 2.2 % alcohol and the same quantity of 4.6 % alcohol? The answer at first glance would seem to be the average of the two, but I'm doubtful of that (seems too easy). Could you guys help me out? Thank you so much in advance. Killiondude (talk) 07:19, 14 March 2009 (UTC)[reply]
Think of it this way: if you have one liter of mixture at 2.2%, how many liters of alcohol is there? Ditto for the 4.6% solution. Combine the two, you have two liters of which X+Y liters is alcohol; how many percent is that X+Y of two liters. (Yup, taking the average does work.) 88.112.62.225 (talk) 09:48, 14 March 2009 (UTC)[reply]
When you mix, say, 1L of 100% ethanol and 1L of water, you get something less than 2L of the solution. However, as you've only got small alcohol amounts (look like beverage-ballpark concentrations?) the volume should not change very much, so yes, you can just take the average. 77.12.9.104 (talk) 10:40, 14 March 2009 (UTC)[reply]
Cataract#Cataract_surgery says that operations have been happening since 600BC. It also says that local anaesthetics are used. What would have happened to 600BC patients? And does anyone have any idea how the idea of operating on an eye to cut out milkiness might have come about? -- SGBailey (talk) 08:34, 14 March 2009 (UTC)[reply]
Nothing? Well they may have used opium or something but I suspect in many cases nothing was used. I'm not sure but I don't think cataract surgery is the extremely bad when it comes to pain (but I'm not volunteering to try it). You might be interested in surgery and anaesthesia which discusses this (surgery very briefly although it does say "Before the advent of anesthesia, surgery was a traumatically painful procedure and surgeons were encouraged to be as swift as possible to minimize patient suffering") Nil Einne (talk) 13:25, 14 March 2009 (UTC)[reply]
Jaundice
Hi all I would just like to make it clear I am not requesting any medical advice from anyone, I am merely rearching the diagnosis and treatment of jaundice. After hours of research, there are a few things which still confuse me, I hope someone can help. First of all, are doctors looking for elevated concentrations of bilirubin in the bloodstream when taking the full blood count? I read somewhere that elevated conjugated bilirubin suggests obstruction of the common bile duct and elevated unconjugated (insoluble?) bilirubin means that there has been excessive destruction of red blood cells. If it is suspected that hepititis is the cause of jaundice I believe doctors use 'viral markers' for heptititis A,B and C to try and ascertain whether or not this is the case. What are viral markers and how is this test conducted? Presumably a blood sample taken to search for the presence of either of the hepititis viruses? When a gallstone obstructs the common bile duct I believe removing the gall bladder is an option - but I thought - upon removing the gall bladder would not the gall stone still be there causing an obstruction? Also does anyone know what causes the dilation of the bile duct when it is obstructed? Sorry to ask so many questions - I am not expecting one person to answer the whole lot if you can answer just one it would help a lot. Many thanks. —Preceding unsigned comment added by 139.222.240.117 (talk) 15:35, 14 March 2009 (UTC)[reply]
As you suggest we can't provide medical advice here, but it seems that your questions can be answered fully without providing medical advice. Our Jaundice article does contain a great deal of relevant information and links to more, including answers to many of your questions.
Not sure what you mean by "full blood count", so I don't know how to answer the first question. The total and direct bilirubin levels are included in many blood chemistry panels, but are not included in the cell-counting tests often referred to as a complete blood count.
Our article on Hepatitis has information on the various causes, and links to each of those with info on the markers. The markers are generally measured in a blood specimen as you surmise. There are many markers, so recapitulating that content here might not be sensible. If you have specific questions, just ask and I'm sure people here can answer.
A gallstone in a bile duct can result in increased pressure behind the obstruction, resulting in dilated ducts. There are a variety of ways to remove the stone, addressed here. You're correct that removing the gallbladder would only remove a stone in the gallbladder itself or in the removed portion of the cystic duct.
I hope this helps. --Scray (talk) 16:15, 14 March 2009 (UTC)[reply]
(After EC) A complete blood count (CBC) is really only measuring blood cells (red blood cells, white blood cells, platelets) and some other indices that are useful in some circumstances). Measurement of serum bilirubin is a separate test, although it is also performed on blood sample.
Before answering the rest of your questions, here's a quick blurb: Bilirubin is a degradation product of heme compounds, among which the most abundant is probably hemoglobin in the red blood cells. When a red blood cell is lysed, the hemoglobin is converted to (unconjugated) bilirubin and transported to the liver, where it is enzymatically conjugated to become more water soluble. The conjugated bilirubin then makes its way through the bile canaliculi into the gall bladder, where it is stored before being ultimately excreted into the small intestine for disposal in the feces.
Hemolysis will result in a temporary increase in uncongugated bilirubin. The liver is usually functioning normally, however, so any bilirubin that is conjugated there will be disposed of normally through the gall bladder. The consequences of a gall stone blocking the bile duct depends on its location. Since new bile is being continuously produced by the liver, a blockage will create distension of the bile system upstream of that location (like damming a river or an accident on a highway). Depending on the location of the stone, you might just get distension and inflammation of the gall bladder (cholecystitis), or it might block the flow of bile from the liver and therefore cause conjugated bilirubin to "spill" into the bloodstream, since there's nowhere else for it to go. Surgeons can sometimes use endoscopic surgery (ERCP) to pluck a stone out of the bile duct but if the gallbladder is inflamed, a cholecystectomy is performed. Note that because of the anatomy (see bile duct), there is still flow of bile from the liver through the common bile duct even after the gall bladder is removed.
In acute hepatitis there is damage to the liver cells, such that when they burst open they release their contents (including liver enzymes and conjugated bilirubin) into the bloodstream. Chronic hepatitis that leads to cirrhosis might eventually reduce the enzymatic capability of the liver such that unconjugated bilirubin predominates. It depends on the situation. The tests that are usually done to detect viruses (including those that cause hepatitis) are blood tests based on either the patient's antibodies -- which can indicate current or past infection -- or detection of the viral nucleic acid using polymerase chain reaction (PCR) or other such tests. The advantage of the latter molecular tests is that if properly calibrated they can give information about viral load. Does this help? --- Medical geneticist (talk) 16:40, 14 March 2009 (UTC)[reply]
Cholecystectomy removes stones that are already present in the gallbladder. It also prevent new stones from arising. If a stone is blocking the common bile duct, the commonest procedure is ERCP to remove the stone.
It has been observed that the path of light turns in the presence of black holes. But there can not exist any gravitational force as light has no mass. Please explain.--Lightfreak (talk) 16:58, 14 March 2009 (UTC)[reply]
See gravitational lens. The mass bends spacetime, while light takes the shortest path through spacetime. There is no "gravitational force" in General Relativity—just warping of spacetime and associated accelerations. --98.217.14.211 (talk) 17:04, 14 March 2009 (UTC)[reply]
While 98.217.14.211's explanation is ideed correct, it is good to point out that even within newtonian approximation a light ray trajectory would bend. In newtonian mechanics the path of a particle under a gravitational field is independent of the particle's masss, depending on the particle's initial velocity alone. Dauto (talk) 17:59, 14 March 2009 (UTC)[reply]
True, true. Indeed, the question is not whether the light is bent by gravity, but by how much. GR and Newtonian physics predict different values for it and are thus distinguishable experimentally along this line (among a few others). --98.217.14.211 (talk) 18:06, 14 March 2009 (UTC)[reply]
Photons (which make up light) most certainly do have mass - but only by virtue of their speed. Their 'rest mass' is zero. Also, the path of light is bent by much more ordinary objects than black holes. In fact, Einsteins theory of relativity predicted this - and the scientists who verified his theory did so by carefully measuring how starlight is bent by the mass of our sun. (They had to wait for a total eclipse to be able to do this - so it took a few years.) As others have said, gravity bends space - so the photon (in a sense) is travelling in a straight line through space that has been bent - hence it APPEARS to be travelling along a curve to outside observers. Anything with mass bends space to some degree or other...it's just that the amount of the bending is so small that it's not really noticable for things like stars(!) unless you have some pretty sophisticated equipment...but around a black hole, it's very noticable. SteveBaker (talk) 21:31, 14 March 2009 (UTC)[reply]
How many domestic turkeys are there in the world? We have numbers for most domestic livestock, shhep, pigs, cattle, but not turkeys and I would like to know. 12.216.168.198 (talk) 17:00, 14 March 2009 (UTC)[reply]
:Here are the 2000 US production figures. [7] You'd have to go country by country and need a lot of time and a calculator. This site has an overview. [8] Good luck. 76.97.245.5 (talk) 17:56, 14 March 2009 (UTC)[reply]
The UN agriculture estimates are available at: [9]. The database includes the ability to search by individual country, by region or by world total. Turkeys are one of the tracked products. They have the figure of 636,000,000 turkeys slaughtered in 2007[10] giving 5,885,012 tonnes of turkey meat. They do not, however, tell howe many animals are alive in total, only how many are harvested. And this entry includes the code A which means "May include official, semi-official or estimated data" Rmhermen (talk) 15:58, 16 March 2009 (UTC)[reply]
Why is it that bullets often don't have nice round numbers for their calibers?
The article on firearm cartridges lists many types of cartridges. Many of them seem to have strange values for their calibers. For example, in the case of the .308_Winchester, 0.308 inch is not a nice round number either in metric or in U.S. customary units. Is there a reason for choices like that? —Preceding unsigned comment added by 98.114.146.54 (talk) 19:17, 14 March 2009 (UTC)[reply]
I kinda suspect this relates back to when bullets were simple spherical lead balls. They would probably have specified the bullets by weight - so the weight may have been a nice round number - but the resulting caliber would have turned out to be some inconvenient number. But that's a guess - I don't know for sure. Alternatively, our article caliber discusses bullet sizes but about the only thing that sheds any light on this is the confusion between measuring the diameter of the barrel to the outsides of the grooves or the inside. I suppose that a nice round-number 0.3" internal diameter might grow to 0.308 measured to the bottoms of the grooves. I'm sure someone here will know better. SteveBaker (talk) 23:26, 14 March 2009 (UTC)[reply]
The article on the Winchester links to its "parent case", the .300 Savage, though that's a bit confusing because both the .300 savage page and the winchester page list the actual bullet diameter as .308. Could one of those be a mistake? 219.102.220.90 (talk) 23:31, 14 March 2009 (UTC)[reply]
Right - but the 0.008" (eight THOUSANDTH's of an inch!) difference sounds like just the right amount to account for the 'rifling' - the spiral grooves inside the barrel. The bullet has to 'take the rifling' - meaning that it has to squash into those grooves. Eight thousandths of an inch sounds about right to me. SteveBaker (talk) 01:03, 15 March 2009 (UTC)[reply]
OK, but my issue was that although both have the same diameter (and presumably a 0.008" rifling), one is called a .300 and the other a .308. Is it reasonable to think that they may have chosen to brand the Savage with its base diameter, but the Winchester with its diameter + rifling thickness, perhaps to distinguish them or for some other marketing purposes? If so, that would imply that the "not nice" caliber of the Winchester was, at least in part, a marketing choice. 219.102.220.90 (talk) 04:12, 15 March 2009 (UTC)[reply]
According to caliber: "In firearms, the caliber is the approximate diameter of the bullet used. In a rifled barrel, the distance is measured between opposing lands or grooves; groove measurements are common in cartridge designations originating in the United States, while land measurements are more common elsewhere."...does that explain it? 8 thousandths of an inch sounds like a believable difference between land and grooves. SteveBaker (talk) 04:50, 15 March 2009 (UTC)[reply]
No, the caliber names are not this precise. They are historical names, often, and the physical diameter, rifling or not, is not precise to the "name" of the bullet. What's more, there are some rounds that have roughly equivalent sizes (7.62mm and .30-06, for example), but are not precisely the same size or round. Rifle rounds and their caliber should be understood as rough approximations of their size, but not precise measurements. This makes sense too when you realize that many of the most widespread rounds were invented over a hundred years ago (the 30-06 is the -06 because it was invented in 1906). Shadowjams (talk) 10:47, 15 March 2009 (UTC)[reply]
The rifling is important because without it the bullet could 'roll' around some random axis and the magnus effect would deflect the bullet reducing acuracy. Dauto (talk) 01:48, 15 March 2009 (UTC)[reply]
Well...yes...but what does that do to explain the dimensions people choose for bullets? SteveBaker (talk) 04:50, 15 March 2009 (UTC)[reply]
The answer to this question is not scientific. It's more a consequence of history, marketing, and randomness. A number of rounds were made in imprecise diameters for unknown reasons. But once they were established, it was an issue of relative changes. More critical, the secondary number on many cartridges, after you get past the ".30" or "7 mm", are purely issues of powder, marketing, or historical significance. To make it even more complicated, many calibers are not what they seem to be. A number of bullets have "calibers" that are very different from their actual fractions of an inch measurements. For a little bit of background check out Gregg Lee Carter, Guns in American Society, isbn 1576072681, page 102-03. It's available on Google books. There's a small section that will explain a little bit of the insanity. If you want a historic reason why a particular cartridge is why it is, I don't know it, but if you find it out, please add it to the appropriate article. Shadowjams (talk) 10:42, 15 March 2009 (UTC)[reply]
Why do some ducks quack constantly?
Having observed a lot of mallard ducks recently, I've noticed that the males in particular seem to quack almost continuously when just walking or swimming around(especially if they're with females). Is there any reason for this constant noise-making? 69.224.37.48 (talk) 21:07, 14 March 2009 (UTC)[reply]
Same reason some young man need noisy motorcicles, I suppose. Dauto (talk) 21:11, 14 March 2009 (UTC)[reply]
Er, are you sure it is the male that is quacking? As far as I know it is only the female that quacks. Here is what Steve Madge and Hilary Burn say about Mallards in their reference book Waterfowl (p. 211): "Voice. Quite vocal, especially female. Male utters a soft, rasping 'kreep'. Female's most obvious call is a series of quacks, quite mocking or laughter-like in delivery, descending towards the end, 'QUACK-QUACK-QUACK-quack-quack-quack...', heard mostly in late summer and autumn. Similar descending series of quacks are uttered by several other females of the genus." Possibly the mallards you are observing are hybrid or feral domestic ducks that haven't read the book I quote. This still doesn't answer your question as to why they quack so much, regardless of whether they are male or female.--Eriastrum (talk) 22:50, 14 March 2009 (UTC)[reply]
Certainly our article duck says that only the females quack. Bird vocalization says that short 'calls' like quacks are used to keep the flock together and to alert fellow flock members to danger. Perhaps they are only quacking when you are nearby and posing a danger to them. You might not think you are a danger but...mmmm...crispy duck with orange sauce. SteveBaker (talk) 22:51, 14 March 2009 (UTC)[reply]
Your answer may be overpopulation. "Duck territories" on ponds and in public parks are much closer together than they ought to be. That has led to lots of unfavorable behavior changes. Things like a bunch of juvenile ducks getting together and gang-raping a female, females getting drowned by a bunch of males trying to mate, juveniles of both sexes getting killed by older ducks; all that has been described as a result. Apparently experts have some special terms for male quacking. (All male ducks in the poll refused to quack when questioned :-) OR: Male Mallards have been observed to issue a variety of calls/quacks for different purposes: food call (cascading downwards), mating call, attack/retreat calls (the Donald Duck like enraged screams), "ranging quack" issued while a pair is together to keep the female close, particularly in uncertain situations. (This is a sort of under his breath grumble and may be what you have heard.) Although it may seem counterproductive to get noisy when a predator is near, lots of birds making noise in different directions actually confuses most predators because they find it harder to decide which one to go chase. Eriastrum's explanation that what we see most often are actually some hybrids might have something to do with it, too. Particularly interbreeding with domestic species, because the above behavior has been observed in public parks on 3 continents. (Does our KurtshapedBox do ducks, too, or just gulls and doves?)76.97.245.5 (talk) 10:26, 15 March 2009 (UTC)[reply]
The "ranging quack" sounds about right; the male mallards I've seen usually make this (fairly quiet and nearly constant) sound when with a female. 69.224.37.48 (talk) 16:21, 16 March 2009 (UTC)[reply]
CO2 in an aquarium
Hi. Let's say a small aquarium has an abnormally high pH level. Would blowing in one's breath through a straw help to lower the pH? Or would this have too small an effect or would it be more harmful than helpful to the occupants? Thanks. ~AH1(TCU) 21:37, 14 March 2009 (UTC)[reply]
So your theory is that dissolving CO2 from your breath will create enough carbonic acid to make a measurable difference? Well, you're right that there is CO2 in your expelled breath and that when you dissolve CO2 in water it makes carbonic acid...but the question is "how much?". Gut-feel says not enough to make a difference. Only 5% of your exhaled breath is CO2 - and only a tiny amount of that will actually dissolve in the water because it's not under enough pressure and you're probably making quite big bubbles where the interface between water and gas doesn't have enough area to allow much of that CO2 to meet the water before the bubble reaches the surface of the tank. When they carbonate fizzy drinks, they use pure CO2 at a pressure of 100 to 150 psi. SteveBaker (talk) 22:49, 14 March 2009 (UTC)[reply]
I agree, especially as it's a "small aquarium" with an "abnormally high pH level". You're better off giving small, regular water changes with more stable pH water.91.111.85.208 (talk) 23:41, 14 March 2009 (UTC)[reply]
The effect you may be looking for is dispersing more oxygen in the tank and thus encouraging aerobic rather than anerobic entities to thrive. This would allow ammonia from fish waste to get broken down. The problem is twofold: You'd stir up sediments from the bottom or your aquarium, thus severely decreasing water quality until the population has changed. Your exhaled air contains less oxygen than the ambient air. (Not sure how big an effect that would have). Incremental water change suggested above sounds good. Also ask at your local aquarium supplies store. They usually have several products available to counteract acute ph imbalance. (like e.g. tablets, "green sponge" filter, powder etc.) Which product you need depends on a lot of things including what fish, plants and other creatures you keep, temperature, size of your aquarium. etc. So either call ahead and ask or bring as much data on your aquarium as you can. This page might also be useful. [11] - 76.97.245.5 (talk) 06:19, 15 March 2009 (UTC)[reply]
March 15
Melatonin activity and the human eye
hi guys... do you know where i can find info on melatonin and race/ eye colour?
i mean, it definitely has something to do cause melatonin depends on light, since for example blue eyes are more sensitive to light i imagine melatonin in the pineal gland is different in diferent races.
also, does the sensitivity of the melatonin receptors in the eye have anything to do with eye colour? like for example, are the melatonin receptors more sensitive in blue eyes than they are in brown eyes?
thank you! hopefully I can find some info.
oh and also haha, does eye colour affect eye sight? like does a really light blue eyed person see things 'differently' than a brown eyed person?
Or may be you're not confusing them, but why should eye color play a role in the circadian regulation? Dauto (talk) 01:37, 15 March 2009 (UTC)[reply]
I'm not confusing melatonin with melanin...i know they are different but they are both related and affect each other.
and why would eye color play a role in circadian regulation?
because colour is related to light 'intake' and circadian rythm is also. —Preceding unsigned comment added by 65.183.130.151 (talk) 16:20, 15 March 2009 (UTC)[reply]
No, they're not related. One is a pigment, the other is a hormone. Melatonin itself isn't affected by light, melatonin levels in the blood are, through a complex set of mechanisms, which are not related to your eyes. Even blind people have lower melatonin levels in daylight. And eye color doesn't change 'intake' of light one bit. The light you see is passing through your pupil, not the colored portions of your eye. --130.237.179.182 (talk) 20:47, 15 March 2009 (UTC)[reply]
Pain in the...eye
So after reading arc eye, snow blindness and flash blindness, as well as perusing through eye disease, I'm still in the dark as to how bright lights cause pain and permanent loss of vision. Why do our eyes hurt when we see very bright lights? The retina allegedly has no pain receptors...is it strain on the iris dilator muscle trying to contract very hard? Or an interpreation by the brain of intense light? And aside from UV damage to the cornea, what is the mechanism by which very intense light (I'm talking nuclear flash or laser in the eye kind of intense) can blind a person, or is that just hollywood dramatization? Thanks. Someguy1221 (talk) 07:14, 15 March 2009 (UTC)[reply]
Retina has many light receptors. These receptors never grow in number, but instead, may deplete over time. this is why older people have weak eyesight. Intense light may destroy these light receptors and may cause blindness. the pain in the eye is because of the fact that iris, that controls the amount of light entering the eye, tries to reduce the amount of intense light entering the eye.--Lightfreak (talk) 08:27, 15 March 2009 (UTC)[reply]
A nuclear flash - at a distance where it's not going to kill you - won't blind you. Richard Feynman was the only person to watch the world's first nuclear explosion with his naked eyes (well, actually, 'eye' - he closed the one eye just in case he had a slipup in his math). In several of his autobiographies - he explains why he knew that was a safe thing to do. On the other hand, even a relatively small laser (such as a laser-pointer) will damage your eye if you stare at it for more than a half second or so. The iris is intended to shrink to exclude harmful amounts of light - but there is a limit to how small it can get. A laser beam can easily get through that hole. In addition to the pain from the iris muscles contracting - there definitely is a pschological element to it. If you use computer graphics to display all of the artifacts of a bright, blinding light on a computer screen - in a situation when they are 'immersed' in the on-screen action - you can convince people that the light is painfully bright, when in reality even if the entire screen were lit up at maximum brightness, it would not give you a moment's thought. SteveBaker (talk) 13:10, 15 March 2009 (UTC)[reply]
Just a reality check on the supposed devastating amount of energy a laser pointer could pout through the iris. A laser pointer says "Class 3a laser product. Max output < 5 mW. Wavelength 630-680 nm." How many mW of solar energy would be reflected through the pupil if you looked at a white surface large enough to fill the visual field illuminated by full sunlight, which would be bright but would not be expected to cause blindness? Pupil (eye) says it can narrow to as small as 3 mm. Solar energy issaid to be about 1 kilowatt per square meter. White paper is said to reflect about 85% of the light hitting it. So how many mW of energy would enter hit the 3mm pupil when you look at a white painted house, or car, or white paper, or snow (albedo 96% per [12]) in full sunlight? Woul'nt it be somewhat more than 5 mW? Edison (talk) 15:13, 15 March 2009 (UTC)[reply]
According to the US laser health and safety guidelines: a class 2 red laser will damage your eye with less than a quarter second of exposure. The concern is that this can be less than your blink response. Hence all legal laser pointers (in the US at least) are class 1 or (at most) 1M. Those can still do bad things to your vision - but not if you know to quickly close your eyes and turn your head away because you have more time to react. With a class 3 or above - you have no chance. Pretty much any exposure is enough to blind you...these things are dangerous! SteveBaker (talk) 01:27, 16 March 2009 (UTC)[reply]
And thus the question, how do they blind you? Someguy1221 (talk) 05:45, 16 March 2009 (UTC)[reply]
I think the key detail is that light scattering off a piece of paper spreads out, a laser doesn't (significantly). I'm not sure how to calculate how much light would getting into the eye from those things, but there is a simple reality check - compare with looking directly at the sun. If solar energy is 1kW/m2 then a 3mm diameter disc would receive 7mW. Comparable to shining a Class 3a laser at your eye. However, I was having a discussion over dinner just last week with a physicist and a chemist who each use big lasers (Class 3 and 4) and apparently how dangerous a laser is doesn't just depend on its power. A powerful laser in the visible part of the spectrum will make you blink and look away very quickly, so the danger is minimal (still not a good idea to try, though!). A slightly less powerful IR laser will burn straight through your retina before you realise what is happening. (At least, I think the key detail was wavelength, I don't remember everything they said - the bit about power not being all important is definitely true, though.) --Tango (talk) 15:34, 15 March 2009 (UTC)[reply]
Tango - Yow. Both interesting and shudder-inducingly informative; nice response.
Edison - from a couple of different tacks, explaining the same principle of why concentrated low energy may have a lot more effect than diffuse high energy:
"Sharpness" represents the fact that when you concentrate force into a very small area, it has a much greater effect. Look at the tip of a pin, or the edge of a razor blade - they have very tiny surface areas. One pound of force concentrated into a square 0.1 mm wide (100 lb/mm2) may easily cut through something, while 100 pounds of force may have no effect whatsoever if dispersed over a comparatively "huge" square 1 cm wide (1 lb/mm2).
Similarly, consider a space heater that puts out 10,000X amount of energy per second into a cubic 10 m wide room (10 X/m3). It keeps the room warm, but never comes close to burning you, because the energy is diffused into a large volume. But if you touch a spot on the heater for one second, absorbing a tiny 1X fraction of the energy into a "cube" of flesh 1 cm wide (1,000,000 X/m3), you get burned.
Does this make it any clearer, or just more confusing? arimareiji (talk) 20:22, 15 March 2009 (UTC)[reply]
Incidentally, the US government did do many studies on how much light and at what distances from a nuclear explosion would be needed to do eye damage. --98.217.14.211 (talk) 15:34, 15 March 2009 (UTC)[reply]
Back to basics: explain why solar energy reflected from a snowbank or white painted wall filling the visual field is so much less dangerous than the 5 mW laser pointer. I scent mumbo-jumbo. Edison (talk) 02:20, 16 March 2009 (UTC)[reply]
Short answer: Because it is more spread out. (Long answer, see above!) (Although, I'm not actually sure it is more dangerous - snow can cause temporary blindness and I'm not sure a 5mW laser pointer is going to cause much more than that unless you are really stupid with it.) --Tango (talk) 12:12, 16 March 2009 (UTC)[reply]
One factor that has been missing from this discussion is how "spread out" (more technically, collimated) the light is. This factor is important because the eye is not just a single large photoreceptor with some area; it has a focussing system - a lens. A perfectly collimated light source shining on a perfect lens would focus the light to a single point, which would burn anything on that point regardless of the irradiance (power per unit area) of the light. Of course no light source or lens is perfect, but laser light is much more collimated than sunlight. The relevant unit here is radiance, sometimes referred to as brightness. The higher radiance of a laser is why even a low power laser is much more dangerous than sunlight. Someone42 (talk) 12:19, 16 March 2009 (UTC)[reply]
That's been missing from the discussion? I'm sure I mentioned it about half a dozen times... --Tango (talk) 15:32, 16 March 2009 (UTC)[reply]
Death
Here is the first scenario. A healthy person is "locked away" in a room, with no chance for escape or outside assistance/intervention/communication. The room has an infinite supply of air/oxygen pumped in ... and the room has an infinite supply of good drinking water available. Would that person be expected to die? Or can he live like this indefinitely (up until his inevitable and expected "natural death")? If the former, how long would it take to die? And what would be his cause of death? The second scenario is exactly as the first, minus the water. Same questions. In these scenarios, both the person's physical body and mind are completely healthy ... so that he would not die of any (pre-existing) disease, nor commit suicide, etc. Also, the room is perfectly comfortable, so that heat/cold/etc. is not an issue. If it makes any difference, we can also throw in good working plumbing/toilet facilities in the room to remove waste. Thanks. (Joseph A. Spadaro (talk) 18:40, 15 March 2009 (UTC))[reply]
He would die of starvation in a few weeks in the former and of thirst in about three days in the ladder. — DanielLC 19:24, 15 March 2009 (UTC)[reply]
Yes. No. Depends on a wide variety of factors, including how much fat and muscle he has. Starvation.
Yes. No. Generally, one to two weeks. Dehydration.
The Scottish used to wall enemies up like this in cupboard sized spaces in their castles, although they may in some cases have left a small hole to allow food and water in. 84.13.169.19 (talk) 22:10, 15 March 2009 (UTC)[reply]
In some of the above replies, you have answered that the person dies of starvation / dehydration / etc. I know that that is what happens to the person's body (i.e., he becomes starved and/or dehydrated) ... but is that what he actually dies of? In other words ... does he really die of, for instance, "multiple organ failure" (or some other medical terminology) ... if indeed the starving leads to vital organs failing, that is? Thanks. (Joseph A. Spadaro (talk) 01:06, 16 March 2009 (UTC))[reply]
Multiple organ failure is an option, sure. Our article on starvation outlines the various effects of starvation pretty well. It's impossible to say what exactly would kill the person in such a situation, but it could be a heart attack, or it could be the result of an infection, or scurvy, or... there are lots of things, but the point is that if the body runs out of energy, it will eventually break down one way or another. (Also, you mention that they wouldn't commit suicide, but psychological symptoms -- including depression -- are generally associated with starvation, and a person trapped in a room with nothing to eat might well commit suicide.) Likewise, dehydration can be fatal pretty quickly (and can also be associated with starving, which can cause diarrhea). Dehydration tends to result in kidney failure, but other internal organs will also stop working. Regardless of whether the problem is starvation or dehydration, if you take away the body's fuel, it'll start to shut down. The exact order this happens in probably varies, depending on the patient. -- Captain Disdain (talk) 02:07, 16 March 2009 (UTC)[reply]
A friend who went through "survival school" said that they teach the rule of "threes:" you can survive three minutes without oxygen, three hours without shelter, three days without water, and three weeks without food. Your scenario suggests death in about three weeks if food is denied while air, shelter and water are provided. Milage may vary. Edison (talk) 02:17, 16 March 2009 (UTC)[reply]
Why would three hours without shelter kill anybody except under extreme weather conditions? Dauto (talk) 03:28, 16 March 2009 (UTC)[reply]
I'd like to second Dauto's question, this seems interesting... could you elaborate, Edison? --Ouro (blah blah) 07:33, 16 March 2009 (UTC)[reply]
Indeed, how long you can last without shelter depends on the circumstances. It could vary from anywhere between a few minutes (you're in the Arctic and your tent blows away while you aren't wearing your Arctic clothing) to pretty much indefinite (in the tropics, say, as long as you have a decent hat). Shelter was probably included in there because that is the order you are generally taught to deal with your primary needs in. Obvious, if you don't have air, you need to sort that out pretty quickly! After that, you worry first about shelter, then water, then food. Unless you are already seriously dehydrated, that will pretty much always be the best order. Even if you don't need shelter in order to live it has massive psychological benefits. --Tango (talk) 15:30, 16 March 2009 (UTC)[reply]
I'd just like to add that one morbidly obese person who was quoted on the BBC lived for over a year on water and vitamins - so this might suggest someone could live longer than three weeks (until the vitamin part took effect, in which case a disease like anemia or scurvy would kill them). One source suggests eight to twelve weeks. - Jarry1250(t, c) 20:47, 16 March 2009 (UTC)[reply]
If you are in a place where it is not too hot and sunny and not too cold, then shelter might be a less acute need than water, (but still following air!). If it is extremely cold, then you need to find or build shelter pretty quickly to avoid dying of heat loss. See [13]. This apparently dates back to U.S. military survival training. Edison (talk) 17:25, 17 March 2009 (UTC)[reply]
Irish republicans who were on hunger strike in British jails in Northern Ireland survived for 94 days without food. Of the nine who set out to do that, three died - but the rest survived - suggesting that 94 days isn't just a one-off flook. SteveBaker (talk) 02:35, 18 March 2009 (UTC)[reply]
Tesla's wireless electricity
According to this article, Tesla tried to create a world-wide, aerially-broadcast energy network. Would this have had health or environmental implications? Would the electricity mess anything up, or would we be safe? 86.8.176.85 (talk) 18:53, 15 March 2009 (UTC)[reply]
It would mess _everything_ up. The amount of RF interference would be ridiculous. --130.237.179.182 (talk) 20:44, 15 March 2009 (UTC)[reply]
RF interference with what? Modern technology, certainly, but the question asked about health and environmental issues. I'm not aware of any proven RF hazards in that area until it gets so intense as to directly cause heating (like in a microwave oven). --Anonymous, 21:20 UTC, March 15, 2009.
Some people have expressed concern about the health effects of high-voltage pylons near homes. But there seems to be no basis for their apprehension.
For significant distances and significant amounts of power, there is no known method of transferring electrical power without the use of wires.
A transformer will do it by employing a magnetic field. But that involves only an extremely short distance.
I once read a newspaper article about a farmer who had a metal fence that ran alongside an overhead power line. The farmer was picking up and using electrical power from the fence. He was taken to court for it! I don't know how much power he picked up, or what the voltage was, but the distance was small.
However, a crystal radio set does receive a tiny amount of power from a rather distant transmitting station and put it to use (legally!) to actuate headphones. It is amazing that such a small amount of power will do it. The power must be in the microwatts.
In Wikepedia, the article Crystal radio, (in the section "Attempts at recovering RF carrier power") says that claims have been made that power from a radio station carrier wave can be used to amplify the output of a crystal radio. But no details or circuits are given. (A crystal radio itself does not amplify.) The "Construction and operation" discussion which follows is also interesting.
However, the obvious problem with sending significant amounts of power through space is that anyone can pick it up for free (like a radio signal) unless some means can be devised to make it available only to paying customers. – GlowWorm. —Preceding unsigned comment added by 98.17.37.175 (talk) 22:31, 15 March 2009 (UTC)[reply]
For anything but very short distances (less than WiFi can transmit), it would be wildly impractical using current technologies. If we can focus and recapture extremely coherent EMR that's minimally absorbed by intervening matter, it may be possible, but if you promiscuously radiate energy in all directions, you lose the overwhelming majority of it. Entropy's a bitch. arimareiji (talk) 23:05, 15 March 2009 (UTC)[reply]
In some cases, radiated power that is not expended externally is periodically returned to the source. A coil with AC flowing through it exhibits that property. The collapsing magnetic field returns energy to the source unless a conductor intercepts the field. The conductor would need to be part of a complete circuit for any appreciable amount of power to be taken by it. Obviously, an AC magnetic field cannot be used to transmit power for any great distance - every conductor in its path would absorb some of the energy. At present there is no known method of transferring a significant amount of electrical power broadcast (as Tesla planned) or by a directional beam. – GlowWorm. —Preceding unsigned comment added by 98.17.37.175 (talk) 01:19, 16 March 2009 (UTC)[reply]
Tesla claimed that electromagnetic radiation consisted of longitudinal waves of compression and rarefaction, rather than transverse waves as called for by Maxwell. He built a tower which was intended to send energy to great distances, but which was not shown to do so. He made some major contributions to electrical technology, but also made periodic wild claims. Edison (talk) 02:13, 16 March 2009 (UTC)[reply]
I agree with GlowWorm; as far as I know, it has never been proven that radiation from those huge electrical pylons right over your head is harmful, but somehow I think a huge amount of wireless energy traveling through someone wouldn't be good for people (it's like the previously mentioned radiation, except ALL of the energy traveling through the pylons being transmitted), especially for those with pacemakers and such. Not to mention the ridiculous amount of interference and possible damage to anything electrical that passed in it's range. -Pete5x5 (talk) 17:57, 16 March 2009 (UTC)[reply]
Many normal items can act as a (rather inefficient) antenna. This can include metal clothes hangers, wire fences, even dental work. Normally the amount of energy received is insignificant (although, in rare cases it's enough to hear a radio station on these items). However, if you had a billion times as much energy in the air, you would then get a billion times as much received by all these accidental antennae, causing fires and exploding people's heads from time to time. StuRat (talk) 02:37, 17 March 2009 (UTC)[reply]
This is all true - but over shorter ranges, there is a TON of research into the idea of broadcasting power to things like laptops and cellphones. Here for example. You can broadcast power over shorter ranges with much less danger and trepidation. The idea being that instead of having all of those low voltage chargers with the ubiquitous wall-warts, you'll have just one WiTricity generator build in somewhere like under your desk, for example - and any appliance placed on top of or nearby (eg in your pocket) would automatically get charged up. Since connectors are the least reliable parts of most small devices, this make a lot of sense. This stuff is not far off into the future - there are plans for actual WiTricity products to appear in just a couple of years. SteveBaker (talk) 02:29, 18 March 2009 (UTC)[reply]
Right. But, of course, the energy levels from such a system are far lower than those Tesla imagined, making it much safer. StuRat (talk) 17:02, 18 March 2009 (UTC)[reply]
Wadeaminnid. Is "WiTricity generator" and whatnot just marketing chitchat for the induction chargers already present in every electric toothbrush? And... would not a "WiTricity generator" continue to radiate power even if there were no devices soaking it up? And, what advantage would such a scheme have over a standarized charger with wires? Y'know... One wallwart to rule them all, and in the darkness bind them. ;) -- Fullstop (talk) 14:21, 19 March 2009 (UTC)[reply]
Chargers with wires and induction chargers still require that you place the device in a specific location and maybe plug it in. Forget, and your device isn't charged. Plugs also tend to fail. I lost a laptop that way. There is one advantage to the current chargers, though (besides electrical efficiency). It's hard to lose an object if it's plugged into the wall. StuRat (talk) 15:08, 19 March 2009 (UTC)[reply]
Roses: meaning of "perpetually" or "repeat" flowering
The gardening book I'm looking at distinguishes between perpetually and repeat flowing roses. What is the difference, and which is better? I have read the Rose article, and the gardening book does not define the difference. 84.13.169.19 (talk) 22:05, 15 March 2009 (UTC)[reply]
The perpetual flowering roses will have a small number of flowers all through the growing season, spring, summer and autumn. The repeat will come out in a second burst with a blank period in between. Better is hard to say as each kind will be more attractive at different times. Graeme Bartlett (talk) 02:53, 16 March 2009 (UTC)[reply]
Remember to deadhead the roses after the first bloom. (cut off the dead flowers), so that energy goes into new flowers rather than rose hips.
When is certain pet article content a "How To"
I'm pretty new, so I'm sorry if this is something that would be common sense for more established wikipedians.... I am looking at small animal pet articles such as house rabbit, syrian hamster, fancy mouse, fancy rat and so on... some of these contain information on the care of the species as a pet (caging, feeding, handling, bedding etc). At what point does go from being informative about the article's subject to being How To? If these topics are appropriate, what would be best way to address the somewhat controversial issue of what kind of bedding(s) are safe vs toxic. Currently, the topic is avoided in some articles, and presented one-sided in others. Should each species' article be edited to have the different POV's supported with article references, and then watch every article to make sure that edits are reflected across all of them; or should "pet bedding" be made into an article, and each pet species article then point to that article? (I'm leaning towards this being too much of a How-To that should be deleted, or if it is appropriate to the articles, then I'd rather see "pet bedding" being its own article..., but I don't want to step on any of the many toes of the different small pet article editors!) --6th Happiness (talk) 23:16, 15 March 2009 (UTC)[reply]
Your best bet for questions of this nature would be to run them by folks at either the Help Desk (if you're trying to find the relevant policy pages) or the Village Pump (if you're looking for a more free-ranging discussion about what the policy should be or how it ought to be applied). TenOfAllTrades(talk) 23:45, 15 March 2009 (UTC)[reply]
Just a couple of suggstions, if you see them before leaving: At least in the hamster article, there are a few sentences that are too close to How-To and a few that are just downright regrettably-shallow advice. That type of info can and should be pulled out of the articles. Specifically wrt bedding, I would think it's completely appropriate to briefly note in specific animals' articles why certain bedding types are bad based on biology - but not to go on at length about how often to change it, or whether your hamster likes paper or hemp bedding, etc. As to whether a longer article on pet bedding would be viable, I would think it can be. But I'm also a lazy bum, so I'll leave the researching and writing to you. ^_^ arimareiji (talk) 23:54, 15 March 2009 (UTC)[reply]
Is there an easy DIY method to convert the clear plastic shell of an LED light bulb into a frosted one (without significantly reducing the light output)? —Preceding unsigned comment added by 173.49.9.243 (talk) 02:41, 16 March 2009 (UTC)[reply]
It would depend on the type of plastic used. Dipping the bulb quickly in Acetone and letting it air-dry will likely accomplish your goal, though if you're trying to compensate for the extreme directionality of the light from most LED bulbs, a simple bulb frostover isn't going to get the job done. —ScheinwerfermannT·C03:43, 16 March 2009 (UTC)[reply]
(ec)I've used various organic solvents (takes some experimentation with solvent and time depending on the plastic) to get frosted effects on clear plastic parts. Could also try sand-paper or steel wool to get a brushed surface effect. Never tried it on LED lightbulbs. DMacks (talk) 03:46, 16 March 2009 (UTC)[reply]
OR try little dabs of superglue. Use pin to apply. 76.97.245.5 (talk) 07:33, 16 March 2009 (UTC)[reply]
Most people just sand the plastic envelope slightly. It does lose a little light. There are wideangle leds you can buy if that's what you want. 75.62.6.87 (talk) 10:07, 16 March 2009 (UTC)[reply]
Optimum sizes/shapes for ice cubes
What would be the best (including practicalities like glass sizes) sizes and shapes for ice cubes to make them melt faster or slower? I'd have thought that a big ice cube would melt more slowly, but would a sphere or cube or any other shape be best? 86.8.176.85 (talk) 03:15, 16 March 2009 (UTC)[reply]
My anecdotal observation has been that a long, cylindrical form works better than any of the more traditional cube variants. In my experiments carried out using different rubber ice moulds from IKEA, I found that the cylindrical ices froze fastest and were quickest and most efficient at cooling down drinks. The fast freezing and drink cool-down are probably due to the large surface area of the cylindrical form, while the perceived efficiency is probably because the ice cylinders cool the whole height of the drink. Cubes, on the other hand, float on top and supercool the upper portion of the drink while leaving the lower portion largely uncooled. —ScheinwerfermannT·C03:41, 16 March 2009 (UTC)[reply]
The surface area of the ice determine the rate at which heat gets in--the larger the area, the faster the heat transfer. With a certain rate of heat transfer, ice cubes with less volume obviously melt faster. If you want the ice to melt (and cool the surrounding fluid) as quickly as possible, you'd want a high surface-area-to-volume ratio. A sphere has the lowest ratio, so definitely don't use one.
If this is a practical question, I think the best solution is to grind up the ice cubes, whatever shape they happen to be, and dump the pieces into whatever has to be cooled. If you want to have the ice melt faster, just grind it into smaller pieces. Even minimal crushing will increase the surface-area-to-volume ratio to a value much higher than any single ice cube can realistically have. --Bowlhover (talk) 04:58, 16 March 2009 (UTC)[reply]
This assumes that the main goal of the ice cubes is to cool the drink quickly. In some circumstances, you might prefer ice cubes that cool slowly, over a long period, in which case spheres might be more desirable. jeffjon (talk) 14:03, 16 March 2009 (UTC)[reply]
About the optimality of the spheric shape: it is true that a ball has the surface of minimal area among all bodies with the same volume (that is, solves the three dimensional isoperimetric problem), but, to be precise, what matters here is that a ball has the minimal thermal capacity among all bodies with the same volume; the two variational problems being not directly connected. pma--79.21.30.83 (talk) 16:44, 16 March 2009 (UTC)[reply]
Crushing will certainly generate the best surface-area to volume and for practical purposes will undoubtedly cool your drink faster than any other shape. But it's kinda cheating if you're trying to build a single lump of ice. What you need is some kind of fractal surface - a sierpinski sponge perhaps - pleasing because it's so much like a regular ice cube - but able to dissolve in an arbitarily short amount of time. If course constructing such an object in your refrigerator might be a bit of a challenge! SteveBaker (talk) 00:05, 17 March 2009 (UTC)[reply]
Having infinite area, the sierpinski sponge would indeed melt instantaneously. Having zero volume, it would do no cooling at all. :) Dauto (talk) 04:39, 17 March 2009 (UTC)[reply]
If your point is to cool your beer cooler fast and keep it cold, You might want to try adding some salt to the ice. That will reduce the melting point of the ice several degrees making the ice melt fast. Make sure you wash the beer bottles before opening them. Dauto (talk) 04:45, 17 March 2009 (UTC)[reply]
Animal olympics
If there were an animal Olympics, which species would win which events? What would win 100m, weightlifting, any of the events where an animal could sort of compete. 86.8.176.85 (talk) 05:47, 16 March 2009 (UTC)[reply]
Are you looking for absolute numbers or would you figure in relative body sizes. Have a look, we probably have a couple of lists somewhere. (Sorry but I got to turn in so can't/ won't be more help. Speed record's a start.76.97.245.5 (talk) 07:32, 16 March 2009 (UTC)[reply]
I think what you really want to know is which of the animals is the strongest, fastest, etc... right? Or maybe you just dig crazy animal Olympics. Hell, why not! But honestly, that's a problematic theme, because it's kind of hard to figure out how to measure or even compare these animals. In a lot of cases, this would involve guesswork: for example, gorillas are really, really strong, but it's hard to make them do bench presses, so the scientific data on how strong they precisely are tends to be sketchy. In fact, the definition of strength can also be iffy: an elephant can haul amazing loads, but I'd bet that a blue whale is still stronger. So how do you measure that? And then again, surely proportion has to count for something: all of these animals are pretty much lightweights compared to ants, which can lift many times their own body weight... To switch tracks a little, speedwise, a cheetah can pretty much beat anything on land on a 100m sprint -- they can sprint at up to 120 km/h. And yet a peregrine falcon will leave it in the dust; they've been clocked at 250 km/h when diving. We'd definitely need some ground rules here -- in addition to ridiculously cooperative animals... -- Captain Disdain (talk) 10:41, 16 March 2009 (UTC)[reply]
I think the animal Olympics would need to borrow a page from the Paralympic Games and institute a classification system, where the various animal athletes would be grouped for competition according to their physical function. So we could have the 100m for biped, quadruped, avian, aquatic (mammal), aquatic (non-mammal), invertebrate, etc. - EronTalk 14:31, 16 March 2009 (UTC)[reply]
Solar cooker
why is glass plane/cover used in a solar cooker? —Preceding unsigned comment added by Pratimap (talk • contribs) 07:39, 16 March 2009 (UTC)[reply]
The glass cover allows sunlight to enter the device unimpeded, but upon entering, some of the sunlight's energy is converted into heat within the cooker. The cover then traps the heat by blocking the escape of hot air. This is the "heat trapping" type of solar cooker, and other types exist as well. Read more at Solar cooker. Someguy1221 (talk) 08:32, 16 March 2009 (UTC)[reply]
Glass is also pretty opaque to infrared, so it stops heat escaping as radiation, as well. (This is how the greenhouse effect works in the case of actual greenhouses.) --Tango (talk) 15:22, 16 March 2009 (UTC)[reply]
Glass is transparent to IR, or else thermographic cameras won't work. Greenhouses trap heat by preventing warmed air from mixing with the surrounding atmosphere or rising to high altitudes, as explained by Greenhouse effect#Real greenhouses. --Bowlhover (talk) 21:06, 16 March 2009 (UTC)[reply]
You really can't lump the entire IR spectrum together like that. Glass has transmission/absorption peaks and valleys throughout the IR range, which is why, simultaneously, 1) IR cameras can use glass lenses, and 2) glass bending and laminating operations can use IR to heat the glass efficiently. jeffjon (talk) 13:12, 17 March 2009 (UTC)[reply]
Watch one of those police programs on TV where they have thermal imaging - the windows of houses look like solid white squares, you can't see inside the houses through them. That's because IR is pretty much opaque at the relevant wavelengths. I'm not sure how the glass lenses in such cameras work - perhaps it's a different type of glass? --Tango (talk) 14:29, 17 March 2009 (UTC)[reply]
Yes it's some kind of quartz-like stuff. IR does go through glass - just not very efficiently. One of the major reasons you don't see thermal signatures through house glass is that we go to a lot of trouble (with double-glazing, IR-reflective coatings and such) to insulate them, SteveBaker (talk) 02:07, 18 March 2009 (UTC)[reply]
Killer cancer
I'm not seeing this in our articles. What are the most common proximal causes of death associated with cancer? Metastatic growths in the brain or heart would obviously be good candidates, but probably not the only major ones. What do tumors typically do to people that cause the body to cease functioning? Obviously with a group of diseases as diverse as cancer there are probably many possible ways it can kill you, but I just looking for the common ones. Dragons flight (talk) 08:18, 16 March 2009 (UTC)[reply]
It varies significantly between types of cancer. I found a number of reviews of the precise question on PubMed: [14][15][16][17][18]. I recall from some or another doctor that infection is in general the single most common cause of death amongst cancer patients. Someguy1221 (talk) 08:48, 16 March 2009 (UTC)[reply]
Measurement of breast size by water displacement
Hi I was wondering if anyone had any idea where I could find some information regarding this please:
Basically sometime around 1985-1990, James Owen Drife led a study where they measured women's breast size through submersion in water, (and presumably its displacement), which caused a far bit of newspaper controversary, at least in the UK.
Does anyone know where this was published? Or even in which newspapers it was reported? Or just some more information on it??
Many thanks Duke Of Wessex (talk) 08:45, 16 March 2009 (UTC)[reply]
He wrote an article on what you describe in 1975 (available free here) in the British Medical Journal. Drife has published 20 articles on various issues relating to breasts, but I'm not sure any of the ones contain what you described based on their titles. But they are available for free from pubmed, except for one which I have read but is a review and not a research paper. Someguy1221 (talk) 09:02, 16 March 2009 (UTC)[reply]
Thanks for those links, (and in super-fast time!), I think the 1975 one is what I'm after, but have you (or anyone) any idea if it was mentioned in the newspapers at the time? Or more recently? Thanks! Duke Of Wessex (talk) 16:11, 16 March 2009 (UTC)[reply]
The obvious problem with this method is that breasts are generally attached to someone, so you can't determine the displacement of the breasts alone. Deciding where the breasts end and the rest of the person begins is not an easy or precise task. StuRat (talk) 02:22, 17 March 2009 (UTC)[reply]
Why doesn't clingfilm / plastic wrap cling to Parmesan?
In my fridge, once opened, all the cheese are covered in clingfilm. For the vast majority of the cheese the film does what it's supposed to and clings tightly to the cheese, wrapping it up. With parmesan, however, it doesn't - it's almost as though it loses its static, and instead of clinging to it, simply covers it loosely. Why? It's not a case of the same piece of film being opened and closed multiple times, as it will happen with a fresh piece of film - after a certain period of time, when I go back to the fridge to get it out, it's given up the ghost and gone all loose... pushthebutton | go on... | push it! 09:55, 16 March 2009 (UTC)[reply]
Parmesan cheese (Parmigiano-Reggiano to purists) has a slightly oily surface; you can feel the difference when you pick up a wedge of the stuff. The film just slides off. (The fats in most other cheeses tend to stay quite solid at refrigerator temperature, so there's less sliding.) TenOfAllTrades(talk) 13:56, 16 March 2009 (UTC)[reply]
I put a section in Plastic wrap on how it works. To elaborate a bit on Ten of all Trade's "oily" explanation: the wrap will bond lightly with the fat molecules on the cheesy surface, but those molecules are not tightly bonded to the cheese. In butter or American cheese there is enough of a smooth surface that is tightly bonded to the rest of the block so the wrap will stick. 76.97.245.5 (talk) 14:15, 16 March 2009 (UTC)[reply]
Transmission line simple problem
Hi, I'm trying to solve Problem 1 at [19], but I'm not sure, any help will be appreciated. What I do is apply Ohm's law at t=0, so that the voltage wave is -1 volts towards de open circuit. That way I'll get a series of -1 and 0 voltage levels at the short circuit and 1,0,1,0 at the open circuit. Is this correct? Thanks! --62.57.238.224 (talk) 10:49, 16 March 2009 (UTC)[reply]
I think you're forgetting a few things, mainly the reflection off the short. Draw a diagram and follow along:
The initial -1V wave travels to the right and reduces the voltage on the line to 0.
The initial wave (-1V) is reflected with coefficient 1.
Note that the open end is now at -1.
The first reflected wave (-1V) travels left, reducing the voltage on the line to -1.
The first reflection is reflected from the short, with coefficient -1.
Note that the reflection instantly cancels the incoming wave, so the short is always at 0.
The second reflection (+1V) travels right, raising the voltage on the line to 0.
The second reflection is reflected with coefficient 1.
The open end is now at +1.
The third reflection travels left and raises the voltage on the line to 1V.
The third reflection is reflected with coefficient -1.
I think there is a contradiction between the formula of the lorentz transformation and the length contraction in special relativity.
In the formula , suppose a coordinate system K' is moving with a relative velocity to K equal to v. Then if we solve the formula for t' = 0, x' = 0 and a v less than c, we will surely get a value greater than 1. So what will happen is that a rod measuring 1m in K' will appear to be longer as seen from K. But this is in contradiction with the length contradiction formula, which states that the length will decrease. Please explain. (if this is really a discovery, please guide me to get a patent for it because i don't know the procedure as i am only 14).--harish (talk) 11:57, 16 March 2009 (UTC)[reply]
If you put t’=0 and x’=0 in the formula for the Lorentz transformation, according to me the result would be x=0. This just means that the origin of both systems K and K' (i.e. the points x and x’) are coincident at the moment t=0 (i.e. before the system K' has moved relative to K at all). This is just a trivial result, really... Or are you doing something else? MuDavid 12:17, 16 March 2009 (UTC)[reply]
The question was asked by the same person, which means he reamains unconvinced. Dauto (talk) 13:10, 16 March 2009 (UTC)[reply]
Simple explanation is that if you measure the distance between two space-time events that are simultaneous in K' (i.e. have the same value of t') then you are measuring length from the point of view of K'. And from the point if view of the K' frame of reference, L' is indeed greater than L. But if you want to measure length in the K frame of reference then you need to measure the distance between two space-time events that are simultaneous in K (i.e. have the same value of t), in which case in turns out the L is greater than L'. As a general principle, the difference between the space co-ordinates of two points in space-time that are separated by a space-like interval is maximised in the frame of reference in which they are simultaneous.Gandalf61 (talk) 14:21, 16 March 2009 (UTC)[reply]
Gandalf, from the expression for the invariant 'distance' (where and are the space coordinate distances between the two events and and are the time differences between the two events) we see that if the primeless frame is the one where the two events are simultaneous , then , which makes minimal (not maximal as you stated). —Preceding unsigned comment added by Dauto (talk • contribs) 19:27, 16 March 2009 (UTC)[reply]
Yes, indeed. And, now I think again, my final point was not relevant to the original question anyway. Gandalf61 (talk) 13:17, 17 March 2009 (UTC)[reply]
Yes, I agree - for the second time around, our OP is incorrect. ...And as for a patent...it varies under the laws of different countries - but in most places, you can't patent an equation - even if it's correct. SteveBaker (talk) 23:36, 16 March 2009 (UTC)[reply]
I've always thought patents were for commercially useful inventions, and that scientific and mathematical discoveries go in academic journals. --Bowlhover (talk) 14:40, 17 March 2009 (UTC)[reply]
Thank you someone42 and dauto. I have now understood that i ahve done a fundamental error. yl' = l was the thing i already knew. But I confused l' and l. Now i have understood that l' will be smaller than l. So when we want to find l', we take y(the constant) to the other side so now we have to solve l' = l/y which will give a value smaller than l. Thanks again. Actually I wasn't able to see the answers for the archived question a few days after.--harish (talk) 17:02, 18 March 2009 (UTC)[reply]
Just in case this was a homework question, please keep in mind that the guidelines suggest that we should try to avoid answering homework questions (though we're happy to give a helpful nudge in the right direction if the OP shows that an effort has already been made. --Scray (talk) 23:09, 16 March 2009 (UTC)[reply]
nutrition
at what temperature a body starts to feel in coldness and a temperature out side his body is 22???thank you —Preceding unsigned comment added by Nisreen mansour (talk • contribs) 14:26, 16 March 2009 (UTC)[reply]
Moving the following from the mathematics desk, posted by the same user under an identical header. —JAO • T • C 14:29, 16 March 2009 (UTC)[reply]
how can i organize my food per a day?
how many calories i'm suposed to include in my daily meals??
what are the most important kinds os food i may eat in order to make a 'diet'?
i'm 12 years old and am 72kg that is so bad:S
Specific advice should be provided by a medical professional. We have an article on the US Dietary Reference Intake, but that's provided for adults aged 40-50. As our dieting article notes, dieting in youth can be extremely hazardous. Consult a professional to develop a plan that is safe and healthy. — Lomn 14:49, 16 March 2009 (UTC)[reply]
If your school has a School nurse she can help answer your questions. She's there for students' health and should have relevant information available. 76.97.245.5 (talk) 15:07, 16 March 2009 (UTC)[reply]
why?who?when?what? (questions)
why do a person cry?
why do a person cough?
why do a person laugh?
why do a person shout?
how do a person feels when he sneeze ?why?
who can help by answering these questions?ineed them am doing a project just any umm inf.about it i hope findung please help
!! without details!!bye —Preceding unsigned comment added by Nisreen mansour (talk • contribs) 10:35, 16 March 2009
Hi. OK, so I remember asking a question about the merger between Andromeda, the Milky Way, and Triangulum a while back, and whether their black holes might collide. They might miss, but now it looks like collisions between supermassive black holes as a result of galaxy mergers might not be so rare after all: [20][21][22]. If two black holes collide in this manner, could the ensuing explosion have effects on Earth? Remember that explosions such as this may travel at close to the speed of light, so the explosion itself would not take much longer to reach us after the light from the explosion has reached us. Could a similar scenario occur between Milky Way, Andromeda, Triangulum, and possibly a few other galaxies? Thanks. ~AH1(TCU) 15:54, 16 March 2009 (UTC)[reply]
As far as I know, the details of black hole mergers is still an open question. However, I don't know of any reason for a massive explosion. There would be lots of gravity wavesgravitational waves oops! emitted, but they would have to be really powerful to cause any harm to Earth from such a big distance - I would be surprised if they were that powerful. --Tango (talk) 16:10, 16 March 2009 (UTC)[reply]
Well, you'd get a big mess from the black holes becoming active feeders, and their accretion discs interacting would likely result in a big mess. As I recall, Death from the Skies discusses this in one chapter. I believe the odds tend to favor minimal effect on the solar system (there's a good chance it gets ejected from the galaxy entirely) unless it happens to be along the polar axes of the SMBHs, which is fairly unlikely. — Lomn 16:17, 16 March 2009 (UTC)[reply]
See gravitational wave (not gravity wave!), which says "even waves from extreme systems like merging binary black holes die out to very small amplitude by the time they reach the Earth". Presumably if we were in the line of fire for any resulting relativistic jet it would be a lot more noticeable. --Sean 17:01, 16 March 2009 (UTC)[reply]
Oops! Fixed. --Tango (talk) 17:06, 16 March 2009 (UTC)[reply]
See Caliper scroll down to dial caliper. Be sure your dial is set to zero before you start and don't forget to add the readings from the slide. 76.97.245.5 (talk) 17:25, 16 March 2009 (UTC)[reply]
With proper care, such a measurement is very near accurate. Edison (talk) 14:17, 17 March 2009 (UTC)[reply]
German toilet
Why do German toilets have a little shelf?--80.58.205.37 (talk) 17:47, 16 March 2009 (UTC)[reply]
Far greater minds than mine have pondered (and probably solved) this question, but I think it is simply an excuse for German women to insist that men sit down to pee, because (with the shelf) they argue that pee splashes out of the toilet creating a mess worse than death. Why they need to emasculate men so badly they have redesigned the toilet, I do not know. 77.12.50.107 (talk) 19:15, 16 March 2009 (UTC)[reply]
Apparently it's designed to facilitate examination of one's feces. --Sean 21:52, 16 March 2009 (UTC)[reply]
For those like me who had no idea what this was talking about but are curious, here's a helpful link. Maybe I'm just being culturally insensitive, but ew. arimareiji (talk) 22:11, 16 March 2009 (UTC)[reply]
The last Vespasienne in Paris
I have observed similar - but much smaller - shelves in French toilets. Fortunately, us boys are able to negotiate these smaller devices from our lofty peeing posture...and of course there is always the pissoir or vespasienne (WHAT! We have no articles on these magnificent monuments to male urination?)... But sadly, I have yet to visit any country (the US included) who have reached the pinnacle of success of The Great British Loo. US toilets come close - but the failure to master the simple concept of the siphon dooms them to dribble and leak and need all manner of careful tweaks and adjustments. The worst I've encountered is certainly on some of the Greek islands where the diameter of their sewer pipes are mathematically guaranteed to block for any human of normal 'caliber'. They insist that you deposit used toilet paper in a small basket provided for this very purpose (cue ungodly smells and health hazards). One 'safari lodge' in Kenya was particularly lacking. "Where is the toilet?"..."Everywhere" (accompanied by a sweeping gesture across the entire landscape outside the hut). Sigh. SteveBaker (talk) 23:22, 16 March 2009 (UTC)[reply]
The original reason had more to do with flushing. 2 Systems used to be common in Germany: a thing called "Druckspüler" which basically produced a high pressure jet of water. The second is a cistern mounted near the ceiling. (About 2 yds. above the commode.) Both created a significant amount of water pressure when flushing. Reportedly an American style flushing toilet then could create a whirlpool effect that let the "item to be flushed" stay in the bowl. Most Germans answering to online questions stated that they preferred the German system (called Flachspüler), because with the flush toilet water from the bowl may spray up onto one's butt (following the equal but opposite reaction principle). (If you can read German google the topic. Lots of toilet humor.:-) 76.97.245.5 (talk) 23:31, 16 March 2009 (UTC)[reply]
To get splashed on the butt while flushing, you'd need to flush while seated. I always stand up before flushing; doesn't everyone else ? StuRat (talk) 01:44, 17 March 2009 (UTC)[reply]
Nope, they're talking about water splashing back up when solid feces drop into the bowl. Not while flushing. People did say it was easier to get a stool sample with a "Flachspüler" but that was not cited as the major advantage. It seems merely a side benefit. There seem to be quite a number of well established urban myths circulating. 76.97.245.5 (talk) 14:16, 17 March 2009 (UTC)[reply]
Wait, you just said "with the flush toilet water from the bowl may spray up onto one's butt". StuRat (talk) 19:08, 19 March 2009 (UTC)[reply]
This topic is very interesting but does it really belong in the "Science" desk? :) --Taraborn (talk) 17:27, 17 March 2009 (UTC)[reply]
The OP probably didn't know why German toilets are like that and speculated that it has to have some scientific explanation. --Mr.K.(talk) 20:12, 17 March 2009 (UTC)[reply]
I've been building up pressure ever since I've read Tarborn's comment, but I'll try not to do a dragon flaming here. If the topic didn't develop into something "scientific" enough for some posters, how is this in the nature of the question? I apologize for not giving sufficient fluid dynamic background for my response, but that's not an area I'm comfortable in. Most reliable information being only available in German and buried in a deluge of urban myth and humorous ghits surely doesn't help us answer. I don't find Taraborn's comment appropriate in the least, though. We are already so firmly sticking to our "no medical advice" rule that people need to add grovelling disclaimers to any question even remotely connected to the human body or (heaven forbid!) diseases. Now we ridicule OPs for daring to ask whether there's a scientific background for a certain engineering feature? The fact that the answer in this case is more rooted in marketing, patent rights and consumer preference should not be taken as an excuse to discourage questions. I probably wouldn't have wasted a minute of thought on this if the above post weren't symptomatic of a sentiment I increasingly encounter to discourage asking questions in favor of regurgitating memorized "established facts". Engineering may not be quantum physics but pondering questions is what elevates it above assembly line work. I would wish people who are unwilling or unable to answer questions would take their posts elsewhere. Even wikipedia provides ample room for that on other pages. BTW: I was told the ref. desks were supposed to work as wikipedia's librarians. Any librarian who put that much effort into determining whether or not to answer a question instead of pointing the person at least toward the right aisle or shelf would deserve to be let go. 76.97.245.5 (talk) 15:27, 18 March 2009 (UTC)[reply]
While I agree with your sentiments, in general, in this case I interpreted Taraborn's comment as just meaning it would be better to post this on the Misc Ref Desk. I don't happen to agree, as there is definitely science and engineering involved in any answer to this Q, but I'm not mad at Taraborn for making the comment. StuRat (talk) 16:56, 18 March 2009 (UTC)[reply]
Yes, I was thinking what StuRat said, just that... And if you get that angry so easily my advice is that you should stay away from internet conversations, but I don't know if this is medical advice. --Taraborn (talk) 20:18, 18 March 2009 (UTC)[reply]
bladder removal
Does bladder removal surgery effect male verility and what other side effects 66.53.123.127 (talk) 18:29, 16 March 2009 (UTC)[reply]
Bladder removal? Is that even possible? The bladder is a vital organ. Do you mean gall bladder? --Tango (talk) 18:39, 16 March 2009 (UTC)[reply]
The bladder isn't a vital organ, perhaps you're thinking of the kidneys, which filter waste from the blood and produce urine. The bladder only stores urine. As long as a path exists from the kidneys to the outside of the body, the waste can still be eliminated. Of course, without either an internal or external bag of some sort, urine will just drip out continuously, which is a major quality of life issue, though not fatal (unless it leads to death by suicide or some other cause). StuRat (talk) 01:16, 17 March 2009 (UTC)[reply]
Yeah - and if you're ever inclined not to panic over a few lice - check out the impressive list of human diseases that are attributed to Rickettsia's. Our article lists: typhus, rickettsialpox, Boutonneuse fever, African Tick Bite Fever, Rocky Mountain spotted fever, Australian Tick Typhus, Flinders Island Spotted Fever and Queensland Tick Typhus!! Sadly the ticks don't seem to mind them at all. Yikes! SteveBaker (talk) 23:05, 16 March 2009 (UTC)[reply]
C'mon now Steve, be fair. I've voted for a few lice, and some companies give 'em big bonuses. --Scray (talk) 23:12, 16 March 2009 (UTC) [reply]
Don't you mean you've voted for ticks ? "Politics" = poly + ticks, meaning many blood-sucking parasites. StuRat (talk) 01:02, 17 March 2009 (UTC)[reply]
No - you have the wrong derivation of the term. Politician is a mispronounciation of the french polyteteian - specifically a person with two or more faces. Traditionally, most politicians are, to this day, two-faced. SteveBaker (talk) 01:38, 17 March 2009 (UTC)[reply]
Glad you provided the link, because otherwise I wouldn't have known which set of spineless bloodsuckers you meant. arimareiji (talk) 04:28, 17 March 2009 (UTC)[reply]
That was vicious. Nice one! --Scray (talk) 04:35, 17 March 2009 (UTC) [reply]
...here they are! --pma (talk) 18:37, 17 March 2009 (UTC)[reply]
Some little parasites suffer from smaller parasites: "Great fleas have lesser fleas upon their backs to bite'em, and little fleas have lesser fleas, and so ad infinitum." Edison (talk) 14:15, 17 March 2009 (UTC)[reply]
By the way, Edison's quotation is from A. de Morgan, who quoted Swift, and I wonder if Swift was quoting some other source (suddenly an horrific idea: is this a never ending chain of quotations?) --pma (talk) 11:08, 18 March 2009 (UTC)[reply]
Note that there is another version: "So naturalists observe, the flea hath little fleas upon his back to bite'em. And little fleas hath lesser fleas, and so proceeds, ad infinitem." To whom is that one credited? Edison (talk) 23:29, 18 March 2009 (UTC)[reply]
That looks like a conflation of the two verses. Axl ¤ [Talk] 08:08, 19 March 2009 (UTC)[reply]
Euclid's Elements
At the end of the opening of the article Euclid's_Elements it states "Not until the 20th century, by which time its content was universally taught through school books, did it cease to be considered something all educated people had read." Who/what/why/where/when did this happen? I find it interesting and perplexing to note the swift roundhouse kick delivered by Euclid_and_his_Modern_Rivals to its competitors in the late 19th century, and also Einstein's first words in his book on special relativity: "In your schooldays most of you who read this book made acquaintance with the noble building of Euclid's geometry, ..."
If the Elements was so deeply entrenched in most education systems, what or who was the driving force behind getting rid of it? —Preceding unsigned comment added by 99.255.228.5 (talk) 21:46, 16 March 2009 (UTC)[reply]
We haven't gotten rid of it - we teach the same principles - just without the archaic language and old-fashioned terminology. I was certainly taught geometry from the axioms and theorems of Euclid...just not from that exact book. As a work, it's really remarkable in being probably the first book to approach mathematics methodically. Define some "obvious" axioms - then use the axioms to prove some simple stuff - then build proof on proof until you have things coming out of the system that are truly NOT obvious. It's what mathematics is all about. It's almost incidental that it teaches us the basics of geometry - although that's why most people would have been taught it.
Furthermore, huge, interesting and (above all) useful areas of mathematics have been opened up by methodically pursuing what happens if you deny one or more of Euclid's axioms and follow where that leads you. Non-Euclidean geometry has come about (ironically) because of Euclid - where the Euclidean stuff was pretty much already known - but just not proven so rigorously. SteveBaker (talk) 22:59, 16 March 2009 (UTC)[reply]
I had a reasonably good math education in high school in Ontario, Canada, in the late 1960s / early 1970s, and we certainly did not learn Euclid's axioms. I never learned them in school, although I did read the Elements for fun later. We learned how to do formal proofs in geometry in high school, I think in grade 10, but they were not founded on an explicit set of axioms. On the other hand, in grade 13 we did some group theory on abstract operations, and that involved what amounted to reasoning from axioms. --Anonymous, 03:45 UTC, March 17, 2009.
This is the OP. I fully agree with both responses but also assert that there has been a major paradigm shift in math education. If you compare learning from a standard, universally agreed upon, axiomatic curriculum, like with the Elements, with the ever-changing, ad-hoc curriculum we have today (here in Canada at least), you have to admit something has changed. I was hoping for some literature on the subject but it's probably not that simple. —Preceding unsigned comment added by 207.245.46.74 (talk) 18:57, 17 March 2009 (UTC)[reply]
I believe it would be wrong to go back to Euclid's book for modern teaching. It truly is tough to read - even with a pretty good translator - because the language and the form of stating things is just so stilted. We do need to teach our kids to be able to discuss things with other MODERN mathematicians - so Euclid has to go. Now, the question of whether something modern should be taken as an alternative standard becomes just another debate about textbook A versus textbook B...which is a much more difficult debate. SteveBaker (talk) 21:18, 17 March 2009 (UTC)[reply]
One reason is perhaps that mathematical arguments no longer use geometry as their foundation, as they once did. Nowadays mathematical concepts are built up from sets and some axioms about how to manipulate them. Also, as some other responses have mentioned, Euclid lacks a lot of the formal language that makes today's mathematics more rigorous. A line is breadthless length (book 1, definition 2) is fine to intuit but it needs formalization in order to be something you can work with mathematically. Strad (talk) 00:43, 18 March 2009 (UTC)[reply]
Actually, the most obvious way to modernize Euclid (and that taken by Hilbert) is not to rigorize the definitions of points and lines, but to avoid defining them at all. Algebraist 00:47, 18 March 2009 (UTC)[reply]
Painful bumps in Inner Lip
About four days ago, I started feeling a tiny bump on my bottom inner lip and in a matter of hours, it got bigger and painful (about the size of a bell pepper seed). It was flesh-coloured and had a little red dot. I went to bed that night and by the next day, it had disappeared. Today, I'm feeling the little tiny bump again and I'm afraid it's going to happen all over again. I'm freaked out because I don't know what it is. Has anyone experieced anything like this or have any information that might help?
Many thanks.
AC —Preceding unsigned comment added by 189.216.26.199 (talk) 22:44, 16 March 2009 (UTC)[reply]
I'm sorry but we are not allowed to answer this sort of medical question here on the reference desk. If you are concerned - you should consult a doctor. Sorry. SteveBaker (talk) 22:49, 16 March 2009 (UTC)[reply]
To expand on that, anonymous advice from random people on the internet is worse than useless when it comes to your health. Go see a doctor, tell them what you told us, show them, etc. 79.74.9.81 (talk) 22:54, 16 March 2009 (UTC)[reply]
Sorry, I didn't know that. Thanks to both.
AC —Preceding unsigned comment added by 189.216.26.199 (talk) 22:57, 16 March 2009 (UTC)[reply]
what would happen if u consumed the leaves,flower...ect. of this plant?
would the effects of ibogain be felt? or is the plant poisones? —Preceding unsigned comment added by 76.14.124.175 (talk) 00:48, 17 March 2009 (UTC)[reply]
beacause Piperidine and piperazine are very similar, do they have the same effects on the brain? —Preceding unsigned comment added by 76.14.124.175 (talk) 01:00, 17 March 2009 (UTC)[reply]
(post e.c.) Neither article mentions psychotropic functions for either Piperidine or Piperazine, although some of their derivatives are psychoactive as Scray mentioned above. I'm not sure about the metabolites. Although they have similar functional groups and are fairly close in shape and size, that does not always translate to similar behavior biologically. Docking (molecular) describes the basic idea: small differences in shape can have major effects on the ability of a compound to bind to an enzyme's active site (or other relevant portion). Sifakatalk 02:33, 17 March 2009 (UTC)[reply]
Both piperidine and piperazine block nicotinic cholinergic receptors. Piperidine is more potent than piperazine. [By the way, piperazine is used to treat parasitic infections in people.] Axl ¤ [Talk] 10:47, 17 March 2009 (UTC)[reply]
Yeah, because it's substantially more toxic. To humans too. The reason why these are on drug schedules isn't because they're psychoactive or remotely close to it. It's because they're very common precursors in organic chemistry. Which would include drug synthesis. --Pykk (talk) 19:46, 17 March 2009 (UTC)[reply]
Theory of Chemical Emotions: Pointless to Pursue Happiness?
Since most of our emotions are chemical reactions in the brain, and while the events of our lives do trigger the release of those chemicals, they do not increase or decrease production (apparent from exercise, stress, eating habits, and drugs). So two genetically identical twins with similar exercise, stress, and eating habits should experience the same total amount of happiness, right? Regardless of what is happening to them? (assuming they can keep themselves from getting stressed out about the events). One of the twins might have events that trigger lots of happiness in short bursts while the other has a more constant rate of happiness, but they should both experience the same total amount.
If this is true, doesn't this completely undermine the point of perusing things that make us happy if we will inevitably experience the same amount of happiness regardless? Thus we should foremost pursue good eating habits, exercise habits and controlling our stress levels and not worry about anything else (especially since worrying lowers our Serotonin production)? Also if this were true it would redefine what services we need to provide to 3rd world countries as charity as they will find their own happiness in their poverty as long as they can be well fed and control their stress levels, correct?
Something seems really wrong about this theory but I'm not sure where the hole is. It does readily explain why people who have everything find sadness in small details (like being spoiled) and people who have nothing still find happiness in the small details, though to say that we each have an amount of happiness specifically determined by genetics, stress, eating, and drugs seems a little much. What am I missing? Thanks. Anythingapplied (talk) 01:53, 17 March 2009 (UTC)[reply]
I don't see how any of this changes the way we should treat the less fortunate (including what we call the third world). Actually the whole thing about people having "nothing" being just as happy as others is bunk. In case you've never tried it being poor is really stressful. Wealth makes people happier until they reach some place around middle to upper middle class, additional wealth after that point doesn't do anything for happiness. Since what it means to be middle class changes over time I imagine this response ties to our evolved sense of justice which is tied into the chemical system you mentioned. Anyways I'm not going to offer a well wrapped answer but I will say that Walt Disney said something to the effect that "for every smile there must be a tear" and XKCD make a good point about arboreal rodents.--OMCV (talk) 02:17, 17 March 2009 (UTC)[reply]
I'm not at all familiar with this particular topic but I have a feeling that part of the problem may lie in your premise: happiness is not the same as the level of neurotransmitters. The interactions in the brain that translate out to one's state of mind are not necessarily correlated with the simple total amount of particular neurotransmitters. I'm not a neuroscientist but my guess is that there is a good spread of natural variation in global neurotransmitter levels and that two people with rather different neurotransmitter level profiles can report similar moods while people with similar profiles can report very different moods. If it was clearcut, scientists would be reporting conclusive findings to that effect long ago (and wikipedia would have the info in the relevant articles). I think it's fair to say that scientists pretty much don't know how biochemical interactions in the brain scale up to things like mood although there are some decent theories as to what factors are relevant. Sifakatalk 03:19, 17 March 2009 (UTC)[reply]
While I'm far from an expert on this, I'm pretty sure your premise "do trigger the release of those chemicals, they do not increase or decrease production (apparent from exercise, stress, eating habits, and drugs)" is incorrect. When neurotransmitters are released they are eventually replaced. It's not like you can use up all of your neurotransmitters in the long term and never have them again (in the short term obviously the level may get low). In any case there is also the fact there is bound to be some natural turnover (it's all very well having the neurotransmitters but there's clearly a big difference between when they affect you and when they don't) and I'm pretty sure some studies have shown you can get an increase in the baseline level with things like exercise etc. Also I don't think it makes much sense to say "One of the twins might have events that trigger lots of happiness in short bursts while the other has a more constant rate of happiness, but they should both experience the same total amount" for starters how the heck do you quantitise hapiness like that and secondly why can't one of the twins have events that trigger lot of happiness while also having a high constant rate? Nil Einne (talk) 11:18, 17 March 2009 (UTC)[reply]
There is some research that indicates a persons "happiness" measured by a variety psychological tests is rather resistant to most environmental influences. People who are happy are happy despite what happens to them and people who are sad are sad despite what happens to them. This is also true for self-confidence and a number of other moods/personality traits. This means regardless of what people do they won't be substantially happier. So the levels of neurotransmitters might fluctuate but they keep a steady average, a baseline. Grounding this phenomenon to biological/chemical basis is only reasonable. I wouldn't know how to cite any of this.--OMCV (talk) 11:44, 17 March 2009 (UTC)[reply]
Anyway what's the point of pursuing happiness? You might as well drug yourself up as do something so pointless with your life is my feeling. Though I guess I'm fairly happy anyway so it's no great deal to me. Dmcq (talk) 12:24, 17 March 2009 (UTC)[reply]
The idea is mentioned in happiness where it says "The happiness set point is a notion proposed by Lykken and Tellegen that we all have a baseline level of happiness that we return to. Although good and bad events may shift us from this baseline temporarily, we cannot permanently increase or decrease our happiness levels in the long term. Others have since challenged this pessimistic view, some drawing on neuroplasticity as evidence that our happiness level is not set in stone." although the reference looks crap. But better [23] and [24]. From a brief skim thorough, neither appear to accept the notion that happiness is a permanent unchangable baseline so there's no point trying to increase happiness. Instead they suggest people go about it the wrong way. (The second also notes there are some events which lead to a permanent reduction in the baselione.) Indeed the fact that we know our happiness can change even if only temporary is in direct contrary to the original OPs contention and IMHO suggests it's unlikely we should think happiness is an unchangable baseline so don't bother trying to change it. The notion of a baseline means that eventually people normally adapt back to their baseline. It does not mean that the happiness they had was irrelevant. It's not like their go thorough a period of sadness to pay back for the short term happiness. Clearly someone who has no blips would have been 'less happy' (if you really want to quantitise it like that) then someone with the same baseline with several happiness blips. Even if you can never change your baseline, the fact that you have had quite a lot of blips in your life seems significant to me. Note neither of the references mention neurotransmitters at all, not surprising IMHO since our understanding of human psychology and how that relates to the way the brain works is still way too much in it's infancy to go making such bold assertations. So I still stick by most of my original post, if you really want to talk about neurotransmitters our a happiness blip may result in a temporary increase in the production of neutrotransmitters. It may not result in a permanent increase (I didn't suggest it would) but there is likely to be an increase. Over time, the level usually comes back to normal (or alternatively we adapt to a permanently higher level, do we know which?) but it's still incorrect to suggest it doesn't result in an increase in the short term. Now as for the second part while I may have been slighly inaccurate in my suggestion you can have a higher constant level (or baseline) the fact remains the twin who has many blips of happiness is likely to have had more 'happiness' then the twin who had a constant level. The twin with the blips doesn't reduce their level to compensate rather the normal level remains static with blips except the other twin doesn't have blips. Now obviously there is a risk when you have blips of happiness you're going to have blips of sadness (dating someone, ooops you broke up; going on a trip to *name location here*, ooops kidnapped and held for ransom) but that's surely a different issue. (In any case, it seems to me that any consideration of achieving happiness should not start of from the notion that you have similar "exercise, stress, and eating habits" since surely these should be a consideration in persuing happiness. Nil Einne (talk) 21:01, 17 March 2009 (UTC)[reply]
Flashbangs
How do flashbangs work? How can they make a person temporarily blind and make the ears go numb? —Preceding unsigned comment added by 116.71.46.119 (talk) 17:18, 17 March 2009 (UTC)[reply]
(After ec) The entry for Stun grenades in our hand grenade article explains how they work. In brief, they use a bright flash of light that activates all photosensitive cells in the retina combined with loud blast that disturbs fluid in the semicircular canals of the ear.- EronTalk 17:30, 17 March 2009 (UTC)[reply]
car farts
When I turn the steering wheel of my 2005 Ford 500 all the way in one direction, moving at a slow speed, like backing up or easing into the garage, I sometimes hear a noise that sounds like a fart. I'm thinking it might have to do with the power steering. What do you suppose might be happening? --Halcatalyst (talk) 20:14, 17 March 2009 (UTC)[reply]
I've had this before, my tire was rubbing against the wheel well. 192.45.72.26 (talk) 20:42, 17 March 2009 (UTC)[reply]
There are actually MANY possibilities:
An tire that's about to fail due to tread-separation.
A tire that's rubbing against the wheel liner (but WHY? is the important question - has a plastic wheel liner come loose? Is your steering badly screwed up? Did you recently change wheels or something?)
The plastic shroud around the steering column may be catching against the steering wheel.
At the extremes of travel, you are stressing the power steering to the max - and if you try to steer 'past the end-stop' then "very bad things" can happen to it.
If the noise is coming from behind you then it could be a problem with the differential.
It would help to eliminate some of these if you could try to have someone push the car while you turn the steering that hard with the engine turned off and the drive in neutral. If it doesn't make the noise then that eliminates the power steering. You can usually remove the plastic shroud around the steering column with just a couple of screws and eliminate that. Knowing where the sound is coming from would be fantastically helpful...if you can get someone to stand outside the car while you slowly drive in tight circles in a parking lot or something - they can listen at each corner and perhaps identify the sound's location. SteveBaker (talk) 21:07, 17 March 2009 (UTC)[reply]
If the RefDesk doesn't give medical advice, should we also refrain from providing automotive advice and suggest that the OP seek an evaluation by a professional mechanic? :)
Actually, it would seem to make sense given the possibility of a car accident resulting from a serious mechanical malfunction. —Preceding unsigned comment added by 64.91.177.4 (talk) 23:23, 17 March 2009 (UTC)[reply]
I suspect that the issue of medical and legal advice is likely because of legal reasons, as while an individual might be correctly certified to give such advice, there is no convenient way to determine that. Are there laws against uncertified individuals giving auto repair advice in the same manner as giving medical advice without a license? I rather doubt it. 65.167.146.130 (talk) 13:32, 18 March 2009 (UTC)[reply]
There's also the risk of real harm. That applies here. Doesn't matter if its legal or not. If there's a risk soemone could be harmed from dud advice - then we shouldn't be offering it. Mattopaedia Have a yarn 05:11, 19 March 2009 (UTC)[reply]
Then we shouldn't give advice on dieting, exercise, carpentry, or anything involving someone moving, or coming into contact with anything, as there is risk in nearly everything anyone ever does. If all else fails, I say use common sense. 65.167.146.130 (talk) 14:05, 20 March 2009 (UTC)[reply]
I promise I won't sue you guys! IMO the restriction on legal and medical advice is a matter of not having a license. Someone could check over on the Humanities desk, but I'm pretty sure. I'm completely certain I appreciate the advice you've given here. Thanks! --Halcatalyst (talk) 14:36, 20 March 2009 (UTC)[reply]
Astronomy/night sky question
Hi, I have one of those awful, "I saw something, what was it?" questions. I hope someone can give me some clues though.
Tonight (while waiting for a bus) I saw 2 lights in the sky. 1 was about the brightness of bright stars (eg. the 3 of orion's belt), and another to the lower right of this one was fainter. I feel as though there may have been a faint line connecting the two, but can't be sure. Orientation shown here:
*1 bright
*2 faint
They moved up and left together, relative to stars. As they did, first "2" faded and disapeared, then the brighter light also faded, became redder, and disapeared. The distance between the 2 lights was 1-2 thumb widths at arms length. The speed they moved was about the speed of other planes (that were also visible in the sky), but they seemed to be too far apart for this obvious explanation. Also their fading and changing colour makes me think it probably wasn't a plane.
Oh, this was in Germany (Berlin-ish), facing South to SW ish. Not very high in the sky, I only just had to tilt my head back to see it clearly. About 8-8.30pm 17/3/09.
Any suggestions, or requests for clarification? Thanks!
It appears you were lucky enough to catch a glimpse of the Space Shuttle as it approached the ISS. This site indicates that the IIS was briefly visible in your area, and I would expect the Space shuttle to be nearby. -- Tcncv (talk) 22:12, 17 March 2009 (UTC)[reply]
I don't know precisely what you saw (Tcncv's suggestion is possible), but they certainly sound like satallites. When they faded and disappeared that was because they were moving into the Earth's shadow - they turned red for the same reason the moon appears red during a lunar eclipse, the light reflecting off them has travelled through the Earth's atmosphere to get there. The fact that there were two of them could mean with was the ISS and Space Shuttle (although I would expect the ISS to be quite a bit brighter than the stars that make up Orion's belt), or it would just have been coincidence that two satalites appeared nearby in the night sky (they could have been at very different distances, so not very close together). --Tango (talk) 22:21, 17 March 2009 (UTC)[reply]
According to this report, the shuttle was scheduled to dock with the ISS at about 16:12 CDT (UTC-5), which would have been about 22:12 your time (UTC+1). The sightings web site indicated that both would have been visible simultaneously between 20:09 and 20:11 local time, so it's pretty clear that's that you saw saw the the space shuttle Discovery as it approached the IIS for rendezvous as part of mission STS-119. I've seen the ISS pass overhead before, and it appears like a bright star, maybe not quite as bright as Venus. The apparent motion is comparable to a high flying passenger airliner. The same site I referenced above can be used to predict sightings just about anywhere else on earth, as long as it is withing the latitudinal extent of the orbit. -- Tcncv (talk) 23:03, 17 March 2009 (UTC)[reply]
The separation mentioned sounds about right for 2 hours before docking, so I agree, that's almost certainly it. A lucky sighting! I've seen the ISS too, it's very bright (brighter than any star, I think) - I expect the OP misjudged the brightness (easily done if you aren't don't have much experience with astronomy). --Tango (talk) 23:12, 17 March 2009 (UTC)[reply]
For comparison, the Apparent magnitude article puts the ISS close to Venus in brightness, depending on the angle of the station and the phase of Venus. -- Tcncv (talk) 23:27, 17 March 2009 (UTC)[reply]
The ISS is already a pretty good naked eye object - it crosses the sky in a matter of a minute or two - so it's easy to mistake it for an aircraft or something. Just before dawn or just after dusk when the sun is at the right angle to have it be sunlit in an otherwise dark sky - even with the naked eye, you can see it's not just a bright dot - it has quite visible 'wings'. Before today, it has not been as bright as Venus - but while the shuttle is docked - and after it leaves in a few days and they deploy the new solar panels that it's delivering - the ISS will get appreciably brighter than Venus and stay that way. SteveBaker (talk) 01:57, 18 March 2009 (UTC)[reply]
This 2006 image at the Astronomy Picture of the Day will give you a good ideas of the apparent size. The station is several times larger now, but its roughly 100m size viewed at 350km altitude (farther if you consider the viewing angle towards the horizon) is still a fly at the end of a football field. (OK, maybe it's a big fly.) -- Tcncv (talk) 03:19, 18 March 2009 (UTC)[reply]
More like a golf ball at the other end of a football field...in proportion to a 100m football field, I make it about 3cm. But it's glowing pretty bright - it's more like looking at a lit-up light bulb at the other end of a football field - but I watched it during the last shuttle mission (it's always more visible with the shuttle docked next to it because the shuttle faces its white upper-side towards the sun so the solar collectors inside the doors can do their thing - so it's particularly reflective. For sure, I had no trouble seeing that it was more than just a dot...you could tell it has "wings". SteveBaker (talk) 05:13, 18 March 2009 (UTC)[reply]
No solar arrays on the shuttle, the inside of the doors have radiators. When docked to the station the shuttle/station stack attitude isn't determined by the sun either, instead the attitude is one where no propellant is required to maintain the attitude. anonymous6494 08:24, 18 March 2009 (UTC)[reply]
March 18
Launching a satellite via balloon
I recently read a story of 4 teenage spaniards who were able to take a bunch of meteorological equipment and a camera 20 miles high. The pictures that were returned are stunning. A camera and meteorological equipment sounds very much like a satellite to me. If you add a couple of fireworks to the mix for a second stage, or whatever you guys can dream up...how difficult would it be for a bunch of teenagers to make a satellite orbit the Earth a few times? I mean really, is it that hard? Sappysap (talk) 01:36, 18 March 2009 (UTC)[reply]
Sadly, yes, it really is that hard. Balloons are relatively easy. You don't need any fuel - just a big enough envelope and a lot of suitable lightweight gas and you'll get up to "the edge of space" (whatever THAT means)...however, as soon as you run out of air - there is no more bouyancy and you can't go any higher no matter how clever you are. To get into low earth orbit means getting your rocket up to around 8 kilometers PER SECOND. 28,000 kilometers per hour. 17,000 miles per hour....that's pretty serious stuff. SteveBaker (talk) 01:49, 18 March 2009 (UTC)[reply]
That's not to say it's impossible to do, of course. Da Vinci Project was an X-Prize attempt. (They were not able to complete their space-craft.) However, I'm sure that their balloon would have been considerably larger than a weather balloon.
Here's another really cool balloon project that I read about recently. It's pretty awesome if you ask me. High Altitude Glider ProjectAPL (talk) 12:50, 18 March 2009 (UTC)[reply]
For average teenagers, putting something into orbit is not feasible. If however, you took an exceptional group of teenagers, and adequately funded their project, it is possible, but how many teenagers do you know that would be able to maintain focus for long enough to build a suitable launch vehicle from scratch? 65.167.146.130 (talk) 13:26, 18 March 2009 (UTC)[reply]
And would they still be teenagers when they finished? APL (talk) 13:32, 18 March 2009 (UTC)[reply]
The term for this technique seems to be "Balloon Assisted Launch". And it would not be easy, and probably not within the grasp of hobbiests, but the airforce and other space agencies seem to be considering it seriously. APL (talk) 13:38, 18 March 2009 (UTC)[reply]
Yes, the current system of launching rockets from a stationary position, close to sea level, seems designed to waste as much fuel as possible. I suspect that as the era of cheap fuel ends, this practice may end, too. Launching from a balloon or piggyback on a large jet would reduce fuel and vehicle size requirements considerably. They could also launch from a mountaintop, with a great deal of momentum, if a launch tube was hollowed out of the mountain (or placed on the side of the mountain) and the rocket was accelerated using steam pressure, similar to the catapults on aircraft carriers. StuRat (talk) 16:38, 18 March 2009 (UTC)[reply]
The problem that most people don't understand is that getting into orbit isn't just about getting high enough - that is something a balloon with a simple rocket could probably manage. The problem is that to be in ORBIT - you need a horizontal speed of 8km/sec. The balloon doesn't really help you in that regard. In fact, if you got a rocket going at 8km/sec horizontally at sea level - barring air resistance, it would go into orbit. Really all that the balloon buys you is getting above enough atmosphere that your rocket motor's power can be devoted to getting up to that orbital speed. That's not an inconsiderable amount mind you...but you've still got to get that 8km/sec from somewhere - and that's hardly a science fair project! Launching from aircraft at high altitude HAS been done - Scaled Composites SpaceShipOne, for example. It didn't get into orbit either - same reason - it did get up high enough - but without that 8km/sec - it just came right back down again - as expected...but launching from a plane definitely helped. But recall that a pretty large plane (a 747 for example) can only just lift an empty space shuttle - and that's without a full fuel load, SRB's, payload and so forth. We'd need entirely bigger aircraft to launch the kinds of substantial loads we need for things like assembling space stations and trips to the moon. Rockoons (rockets launched from balloons) have also been tried. Problems in that case are to do with injecting the rocket into the DESIRED orbit rather than from just any old orbit from a spinning, drifting who-knows-what balloon. The idea of launching from a tube (whether in a mountain or whatever) has also been attempted...just before the first war against Iraq, Saddaam had started to build 'Project Babylon' - a gigantic gun that would have been able to propel a satellite into orbit (or shoot a nuclear weapon to any point on the globe). The US 'Project HARP' was a similar idea. So I guess that all of these things have been tried - one way or another. SteveBaker (talk) 01:39, 19 March 2009 (UTC)[reply]
I wonder which portion of a rocket's fuel is used to fight air resistance. Note that there's no fixed amount of air resistance to overcome to reach orbit, as a slower ascent would require less fuel to overcome air resistance. Hence the advantage of a balloon, which could rise at a much slower rate and cause less air resistance. StuRat (talk) 15:21, 19 March 2009 (UTC)[reply]
Well, we do launch rockets vertically - and not horizontally - and in fact we gradually transition from vertical flight to horizontal (well, perhaps "radial" to "tangential" is better here) - and I suspect that the reason for that is that taking off vertically gets you through the densest air resistance in the shortest distance. Ascending through the atmosphere relatively slowly - and then kicking it up a notch once you're out of the worst of the atmosphere is EXACTLY what modern multi-stage rockets do. The most intense g-forces in a shuttle flight are long after take-off. But in the absence of atmosphere - you'd climb vertically only enough to clear any nearby mountain ranges - then head off more or less tangentially. As your speed builds, you'd get higher. SteveBaker (talk) 19:52, 19 March 2009 (UTC)[reply]
Light can't be seen unless it's reflecting off of matter
Is this a fair statement to make? That light is invisible unless it's reflecting off of matter? ScienceApe (talk) 02:09, 18 March 2009 (UTC)[reply]
Only photons that strike a detector are detectable by it, so unless they enter the eye, the eye can't see them. Now I don't know about reflecting be required (you can see a lit light-bulb directly:), but somehow the light has to become directed towards the eye. DMacks (talk) 02:18, 18 March 2009 (UTC)[reply]
Sort of depends on what you mean by the verb see, or more precisely, what you intend by using a term as the direct object of that verb. It could be argued, if one wanted to be argumentative for the sake of it, that you can never see light at all, not in the sense that you can see, say, a desk. What you see would be the source of the light, or the thing illuminated by the light.
Unless of course the light beam you're looking at is so intense that you can shine another light source on it and get a significant amount of scattering of light by light, which is a redlink that someone should really direct to the correct article. But in that case I'm not sure how long you'd live. --Trovatore (talk) 02:32, 18 March 2009 (UTC)[reply]
Well, no, that's different — you're still not "seeing" the light in the sense of detecting how it scatters other light. You're seeing the air or the dust or something. --Trovatore (talk) 02:39, 18 March 2009 (UTC)[reply]
Does Rayleigh scattering work that way? erm, still looks like matter particles in there though. :/ C'mon Trovatore, get that article blue-ing! Julia Rossi (talk) 02:40, 18 March 2009 (UTC)[reply]
Yeah - in both Rayleigh and Mie scattering (related but different things), the light is scattered off of something. SteveBaker (talk) 02:44, 18 March 2009 (UTC)[reply]
OK, so what about SOLBL? I would have assumed that the article must exist and I was just using the wrong search term. But searches like photon-photon scattering also come up blank. On the other hand a Google search for "scattering of light by light" gets lots of hits under that exact name and doesn't immediately suggest any synonyms. --Trovatore (talk) 02:54, 18 March 2009 (UTC)[reply]
Well, contrary to popular opinion - there are still a few things we don't have articles about. SteveBaker (talk) 04:49, 18 March 2009 (UTC)[reply]
There is no important difference between the light reflected from a surface and the light emitted from a surface...as far as the eye is concerned, it's all just light...so yeah - you can see light without it being reflected off of something...if your eye happens to be in the way. What I suspect our OP is wondering is if (for example) you were out in deep space - in a vacuum - with a big chunky laser beam shining a beam off into space just a foot in front of your face...would you be able to see the beam? And the answer there is no - because none of the light is reaching your eye - it's just shooting off into the distance. So in that sense, you can't see the light unless it's "reflected" (or perhaps "scattered" or "refracted") into your eyes. In all the action TV series when the good guy is breaking into the bank vault and all of the red security lasers are entirely visible...that's pretty much bogus. The light is somewhat scattered off of dust and such in the air - but even so, only the very brightest lasers actually light up the air as they travel through it. SteveBaker (talk) 02:44, 18 March 2009 (UTC)[reply]
I was making a linguistic point, not a physics one. As I said, a deliberately picky point, at that, not intended seriously. The point is that you say that you see the desk, not the light reflected from the desk. So "seeing" light, in that sense, is mostly impossible. Modulo SOLBL, which I'd still like to hear more about. --Trovatore (talk) 02:56, 18 March 2009 (UTC)[reply]
Yes - I suppose so. The problem here is that the linguistics pre-date the science by a considerable amount of time. As recently as when Newton was alive and trying to get a grip on what light is, there was still a common belief that somehow light came OUT of our eyes in order to see things. So it's not surprising that we talk about "seeing a desk" as a shorthand for "seeing light reflected from a desk". But it does go a little deeper than that. We can "see a desk" by virtue of it blocking light rather than reflecting it. If the sun is behind the object and all you can see is a sillhouette, you STILL talk about "seeing the object" rather than seeing by the lack of light behind it. We're also in a slightly odd position when we talk about seeing an object that's reflected in a mirror - when what we're really "seeing" is the mirror itself (by those standards). But when we talk about "seeing a desk" - we don't say "seeing the sun"...even though what we're really seeing is the sun reflected in the desk. So language is (as always) a mess - and we're better off defining our terms when it comes to proper scientific matters. SteveBaker (talk) 04:49, 18 March 2009 (UTC)[reply]
But light does come out of my — er, I mean, Superman's eyes. Yeah, that's the ticket. Because I'm not Superman, of course. Ha ha. Nope, not me. --Trovatore (talk) 07:54, 18 March 2009 (UTC)[reply]
Despite all the linguistic niceties the OP ask a prety simple question: "Is this a fair statement to make? That light is invisible unless it's reflecting off of matter?" to which there is no other reasonable answer then: No, that's not a fair statement, all light within the visible spectrum is visible as long as it reaches your eyes. That last requirement applys wheather the light has been reflected by a surface or not. Dauto (talk) 05:03, 18 March 2009 (UTC)[reply]
Probably you're trying to describe the fact that a "beam" of light can't be seen directly. But you're neglecting the case where light strikes your eye directly from the source. (ie: Look at the sun. (PS: Not for long.))
It'd be reasonably correct to say "Light is invisible unless it's reflecting off of matter or striking your eye directly.". APL (talk) 12:46, 18 March 2009 (UTC)[reply]
You could simplify further with "Light is invisible unless it enters your eye". Everything else is window dressing; your retina doesn't care what path the photon took to get there. TenOfAllTrades(talk) 13:37, 18 March 2009 (UTC)[reply]
technology
what are the roles of technology in growth of the economy.citing examples& applications —Preceding unsigned comment added by Solit (talk • contribs) 05:56, 18 March 2009 (UTC)[reply]
How does it affect our lives to know why particles have mass
well i recently read that the Large Hadron Collider will also reveal through its experiments about WHY particles have mass? But what real use is this of to us? I mean there must be some big way in which this can be used but i fail to understand how?!?!?! Like technologically - how is it useful to figure out WHY a particle has mass? Wouldn't it be better to use all that time and money in using the LHC for some better useful experiment?Vineeth h (talk) 06:57, 18 March 2009 (UTC)[reply]
Thank you for signing this time but in future, please modify your original question if you make a mistake rather then posting again. I have removed the duplicate question Nil Einne (talk) 07:34, 18 March 2009 (UTC)[reply]
I don't know if this is what you're looking for, but here's one possible answer:
"The first question which you will ask and which I must try to answer is this, 'What is the use of climbing Mount Everest?' and my answer must at once be, 'It is no use.' There is not the slightest prospect of any gain whatsoever. Oh, we may learn a little about the behavior of the human body at high altitudes, and possibly medical men may turn our observation to some account for the purposes of aviation. But otherwise nothing will come of it. We shall not bring back a single bit of gold or silver, not a gem, nor any coal or iron. We shall not find a single foot of earth that can be planted with crops to raise food. It's no use.
So, if you cannot understand that there is something in man which responds to the challenge of this mountain and goes out to meet it, that the struggle is the struggle of life itself upward and forever upward, then you won't see why we go. What we get from this adventure is just sheer joy. And joy is, after all, the end of life. We do not live to eat and make money. We eat and make money to be able to enjoy life. That is what life means and what life is for."
It is the nature of basic research that we don't know beforehand what usefulness any discoveries that come up will have. Faraday was asked about what practical use could there possibily be for his researches on electricity. Turns out our modern society would not work at all without the knowlege of electricity. I would not expect any immediate practical aplications to come out of LHC's discoveries, but that's not why we do it. The purpose of the LHC is knowlege, nothing more. Dauto (talk) 15:13, 18 March 2009 (UTC)[reply]
We don't know why. But then we didn't know why we needed to know about quantum theory either...yet the computer you are reading this email on right now wouldn't exist if we hadn't figured that out. Perhaps discovering the properties of the Higgs Boson will allow us to teleport objects - or maybe time travel will become possible - or perhaps we'll discover that an old coke can plus a discarded copy of the New York Post dated 13th January 1956 is all we need to fix up global warming. I very much doubt it'll be any of those thinge - but we don't know BECAUSE we don't know. What we DO know is that in almost every 'pointless' experiment of this kind, we've found something that eventually became useful - perhaps directly - perhaps indirectly. Hence doing this kind of thing - even though the cost is outrageous - is what keeps technology purring along. SteveBaker (talk) 22:32, 18 March 2009 (UTC)[reply]
Plus, it will strengthen the resolution between the ongoing conflicts in the unifying theories of the universe. It will give us a direction in the knowledge of how this universe came about. Higgs is a theoretical particle not having been detected so far, only predicted by theories. It will confirm whether or not those theories are right, whether or not we need another physical theory. I can't wait to see the resumption of the LHC experiment. - DSachan (talk) 22:40, 18 March 2009 (UTC)[reply]
Evolution
I posted this on the evolution talk page, and apparently Wikipedia isn't a forum so I'm posting it here:
"I know this has been posted a million and three times and is covered in the FAQ but I want to be absolutely sure, could I in good concious go on national television tomorrow and declare "Evolution is a fact"? The article "Evolutions as theory and fact" is too complicated and doesn't have a simple "if you look at in a general way then A, if you look at it this way then B". I get other pages on the web written by biologists and doctors saying that "Evolution is not a fact, but is likely to be true". Wikipedia keeps mentioning something like mathematical meaning and logical meaning and I just want some disambiguation- I know Wikipedia is not a forum, so just delete this is no-one is willing to answer, I just wanted to make sure. If someone could give me a good "phrase" I could say if I would be going on television to explain this (I'm not really going to be on a TV, just for the sake of an argument), i.e. in a concise and simple manner: "Simply put, if you look at it from a scientific viewpoint... but if you look at it from a logical viewpoint..."." --BiT (talk) 08:08, 18 March 2009 (UTC)[reply]
The reference desk isn't a forum either and sorry but I don't understand what you are asking. But evolution is a fact and a theory. You can confidentally go on to television tomorrow and declare it if you want. This is explained about as simply as possible in our article "First, the "fact of evolution" refers to the observed changes in populations of organisms over time, which are known to have occurred. Second, the "theory of evolution" refers to the modern evolutionary synthesis, which is the current scientific explanation of how these changes occur." There is also Evolution as theory and fact#Evolution compared with gravity which may or may not help. But if you want to be able to confidentally go on to national television and explain evolution then you really need to understand it. You can't confidentally go on to television and defend something without understanding it IMHO, there is no shortcut. If not you're liable to make similar mistakes in defending evolution to those creationists make when attacking evolution which helps nothing (and creationists are notorious for being very well prepared and picking at any little mistake). Our wikipedia articles are decent enough so start reading and come back if you have any specific questions Nil Einne (talk) 09:00, 18 March 2009 (UTC)[reply]
The OP mentioned going on television to ask how true the statement "Evolution is a fact" is, not because he actually plans to go on television. --Bowlhover (talk) 15:00, 18 March 2009 (UTC)[reply]
The OP said "I want to be absolutely sure, could I in good concious go on national television tomorrow and declare "Evolution is a fact"?" and "If someone could give me a good "phrase" I could say if I would be going on television to explain this (I'm not really going to be on a TV, just for the sake of an argument)". I'm not sure if I understand this but I think the OP is saying he/she wants sufficient understanding such that they can be confident enough that they could say it on television without fear of looking stupid (not because they actually plan on going on television but as an example of the depth they want although IMHO a better example would be being able to explain it to a conference of evolutionary biologist :-P). Perhaps my understanding is wrong but I don't believe your claim the OP wishes to go on television to ask how true the statement is is correct either. Nil Einne (talk) 19:36, 18 March 2009 (UTC)[reply]
Yes, you are absolutely correct. A conference of evolutionary biologists might have been a better way of putting it but I doubt I can teach them anything about biology :p --BiT (talk) 10:53, 19 March 2009 (UTC)[reply]
Sir David Attenborough recently went on the BBC and did exactly what you want to do. I suggest you go onto the BBC website and see if you can find the part relating to this: I suspect it's part of their Darwin season. --TammyMoet (talk) 09:53, 18 March 2009 (UTC)[reply]
That evolution has occurred is a fact, like gravity is a fact. How evolution occurs, like how gravity works, is a theory. --Scray (talk) 11:02, 18 March 2009 (UTC)[reply]
To put it another way, the word "evolution" has two different meanings which people routinely conflate. I don't think it's a good idea to say "evolution is a fact and a theory". It's a syllepsis or antanaclasis or some such thing. Better to say something like "there's a fact of evolution and a theory of evolution and they're different things". Better still would be not to use the phrase "theory of evolution", or for that matter "theory of gravity", since the theories explain a lot more than just evolution or gravity. There's a scene in Dirk Gently's Holistic Detective Agency in which Dirk mocks Newton's contribution to physics by releasing an object, watching it fall to the ground, and saying "someone was bound to notice sooner or later". Well of course that kind of gravity was known to the ancients; what Newton figured out was that a single force could explain both gravitation (i.e. things falling to earth) and the motions of the heavenly spheres. I don't know if that mistake was Dirk Gently's or Douglas Adams's, but either way it wouldn't have happened if we didn't use the term "theory of gravity". Darwin's theory didn't only explain evolution (i.e. the changes in organisms over time as seen in the fossil record), it also explained, for example, the existence of species (which, unlike evolution, was known to the ancients). You could call it "Darwin's theory of species". At least that would force the creationists to be more specific about what they're railing against. -- BenRG (talk) 12:38, 18 March 2009 (UTC)[reply]
First of all I don't know the difference between syllepsis and antanaclasis. I understand that evolution can be both a fact and a theory but what does the theory of evolution refer to, and what does the fact of evolution refer to? What parts of evolution aren't proven? --BiT (talk) 11:06, 19 March 2009 (UTC)[reply]
Personally, I avoid using the word "fact" in science, it causes no end of problems. Science is made up of theories. Some of those theories have so much evidence supporting them that the chance of them being wrong is minute - some people like to call those theories "facts", but really it's an arbitrary cutoff. There is no qualitative difference between a "theory" and a "fact". --Tango (talk) 14:19, 18 March 2009 (UTC)[reply]
I'd say avoid worrying about terminology altogether. Evolution is a model of the natural world, and just because of that, it's a theory. It also has a certain amount of evidence. Whether that amount of evidence is enough to make evolution a fact is up to the individual to decide. --Bowlhover (talk) 15:00, 18 March 2009 (UTC)[reply]
Just because evolution is a fact, does not mean that everything connected with it is a fact. There are modern legends such as our ancestors developing in a warm pool of slime, or that they crawled out of the sea. These ideas are not proven sufficiently to be called facts. Graeme Bartlett (talk) 20:57, 18 March 2009 (UTC)[reply]
Actually the origin of life has nothing to do with evolution. That would be abiogenesis. ScienceApe (talk) 02:04, 19 March 2009 (UTC)[reply]
could I in good concious go on national television tomorrow and declare "Evolution is a fact"? - on National Television - yes, absolutely. In front of the Nobel Prize committee...maybe not. We have to be careful about the word "fact" in rigorous scientific debate. It is possible that everything we know and see comes out of a large computer called "The Matrix" and evolution is totally false. That's a certainly a possibility. Hence we can't say (with 100% scientific rigor) that ANYTHING AT ALL is a "fact". However, if you were to ask "Is it as likely that Evolution is true as Gravity is true" - then yes, evolution is true - and that's plenty good enough for ALL practical matters.
The article "Evolutions as theory and fact" is too complicated and doesn't have a simple "if you look at in a general way then A, if you look at it this way then B". - Sorry about that. That IS a subject for the article's talk page.
I get other pages on the web written by biologists and doctors saying that "Evolution is not a fact, but is likely to be true". - See my response to your first question. Evolution is as true as Gravity - neither are 100% certain. Evolution is at least as true as ANYTHING you know to be true - Gravitation, Quantum theory, Relativity, Thermodynamics, your home phone number. That's "good enough" for all but the most ridiculously hardened sceptics - and philosophers (who, as I have pointed out in the past - are a waste of quarks).
Wikipedia keeps mentioning something like mathematical meaning and logical meaning and I just want some disambiguation...If someone could give me a good "phrase" I could say if I would be going on television to explain this... - Oh - you want a sound-bite! Why didn't you just say so?!
"Evolution is a scientific fact that is at least as solidly proven to be true as are (for example): Gravitation, Quantum theory, Relativity, Thermodynamics, Electromagnetism, The Big Bang, Atomic theory, The Germ Theory of Disease, Genetics and the scientific theory that "The Earth Is Not Flat" - HOWEVER, neither Evolution - nor ANY of those other things are quite as certain to be true as that 2+2=4 or that there are infinitely many prime numbers. For these mathematical truths are things that may be proven by the power of thought alone - where the other things require us to believe that the results of our experiments are meaningful when applied to the real world. It is just possible that none of our senses are to be trusted. If it should somehow turn out that we are living in a world of make-believe or that we live in a simulation of a real universe that's running (like "The Matrix") in a big computer someplace - then 2+2 still equals 4 - but we can't know that anything we've experienced is true. Since we have no way to prove that we aren't inside "The Matrix" - we can't regard Evolution - or any other scientific theory as "fact" to the same degree as we regard 2+2=4 as a "fact". In practical terms, we accept these other big scientific principles as "true" - and Evolution is right up there with the rest."
The trouble is that the 'nut jobs' who want the universe to be run by supernatural deities need to find any chink in the armor that is scientific proof that they possibly can. Hence, they are more than happy to corner some poor unsuspecting scientist and ask things that are (in essence) like asking: "Is Evolution as certain to be true as that there are an infinite number of prime numbers?" - and an honest, serious scientist has to say "No - it's not". The nut jobs then happily frolic off into TV-land and say "Scientists everywhere will tell you that Evolution isn't necessarily true" - without considering what exactly the scientist actually meant. So, should you happen to get onto national television - you should ON NO ACCOUNT say that evolution might not be true. You have to use a circumlocution such as "Evolution is as true as that I'm standing in front of you right now!" or "How sure are you that if I drop this brick that it'll fall to the floor? Well, that's how sure we are that evolution is true.".
Ok I've got to give a standing ovation to SteveBaker, props to you. Bear with me while I respond:
I wasn't really meaning in the sense of being so philosophical (I forgot which branch of philosophy says that it's possible that the world is a lie) that you don't believe anything at all, but other than that you explained it pretty well. I want to point out that I don't plan on holding lectures for the Nobel Prize committee, I'll just say thanks for the awards and leave. Of course we can't be 100% sure that evolution is correct, who knows, maybe some god made the world just as it is to fuck with evolutionary scientists and maybe all paleontologic evidence is just god fucking with us as some claim, maybe god made gravity seem like 'fact' just to make it stop working one time to see the reaction. Also I want to point out that evolution wouldn't have been any more false in the Matrix than it was in the 'real world' (if we assume that the real world was 'real' and not a part of another Matri system) as it was a replica of the world as it was around 2000 if I remember correctly, so if we assume that evolution is correct here it would have also been correct in the Matrix.
True.
I went through a phase where I tried to be as sceptical as I could, never assuming anything and staring every sentence with "it could be assumed in correlation with the environment that I detect that, in the terms of this world that I perceive to be true, that what you seem to say can be wrong" (a slight hyperbole). That didn't last long.
No way! You aren't going to give me an actual soundbite?? Awesome. Ok, I get your point. Only things that are based on something that is predetermined to be true can be 100% true. We give that if we add two apples then we get four apples, then 2+2=4 is an absolute truth in the same way that "every man is a rapist, I am a man, therefore a rapist" if we assume that what I'm saying is true about every man being a rapist.
Thanks you so much for this, I agree with you an the 'nut jobs' and I decided to look this up after seeing a clip of Bill O'Reilley that just pissed me off. Now I know that I can declare that evolution is pretty much as proven as the common man cares. The problem is as Bertrand Russell pointed out that "...fools and fanatics are always so certain of themselves, but wiser people so full of doubts." Those are good points about what I should say instead saying "evolution isn't true" but rather giving people a quick point of reference like you've given me here (i.e. if you believe that we aren't really in the Matrix and that I'm here talking to you then yes, evolution is real). Of course wondering whether the world really exists when asking such questions is really nitpicking because that's not the point of topic. I also see that you use Linux and develop games? I like you --BiT (talk) 10:53, 19 March 2009 (UTC)[reply]
The philosophical viewpoint that you're thinking of is "solipsism". Axl ¤ [Talk] 11:11, 19 March 2009 (UTC)[reply]
OK - so now that we've established that our OP is indeed sane and NOT going to discuss anything like this in front of the Nobel Prize committee - we can stretch the point a little. I actually believe that Evolution is as true as 2+2=4 or that there are infinitely many primes. It is a mathematical truth that:
in a system in which entities can replicate themselves to make subsequent 'generations'...and...
the information about the construction of entity is contained within the entity itself and is copied into the 'next generation'...and...
when that replication process has a small - but non-zero error rate...and...
where small details of the construction of these entities can change the probability of them replicating...
THEN evolution must be true for that system.
As true as that 2+2=4 in fact because you can prove all of that from those basic requirements. So in ANY system in which those conditions prevail, evolution must actually happen.
So EVOLUTION (as a process) is as true as that 2+2=4. What is only as true as (say) the theory that the earth is not flat - is that evolution actually happens here on earth and explains everything we see around us. That's a teeny-tiny bit less true. But I could write a computer program that demonstrates evolution working using only arithmetic and logic. (This has in fact been done, many times). If I was sufficiently careful, bored and determined - I could run that program in my head instead of in some computer and the results would be the same (Church-Turing thesis and whatnot). So I could - in theory demonstrate an actual evolutionary system working in practice using only what's inside my head.
Hence we need a new sound-bite. Meh - write your own.
Thanks for your suggestions in my previous question about methanol. I have a more basic question now. In a mixture of MeOH/water, do the 2 substances evaporate at different rates/temperatures, or does the mixture behave as a new "pure" liquid? I'm not talking about distillation, more like just the first step of distillation where the liquids are evaporated.
Raoult's law (already mentioned) is the important bit here. Basically, the vapor pressure (which in an open container is essentially the rate of evaporation) of each component will depend both on the concentration of each component AND on the temperature of the mixture. Take the case of a 50/50 methanol/water mixture. At any given temperature, the methanol will evaporate faster, so initially, the mixture will become a lower proportion of methanol. However, as the methanol concentration decreases, it's rate of evaporation will ALSO decrease compared to that of the water; water's rate of evaporation is increasing at the same time since its proportion in the mixture is rising as well. Since we have two competing processes (the higher initial evaporative rate, which is decelerating due to lower concentrations later on), the mixture will arrive at an equilibrium at some point along the way. Basically, at any given temperature, there will be a characteristic equilibrium ratio of methanol-to-water that the entire system will settle into. As you increase temperature, that ratio will tend towards the "azotropic ratio" at the boiling point of the lower-boiling liquid, which for methanol/water would be 0/100 (per our earlier discussion)... --Jayron32.talk.contribs 03:41, 19 March 2009 (UTC)[reply]
learning languages
Hello Wikipedia,
I read last night that, should a human not have learnt a language by the age of 6, he loses the ability too. This, i cannot believe. Whats the theory behind it and how can there possibly be any evidence for it (its hopefully unethical to deprive a child of his development?!).. thanks81.140.37.58 (talk) 11:06, 18 March 2009 (UTC)[reply]
I don't know, but you don't have to deprive a child of language development to know that some people don't develop language skills. I suspect it's probably because by the age of 6, the language centers of your brain are fully developed and capable of learning language. If, by the age of 6, you have not achieved some form of language retention, there's probably a problem elsewhere that means you can't. All speculation. —Cyclonenim (talk · contribs · email) 11:36, 18 March 2009 (UTC)[reply]
There is some evidence (from feral children, for example) that a human who has not had the opportunity to learn any human language by around 6 will never be able to do so later - see Critical Period Hypothesis. 87.112.22.179 (talk) 11:38, 18 March 2009 (UTC)[reply]
You may also wish to consider posting on the languages desk, once this thread has been archived in a few days. (Posting in two places at once is considered rude.) The linguists who hang out there know a thing or two about language acquisition. BrainyBabe (talk) 15:56, 18 March 2009 (UTC)[reply]
Now for some thoughts on why this might be. Our brains are initially "like a blank slate", in that nothing beyond some basic instincts is actually hardwired. The rest all must be learned. As we get older, our brains are no longer as open to learning. This is because things we've already learned become permanently burned into our brains. Why ? So we don't forget critical things we've learned, like how to walk. Small children have the ability to learn rapidly, but at the cost of forgetting quickly and being unable to distinguish fantasy from reality.
Communication is similar, in that we learn a method of communication and then tend to use that all our life. We can learn new words, as that's just a small change, but learning a whole new language is a bit trickier. Many can only learn an additional language by relating it back to their original language. Thus, if they had no original language, they couldn't learn the new one. There are exceptions though, as some people can learn, and actually think in, a new language. StuRat (talk) 15:58, 18 March 2009 (UTC)[reply]
What do you mean by "the age of 6"? I believe the critical age for learning a language is the age of 6 months.--Mr.K.(talk) 16:12, 18 March 2009 (UTC)[reply]
What? Many children don't start speaking until they are one or two years old, so that's patently not true. Unless you're thinking of something different. —Cyclonenim (talk · contribs · email) 18:57, 18 March 2009 (UTC)[reply]
Just because they can't speak doesn't mean they can't learn the language. Learning which sounds have which meaning is the first step, and learning how to make those sounds with their mouths is the next step. StuRat (talk) 14:54, 19 March 2009 (UTC)[reply]
I meant, children must get exposure to language before the age of 6 months or they won't be able to learn any full-fledged language. Of course, empirically testing this assertions may be immoral, however, it has happened.--Mr.K.(talk) 16:59, 19 March 2009 (UTC)[reply]
Surgery complications and PT age
What "percentage" is there for possible complications with inguinal hernia repair for an otherwise healthy 40 year old, compared to an 83 year old with Atrial Fib on Wafarin (but otherwise healthy/normal weight etc).
IE: <10% chance of complications for the 40 year old?
>25% for the 83 year old due to having to stop Warfarin 4 days prior to surgery?
Is there a data bank that can provide this information?
The complication rate for any procedure varies depending on multiple factors, such as: age, sex, other health problems (which you already identified), as well as the location (the country, the hospital), there are also slight seasonal variations, and individual surgeons may have slightly differing complication rates for a given procedure. The other big variable is what type or types of complication you want to know about - since the rate of these also vary widely, and are also affected by everything else I mentioned. As far as I know, there's no one data bank for this, and if there was, I wouldnt rely too heavily on whatever it said because it'd necessarily have to average out all of those factors. If its a procedure you're contemplating having, discuss this with your surgeon. S/He will be aware of the local factors that affect risk and will be able to discuss them with you. Mattopaedia Have a yarn 05:29, 19 March 2009 (UTC)[reply]
Question about the knee
Im not seeking medical advise, i just want to know if a torn ACL can cause artrithis and in how much time? Thank you DST —Preceding unsigned comment added by DSTiamat (talk • contribs) 14:09, 18 March 2009 (UTC)[reply]
I don't think a torn anterior cruciate ligament can lead to arthritis, which is a disease affecting the joints, not ligaments or tendons. If you are concerned, however, please see a physician. —Cyclonenim (talk · contribs · email) 15:24, 18 March 2009 (UTC)[reply]
Our article Osteoarthritis#Two types? says "Some investigators believe that mechanical stress on joints underlies all osteoarthritis.." These researchers found a complete tear to be worse than a partial tear [25]. Maybe related or unrelated researchers have found that interrupted blood supply to the extracellular matrix of joints following surgery inhibited formation of cartilage when compared to methods where care was taken to preserve blood supply. Scarring (we don't seem to have a page on internal scarring) could be a factor here. 76.97.245.5 (talk) 16:33, 18 March 2009 (UTC)[reply]
From the Oxford Textbook of Orthopaedics and Trauma, pages 1207–1208: "Episodes of giving way may cause further injury to menisci and the articular surface. Reconstruction of the ACL has not been shown to prevent the development of osteoarthrosis. Reconstruction of the ACL may accelerate the development of osteoarthrosis." No timescale is indicated.
In paediatrics, page 2757: "Angus and Hall retrospectively studied ... the outcome of 27 children with arthroscopically documented ACL tears, 18 of which were partial tears. No activity restrictions were placed on the patients following diagnosis. At follow-up, 11 of 12 patients under the age of 14 were not satisfied because of functional knee instability. Most authors agree that functional instability, with associated damage to the menisci and articluar cartilage, will ensue in a patient with an ACL tear who returns to a high demand sport.... McCarroll et al. followed 38 patients with arthroscopically documented complete ACL tears for an average of 4.3 years following injury and found that 27 of the 38 patients treated nonoperatively developed subsequent symptomatic meniscal tears."
Yes, a torn ACL can lead to OA. As for how long it takes- that depends on what you do with the knee. Lots of high impact, high demand activity generally equates with a faster rate of progression to OA (& a higher rate of re-injury), than low impact, low demand activity. Age also figures, as does sex, insofar as these factors are related to the types of activities one may be likely to undertake (for example a 20-something male football player may have a higher rate of progression than than a 50-something female who walks & swims a few times a week & has a sedentary job). Genetic susceptibility may also play a part. in other words: How long is a piece of string? Mattopaedia Have a yarn 05:38, 19 March 2009 (UTC)[reply]
Materials
Moved from Miscellaneous desk
I'm back! Based on facts ( and opinion, if you wish. Just make sure I know it's opinion.) which material do you think would work best for a windmill? Also based on how sturdy it is, how the weather effects it, cost, stuff like that. It can have drawbacks.
1. Titanium
2. Carbon Fiber
3. Magnesium
If you have any other suggestion, feel free to add. I'm just having trouble deciding on which to choose. <(^_^)> Pokegeek42 (talk) 22:27, 17 March 2009 (UTC)[reply]
Ah yes! Tensile strength! I think that might be important. <(^_^)> Pokegeek42 (talk) 22:32, 17 March 2009 (UTC)[reply]
For what parts of the windmill? The demand in the case of blades (for example) might be lightness or rigidity or tensile strength - but for the framework, extra weight might actually be beneficial and you'd perhaps be more interested in compressive loads. A lot depends on the design of your windmill too. SteveBaker (talk) 03:04, 18 March 2009 (UTC)[reply]
An interesting and somewhat relevant article: [26]. Bus stop (talk) 04:02, 18 March 2009 (UTC)[reply]
Maybe this should be on the science desk? That's where all the smart engineering types hang out. --JGGardiner (talk) 04:43, 18 March 2009 (UTC)[reply]
Carbon fiber would be pretty good as it's light and strong, except it's very expensive in the quantity that you'd want. Titanium is very strong, but heavy and therefore probably wouldn't be greatly affected by the wind. Magnesium, if pure, could be compared to Aluminum in terms of strength and weight, so it's probably the best option there. That's just in regards to the blades, though, because as Steve mentioned weight may well be beneficial to the framework of the windmill, in which case Titanium could be a good option (but also fairly expensive for large quantities). I'd have thought a steel structure would work better for that aspect. —Cyclonenim (talk ·contribs · email) 15:21, 18 March 2009 (UTC
I'd go with plastic for the blades (painted to protect against UV degradation) and steel for the frame (painted to prevent rust). The materials you named are rather expensive and probably only needed for the most extreme windmills. If looking at it in terms of amount of time until the windmill pays for itself, you'd want to keep the costs down as much as possible. The magnesium might also have the problem of burning when struck by lightning. The titanium is highly reflective, so you'd need to paint it to keep from blinding people from the Sun's reflection on the blades. Carbon fiber might be decent, but, again, is much more expensive than plastic. StuRat (talk) 15:39, 18 March 2009 (UTC)[reply]
Don't forget about galvanic corrosion if you use Mg. —Preceding unsigned comment added by 65.167.146.130 (talk) 20:14, 18 March 2009 (UTC)[reply]
Alrighty then. I've got enough to get started here. Thanks, guys! <(^_^)> Pokegeek42 (talk) 22:17, 18 March 2009 (UTC)[reply]
INDENTED CONCRETIONS
The Tununk Shale Member of the Mancos Shale Formation in Emery County, Utah, contains many spherical “cannonball” concretions. In one unique area, about 1.5km x 200m, the familiar cannonballs are outnumbered by others, 10 to 30cm in diameter, in which the spherical shape is modified by one or more indentations, 1.5 to 5cm in diameter and 1.5 to 4cm deep. (Pix @ http://picasaweb.google.com/fossilcrete/ForWeb#slideshow/5314320039662488930) Opening the concretions reveals a septarian-like interior with one of the dark septaria connected to the indentation. One concretion, bisected along the axis of the indentation, contains an inclusion connected to the indentation which appears to have cell structure and possibly be biological in origin. Do similar indented concretions exist in other areas? What caused the indentations? What is the the cellular inclusion? BobPeyton (talk) 15:54, 18 March 2009 (UTC)[reply]
My first thought on looking at the inclusion was that it was a fossilised bone of some kind such as seen here [27]. Bones of marine vertebrates have been reported from the Tununk Shale [28] so I would go with that as at least a possibility. Many concretions have a fossil at the centre, presumed to have acted as a nucleus for the growth. Can't come up with a good reason for the indentation though. Mikenorton (talk) 16:40, 18 March 2009 (UTC)[reply]
Super conducting armor vs. Lightning
Lets say you have a tank with armor that's super conducting and has zero electrical resistance. You zap it with an electron particle beam or lighting over and over again. Is it true, that it will never take any damage? ScienceApe (talk) 15:55, 18 March 2009 (UTC)[reply]
This may be a very naive approach, but I'm imagining whether lightning rods would take any damage struck again and again. I imagine there is probably some small amount of damage not from the charge directly but indirectly—say, if it created pressure effects in the air or ignited or burned something very close to the rod? --140.247.254.34 (talk) 17:04, 18 March 2009 (UTC)[reply]
The resistance would cause the conductor to heat up, which a super-conductor would not. That heating would probably result in damage eventually. --Tango (talk) 19:41, 18 March 2009 (UTC)[reply]
Thinking out loud -- the superconductor is still going to accumulate charge even if it doesn't accumulate heat, right? And that charge will eventually have to do something. Pump in charge at a high enough rate and you're likely to overwhelm whatever mechanism deals with it -- discharge to ground melts the rock underneath you, spark jumps across to the interior of the tank, something. So, while your armor may be invulnerable, your tank likely isn't. — Lomn 20:12, 18 March 2009 (UTC)[reply]
At the point where the lightning hits the superconductor, there is a hot plasma, possibly several thousand degrees. This is quite likely to damage your superconductor. Graeme Bartlett (talk) 20:37, 18 March 2009 (UTC)[reply]
Superconductors lose their superconductivity when the current density gets too big. They are not magic or invulnerable. Edison (talk) 23:25, 18 March 2009 (UTC)[reply]
To expand on the point about hot plasma most superconductors need to kept at sub liquid helium temperatures. If they rise above these temperatures their conductivity is lost and the electronic energy they contain is released as heat. Its a very delicate process charging and handling super conducting magnets. It possible for NMR and MRI magnets loss their superconductivity if they are jarred or damaged. The loss of superconductivity is called a quenching, in an uncontrolled the coil rapidly heats spreading resistance through the coil which boils the coolants, liquid helium and liquid nitrogen. This can be very dangerous for researchers, patients, doctors since they can be frost bitten or suffocated by the boiling coolant. For these and the other reasons mentioned superconductors don't make good armor.--OMCV (talk) 03:47, 19 March 2009 (UTC)[reply]
Laser application
Re-glazing of bathroom ceramics is mostly done with acrylic based products. I find the results only marginally satisfactory. Would it be possible to use a laser to melt Ceramic glaze / Vitreous on to the existing tile/cast iron tub? (following appropriate prepping.) Would the thermal stress induced in the tile crack it? Could a suitable laser be constructed cheaply and portable enough to be a DIY or rental unit? 76.97.245.5 (talk) 16:48, 18 March 2009 (UTC)[reply]
A portable laser with enough power to melt ceramic is unlikely to be safe enough to use without specialist safety equipment. It is also likley that such a laser would need more power than a standard house could provide. Most industrial lasers, which would have the power you require run from a 3-phase supply with a high current rating. Most also have water coolers attached to extract the excess heat - lasers are not efficient at converting electricity into light beams. -- SGBailey (talk) 16:56, 18 March 2009 (UTC)[reply]
It would also take a long time, I would imagine - a laser is, by design, very concentrated and ceramic has very low thermal conductivity, so I would expect you would have to point the laser at every single point on the tile you want to reglaze. That would mean running the laser up and down the tile in very thin strips. --Tango (talk) 17:10, 18 March 2009 (UTC)[reply]
Good question. I used to use a iron bathroom sink as a forge, the glaze would get sticky when it got hot but the whole thing was fine when it cooled down. Whether or not you could heat only part of the iron and glaze is a question I would like to know the answer to also. 121.214.10.38 (talk) 03:06, 19 March 2009 (UTC)[reply]
@Tango one could construct a mirror/prism thingy to guide the beam (sort of like at a disco) that should be doable. This paper I found indicates it would still be too slow overall [29]. A focus area of 0.3 mm seems feasible. Staying with metric that would take 50 passes per 15 cm2 tile. So one would have to be able to generate sufficient heat to take only of a fraction of a second per pass or you'd need an hour per tile. Bailey's answer indicates it wouldn't be feasible anyway. I had hoped, since one wouldn't need a specific wavelength nor narrow specs, a high power output laser would be possible. Too bad. Maybe something like a blow torch with an automated guidance system could work. That would be a lot more likely to set the house on fire, though. :-( Thanks for all the input. 76.97.245.5 (talk) 05:02, 19 March 2009 (UTC)[reply]
earliest/latest snow
I am looking for info on the earliest and latest recorded snowfalls for several cities including St Paul MN, Omaha NE, Des Moines IA, Chicago IL, and St Louis MO. Does anyone have a website or something to point me to?
Here's one for Chicago: [30] However, I think it's worth noting that as you move northward, you'll need to rigorously define "earliest" and "latest". What happens if it snows in June? — Lomn 21:23, 18 March 2009 (UTC)[reply]
Or July (1816, Year Without a Summer), or August (Alberta, Canada), for that matter? Also, do a few flakes on the outskirts of a city witnessed by a few people count as a snowfall event? ~AH1(TCU) 22:21, 18 March 2009 (UTC)[reply]
And you can get hail even in the middle of summer in warm climates, frequently associated with tornadoes. StuRat (talk) 14:32, 19 March 2009 (UTC)[reply]
A city will usually have an official weather station (generally at the airport), run by an official weather service with rules on how to measure the weather, and it's what happens there that counts as the city's weather. --Carnildo (talk) 23:26, 18 March 2009 (UTC)[reply]
Hail doesn't count as snow, not even close. I remember one occasion where soft hail (graupel) fell in the summer in Northern Ontario, and it was reported as 27C (80F) and snow, but actual snow doesn't fall at those temperatures. However, snow can sometimes fall at temperatures as high as 10C (50F) with low humidity and at high elevations, but the highest temperature I've seen snow at where I live (S. Ontario) was about 6C (43F), and the latest and earliest days I've seen snow here were in late May and mid-October. ~AH1(TCU) 17:44, 19 March 2009 (UTC)[reply]
How to write on a photgraph
The instructions for a photo contest are 'label the back of the photograph with your name, phone number, etc. etc.'
Are there particular types of labels that are good for this purpose? E.g., they won't damage the photo; they can be removed later if desired?
Write on a piece of paper, sellotape that piece of paper to the back of the photo - should work fine. Alternatively use a soft-tip marker pen that doesn't smudge.
While I have no specific information, I suspect that the rules for a marker pen may be the same as for writing on CDs, i.e. use a "non-toxic" pen which doesn't deposit strong solvents in the ink which could soak through and damage the image surface on the other side. I use a Staedtler Lumicolor CD-R pen. Franamax (talk) 02:17, 19 March 2009 (UTC)[reply]
I think what you want is a grease pencil, a.k.a. wax or chinagraph pencil. The wax does not penetrate, so you can wipe it off later. --Scray (talk) 03:07, 19 March 2009 (UTC)[reply]
This must be a rather old-fashioned contest. I'd have expected it to say "label the CD containing your (digital) pics with your name, phone number, etc.". StuRat (talk) 14:29, 19 March 2009 (UTC)[reply]
If you do write on a paper photo, use a very hard surface under the photo to avoid putting an indentation into it which will be visible on the front. This could be a smooth shhet of class or metal. Graeme Bartlett (talk) 20:15, 19 March 2009 (UTC)[reply]
Thank you all for your inputs.
StuRat: You are correct, it is a very old-fashioned contest. Imagine looking at photographs on paper!
The zeroth law of black hole thermodynamics states that the surface gravity of a black hole is constant at a given temperature, right? Isn't this essentially proof of existence of a force carrier particle for gravity? I'm thinking that in standard thermodynamics, this applies because a change in temperature equates to a change in entropy, and we observe this by looking at the vibrational aspect of particles. Can this not be transfered over to black hole thermodynamics? I'm probably missing something big, so feel free to rip this idea to shreds. —Cyclonenim (talk · contribs · email) 21:50, 18 March 2009 (UTC)[reply]
I read somewhere that the only three laws of physics that probably aren't broken by black holes are gravitation, electromagnetism, and rotation. So, I'm not sure if the usual rules involving temperature apply properly in a black hole. However, it's probably still possible to predict the laws of physics as they apply to a black hole, and maybe some experiments such as those at the LHC will help improve our understanding, but I'll wait for someone with a more detailed answer as well. ~AH1(TCU) 22:17, 18 March 2009 (UTC)[reply]
Perhaps you should better explain the point you are making and the reasoning behind it. It is not clear (at least to me) how you want to go from the zeroth law to the existence of a force carrier particle. Your idea about entropy seems to be going in the right direction but you did not develop it enough. Dauto (talk) 01:08, 19 March 2009 (UTC)[reply]
Surface "temperature" of a black hole is likely determined by events like Hawking radiation, and the rate of of "evaporation" due to Hawking radiation is mathematically proportional to the "size" and therefore surface gravity of the black hole. So if you measure the "temperature" of the black hole, what you are measuring is the kinetic energy of the particles lost via "evaporation". Our article on Hawking radiation covers this in exhaustive mathematical detail, but the basic principle is stated in the article more or less... --Jayron32.talk.contribs 03:26, 19 March 2009 (UTC)[reply]
My point was, in a completely speculative manner, that because the surface gravity of a black hole is proportional to the temperature, this seems remarkably similar to standard thermodynamics where the energy of a particle is given by its temperature (because of more vibration). —Cyclonenim (talk · contribs · email) 07:41, 19 March 2009 (UTC)[reply]
meteorite
Could this rock that was found in Ohio be a meteorite? It weighs 8.6 lbs.
I can't see the pictures.. is it just me? I'm not good enough at wiki to see where code may or may not be wrong. Can I get a second opinion? -Pete5x5 (talk) 01:37, 19 March 2009 (UTC)[reply]
Those images don't seem to exist either here or on Commons. I think you might need to put the "File:" prefix in front, but doesn't matter, 'cause I can't find them anyway... Franamax (talk) 01:54, 19 March 2009 (UTC)[reply]
I can't see it either. Dauto (talk) 01:47, 19 March 2009 (UTC)[reply]
Well, the <gallery> is incorrect - you need to put "Image:" or "File:" in front of each image - but I tried doing that and none of the images showed up. Then, the image uploader removes underscores from filenames - but doing that doesn't make them show up either. I suspect that the OP has not uploaded them successfully. SteveBaker (talk) 01:54, 19 March 2009 (UTC)
The trouble is not in your set. It's me. My next question is will a laptop still work after I throw it out the window? I will try to add the pictures when one the kids stops by. Please stay tuned.Curiouspatty45 (talk) 00:14, 20 March 2009 (UTC)[reply]
How does one teach a parrot to ride a tricycle?
Not a joke question. You can seriously buy small tricycles designed to be ridden by parrots online. How does that work then? If I bought one and showed it to my macaw, she'd probably just look at me as though to say "what do you expect me to do with THAT thing?". On the other hand, it might be a lot of fun for her, if I had the first idea about how I was supposed to teach her to pedal. Anyone know what I'm talking about here? --84.70.216.219 (talk) 23:15, 18 March 2009 (UTC)[reply]
See Operant conditioning and Shaping (psychology). Positive reinforcement is the key. Also be extremely patient, and do not continue a session when the bird does not want to play any more. You might start with basic bird training [31]. Edison (talk) 23:23, 18 March 2009 (UTC)[reply]
She didn't hit anything. Could the fall have been the result of a brain condition? How may a simple fall cause such a death. 69.203.78.244 (talk) 03:48, 19 March 2009 (UTC)[reply]
It can take surprisingly little to cause a serious head injury and what seems like a minor injury can become life-threatening very quickly. See traumatic brain injury. (And wear a helmet. They save lives.) - EronTalk 03:59, 19 March 2009 (UTC)[reply]
Complete and utter speculation based on TV medical dramas and 'stuff I read somewhere' here - but AFAIK, a bang to the head can cause a bleed in the brain which, whilst not immediately fatal (or even apparent) can continue to leak blood into the surrounding spaces in the following hours. Eventually, if there's no more space for the blood to go, the intercranial pressure starts to build up to a dangerous level and the brain starts to gets squeezed. Without immediate medical attention, the base of the brain gets squeezed out, toothpaste-like through the hole in the base of the skull - at which point, the only effective treatment for the condition is a pine box. --Kurt Shaped Box (talk) 04:03, 19 March 2009 (UTC)[reply]
Since there's no publicly released information about the mechanism of injury or her medical condition, any response to this question is purely speculative as it applies to Ms. Richardson, and what follows is not intended to imply any one mechanism or cause of death, only what is possible.
That said, the are numerous ways a person could die from a closed head injury, including the slow bleeding scenario KSB described, which is usually a subdural haematoma. Other causes attributable to bleeding include extradural haemorrhage, subarachnoid haemorrhage, although this usually has a more precipitous onset, and intracerebral haemorrhage, to name a few. There are many conditions that increase the risk of some of these catastrophic bleeding problems, some of which are berry aneurysms and arteriovenous malformations. Contre coup type head injuries, and other blunt force, closed-head, traumatic injuries can lead to death through increasing cerebral oedema, ultimately causing the herniation of the lowest parts of the cerebellum throught the foramen magnum, which causes compression of the brain stem, where important things like consciousness, breathing and heart rhythm are controlled. This causes death. This is the process KSB described above, and is described by many doctors as "coning." It is caused by anything that increases intracranial (inside the skull) pressure sufficiently. More obscure causes in the setting of trauma exist, the first that comes to mind is acute high-pessure hydrocephalus that can be caused by a colloid cyst of the third ventricle blocking drainage of cerebrospinal fluid from the lateral ventricles. I could go on, but I won't! Mattopaedia Have a yarn 06:07, 19 March 2009 (UTC)[reply]
It is reported that it was an epidural haematoma which sadly affected Natasha. This occurs when a bleed occurs in your head, between a layer called the dura and the skull. This causes an increase in intracranial pressure, resulting in a sort of compressive mechanism on the brain. Roughly 15-20% of people die from this condition, often because it's not as easy to diagnose as the other haemorrhages and haematomas listed above by Mattopaedia. —Cyclonenim (talk · contribs · email) 07:45, 19 March 2009 (UTC)[reply]
But she didn't hit anything, if the reports are correct! Thanks for the impressive list, too--though the skull is strong it's crazy how many ways the brain can go wrong. 69.203.78.244 (talk) 13:18, 19 March 2009 (UTC)[reply]
Brain injuries don't require an external impact. Sudden deceleration can do it, too, due to the brain's inertia causing it damage when it slams against the inside of the skull. StuRat (talk) 14:21, 19 March 2009 (UTC)[reply]
And, she did hit something - she hit the ground. That acounts for both impact and sudden deceleration. This story quotes a couple of ski patrollers who note that falls on flat sections of ski runs can be more dangerous than falls on slopes, as the skier just drops and stops rather than tumbling or sliding down the hill, which can absorb some of the impact. - EronTalk 15:04, 19 March 2009 (UTC)[reply]
Indeed - I can tell you from experience that compacted snow is very hard. I've hit my head on the ground after a skiing fall, and it isn't pleasant (I've never required hospitalisation, fortunately). The worst such time was, indeed, on a flat section - right at the bottom of a dip, so I was going flat out, hit a bump, hit the ground and stopped immeadiately. I was completely dazed for several seconds. I don't find it at all hard to believe that someone less fortunate than me could get a fatal head injury from a similar fall. --Tango (talk) 19:16, 19 March 2009 (UTC)[reply]
Yellow cheese
What causes some cheeses to be yellow/orange? 99.245.16.164 (talk) 03:53, 19 March 2009 (UTC)[reply]
A possible problem with spinning for Artificial Gravity
I have heard several way involving spinning a ring, or surface, or something to create centrifugal force for artificial gravity. I have always wondered: What would happen if I jumped up off the surface? Once I lost contact with the spinning surface, would I be weightless, or would my velocity bring me down again? Tiailds (talk) 04:18, 19 March 2009 (UTC)[reply]
If you start out spinning with the ring, you will have a lateral velocity. When you jump, that lateral velocity component does not change, so you will continue moving in that direction until you encountered the ring again. You will also have some amount of angular momentum, that will keep you rotating with the ring, so you will likely land in a roughly upright position. In extreme cases this would not be true and you could land at an awkward angle.
In contrast, if you started running in the direction opposite the ring rotation and managed to match that rotation, the centrifugal force would disappear and a jump would launch you into a weightless condition with the ring rotating around you. You could almost think of this as the equivalent of achieving orbital velocity in this inside-out environment. -- Tcncv (talk) 04:55, 19 March 2009 (UTC)[reply]
(EC with above)The idea is that you are on the inside of the spinning surface. Under those conditions, regardless of where you jump from, your straight-line motion (which your inertia will have once you are no longer in contact with a rotating frame of reference) will always bring you back into contact with the surface again. It's the centripetal force which is spinning the ring or whatever that provides you with that motion, not centrifugal force (a fictional force), which is really just the effect of losing contact with a rotating frame of reference and not a real force at all. Since your tendancy will be to move away from the center in both cases, being OUTSIDE the spinning ring will cause you to drift away, but being INSIDE the spinning ring will cause you to always drift into the ring. So you fall back to your "ground". --Jayron32.talk.contribs 05:08, 19 March 2009 (UTC)[reply]
I spent a year and a half on Mars and all I got was this stupid t-shirt...
I have a few questions about a manned missions to Mars which Manned mission to Mars sadly does not answer:
First of all, what would be the length of such a mission? I hear people say that the trip there would take 3 months or so, but the entire trip would take much longer, wouldn't it? I mean, once you've taken three months getting there, haven't you pretty much missed your window of opportunity to get back? The article on exploration of Mars states that the launch window comes around every 780 days, so would that mean that the poor astronauts would have to spend something like a year and a half living on the surface of Mars? I'm having trouble even imagining how much food and fresh water you'd need to bring to stay alive that long (not to mention the psychological effects, I've read The Three Stigmata of Palmer Eldritch).
Second, what about communications with Earth? I mean, when Earth and Mars are sort-of near to each other, it wouldn't be much of a problem (you could live with a twenty minute latency, even if it's a pain in the ass), but assuming I'm right on part number one (a bold assumption), for most of the mission, Mars and Earth would be on opposite sides of the sun! Can you reliably communicate with someone when the sun is up? I'd imagine that the interference would be huge.
Third, what tangible benefits would a manned mission to Mars yield? Yes, I get the whole "triumph of the human spirit" thing and it would make a great television event, but if we just went up there to make measurements and bring back rocks for analysis, can't we just get robots to do that? I mean, yeah, the rovers didn't bring anything back, but I imagine it would be WAY easier to make a return trip with a robot compared to making one with a human being. No need to worry about some dude going ape-shit crazy and slaughtering the rest of the crew for one thing (presumably the robot would have a "become_self_aware = false" line in its code somewhere).
Can any of you fine scholars enlighten me on the subject? Belisarius (talk) 05:25, 19 March 2009 (UTC)[reply]
I'll comment on the second point only. The Sun would certainly block communications when directly in line between Earth and Mars, although that configuration might never occur during the mission (the two planets orbit in different planes, remember). I don't know about the more likely situation where it is almost directly in line, but experiments could be done to find out if it is a problem. And if it is, the thing to do is launch a communications relay satellite into a solar orbit that will keep it far enough away from the Earth-Sun line.
For single-mission use there would be a wide choice of orbits, but for long-term stability, the obvious thing is to use one of the Trojan positions, 60° ahead of behind of the Earth in its orbit. Incidentally, this solution was anticipated in science fiction as early as 1942, with George O. Smith's lighthearted Venus Equilateral stories. Smith was writing in the days of vacuum tube electronics and assumed the relay station would be manned -- as did Arthur C. Clarke when he invented the geosynchronous communications satellite in a nonfiction article about the same time. Smith's first story, "QRM—Interplanetary", is particularly worth looking for. --Anonymous, on Earth, 08:59 UTC, March 19, 2009.
(A) We're not talking about a solo flight. so the 790 days in point one wouldn't be spent in isolation. I would imagine an expedition consisting of a number of ships - minimum three - and dozens in the crew. (B) Magellan's Victoria took three years to circumnavigate the globe; FitzRoy's second Beagle expedition - the one with Darwin - took five. (C) Supplies need not all be carried along. Unmanned ships stuffed with MREs could be launched separately - starting before the manned component - and either inserted into orbit or dropped to the surface. (D) BTW, a second on the Venus Equalateral recommendation. B00P (talk) 09:40, 19 March 2009 (UTC)[reply]
While you're right we're not talking about a solo flight, the psychological effects of such a long trip in which a few people will be in constant close contact and very far from earth with limited contact are definitely something that has received a great deal of consideration (as with the physical effects) and is one thing that has been studied in numerous ways (e.g. [32] & [33]). Take a look at [34] and is also mentioned in Manned mission to Mars. I saw one suggestion a while back that choosing too many astronauts which are too perfect, as is the norm may actually be a mistake because they may not get along very well with each other over such a long time so there are definitely lots of different ideas. Basically of course, we will never know until it happens since there's no way you can simulate the conditions exactly. P.S. I've never heard a suggestion of multiple simultaenous crewed ships before. While I'm sure it has been proposed somewhere, I don't think it's high on the current list of ideas. Nil Einne (talk) 13:19, 19 March 2009 (UTC)[reply]
As having groups of people who can get along well together for years in confined spaces would be critical for the mission, they should make each group go through a test run for several years of isolation first. StuRat (talk) 19:00, 19 March 2009 (UTC)[reply]
That would be an extremely inefficient use of time. A 6 month spell on the ISS together might be good, although not all the people that would go on such a mission would be useful on the ISS (there aren't many rocks for geologists to study in LEO!). --Tango (talk) 19:04, 19 March 2009 (UTC)[reply]
As for supplies, such a mission would likely benefit from far more recycling than is currently done. Oxygen could be recycled from the air, and carbon dioxide removed (and maybe used to grow plants). Water could be recycled from the air (respiration and evaporation from skin and eyes) and from urine. Recycling food could also be done, say by using feces to grow food. Mushrooms, anyone ?
Another option is to produce some of the things we need directly on Mars. There is water ice at the poles, which could be used to supply water, and, after some electrolysis provided by solar power, oxygen. StuRat (talk) 11:55, 19 March 2009 (UTC)[reply]
An interesting thing that happens with my local NPRradio station periodically is that they'll say "at about X o'clock today, we'll lose transmission of this program due to the Sun passing behind the satellite that gives us our feed". And that's with your transmitter in front of the Sun. --Sean 13:34, 19 March 2009 (UTC)[reply]
Manned mission to Mars still has that elephant of "Health threat from cosmic rays" in the closet. I haven't seen us make all that much progress in figuring out sufficient shielding. (Nanotube polymers are a very nice theory, but the spaceship would need more than a thimble full.) As to why, sooner or later our own planet is going to face a huge calamity. It would be nice for the survival of the species - if you are interested in that - to have a population stashed elsewhere by that time. If we intend to head in that direction we'd have to start some when somewhere. 76.97.245.5 (talk) 15:26, 19 March 2009 (UTC)[reply]
I may be misreading this, but in the original post, Belisarius says, "...Mars and Earth would be on opposite sides of the sun! Can you reliably communicate with someone when the sun is up?" The phrase "sun is up" usually refers to it being daytime and the earth does not orbit the sun during the course of a day, but over the course of a year. The sun being "up" would not necessarily be a problem; the sun being "between" would certainly be. Matt Deres (talk) 17:02, 19 March 2009 (UTC)[reply]
Yes, but you can only communicate when the Earth is above the horizon, which would be at the same time as the Sun was above the horizon. The OP's question does make sense. The Sun being up isn't actually a big problem, though, it's only a problem if it is very close to the Earth in the sky. --Tango (talk) 18:08, 19 March 2009 (UTC)[reply]
I'll take a shot at these:
1. First of all, what would be the length of such a mission? I hear people say that the trip there would take 3 months or so, but the entire trip would take much longer, wouldn't it? - yeah - it's partly the launch-window thing, partly that having spent 3 months getting there - and needing another 3 months to get back, it would be kinda silly to stay just a couple of days as we did on the moon. Plus, prolonged periods in zero G aren't good for you - and the guys will need time to recover some of their lost muscle and bone mass for the trip back home. This is also going to be a ruinously expensive trip - we won't be sending half a dozen manned missions there as we did to the moon.
I'm having trouble even imagining how much food and fresh water you'd need to bring to stay alive that long (not to mention the psychological effects - those are all very serious concerns. The plan currently is two-fold. One is to send an unmanned vehicle to mars to manufacture water and (by electrolysis) oxygen and some hydrogen fuel for the return trip - using sunlight for energy, subterranean ice as a water source...whatever. When it has enough supplies built up - we send out our manned mission with enough fuel for a one-way trip - and only enough water and oxygen for the ride out there. We'd need to recycle (we already do that on the ISS for example) - and we'd need to grow our own food en-route using hydroponics and such like. It's not easy - and that's why we didn't do this LONG ago! When we get there - we land a short distance from the robotic mission's landing site - fill up on fuel, water oxygen for the stay - refill again for the trip home. Psychological concerns have been somewhat addressed. Plenty of people have been cooped up in the ISS and in MIR for a year and managed to keep it together that long. Being able to leave the spacecraft and wander out across Mars should make that easier - not harder.
2. Second, what about communications with Earth? - No problem. We've been communicating with the 'Spirit' and 'Opportunity' rovers non-stop for something like five years now! We can still send messages to (and get data back from) the clunky old Voyager probes that have completely left the solar system. This is really not a problem.
3. Third, what tangible benefits would a manned mission to Mars yield? - I have a problem with this too. There is value for sure in having LOTS of humans living their lives on Mars - we need a 'backup planet' in case something terrible happens to ours. For that reason only - we need to make a start on being there - and the first step is to get a small crew out there.
No need to worry about some dude going ape-shit crazy and slaughtering the rest of the crew for one thing - again, it didn't happen with people cooped up in the TINY space of MIR over an entire year (although they certainly had their problems). I think once they get to Mars - they'll be too busy to worry.
(presumably the robot would have a "become_self_aware = false" line in its code somewhere). - :-) Indeed - Asimov's first law of robotics is a "must have" kind of thing...and no putting red LED's in it's fake eyesockets either...that's just not funny! Particularly avoid: "if ( become_self_aware == true ) eye_socket_LED_illumination_level = 1.0f ;"
It took me a while to work out what you were saying that (I didn't cheat and click the link!), but I laughed out loud when I got there - very good! --Tango (talk) 14:54, 20 March 2009 (UTC)[reply]
Strictly speaking, we haven't communicated with Spirit and Opportunity non-stop - there are short periods when they are out of contact due to the position of the Sun. It's only a couple of days a year, or so, though. The lack of real-time communication with anyone other than your crewmates might make life on Mars a little harder than life on MIR/ISS - the psychological issues certainly need to be dealt with, but I don't think any of them are deal-breakers. --Tango (talk) 14:54, 20 March 2009 (UTC)[reply]
Research with Blood
What is the easiest way to overlay blood on to a FiCol or similiar medium before centrifugation? Currently you have to poor blood from one test tube to another prefilled with medium (ficol) 15-50 mL test tube. —Preceding unsigned comment added by 98.154.31.61 (talk) 07:36, 19 March 2009 (UTC)[reply]
I suggest that you start with a tube containing blood diluted 1:1 (to reduce loss of mononuclear cells at the interface) and underlaying with Ficoll. You need a very clean interface to get good separation. To achieve this, use a long pipette attached to a pipette-aide, load it with the desired amount of Ficoll for the blood volume and tube size you're using, insert through the blood to the bottom of the tube, then very slowly dispense the Ficoll, being careful to avoid ejecting a bubble of air! Spin with the brake off, of course. --Scray (talk) 11:07, 19 March 2009 (UTC)[reply]
Waterflow of the Amazon River
I am interested in knowing more about the force and speed of the waterflow/steady stream of the Amazon, i.e. close to the outlet but before the flow is divided by the "branches" of the delta. Perhaps this can be calculated from the daily amount of water going from the river into the sea, with the tide taken into account?
Does anyone have information about the speed of the flow out to sea? It would be an interesting addition to the page.
On the Amazon river page, the information box notes that the "Discharge - average" at the mouth is 219,000 m³/s; I'll let you do the conversion, but you should get a little over 1013 L/day (a truly mind-boggling amount). My impression is that this takes into account tides, etc. The Drainage area section notes that this can increase almost 40% to 300,000 m³/s during the wet season. What is it you wanted to add? The Talk page might be a good place to discuss additions. --Scray (talk) 11:24, 19 March 2009 (UTC)[reply]
Using Scray's numbers, roughly 1013 L/day, divide by 24, then by 60 and then 60 again to get per second which gives us approx. 1.16 x 10^9 L/sec. Seeing that one liter of water is approximately one kilogram, we can assume 1.16 x 10^9 kg if the mass of the water.
Speed of the Amazon is approximately 3 miles per hour, which is 1.34 m/s-1. Seeing as one liter of water weights approximately one kilogram, we can convert Scray's value of 1013 per day into 1.16 x 109 kg of water flowing per second. Using F=ma, 1.16 x 109 x 1.34 gives us 1.55 x 109 N of force. I feel that's unusally high, but I'm not a good physicist so I'll let others rip that working out to shreds. —Cyclonenim (talk · contribs · email) 16:58, 19 March 2009 (UTC)[reply]
A liter of water has a mass of exactly one kilogram, by definition, not approximately, though there are obviously additives that will change the actual measured mass/weight. Matt Deres (talk) 17:06, 19 March 2009 (UTC)[reply]
I was just wondering how much suspended sediment load there would be in a litre of Amazon river water, so I did a back of the envelope calculation taken from some annual figures of discharge and sediment load (6300 km3 per year & 1200 x 106 tonnes per year [35]), and came up with a mere 0.2 g of suspended sediment in each litre; enough to make it look a bit murky but not enough to seriously affect the approximation. Mikenorton (talk) 19:14, 19 March 2009 (UTC)[reply]
Wow, so there's 2.32 x 105 kg of suspended sediment in the Amazon? That's a lot of sediment! —Cyclonenim (talk · contribs · email) 19:34, 19 March 2009 (UTC)[reply]
Just as an aside, the Amazon is recognised as the largest river in the world by volume, but is it true what I read that there is an underground "river" underneath the Nile that is six times bigger than the river on land? ~AH1(TCU) 01:46, 20 March 2009 (UTC)[reply]
That would be the undercurrent of denial, right? ;-) --Scray (talk) 10:44, 20 March 2009 (UTC)[reply]
Beneath the Nile there is an enormous canyon created by the drop in base level associated with the Messinian salinity crisis. That is now filled with silt, I don't know if there is likely to be any significant groundwater flow through this great pile of sediment (2400 m thick beneath Cairo) that could be compared to the surface flow. There is interaction between the Nile and aquifers in its banks in the Cairo area, both discharge and recharge,[36] but I'm not sure you would call any of that an underground river. Mikenorton (talk) 11:44, 20 March 2009 (UTC)[reply]
query
Practical methods of production of callus cultureVidya mandava (talk) 11:07, 19 March 2009 (UTC)[reply]
Web search for "callus culture" provides plenty of information. If you have a specific question, please state it clearly and I'm sure people here will respond with similar care. --Scray (talk) 12:48, 19 March 2009 (UTC)[reply]
Biochemical processes within crocodile...
how can crocodile stay under water so long time? what biochemical processes are within it when it's under water? —Preceding unsigned comment added by Beqa22era (talk • contribs) 11:11, 19 March 2009 (UTC)[reply]
1) They don't. Their nostrils stay above the waterline in their normal floating position, so they can breathe normally.
2) When they do go underwater, just being a reptile allows them to hold their breath much longer, since reptiles are cold-blooded. Warming the body requires a great deal of energy, and "burning" that energy requires oxygen. Therefore, the oxygen requirements for cold-blooded animals are far lower. StuRat (talk) 11:39, 19 March 2009 (UTC)[reply]
Cold-hearted orb that rules the night....
I'm under the impression that the center of the Moon is far cooler than the center of the Earth. This brings up some Q's:
1) What are those two temps ?
2) Why the diff ? Does it have anything to do with the Moon being tidally locked to Earth, but the Earth not being tidally locked to the Moon ?
3) Is there a formula which can predict the temp at the center of a planet or moon, based on it's mass and distance from the Sun ? (I'd include density, but that may also be somewhat dependent on the temperature). StuRat (talk) 11:35, 19 March 2009 (UTC)[reply]
Partial answer to part 1: Various sources for the earth's core temperature are listed here with 7000 c. being most prevalent, 10,000 c. here, and 9,000 here, so as you can see there's little agreement, which is unsurprising given that we have no direct measurements and all answers are currently based on extrapolation. By the way, are you a Moody Blues fan? (or were they quoting someone else when they used that line?)—70.19.64.161 (talk) 12:17, 19 March 2009 (UTC)[reply]
Actually it's "Nights in White Satin": a song which is from an LP "Days of Future Passed" which is about the events of days and nights. Wherever do you get KKK from??? I'm not sure 5 lads from Birmingham (England) would even have heard of the KKK in 1967! --TammyMoet (talk) 14:24, 19 March 2009 (UTC)[reply]
The redirect made me think my spelling was correct. I wish they had a different color for links which point to redirects, to avoid this problem. The KKK members fancy themselves to be feudal knights, and often wear white satin robes (and many would consider them to be "white satans", too). The Birth of a Nation poster demonstrates both aspects. StuRat (talk) 14:50, 19 March 2009 (UTC)[reply]
For (2), that's likely some part of it, but our structure of the Earth article suggests that the prime source of heat is left over from planetary contraction. Given that the Earth is on the order of 80 times more massive than the Moon, I expect that explains the discrepancy nicely. For a partial answer to (1), inner core puts it at approximately the temp of the sun's surface, 5800K. — Lomn 12:21, 19 March 2009 (UTC)[reply]
That value is actually for the outer core-inner core boundary, according to the source quoted, so probably significantly hotter at the centre. Mikenorton (talk) 12:45, 19 March 2009 (UTC)[reply]
This source [37] gives a temperature for the centre of the moon as 830°C (1003°K). It also suggests that this temperature means that the concentration of radiogenic isotopes is greater than within the earth. If it wasn't for this heat source both bodies would be a whole lot colder (or need to be much younger). Mikenorton (talk) 12:58, 19 March 2009 (UTC)[reply]
I had no idea it was that hot. That means there's some point under the surface which is always a good temp for people, doesn't it ? It would also mean that "lunarthermal" power might be possible. StuRat (talk) 14:14, 19 March 2009 (UTC)[reply]
Might have to hold back on the lunarthermal energy, the quoted values for heatflow from the Apollo program are somewhat less than the average for the earth and the average is not enough to make geothermal energy a viable option (aside from heat pumps). As far as reaching a liveable temperature, I would guess just being below the direct influence of the diurnal temperature variation would be sufficient. Mikenorton (talk) 14:56, 19 March 2009 (UTC)[reply]
That and isnt the traditional method for geothermal energy involve large quantities of water to convert into steam? Something the moon lacks. 65.167.146.130 (talk) 15:24, 19 March 2009 (UTC)[reply]
I'd say that density has an effect on it too: Neptune's density and core temperature are both higher than Uranus', for example. ~AH1(TCU) 17:29, 19 March 2009 (UTC)[reply]
Stents
Hi does anyone know why stents, e.g. those used to counteract constriction of the common bile duct; are mesh like in appearance? Why are solid lumps of metal not used instead? Is there any point in them having a mesh structure? Thanks. —Preceding unsigned comment added by 139.222.240.225 (talk) 11:41, 19 March 2009 (UTC)[reply]
I would guess the mesh stints are flexible and move with the tissue better. I think its also good to minimize the amount of foreign matter in any body. The mesh stints can also be compressed while they are being put in place and then allowed to expand to their working dimensions.--OMCV (talk) 12:12, 19 March 2009 (UTC)[reply]
One reason may be that the mesh tubes are somewhat flexible (as noted above), a second one would be that the gaps allow for the continuing function of the walls of the duct and prevent some atrophy of a small section of the relevant passage (coronary, urinary, etc). --Cookatoo.ergo.ZooM (talk) 12:16, 19 March 2009 (UTC)[reply]
Stents have to be cylindrical to allow normal flow through the vessel (or duct) where they are located. They are inserted using a catheter that has a balloon around which the stent is wrapped. The balloon is passed into the narrow section, inflated, and then deflated leaving the stent to maintain the enlarged diameter. If solid-walled, the balloon would have to actually stretch the metal. Instead, the balloon just bends the metal mesh stent to conform to the wall of the vessel/duct (the length of the stent decreases as the diameter increases). --Scray (talk) 12:41, 19 March 2009 (UTC)[reply]
Similar to tights/stockings, really - a mesh is a very stretchy structure. --Tango (talk) 13:45, 19 March 2009 (UTC)[reply]
Help Me! I am stuck on some issues about Evolution
Evolution does away with God. No God. I then worship myself, doing whatever I want owing to no one.
Evolution does not happen around me. I have never seen a chicken turn into a dog.
I frequently see gaps in evolution. “Dino dung contains grass”.
About the dino bird: Why on earth does a dino turn into a bird.
Why do anything when the universe is just going to go kaboom in a billion years.
The Creation “myths” seem alright with me because I know Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years.
The Bible is bullied.
People use evolution for racist ideas. Evolution seems to allow racism. Compassion only came into existence because of chance. The Bible is also used to allow racism, but I read that we are to love every one as ourself. None of the: “I just evolved, no point in life, don't need to love coz love just evolved”.
DNA does not grow on trees. My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it. [Year 11 student in Perth, Australia] —Preceding unsigned comment added by 60.230.212.29 (talk) 11:45, 19 March 2009 (UTC)[reply]
You have a lot of questions there, and it might help to organize them better, say as a numbered list, if you expect answers to all of them. Also, evolution says nothing about the existence of God, just that God isn't necessary for the step of one species evolving from another (although you could still argue that God controls mutations). God may still be used as the cause of the Big Bang, etc. God (or "the gods") used to be thought of as doing everything, from making day and night to the seasons, but we now know that is all just a consequence of the Earth's rotation and revolution. In another example, we now know that the variation in children in a family is due to random combinations of DNA in chromosomes. StuRat (talk) 12:04, 19 March 2009 (UTC)[reply]
Let me say that it's really poor logic to conclude that anything you haven't witnessed personally doesn't exist. Also note that this would apply to everything in the Bible, unless you're a lot older than you seem. :-) StuRat (talk) 12:27, 19 March 2009 (UTC)[reply]
As for gaps in evolution, they are relatively small, and closing all the time as we find more fossils. Gaps in the Bible are absolutely huge, on the other hand, and not getting any smaller. For example, how did we get from Adam and Eve to all mankind ? Was there a lot of incest (as opposed to a Lot of incest) ? StuRat (talk) 12:31, 19 March 2009 (UTC)[reply]
As for your "Why do anything when the universe is just going to go kaboom in a billion years" (it's actually many billions), the same is true in the Bible, only on the order of thousands of years, isn't it ? That nasty Armageddon bit in Revelations ? And in billions of years, who knows, perhaps we will be able to travel to parallel universes which aren't about to die. StuRat (talk) 12:21, 19 March 2009 (UTC)[reply]
You said "Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years". You seem to be confusing evolution with geology. There are some geological formations which are formed quickly, yes. There are others which take millions or even billions of years to form. Plate tectonics is a good example of the later, where the continents all used to fit together. In some cases, it's obvious just by looking at them that they once did. The rate at which they are moving tells us it took many millions of years for them to get where they are now. Rates of radioactive decay also tell us that the oldest rocks on the Earth are around 4.3 billion years old. StuRat (talk) 12:51, 19 March 2009 (UTC)[reply]
To take on another of your Q's, let's talk about why a dinosaur might evolve into a bird. First, feathers are useful for flight, but also provide for good insulation. There are many flightless birds, like penguins, which use them for insulation. Next, flaps of skin can develop on arms to allow for longer jumps from tree to tree or on the ground. This has happened in flying squirrels, too. Then, once these basic items are in place, even a small improvement can allow for longer jumps or glides, both of which are helpful for survival. This eventually leads to all the birds. StuRat (talk) 12:14, 19 March 2009 (UTC)[reply]
If you pray to God for wings, and they sprout out and you fly away, then, by all means, believe in God. If that actually happens, I may even join you in your beliefs. StuRat (talk) 12:46, 19 March 2009 (UTC)[reply]
Neither evolution nor the Bible can be used to define a moral code. Evolution says nothing about morality. The Bible says a great deal; so much, in fact, that it has parts that can support any moral code you want, from slavery, genocide, and hate crimes against homosexuals, to the oppression of women. So, in either case, you come up with your moral code on your own, and only use evolution or the Bible to justify what you already believe. StuRat (talk) 12:42, 19 March 2009 (UTC)[reply]
Evolution does away with the literal interpretation of the bible god; it does away with the YEC's god, but evolution has little to say to millions who have compartmentalized enough to conform their mythos to the real world. Inductive logic is what does away with god. But based on your post, I'm wasting my breath. You need to take evolution in baby steps. Start with biology 101 and move progressively. I doubt that will happen but the problem is that you're so lost in the fundamentals, your knowledge of the subject so narrow, that you can actually say something like "I have never seen a chicken turn into a dog." By saying this you show that you have no understanding of evolution at all. Not even the tiniest scintilla, but have some one or two sentence idea of "things turning into other things for mysterious reasons" that is called evolution. The poster above is trying to be helpful but he's skipping the part where we sit down with you for months and months teaching you the basics so you have the slightest understanding to put his post in context.—70.19.64.161 (talk) 12:30, 19 March 2009 (UTC)[reply]
Have a look at Introduction to evolution and let us know if you have more questions. Btw, if you asked your teacher how you could "gain more DNA to grow wings", he/she probably thought you were joking. Zain Ebrahim (talk) 12:51, 19 March 2009 (UTC)[reply]
If you "know" that volcanos and floods can cause things that scientists say take millions of years than you're mistaken. Perhaps you're thinking of a common claim that the Grand Canyon could have been created during the Great Flood. This doesn't even stand up to casual examination by a layman. A massive amount of water unleashed at once would cut a wide, shallow swath, not a sharp deep one like a canyon. (And of course, once it's completely covered, even this effect would slow greatly.) You can verify this in your backyard with a large tub of water and a garden hose.
"My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it." He is right. The only way you -personally- will will gain additional DNA is divine intervention. Evolution is caused by children having slightly different DNA than their parents. Once you're born you're stuck with whatever DNA you've already got.
"Why do anything when the universe is just going to go kaboom in a billion years." Frankly, I've always thought the answer to this is : "To see how much cool stuff we can do before then." APL (talk) 13:24, 19 March 2009 (UTC)[reply]
And finally, just for the record, DNA does grow on trees! --Sean 13:45, 19 March 2009 (UTC)[reply]
In the form of fruit, no doubt. As for sprouting wings, eventually scientists may be able to use a virus to insert genes (to grow wings) into our DNA. However, the wings we would grow would only be decorative. To make a human capable of flight would require a total redesign of our entire body, including tiny legs. StuRat (talk) 13:54, 19 March 2009 (UTC)[reply]
You say on the first line without God you would do what you want owing to no-one. Have you asked yourself if there really is anything much different you would actually do without God looking over your shoulder? Or are you thinking that other people would behave any differently? Dmcq (talk) 14:19, 19 March 2009 (UTC)[reply]
On the subject of sprouting wings. There is a slight problem with the fact that the Angel type of construction basically adds another set of limbs when compared to ordinary things with wings like birds or bats. You'd not only need divine intervention to get wings, you'd also need a constant miracle to move them or would have to add a rather unsightly hump to your ordinary back. Artist pictures don't show any muscles needed to move the wings. (Not to mention the joint that connects them to the body). I assume they are just a decorative appendage and your divine entity would actually provide for Levitation. 76.97.245.5 (talk) 14:57, 19 March 2009 (UTC)[reply]
Oh my - what a lot of questions. Well, now that you've asked so many - you are honor bound to slowly read through ALL of my carefully thought-out answers! No cheating and skipping the ones you don't agree with!
Evolution does away with God. No God. - Not precisely. Evolution does away with the need to use god or gods to explain how we came to be. You are still at liberty to assume that god(s) made the world in one night on September 12th 1962 - and just made it all "look" like there was evolution. It's a pretty crazy thing to believe - but if you've gotta have a god to sleep at nights - there you go.
I then worship myself, doing whatever I want owing to no one. - Well, you COULD - but you live as a part of society that imposes rules in order to make life bearable - and if you do literally "what you want" - then the odds are good that other people will get pissed about it and you'll find that you are physically unable to continue doing what you want. Societal pressures to behave according to the norms are considerably more effective than religious pressures simply because the punishment or restraint is immediate and vastly more certain. I'm fond of pointing out that the Bible is the most shop-lifted book in the USA. Clearly people who are going into bookstores and stealing them aren't afraid of divine retribution.
Evolution does not happen around me. I have never seen a chicken turn into a dog. - No, but if you lived in New York, you'd have seen rats turn into Warfarin-resistant rats that thrive on eating rat poison. If you worked in a hospital, you'd have seen tuberculosis-causing-bacteria turn into tuberculosis-causing-bacteria-that-you-can't-kill-with-antibiotics. The process is relatively slow. However - (for example) humans appear to have evolved to become lactose-tolerant over a space of a few thousand years - and the process isn't complete yet...that's truly evolution in action. There are MANY cases where evolution can be observed happening for real right in front of your eyes in a test-tube. But to change a chicken into a dog might require millions of years of evolution - and that's something you obviously can't see happening before your very eyes. Just because a process takes a long time isn't a reason to assume that it's not true. It took a long time for a relatively small river to carve out the Grand Canyon...but we don't go around denying that this is how it happened.
I frequently see gaps in evolution. - no you don't. You frequently hear like-minded "intelligent design" idiots CLAIMING that there are gaps in evolution. You've never personally spotted one. In fact, science is still plugging holes - finding fossils isn't something you can do "on demand". If you don't happen to have a fossil that shows something halfway between a smooth-skinned fish and one with scales doesn't mean that there is a horrible "gap" that completely blows away the theory - it simply means that nobody has yet found a fossil of that particular animal. Because we HAVE found long chains of very similar animal fossils that DO show continuous, gradual, gapless change from one species to another - we KNOW for 100% certain that those particular species evolved. And with every 'chain' of fossils we find, the gaps get smaller and less frequent - but to expect to have complete evidence for the pathway from every single creature to every single other creature is stupid. There comes a point (and we're WELL past it) where the evidence is simply overwhelming and the gaps are perfectly explicable. "Absence of evidence is not evidence of absence."
About the dino bird: Why on earth does a dino turn into a bird. - Because of some sort of evolutionary pressure. If running along the ground is too dangerous because of predators (say) then maybe a small genetic change allows the creature to have the musculature to climb trees. That creature does better than the earth-bound dinosaurs - so it survives when the ground-based ones are all eaten by predators. However, the ones in the trees still have to climb down out of one tree and up into the next - so they are vulnerable still. If one baby tree-dino happens by luck to have genetically stronger legs and can jump from a tree to another nearby - it'll spend less time on the ground and it (and it's offspring) will thrive while the ones that have to climb down don't. Now, they only have to go to the ground to get from one clump of trees to the next. But if they evolve a flap of skin or feathers and lighter weight bones - they'll be able to glide between trees that are still further apart. Then they may evolve powerful muscles to allow them to flap a bit. Before you know it (and over half a million years) you have birds. Then something happens to all of the predators (like maybe a meteorite kills them all) and the birds have no more predators on the ground - so evolving to be more capable on the ground so you can eat stuff you only find down there - makes sense. Now you have flightless birds like chickens. When the predatory mammals come back - they evolve into ostritches that can kick the hell out of a predator...and so on and so on.
Why do anything when the universe is just going to go kaboom in a billion years. - Indeed, why? Guess what? It's evolution again. If a bunch of humans got it into their silly heads that they should just lie in bed until they die because life is pointless - then they'll fail to pass their crappy genetic makeup onto any children - so only the kids of the people who suck it up and try to make something of themselves will survive into succeeding generations. Before you know it - we've evolved a powerful drive to survive - to have children and to look after them. Hence we are genetically PROGRAMMED not to shrug our shoulders and give up on the world.
The Creation “myths” seem alright with me because I know Volcanoes and Floods can create what Evolution scientists claim to have taken millions of years. - Bullshit. Please explain how a volcano or a flood turns a dinosaur into a chicken? I explained how evolution can do it. What you are REALLY saying is that this is all too hard for your tiny little brain and you're too stupid to think for yourself so you'd rather be spoon-fed a bunch of nonsense than to actually examine how the universe works - look at the evidence - take your sorry ass down to the nearest decent natural history museum and ASK one of the curators if they can show you some fossil sequences to help you to understand. Nope - it's better for you to have some idiot in a silly costume get up there on a sunday morning and tell you that it all happened by magic. Well, good luck with that!
The Bible is bullied. - The Bible is WRONG. I've actually read the Bible - not just a verse here and there as instructed by some Sunday school teacher. I started at page one and read it all the way through - like a real book. It's CRAP! It's self-contradictory, inconsistent, flat out unbelievable. It starts off with this rabid lunatic of a god who does the nastiest things imaginable for the smallest reason - to someone who is supposed to be kind and caring and it's all rainbows and unicorns. You actually have to read the book with open eyes to see what a pile of steaming crap it really is.
People use evolution for racist ideas. Evolution seems to allow racism. - I don't understand why you'd say that. People have certainly used the Bible to promote racist ideas. Just take a look at the KluKluxKlan nut-jobs! They are passionately religious - and equally passionately racist - and they justify every word of their racist nonsense from the Bible.
Compassion only came into existence because of chance. - Actually, there is evidence that compassion and being nice to people and stuff like that is evolved too.
The Bible is also used to allow racism, but I read that we are to love every one as ourself. - And I read (in the Roman Catholic/Lutheran bible - the first of the 10 commandments - that if you worship an idol - your children, grandchildren, greatgrandchildren and great-great-grandchildren will be punished. Sheesh! So if my great-great-grandfather was worshipping idols - I get punished for it!?! Nice god! The bible also says that if your son swears at you - you should kill him. (Although you aren't actually ALLOWED to kill him...hmmm tricky). Really - it doesn't stand up to close examination.
None of the: “I just evolved, no point in life, don't need to love coz love just evolved”. - Nobody who believes evolution to be true says that. We have EVOLVED to have point to our lives. Heck - I'm an out and out atheist - I love life. I had fun as a kid learning stuff - I loved - I married (although a civil contract would have been OK by me). I have a son - we enjoyed bringing him up right - teaching him moral values - things that make society run well "Don't kill people - don't steal things - but go ahead and covet your neighbours ass - I don't give a damn about that". We've EVOLVED those concerns because we're a tribal society. Getting on with a village of people is how we're programmed to be. Passing our DNA onto the next generation is something we're powerfully driven to do. Anyone who didn't have those drives - passed on in their DNA from their parents - would not have children of their own - their DNA would not get passed on. So only the people with genes that give them the drive to have children get to pass their DNA on...so after not too many generations, pretty much everyone wants kids - most people like raising them. It's evolution that does that.
DNA does not grow on trees. - yes it does! :-)
My science teacher recons that the only way to gain more DNA so I can grow wings is to ask God for it. - your science teacher is 100% correct in that! Certainly you can't "gain more DNA" by any known scientific means - you're absolutely stuck with what you were born with. If/when you pass your (and your partner's) DNA onto your children, their DNA will be a little bit different - and the DNA of THEIR children will be different still. If there is an evolutionary pressure for humans to sprout wings and fly - then perhaps over tens of thousands of generations, that MIGHT happen. Evolution is a slow process. So - if there is a god - you could certainly pray for DNA to grow wings with...and by all means try that. Pray your darnest...plead with God for those wings. Do you REALLY think he'll give them to you? I don't.
Steve, the refdesk is not a soapbox. —Preceding unsigned comment added by 65.167.146.130 (talk) 19:10, 19 March 2009 (UTC)[reply]
Soapboxing refers to a situation where someone pretends to ask or answer a question, but is actually just propagating his agenda (or, in some cases, doesn't even bother with the question part at all). Clearly, Steve is answering the original poster's specific questions, and doing a pretty good job of it, too. Yes, absolutely, you can also tell that Steve has opinions about the matter at hand, but he's not expressing them instead of answering the questions. -- Captain Disdain (talk) 19:30, 19 March 2009 (UTC)[reply]
I actually don't see a question from the OP, merely a long list of statements.65.167.146.130 (talk) 19:57, 19 March 2009 (UTC)[reply]
He may not be soapboxing, but Steve, please dont bite. Livewireo (talk) 20:07, 19 March 2009 (UTC)[reply]
As an aside, I will worship any god, demon, or other deity that gives me the capacity for free flight without any technological support. (I would prefer a pair of wings, but Superman-style flight would also have its advantages.) It goes without saying that I expect this ability up front before I start with the worshiping. I'm an atheist, But I can be bought. :-) APL (talk) 21:19, 19 March 2009 (UTC)[reply]
I'll join you in that religion, but if it's going to be superman-style flying someone had better give me a cape - I'd look stupid without one! --Tango (talk) 23:08, 19 March 2009 (UTC) [reply]
Could I take the free flying stuff - then weasel out of the whole worshipping thing afterwards? SteveBaker (talk) 23:34, 19 March 2009 (UTC)[reply]
Might be unwise. The Lord giveth, and the Lord taketh away - and if He taketh away thy flying at 25,000 feet, thou art screwed. - EronTalk 23:36, 19 March 2009 (UTC)[reply]
That's why sensible gods don't give all their rules in written form - it makes it too easy to find loopholes. If you keep the rules nice and vague you can make them fit the situation however you need. --Tango (talk) 23:39, 19 March 2009 (UTC)[reply]
The Bible is WRONG Hm Steve, what about the very first chapters of the Bible (and some other chapters) being just symbolic? One should read the Bible for it's moral teaching, it's not intended to be used as a science book. Too bad some zealots try to regard it (and try to enforce it) still as a science book, destroying the main concept behind it... and by doing so they are making religion to look ridiculous too. —Preceding unsigned comment added by 79.116.91.3 (talk) 01:19, 20 March 2009 (UTC)[reply]
You haven't read it have you? I tell you - start from page 1 and read to the last page...it's an education. The old testament is NUTS - yeah, yeah - it's all symbolic. So why the heck does it matter if it's just a work of fiction? I don't think the stories surrounding the ten commandments are intended to be symbolic. That bit is really pure slapstick - the guy spends an age up there chatting with god - chiseling the words into literal stone tablets - and when he gets back he drops them (oopsie!) and the break so and has to go back up to god and get another set...but this time, God has obviously lost his train of thought because the second set have completely different rules...this combined with a God who really needs to switch to decaf. SteveBaker (talk) 04:03, 20 March 2009 (UTC) [reply]
Symbolic or not, you can't just cherry-pick the parts that sound nice -- bring up the cuddly "let's all just get along" bits as proof of how wonderful moral guidance the Bible provides and ignore the crazy-ass "the hero of the story murders 200 people for their foreskins to prove his righteousness and get some poontang" bits.
Oops, that was me. I forgot to sign. -- Captain Disdain (talk) 12:08, 20 March 2009 (UTC)[reply]
Moral teachings as in "The most important thing for anyone to do is to cater to the megalomanic whims of their creator."? No thanks. --Tango (talk) 14:48, 20 March 2009 (UTC)[reply]
Just by the way, I can always, always tell when it's SteveBaker who is posting. Your style of writing, it's etched into my memory. Especially with allcaps for EMPHASIS (no pun intended). ~AH1(TCU) 01:39, 20 March 2009 (UTC)[reply]
Never mind the writing style (which is very distinctive, I agree) - you can tell from the length! --Tango (talk) 14:45, 20 March 2009 (UTC)[reply]
A chicken turned into a dog? Here you go.[38] --JGGardiner (talk) 02:46, 20 March 2009 (UTC)[reply]
I was at a trendy restaurant yesterday and they served a salad dressing made of balsamic vinegar and "Soami Oil". Surprisingly, no one could tell me what Soami Oil is. And there is no entry for it on Wikipedia. Any idea what it is? And is it even legal to serve a substance that no one can define? --67.66.110.148 (talk) 15:15, 19 March 2009 (UTC)[reply]
Just a wild guess, but there is Radha Soami Satsang Beas. It might be the newest fad, sort of Ayurveda used to be "in" and every marketing department tried to get it on their label.76.97.245.5 (talk) 15:38, 19 March 2009 (UTC)[reply]
Another very long shot, there's a company in Pune, India called 'Swami Oil Industries', that appears to make edible oils. Mikenorton (talk)
Laser safety
Is there something wrong with the graph at the start of Laser safety#Maximum permissible exposure? As I am interpreting it, the longer that you are exposed for, the higher the dose you are allowed to receive. That seems completely backwards. The second graph looks much more sensible. Should I just delete the first one? -- SGBailey (talk) 15:57, 19 March 2009 (UTC)[reply]
I haven't checked to see if it agrees with the source, but it seems to make sense. It's a graph of total energy absorbed (per square centimetre of eye) against time, so it's saying that the more total energy you absorb, the more time this dose has to be spread out over for it to be safe. Algebraist 16:14, 19 March 2009 (UTC)[reply]
Indeed. The difference between the two graphs is that the first is talking about energy density (J/cm2) and the second power density (W/cm2). The same amount of energy over a longer time is less dangerous because it corresponds to lower power. The same power over a longer time is more dangerous because it corresponds to more energy. --Tango (talk) 16:23, 19 March 2009 (UTC)[reply]
Ahh. OK. Thanks -- SGBailey (talk) 17:03, 19 March 2009 (UTC)[reply]
String theory
I've often heard that the mathematics behind string theory is really, really, really complex and that few can interpret the equations, let alone understand it. Could anyone provide an example of where I can see this stuff? I don't intend to try and understand it, I'm just curious to see how complicated we're talking here. —Cyclonenim (talk · contribs · email) 17:46, 19 March 2009 (UTC)[reply]
Hi. Recently on the non-residential sub-urban streets, especially those with lots of large trucks and side-road sand, I've noticed a particular strong and intermittent smell. It smells rather like three parts glue, two parts rubber, one part latex, one part chlorine, one part automobile exhaust, half a part paint, half a part sand and asphalt, half a part vinegar, a quarter part garbage, and a quarter part gasoline, co-mingled together. Sorry about my confusing decription, but I find it easiest to compare unidentified olfaction to other smells, and idea what it is or what causes it? Thanks. ~AH1(TCU) 17:54, 19 March 2009 (UTC)[reply]
In S. Ontario, in the GTA. Does that help? ~AH1(TCU) 18:30, 19 March 2009 (UTC)[reply]
It could be the asphalt they use to plug potholes. Is there a lot of black patches on the road that look like shiney black glue mixed with rocks? Livewireo (talk) 19:51, 19 March 2009 (UTC)[reply]
It may not be entirely out of the realm of possibility that you are smelling exactly what you have described depending on the surroundings. Truck exhaust, asphalt, garbage haulers, and any typical manufacturing facility (if there are any close by) can all be adding to the mix. cheers, 10draftsdeep (talk) 20:27, 19 March 2009 (UTC)[reply]
Here in North Carolina, lots of trees are in bloom right now, and many, like the Dogwood and Bradford pear trees in my neigboorhood have a rather pungent smell. It reminds me of methylamine sorts of smells (mildly like rotting fish), but lots of blossoming trees do give off odors that many people find unpleasant, like this one. Or it could just be all the stuff noted above. --Jayron32.talk.contribs 00:02, 20 March 2009 (UTC)[reply]
Pharmacological naming convention
I was wondering if there was any convention/rule/guideline for naming new medicine? I see there is a nomenclature for enzymes. Is there anything similar for drugs, such as anesthetics, etc.? --BorgQueen (talk) 18:38, 19 March 2009 (UTC)[reply]
My friend is suffering frm sinus infecion.....he drinks a lot of cold drinks..but at d moment he is suffering frm hi fever nd head ache.
he consulted a doc. nd he said he has got cough depostied in his head.
the doc. has given him medications. and said if these dont work....he needs an operation.
i m a bit scared .is it something serious or is it ok....?????????
pls suggest me wid something......... —Preceding unsigned comment added by Sweetgirl290608 (talk • contribs) 18:39, 19 March 2009 (UTC)[reply]
We are not medical professionals here and we can't give medical advice regarding how serious your friend's case may or may not be. For general information about sinus infections, you should read the article on Sinusitis. - EronTalk 18:45, 19 March 2009 (UTC)[reply]
Specifically, see here. We cannot offer you anything more than this, please tell your friend to see a doctor, and if you're interested, ask to go with him too. —Cyclonenim (talk · contribs · email) 18:46, 19 March 2009 (UTC)[reply]
Focalin shortage?
I've been trying to get a prescription of focalin refilled for about three weeks. They pharmacies say they haven't been able to get it and no one else has either. I asked if it had been recalled and they said no. Is there a shortage? Did they quit making it? Why aren't they able to get it?
I tried to find out who makes Focalin so I could ask them, but I could not find it. Bubba73(talk), 18:48, 19 March 2009 (UTC)[reply]
I don't know the answer to your main question, but the first line of our focalin article says that this company produces it. —Cyclonenim (talk · contribs · email) 19:32, 19 March 2009 (UTC)[reply]
You should ask your doctor for help. S/he probably has samples of the drug that can tide you over until you can get a supply, and also contacts in the drug industry who will be very motivated to get you back on their product. You can also legitimately order scheduled drugs online after doing some paperwork. --Sean 19:42, 19 March 2009 (UTC)[reply]
I did call them today, they are supposed to get back to me. Sorry I missed the manufacturer in the article. Bubba73(talk), 21:14, 19 March 2009 (UTC)[reply]
doors
I had always assumed the huge old wooden doors with the rusty metal hinges were made of oak and iron, but I recently discovered these two materials don't work very well together. What actually happens if they are put together, and what do people use instead?
148.197.114.165 (talk) 21:16, 19 March 2009 (UTC)[reply]
Brass is a possibility. Wrought iron surface is different from cast iron. Annealing doesn't mention it, but this article does [41]. Not sure whether that would affect how it interacts with oak. Since oak was used for tanning presumably before it was used for doors, people probably knew about it's properties. AFAIK oak was often soaked and dried before it was used in construction. They also used pitch as surface treatment. My money would be on the Tannins in the oak wood eating your iron. Some of them are acids. 76.97.245.5 (talk) 22:26, 19 March 2009 (UTC)[reply]
I'm not familiar with the details about how they would react, but I would note that common writing ink until very recently was iron gall ink, made from iron compounds and tannin rich oak galls. -- 76.201.156.15 (talk) 03:32, 20 March 2009 (UTC)[reply]
Iron through wood accelerates the decomposition of the wood by feeding bacteria an essential element in short supply. Also you get the black staining due to the iron tannin compounds. Graeme Bartlett (talk) 05:22, 20 March 2009 (UTC)[reply]
I am currently studying organic chemistry, and I was curious how this particular synthesis could be accomplished. These are the steps I used, and I would like someone to tell me if they are correct. No, this isn't a homework problem, I was just curious how this could be accomplished. I know it's not the most economical way to synthesize it; I was just curious.
1)I used Friedel-Crafts alkylation (CH3Cl & AlCl3) to add a methyl group.
2)I added a diazonium group to the para position using NaNO2 and HCl.
3)I added PCC to oxidize the methyl group to an aldehyde. I'm not sure if I used the right oxidizing agent here.
4)I brominated the compound with Br2 and FeBr3.
5)I replaced the bromine with a methoxide group by adding sodium methoxide.
6)Finally, I converted the diazonium group to a hydroxyl group by adding an aqueous acid (H3O+).
CalamusFortis 21:59, 19 March 2009 (UTC)[reply]
PCC may not work. PCC generally is specific for taking alcohols to carbonyls. I don't think it is strong enough to take a simply alkyl group all the way to the carbonyl. The other steps look OK, so long as the methoxide will not also substitute the diazonium. You may also want to protect your aldehyde once it is made; else you may end up with unwanted side reactions like the Aldol condensation. See Protecting group for more info on this. --Jayron32.talk.contribs 23:47, 19 March 2009 (UTC)[reply]
I see a few problems here, especially if this needs to be any sort of practical (vs "looks possible on paper") approach:
1 Getting a methyl electrophile is probably pretty hard (think about stability of carbocations). Might work, but would be easier to put on...well anything else. Given that you're going to oxidize it, could even be an ethyl or isopropyl, since those additional carbons can be cleaved in step 3.
2 To get diazonium (Ar-N2+), you use those reagents starting from Ar-NH2. For a simple aromatic, those give you the nitroso (Ar-NO). Which could be reduced to the amine.
3 Jayron is right...PCC only oxidizes alcohols well. Need something stronger and mechanistically different for benzylic position (I think KMnO4 is standard).
4 Your ring is *very* electron-deficient at this point (diazonium and aldehyde are electron-withdrawing) so doing another electrophilic aromatic substitution is probably too slow to be practically useful. And I don't think you would get good positional control. Diazonium is probably a strong meta-director and you want to Br go ortho to it.
5 Given how electron-poor the ring is (now with 3 inductively withdrawing groups!) an addition/elimination mechanism for this substution might work, but it's clearly *not* an SN2-type displacement and you have the risk of forming benzyne and then getting the nucleophile adding at a different position. Heck, you've got the diazonium too, which is a much better leaving group. Although it might be unlikely for it to have stayed attached this long.
Overall, might be better to activate the ring first as aniline, then put the para and then ortho substituents on (the NH2 would make the electrophilic reactions go faster whereas diazo and carbonyl each make it go slower), and last diazotize and convert to the hydroxyl. DMacks (talk) 00:04, 20 March 2009 (UTC)[reply]
It should also be noted that synthesizing ANYTHING from benzene is pretty much a pointless exercise; benzene is fairly chemically inert, and substituted aromatic compounds are readily availible. It's about as useful as synthesizing anything with only methane as a starting material. It is theoretically possible, but practically pointless. Our article on Vanilin gives numerous other synthetic pathways to make it, and none are as convoluted as taking it from unsubstituted benzene. If this is a homework problem, I sympathize with you, and say that you should have enough between your initial ideas and those of myself and Dmacks excellent additions to put together a workable synthesis; just know that this is a purely academic exercise; no real chemist would do it this way... like, ever... --Jayron32.talk.contribs 02:54, 20 March 2009 (UTC)[reply]
Free will
Everything is life is subject to the laws of physics, and therefore act accordingly. If you drop a rock it will fall down, if you flip a coin it will fall with some outcome. My question is, isn't everything predetermined? Because everything I do, every action every human being and object does in the world is because of the laws of physics. Am I right in saying that if you flip a coin, flicking it with your thumb with a specific amount of force in a specific environment (something like wind, no wind, rain) everything happens because of physical interactions (e.g. a drop of rain falling on the coin) and could only happen in one way. What I wanted to know, is this true? Is there anything in nature that's random? Is there anything that, given the same environment, given the same forces and objects at the same time- would result in something... else? Can two occurrences that are completely the same in every possible metaphysical (I don't know what that word means, it just sounds smart) manner end up.. not being the same?
I hope I've gotten my point across, what I basically mean to ask "is there anything in life that is really random". I don't have much knowledge of quantum mechanics but I've heard that on a quantum level random things do occur, but my question is whether they are really random? To someone like me who doesn't know much about quantum mechanics, it seems impossible that two coin flips that are the same and are affected by the all the same forces and hit the exact same table on the same place should produce different results. If so, how can there be free will if every action we take is because of some chemical or physical reaction in our environment or bodies? --BiT (talk) 22:31, 19 March 2009 (UTC)[reply]
I would like to add that despite the fact that your line of thought is quite common, I find it very puzzling. I see free will as a sentient being's ability to make good choices given the circunstances. Good choices are more often based on logic than on randomness. Dauto (talk) 23:15, 19 March 2009 (UTC)[reply]
No - there are at least two or three reasons why things aren't predetermined...firstly there is quantum randomness - secondly there are chaotic systems. Both of these things guarantee that at least in some situations you can't predict the outcome of some future event with perfect certainty. At least once during the infinite life of an infinite universe, all of the molecules in your rock will spontaneously leap 6" to the right and not fall as you expected. Well, OK - that's pretty rare - but there are certainly 'macro-scale' things that you can't predict. There IS perfect randomness.
However, I don't think you can parley "randomness" into "free will". I don't think we have free will...quantum randomness and chaos theory notwithstanding.
SteveBaker, I agree with you that quantum randomness is a red hearing in discussions about free will. What I don't understand is why so many people equate determinism with lack of free will. As I see it, exactly the opposite is true. Total randomness destroys free will and determinism preserves it. Dauto (talk) 05:50, 20 March 2009 (UTC)[reply]
I find it rather difficult to define "free will". It requires a concept of conciousness that is somehow outside of science in order to make any sense. --Tango (talk) 23:37, 19 March 2009 (UTC)[reply]
It's a common misconception that true randomness can be found in chaos theory. In fact it cannot. A quick read of our own article will show that these systems "appear to be random" and "this happens even though the system is deterministic". Chaos theory is about systems where the tiniest deviation in the starting condition can produce huge changes in the end condition, which makes them practically impossible to predict, but they are in principle predictable. DJ Clayworth (talk) 23:38, 19 March 2009 (UTC)[reply]
I strongly disagree. Chaotic systems might be predictable in principle - but only if you have literally infinite precision in the measurement of initial conditions....but you don't...you CAN'T - you don't have enough paper to write down all of the digits of data to put into the calculations - and there isn't enough energy in the visible universe to crunch the numbers. Even without resorting to "oh no - you can't measure things that accurately because that nice Mr Heisenberg said 'No'."...a completely classical system can be literally impossible to predict. SteveBaker (talk) 03:32, 20 March 2009 (UTC)[reply]
When we're talking about a philosophical subject like Free Will, the question is "is the future determined" not "can we predict the future". Chaotic systems are determined, whether or not we can predict them. I would submit that to deny that the future is determined we have to invoke Heisenberg and quantum; chaos theory won't do it. DJ Clayworth (talk) 14:13, 20 March 2009 (UTC)[reply]
Well - I suppose at that extreme (both of logical position and linguistic interpretation!) - you are right for truly 'classical' systems when you are only talking about predetermination and not prediction. But - of course - there are quantum effects that are truly random (in the not-predetermined sense). What chaos theory does in the real world is to magnify the true uncertainty of the quantum world into macro-scale uncertainty. In a system such as when the ultimate position of a metal-tipped pendulum swinging over two strong magnets is determined by it's starting position in a 'fractal' manner, and for some regions, the initial position of the pendulum has to be known to literally infinite precision - but for quantum/heisenberg reasons, we know that's impossible. Hence the final position of the pendulum is indeed both entirely unpredictable (even in principle) and not predetermined (in the sense that quantum effects are not predetermined). The chaotic nature of that system magnifies quantum uncertainty to macro scales. So even something as 'classical' as a pendulum over two magnets is affected by quantum randomness - and that's enough to bust open predestination. However (as I said before) I don't think that opens things up to "free will" since we cannot influence either the macro-scale chaotic system that is our brain or the quantum randomness that drives that unpredictability. I suppose if you want to equate free will with some quantum-scale randomness, then you have your "get out clause" - but it's not very convincing. SteveBaker (talk) 14:45, 20 March 2009 (UTC)[reply]
i think that evry thing run with aperfect order ... random theories is a sily way to avoid looking for answers , evry action on this universe will affect the whole universe by the way under the same conditions.
the problem that we are trying to explain the whole universe while we're still ignorant about alot of the world basics,even in the most trustable theories in science we have to assume that the light travel with qunstant velocity , while its not, but this assumption could twist the theory so much in ahigher level , and thats why as the science keep going we try to come up with a more accurate theories .
when you try to build lets say a 1000 mile\ hour car you will need more accurate calculations than the ones you will use to build a 150 mile\hour car .
we always try to simplefy evry thing so we can predict it , and there were evry thing goes wrong . and when evry thing go very very complex for our minds we start to use this randomness theories . —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 02:01, 20 March 2009 (UTC)[reply]
Well - you're in good company. Albert Einstein refused to believe it too - but sadly, the fundamental randomness of the subatomic world is all too real. If your computer has flash-memory in it - then it only works because of quantum randomness. This is more than just some maybe-true theory - we can do real engineering using it and produce real products that depend on it. SteveBaker (talk) 03:35, 20 March 2009 (UTC)[reply]
I apolgose for sounding arrogant, but most people here (except Tango) are missing a very important point because they are so used to the determinism of physics being the unviolable constant in natural science. Let's start at the beginning... the determinism of physics was discovered through the efforts of various scientists like Galileo and Newton who deciphered various physical laws that governed the behaviour of physical bodies. Determinism wasn't always the accepted (or intuitively correct) principle. The discovery of physical laws went up to make up the edifice of physics which was governed by fixed laws. These laws, until the discovery of quantum processses, meant that you could predict the behavious of any physical system accurately as long as you know the state of the system (position and velocity of particles) at a given point. Now here comes the important part... at some point people (like our OP) make the mistake of extend the determinism of PHYSICS to humans as if humans were nothing more than physical systems. The difference is that there is an entity called the will, which comes into the picture to decide how we will behave. This entity of the will lies outside the purview of Physics. I am not talking matphysical mumbo jumbo here. It is an important question in the study of the philosophy of mind - extending to the concepts of materialism/dualism/idealism. In short, the determinism of the physical world does absolutely nothing to undermine the existence of free will - and you don't need quantum indeterminism or chaos theory to account for that. The question of free will is fundamentally a philosophical one, not physical. --ReluctantPhilosopher (talk) 07:28, 20 March 2009 (UTC)[reply]
What was the arrogant part - that you claim humans are more than just "physical systems" with no evidence to back it up? To me all the evidence points to humans being organisms, with which our "will" helps us maintain homeostasis and ultimately reproduce. Although the physical system can act differently, i.e. in suicide. Depression is still a very complex disorder which isn't well understood and many brain regions are involved, so I can't say specifically what is wrong which would lead to a human to kill itself. --82.21.28.65 (talk) 11:11, 20 March 2009 (UTC)[reply]
"you claim humans are more than just 'physical systems' with no evidence to back it up" - well there is no evidence to the contrary either. You are basically arguing the case for materialism. Materialism states that everything is fundamentally physical, with "will", "conciousness" etc. just being words we throw about to account for our experiences. Well it's not a settled question - and the debate is very much alive on it. Dualism and Idealism are other alternatives. I personally believe in a sort of dual aspect theory --ReluctantPhilosopher (talk) 11:55, 20 March 2009 (UTC)[reply]
Well, you're the one positing an extra-physical "will", so you're the one obliged to do better than saying "there's no evidence to the contrary". --Sean 14:11, 20 March 2009 (UTC)[reply]
Well I am not the only one positing an extra-physical will - as I said it's a subject of philosophical discussion. Will, consciousness, mind - do they exist independent of the physical - it is the subject of philosophy of mind. --ReluctantPhilosopher (talk) 14:38, 20 March 2009 (UTC)[reply]
Btw, I would perform the gargantuan feat of solving the mind body problem if I could "do better than" just stating what the different viewpoints are :D --ReluctantPhilosopher (talk) 14:51, 20 March 2009 (UTC)[reply]
Einstein only refused to believe in it until there was an overwhelming amount of evidence for it. Once that evidence was provided he accepted it, as any good scientist would. --Tango (talk) 12:39, 20 March 2009 (UTC)[reply]
I'm not sure that that is correct. My understanding is that Einstein never accepted quantum mechanic's indeterminism and tried until his death to find a deterministic model. A Quest For Knowledge (talk) 13:09, 20 March 2009 (UTC)[reply]
Well, yes, I guess you are right - he accepted most of QM, but not the Copenhagen interpretation of it. As I understand it, it was about 17 years after his death that experiments were performed that conclusively showed things like the EPR paradox should be resolved in favour of QM. I don't think he disagreed with anything that was firmly supported by experimental evidence that was available to him (although I could be wrong - I haven't studied the matter in any depth). The point I was trying to make (rather unsuccessfully, perhaps) was that arguments to authority along the lines of "Einstein didn't believe in QM, so neither do I" are seriously flawed since we have access to more experimental data now than Einstein did when he made those statements. --Tango (talk) 14:42, 20 March 2009 (UTC)[reply]
Carbon Fiber
What exactly is the tensile strength for carbon fiber? And how much does it cost? I can't find the information anywhere. I thought this might be a good place to ask. <(^_^)> Pokegeek42 (talk) 22:42, 19 March 2009 (UTC)[reply]
Our article gives a value of 5650MPa or 820,000 psi for the tensile strength, but note from this source "Overall, the strength of a carbon fiber depends on the type of precursor, the processing conditions, heat treatment temperature and the presence of flaws and defects"[42]. Mikenorton (talk) 23:01, 19 March 2009 (UTC)[reply]
Also, the tensile strength for carbon fiber will depend on the orientation of the fibers, as well as the matrix you use to bond the fibers. It is entirely possible for the tensile strength for a force in one direction to be 2x that in another direction. Also, the manufacturing process will introduce errors that can weaken the carbon fiber, so there is not really a simple answer to this question. As far as cost goes, I am not sure, but I believe a lot of the high costs associated with carbon fiber is not so much the cost of materials, but the cost of labor. It is time consuming to manufacture if you want quality stuff.65.167.146.130 (talk) 13:30, 20 March 2009 (UTC)[reply]
hair drug tests
would washing your hair with aloe vera,chlorine,bleach and other cleaning chemicals gaurenty passing a hair drug test?? —Preceding unsigned comment added by 76.14.124.175 (talk) 23:08, 19 March 2009 (UTC)[reply]
Probabily not. It might make it obvious that you tryed to hide your past drug use though. Dauto (talk) 23:18, 19 March 2009 (UTC)[reply]
No - the drug residues are inside the hair - not on the outside where it could be washed off. I guess you could shave it all off...that would make it kinda difficult to test! But don't forget it would have to be ALL of the hair on your body....hmmm - I guess that also might make it obvious that you tried to hide your past drug use. SteveBaker (talk) 23:27, 19 March 2009 (UTC)[reply]
(EC with SteveBaker) Hey... My wife did her master's thesis research on drug testing in hair, so she is uniquely qualified to answer this. According to her, the drugs are bound in the structure of the hair itself, and any topical washing is going to have no effect on this. Even treatments like bleaching and the like will not remove it; it may reduce the concentration slightly, but there is no way to remove all traces of the drugs from your hair. According to her (who spent two years studying this exact thing, mind you) the only way to get rid of the drugs is to get rid of the hair. Good luck with that! --Jayron32.talk.contribs 23:29, 19 March 2009 (UTC)[reply]
Our article on drug testing notes that hair testing can be done on just the follicle, so shaving won't, er, cut it either. Better hope for a case of this instead. - EronTalk 23:31, 19 March 2009 (UTC)[reply]
Wouldn't that only detect very recent drug use, though? The idea of testing hair is that it can detect drugs that were in the system when that hair was grown, which could have been some time ago. I think shaving your head would work as long as you haven't used drugs in a long enough time that the hair anywhere else on your body isn't long enough (and therefore old enough) to contain traces of them. --Tango (talk) 23:35, 19 March 2009 (UTC)[reply]
Indeed, detectable compounds only remain in the folicle for a short while. Folicle testing could, in theory, tell if you recently smoked a j... But hair testing can show that you smoked one last year... Or last month, or smoked most of last year and stopped six months ago. Its pretty neat stuff... --Jayron32.talk.contribs 02:48, 20 March 2009 (UTC)[reply]
March 20
Supernova confusion, and the fate of nearby/bright stars
Hi. The article on Supernovae states that type Ia supernovae are the result of star-dwarf interactions, type Ib and Ic are the result of truly massive stars, possibly Wolf-Rayets, and that type II supernovae have a mass of at least 9 solar masses. However, this causes a contradiction. The article on the Chandrasekhar limit states that stars with masses greater than 1.4 solar masses will collapse into a neutron star rather than a white dwarf, therefore initiating a supernova. Or, is this defined by the mass of the star in the late phase of its life, when it has burned the hydrogen and helium and begins to swell, thereby losing some of its mass? I see that most stars visible in the night sky do have masses greater than 1.4 Sol. Why are there not more supernova explosions in our own galaxy, then? Is it possible for stars to gain significant mass during their lifetime, other than by ingesting material from a companion? The article on black holes does not mention this, but I read somewhere that a star having a mass over 6 Sol is a good indication it may collapse into a black hole (assuming that any core remnant is not destroyed). Also, when two medium-mass stars with similar masses in a very close binary system collide (due to gravity in the system shrinking their orbits, not a by-chance collision), is the result a supernova or a hypernova? The article on supernovae does not mention this category, and apparently hypernovae refer only to hypergiants collapsing.
If the limit for a star to end as a supernova is indeed 1.4 Sol, then looking at the top ten brightest stars in the sky, it looks like that Arcturus and Vega will explode as supernovae; Sirius and Procyon will also explode as supernovae, but interactions with their companion dwarf star could initiate a type Ia instead; Canopus and Achenar will explode as supernovae, and are just massive enough to perhaps end as black holes, Rigel and Betelguese will be especially energetic supernovae resulting in black holes; Rigil Kentarus will have one star swell to red giant first, probably star A, then shed its outer layers, and if the explosion doesn't significantly disrupt the second star, then possibly its remaining material will migrate towards the remnant of star A; Capella appears to be a binary system of two stars massive enough to generate supernovae, perhaps the explosion of one will disrupt the other, or else we could have stellar matter being drawn towards a neutron star. Most of these stars will probably be well away from Earth, though, by the time the explosion occurs, because a positive radial velocity would cause the star to be farther away, and a negative one probably means the star will have long receded by the time the explosion occurs. Or, is there something I'm missing here? Would this mean that supernova explosions are likely to be common near Earth, and would they significantly affect our atmosphere?
Also, what exactly are the evolutionary phases of higher-mass stars (those heavier than 1.4 Sol, specificly)? Does a blue giant evolve to a red supergiant, does a blue supergiant evolve any farther before exploding, what about white and yellowish-white stars in this category, are they still the young versions of red giants or red supergiants? Also, in the case of supergiant-black hole interactions, such as with Cygnus X1, what is expected to occur when the supergiant itself goes through the end of its life cycle? Thanks. ~AH1(TCU) 01:29, 20 March 2009 (UTC)[reply]
Wow, so many questions... I won't tackle all of them. The gist of most of what you are asking seem to boil down to "what happens to stars that are heavier than chadrasekar's limit but are lighter than 9 solar masses? Some of them will end their lifes as Planetary nebula. This page has a nice explanation. Dauto (talk) 03:18, 20 March 2009 (UTC)[reply]
Nothing ends up as a planetary nebula - as that article says, it's a short-lived phenomenon. --Tango (talk) 12:35, 20 March 2009 (UTC)[reply]
My point was that after shedding the outer layers on a planetary nebula the 5 sol star isn't a 5 sol star no more. So that's the end of the 5 sol star. Dauto (talk) 13:38, 20 March 2009 (UTC)[reply]
hair tests again
thanks for the aswers.
but i'm confused...if ur hair takes in drugs....does that mean almost any chemical put in our bodys go in the hair? or is God just getting back at stoners? —Preceding unsigned comment added by 76.14.124.175 (talk) 02:03, 20 March 2009 (UTC)[reply]
ps. doea ethnicity affect hair tests? —Preceding unsigned comment added by 76.14.124.175 (talk) 02:19, 20 March 2009 (UTC)[reply]
Asking my wife again. It's not that everything you take in ends up in your hair, but most drugs have chemically very similar chemical compositions, and those compounds do tend to accumulate in the hair. After all, the basic idea of drugs is that they mimic chemicals in your brain, and those chemicals also tend to accumulate in certain places like hair and fingernails. It isn't that ONLY drugs do, its that drugs are one of the things that do accumulate there. There are many other things that do, like heavy metals and arsenic, and hair tests can be used to show that a person has been poisoned over a period of time. The deal with hair is not that it magically absorbs drugs; its that it lasts a LONG time, so it carries a record of things you have taken in over a long time. And, ethnicity does effect hair type; your ethnicity can be positively identified by microscopic analysis of your hair... however no person or ethnicity is immune from these hair tests. Again, your only option is to shave your head; however if you shave it after being told that you need to give a hair sample for a drug test, then they will likely know exactly why you did so. Your options are a) don't do drugs or b) don't apply for jobs where it matters... --Jayron32.talk.contribs 02:46, 20 March 2009 (UTC)[reply]
I don't believe shaving your head will do the trick. We don't have hair only in our head. There are also other ways of testing for drugs - read drug test for more, but they don't have a long detection period like hair test.--80.58.205.37 (talk) 12:54, 20 March 2009 (UTC)[reply]
Are humans the fastest long distance runners?
When it comes to the fastest on land, everyone bows down to the sprint of the cheetah. But beyond the sprint, what is the fastest land animal over a substantial distance, let's say 50 miles or so? I've recently heard an assertion that we, as a species, were very successful in our infancy because we evolved to be the best at tracking herds over very long distances. Sappysap (talk) 02:37, 20 March 2009 (UTC)[reply]
I've heard that said, many times. It may be true...but I don't think so. Marathon runners can do 26 miles without a break. However, in the Man versus Horse Marathon - the race was won by horses in the first seven years although a human did win on the eighth event - but on a bicycle (which, IMHO, is cheating). The race was run for 25 years before the first human won on foot. In 28 years of running the event, only two humans have ever won on foot. For some reason that's only a 22 mile race, but it's cross-country - which may give the horse an unfair advantage. But then consider that they horses are HEAVILY handicapped by having to run with a human rider on their backs! If the runners had to carry a 40lb backpack - I think it would slow them down too!
So it's abundantly clear that 22 miles isn't enough to give the human a winning advantage. I had a neighbour in England who was a big time long-distance runner. He did the London-to-Brighton foot race (which I think is 50 miles or so) - also several double-marathons (52 miles) and the South-Downs-Way run (I believe 70 miles) and the Isle-of-Wight race which is also some crazy long distance. But I don't think an average human can do that - even with training.
I dunno - I think it's a tough sell. SteveBaker (talk) 03:04, 20 March 2009 (UTC)[reply]
Yes, true. But may be the 'Man versus Horse Marathon' isn't the best way to test the hypothesis. Horses, after all, are pretty good long distance runners themselves. May be we would do better against animals more adept of short bursts of very fast sprints like impalas? Dauto (talk) 03:54, 20 March 2009 (UTC)[reply]
Harvard anthropology professor Daniel Lieberman claims we are "the animal world’s best distance runners."[43]Clarityfiend (talk) 04:20, 20 March 2009 (UTC)[reply]
26 miles is a single marathon. Many people can do it - probably most healthy adults after a year or three of training. See Ultramarathon for really dedicated runners. --Stephan Schulz (talk) 09:12, 20 March 2009 (UTC)[reply]
But to find out if we're the best we need to compare ourselves to others that are very good. --Tango (talk) 12:26, 20 March 2009 (UTC)[reply]
Humans can run 3,100 miles over the course of 41 days. Does anyone know if a trained horse could do the same? --Sean 14:16, 20 March 2009 (UTC)[reply]
But here is my hypothesis in a nutshell: We know that most people (my wife, for example) can more or less run 26 miles - with a bit of training (she's never run a race over any distance in her entire life - she trained over two months - and finished the London Marathon in a hair over 5 hours - although she did walk some of the way). It's not unreasonable to suppose that pre-soft-living-modern-civilisation-humans could all run at least 26 miles if they had to. But we also know from the Man-vs-Horse thing that AT LEAST the one species we've seriously tried this against can beat us easily over 22 miles WITH A HUGE LOAD ON THEIR BACKS. So I'm betting that horses without riders would have no problem whatever in whipping our asses out to at least a few miles beyond the regular marathon distance. However, we have these ultramarathon loonies who run 50 mile races. It's perfectly possible that the horse gives up at about 30 miles...and that SOME humans can make it out to 50 miles. But if we're taking about maybe 1000 people in the world who run ultramarathons - that's the top 0.00001% of humans. I'm pretty sure we couldn't all do that - even with training. And what if we picked the very best long-distance horse out of all the horses in the world - and trained the heck out of it. Gave it really nice Nike running horseshoes and a digital heart-rate monitor with integrated pace timer - no rider, no saddle - and made sure it had specially formulated 'rehydration' stations every few miles...wouldn't the best horse manage equal amounts of improvement over the general population of horses? I don't think there is any evidence whatever that a 'typical' human could out-run a 'typical' horse over any significant distance...and I don't believe that the top 0.0001% of humans with the best training and support facilities could beat the top 0.0001% of horses if they were given fair training and support (and no riders!). And that's just horses. What about all of the other long-legged runners of the world? I think this one is busted...unless there is some solid evidence to the contrary. SteveBaker (talk) 14:22, 20 March 2009 (UTC)[reply]
There are other animals besides horses to consider as well. What about wolves? 65.167.146.130 (talk) 14:57, 20 March 2009 (UTC)[reply]
When the sun becomes a red giant...
About how long will it take for it to expand from its current size to red giant size (following the collapse of its core once the hydrogen there is used up)? 69.224.37.48 (talk) 03:09, 20 March 2009 (UTC)[reply]
its the biggest question ever ... what's the beginning , what's the source of evry thing .. if i said god is the source, atheistes will be angry.but if i said it's avery powerfull elian had created the earth ... i think they will buy that.
i just need to know whats wrong with god theory ... it might be right . but i think that humans dont like the idea of being a lower cretures ... we are so pride to be god slaves,we need so much to belive that there's no destiny ,so we can make our own.
human evolved from monky...monky evolved from (whay ever)...all the way to the creation of the universe ... from where did the universe came from ... from where that gas came from ... what is the first thing ... what is ground zero.
and if there is no god , and all this religion thing is just acrap,then i think the best thing that happened to the earth is hetler...we must let the smartest,the strongest , the healthiest ones to survive .who cares about moral standards ,we invinte these standards,and we can change them ,i think it's inmorale to leave the weak alife so they can multiply and reduce the chances of our survive,we should eliminate them.
and why do we evolve to have this huge power of thinking ... were we to needy to find answers for the question we had before we have the mind to ask.whats the need driven us to evolve to have this huge brain ... food ..???
will .. after all evry thing could be true , just leave the door open. —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 04:19, 20 March 2009 (UTC)[reply]
There are two (implied) questions you are asking, even if you don't realize it. They have different answers. Question 1 is "What is the process by which the universe was created" or "what went on when the universe came into being". Its a procedural question. The answer, as far as we can tell, is that some form of the Big Bang brought it about, somewhere in the neighborhood of 13-14 billion years ago. Now, while this satisfactorily answers your first implied question, it does not answer your second which is "What is the cause of the Universe coming into being" or "What is the purpose for which the universe was created". The answers to THOSE questions are ultimately unanswerable via direct observation or by inferences from those direct observation. Assigning meaning and purpose to creation isn't really the realm of observational study, so one must derive their own personal answer to the question. Did God make it so? Is it all random? Any answer you arrive at must be arrived at via faith, even if your answer is "The universe has no purpose at all". You may be interested in looking into the field of Cosmogony which discusses the philosophical (as opposed to the procedural) questions of the creation of the universe. --Jayron32.talk.contribs 04:28, 20 March 2009 (UTC)[reply]
Let me point out one thing you said that reveals you haven't thought about that long enough.
You said "i just need to know whats wrong with god theory ... it might be right . but i think that humans dont like the idea of being a lower cretures ..." If that was true, most people wouldn't believe in God. We know that that's not the case.
Now, if we skip all the senselessness about eliminating week people (not a very moral thing to say), we get to the only thing in your rant that actually sounds like a science question:
You asked "why do we evolve to have this huge power of thinking?"
To outwit one another in matters of love and war. Dauto (talk) 04:59, 20 March 2009 (UTC)[reply]
Oh, someone who concludes that if there is no God, Hitler is awesome because without God there's no morality! Why, sir, you have unintentionally created an argument for belief in God! What an amazing coincidence! -- Captain Disdain (talk) 10:53, 20 March 2009 (UTC)[reply]
As far as I understand it, evolution doesn't say that humans evolved from monkeys. Instead, it says that humans and monkeys evolved from a common ancestor. This common ancestor no longer exists (i.e. it is extinct). 12:59, 20 March 2009 (UTC) —Preceding unsigned comment added by A Quest For Knowledge (talk • contribs)
Well, yes, that's true. It's accurate to say we evolved from apes, but monkeys are a separate class of primate - it wouldn't be accurate to describe the most recent common ancestor of modern monkeys and humans as a monkey. (The most recent common ancestor of humans and non-human apes was an ape, though.) --Tango (talk) 13:12, 20 March 2009 (UTC)[reply]
Here we go again...
its the biggest question ever - maybe - but I think I have bigger ones. Abiogenesis is one. Is there intelligent life throughout the universe is another. Are there parallel universes is a third. But this is right up there.
... what's the beginning , what's the source of evry thing - that's an easy one - the Big Bang. We're really very sure about that now. We know pretty much exactly what happened from about the first millisecond of existance. We still need to fill in some details about dark-matter and dark-energy - but we're definitely getting there.
.. if i said god is the source, atheistes will be angry. - No, not angry. Saddened perhaps. Exhausted maybe.
but if i said it's avery powerfull elian had created the earth ... i think they will buy that. - No, we wouldn't. That's really not what the science says and it wouldn't explain how the moon was formed from a collision between early earth and another Mars-sized planet. We don't need 'aliens with godlike powers' as a substitute for 'god' - we have strong evidence for a relatively mundane explanation that centers around stellar remnants, gravitation, that kind of thing.
i just need to know whats wrong with god theory ... - it's "Unfalsifiable". That means that there is no conceivable experiment that could be done to either prove or disprove the theory. The "god theory" is (scientifically) no more and no less probable or provable or credible than that I made the earth and have been keeping quiet about it all these years. There are literally an infinite number of unprovable ("wild-assed") claims you could make - they all have equal status with the "god theory" - and we can't go around believing in an infinite number of random things. On the other hand - we have an exceedingly good 'conventional' theory that works perfectly well without hypothesising supernatural causes. God simply isn't necessary for our explanation of the universe. You might like to read about Occam's Razor.
it might be right. - well, it might but so might be the theory that the Invisible Pink Unicorn (mhhbb) did it...or that roaming gangs of green furry fish did it. I can keep coming up with these stupid suggestions from now until doomesday - they are all just as valid as the "god theory" - there is the same amount of evidence that they are true (ie NONE) and just as easy to prove or disprove (ie IMPOSSIBLE). So why should we give the "god theory" a moment's more attention than the IPU (Invisible Pink Unicorn - mhhbb) theory - at least the incomprehensible but undeniable existence of pineapple and ham pizza provides at least a shade of evidence for the IPU? (I'm kidding - OK?)
but i think that humans dont like the idea of being a lower cretures ... - that's true. When I was a kid - the text books said "Humans are superior to the animals because we have language and use tools." - but then we discovered that bees have a language (involving dancing and wiggling their butts) - and lots of animals use tools (watch a starling breaking open a snail shell by hitting it with a pebble). So the next generation of textbooks said "Humans are unique because we MAKE and use tools."...but then we found that chimpanzees strip the leaves off of thin branches to make tools for getting ants out of termite mounds...and there is a fish that cuts and shapes leaves to make a disguise that it holds over it's body so that birds can't see it swimming by. We are clearly at the 'top of the heap' - but reality keeps reminding us that we're really not that much more superior to the "lower" creatures.
we are so pride to be god slaves,we need so much to belive that there's no destiny ,so we can make our own. - I certainly don't want to be a "god slave". I couldn't imagine what it would be like to believe in all that stuff. To have to continually bow down to an infinitely superior being? Urgh! We have not made up all this stuff we've found out about the universes. We've investigated what the universe has to tell us. We know the Big Bang is true because (in a sense) we sent up a spaceship to take a photo of it! The cosmic microwave background is the clearest proof that the Big Bang really happened. If you take the time to understand the science behind it - you'll be convinced too!
human evolved from monky...monky evolved from (whay ever)...all the way to the creation of the universe ... from where did the universe came from ... from where that gas came from ... what is the first thing ... what is ground zero. - Ground Zero is the Big Bang. We're pretty solidly clear on everything that happened from then to now. What we don't know - and what (if you must) you could attribute to a "God" is what actually caused the Big Bang in the first picosecond of the life of the universe. I don't think we need a supernatural explanation for that - but if you must, you could imagine a god who decides to make the universe and after about a picosecond - steps back and lets it all roll out without touching anything after that. This makes a sort of sense I suppose. It's a "God of the gaps" argument. Wherever we don't yet have a scientific explanation - you can stick God in there. Sadly, those gaps are getting smaller every year. Science is making huge leaps in figuring this stuff out - and every time we plug a hole, there is less need for a god to make a workable explanation. Give it ten years and the role of god will have shrunk from a picosecond to an attosecond. But this raises a bigger question for me. You aren't prepared to accept that the "Big Bang" came from nowhere (despite good evidence pointing that way) - yet you are entirely happy to accept that God "just is" - nobody asks "what is the origin of god?"...but if we were (as scientists) to accept the god-theory, that would have to be the first and biggest new question. "Where did God come from?" When I ask that question, I get some vague hand-wavey thing about him always having been there - or "He's outside of time and space". But when I say that time actually started with the big bang - and that it's meaningless to ask what came "before" - you get all huffy about it and start demanding why I don't have an explanation. Your theory is certainly no better than mine - and Occam's razor says it's a lot worse because it involves a whole extra step that my explanation doesn't need.
and if there is no god , and all this religion thing is just acrap,then i think the best thing that happened to the earth is hetler...we must let the smartest,the strongest , the healthiest ones to survive - but that's not true. Hitler's actions were not acceptable to the majority of humanity - or even to his own people when they finally realised what was happening. So Hitler was attacked from all sides - Europe, Russia, the US...and driven to extinction. He died because the majority of humans could not accept his behavior. That's because we've evolved a mental capacity to reflect the feelings of others - that capacity means that we can put ourselves into the positions of the poor people in those death camps - and we become outraged and belligerent - and we fix the problem. That's an evolutionary response to a failed genotype. Religion had very little to do with that. Plenty of atheists fought against Germany.
who cares about moral standards ,we invinte these standards,and we can change them - some we can - others are so inbred into our genetics that we can't. You can't just decide to do something that's morally repugnant to you. I could no more kill my son than I could kill myself. That's not a matter of logic - it's a matter of what my brain chemistry has made me be. We are like we are because of the genetics of being a "pack animal".
i think it's inmorale to leave the weak alife so they can multiply and reduce the chances of our survive,we should eliminate them. - you say that, but I doubt very much that you'd be able to carry it through. I have no god commanding me not to do that - and I certainly give money to help the needy - I volunteer to help out underprivilaged kids - I donate my time free to answer people's questions here on the Wikipedia reference desks. Without a god - your claim is that I should have no reason to do those things...yet I do! Gladly. For the betterment of mankind - for the survival of the species - for the survival of my genes into future generations. This is a moral standpoint for sure...but one that does not in any way rely on religion to prop it up. I actually agree with most of the more important of the Ten Commandments (although one or two of them are a tad nutty). "Thou shalt not kill" works very well for me! In fact, I'd prefer to avoid the weasel-words added to that that say "oh...unless it's a war or something...or maybe murderers could have the death penalty...and in Texas it's OK to shoot burgulars". No - for me, "Thou Shalt Not Kill" actually means what that bloody stupid book says it does. Not because there is some old white guy up in the clouds somewhere telling me to...it's because my brain tells me that killing (in general) is not a good thing. I have moral principles...pretty strong ones actually. They just don't derive from religion.
and why do we evolve to have this huge power of thinking ... - it helped early humans to be smart. The smartest ones didn't get eaten by the sabre-toothed tigers - so they had more kids - who inherited their parent's smarts - and gradually, via the relentless force of evolution we evolved to what we are now. It's not in any way a mystery.
were we to needy to find answers for the question we had before we have the mind to ask.whats the need driven us to evolve to have this huge brain ... food ..??? - Sex, actually. But food also.
will .. after all evry thing could be true , just leave the door open. - No. It's ridiculous. I don't have the time to go around believing in green furry fish that MIGHT have created the universe - I don't have time to believe that there MIGHT be a teapot orbiting Mars right now. I don't have time for any of the hundred or so wildly different supernatural claims for a "god" or "gods" either. It's unnecessary and (frankly) ridiculous.
Wow! What an inciteful reply! I think you should have used more CAPITAL LETTERS for EMPHASIS though. SteveBaker (talk) 14:04, 20 March 2009 (UTC)[reply]
OK - look I'm not playing sock-puppet-master here - I really didn't notice that my 30 day login period had expired on this PC.SteveBaker (talk) 14:04, 20 March 2009 (UTC)[reply]
Green furry fish? What happened to the aardvarks (mtasnro)? Algebraist 14:26, 20 March 2009 (UTC)[reply]
In the Cyclic Model, the universe follows an infinite number of Big Bang / Big Crunch cycles, first cause isn't an issue because there is no beginning and no ending, just an infinite loop. "All this has happened before and will happen again." A Quest For Knowledge (talk) 14:03, 20 March 2009 (UTC)[reply]
the iron content in steel wool lab queries
for an important lab we're doing titled "percentage of iron in steel wool", a sample of steel wool is placed in excess dilute sulfuric acid, and this supposedly converts the iron present in the steel wool into Fe2+ ions......then, the Fe2+ ions in the solution are titrated against a standard permanganate solution, and thus are further oxidised to Fe3+ ions, while the permanganate ions are reduced to Mn2+ ions..
do you have any idea of the kind of questions that are likely to be asked of me in this lab? also, i'm assuming my teacher will give a 'manufacturer's value of the % Fe'. do you know the equation to figure out the % difference between your value and the manufacturer's claim?
Percent difference? That's a pretty technical article, but the essence is in the "Percent error" formula and the intro: it's a ratio of the difference between the values to the values themselves. You might take one value as "correct" and thus compare to it, or you might just take them both as "someone's data" and consider the average of them to be the value to compare. I would ask a student to write the net ionic equations for the redox reactions involved in this experiment. DMacks (talk) 04:56, 20 March 2009 (UTC)[reply]
You're likely to do stoichiometry calculations somewhere to figure out the mass of iron in your original sample. This can be done any number of ways, but since Fe3+ ions are colored, you could use a spectrophotometer, a series of standardized Fe+3 solutions, and Beer's law to calculate the concentration of Fe+3 ions in your unknown solution. Then, knowing that concentration and volume, you can find moles of Fe3+, which should ALL have come from the steel. You could also do the same via titration with a standardized KMnO4 solution; if you know the volume and concentration of the KMnO4, and have a balanced chemical reaction for the Fe+2/Fe+3//Mn+7/Mn+2 redox reaction, you can also quantitatively find the moles of iron in your unknown, and then its the same calculation as above. --Jayron32.talk.contribs 05:03, 20 March 2009 (UTC)[reply]
potential energy
I was watching TV where i saw a man working in a high way project , this man was trying to crack a big rock , he kept hitting the rock with a hummer until and suddenly it just split into half , i asked about it and get some opinions like a potential energy is being stored in the mass until its enough to crack the mass,
but i think that the hummer is producing a hairy cracks at aspecified plan until its reach that critical edge where it to weak to resist that hit energy , so it jut crack down,what did you think....? —Preceding unsigned comment added by Mjaafreh2008 (talk • contribs) 10:24, 20 March 2009 (UTC)[reply]
The rock is certainly not storing significant energy from the hammer blows. It's much more likely that each blow (or even only some of the blows) create and propagate cracks and fissures, gradually weakening the rock. At one point the rock is weak enough that the last blow splits it. --Stephan Schulz (talk)11:12, 20 March 2009 (UTC)[reply]
As a professional rock splitter, I concur with that. When trying to break up a rock down to a size that you can take back as a specimen you generally concentrate your hammering on any obvious existing weakness such as a crack or a weathered zone. Normally you can see, feel (from the change in the response of the hammer handle) or hear (a change in the sound of the blow) when you've started to propagate a crack just before it finally splits. Mikenorton (talk) 11:24, 20 March 2009 (UTC)[reply]
You could argue that a rock with cracks in it has higher energy that one that doesn't (in the same way that two separate atoms have higher energy than when they are bonded together), but there is no way easy way to get that energy back so I'm not sure I'd call it "potential energy". --Tango (talk) 12:17, 20 March 2009 (UTC)[reply]
When you're propagating a crack through a material, bond-splitting is what you're doing, so some of the input energy is converted to fracture surface energy. Mikenorton (talk) 12:27, 20 March 2009 (UTC)[reply]
I'd bet that you're actually releasing energy in the rock by breaking bonds - but the biggest part of what your hammer blows are doing ends up as heat or sound energy (which in turn is going to be heat energy pretty soon). When you hit the rock - you are causing it to vibrate or accelerate (briefly) - and that's getting turned into heat by friction. So to the extent that the rock gets a bit warmer (and most certainly the hammer does - you can feel it!) you are storing energy in the rock - but not usefully. SteveBaker (talk) 13:14, 20 March 2009 (UTC)[reply]
what are the similarities and dissimilarities between prokarotic and eukaryotic replication,transcription and translation.59.92.238.182 (talk) 12:49, 20 March 2009 (UTC)[reply]
Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:08, 20 March 2009 (UTC)[reply]
Transcription (genetics), Translation (genetics) look promising and weren't that hard to find. (Click on words in blue in a text on wikipedia and it will get you to the relevant page.) If the assigned textbook for your class doesn't give you good enough answers it might be useful to check if you have a well stocked library in the area. 76.97.245.5 (talk) 14:32, 20 March 2009 (UTC)[reply]
Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:08, 20 March 2009 (UTC)[reply]
Yes, wikipedia knows. Here's how you can find out what: copy your word into the white box underneath where it says "search" in the left hand sidebar near the top of this page. Then click on "search". If you can't find a relevant page or have trouble understanding some of the content, please feel free to come back with a specific question. 76.97.245.5 (talk) 14:23, 20 March 2009 (UTC)[reply]
can anyone help...
what is physiology pharmacokinetic model? 59.92.238.182 (talk) 12:52, 20 March 2009 (UTC)[reply]
Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 13:09, 20 March 2009 (UTC)[reply]
Yes, wikipedia can help. Here's how: copy your word into the white box underneath where it says "search" in the left hand sidebar near the top of this page. Then click on "search". If you can't find a relevant page or have trouble understanding some of the content, please feel free to come back with a specific question. 76.97.245.5 (talk) 14:19, 20 March 2009 (UTC)[reply]
Start with the pharmacokinetics article. If that doesn't answer your question, re-post a more specific question and I'm sure we'd be happy to help. --- Medical geneticist (talk) 14:54, 20 March 2009 (UTC)[reply]
![{\displaystyle \mathbf {x={\frac {x'+vt'}{\sqrt[{}]{1-{\frac {v^{2}}{c^{2}}}}}}} }](https://wikimedia.org/api/rest_v1/media/math/render/svg/4d69d3e94eb4b3144568cf00c24281eda80d2fbb)
12:17, 16 March 2009 (UTC)
Please do your own homework.
![[27]](http://www.lapidaryjournal.com/feature/apr05/rocks6.jpg){kind=link}
![[30]](http://home.att.net/~chicago_climo/chisnwmx.jpg){kind=link}
![[38]](http://farm3.static.flickr.com/2353/1797378420_028e3e790c.jpg?v=0){kind=link}