January 19

Attacked by aliens

In reality, what defensive measures does humanity have in place in the event that the earth gets attacked by hostile extraterrestrials? I'd be amazed if the possibility has never even been considered by the US/Russians seeing as though we've been advertising our presence and the location of our planet for the past century or so by emitting radio waves into space. We've even sent spacecraft out of the solar system containing infrmation that explicitly states how to find our homeworld. --84.65.149.111 00:03, 19 January 2007 (UTC)[reply]

Will Smith. Seriously, however, a commonly held correlary to the Fermi paradox is that if there was an alien civilization that had the technology to invade us, they would have perfected interstellar travel. Since we have not even perfected intrastellar travel, it is highly unlikey we could stand against an alien invasion, regardless of preparation. Hipocrite - «Talk» 00:13, 19 January 2007 (UTC)[reply]

Moreover if an alien species has perfected interstellar travel, why would they want to subjectate the human race? I don't see why aliens wouldn't have a sense of decency. Vranak

Maybe they think like us (we've not exactly got the best track record when it comes to dealing with civilizations less advanced than our own on earth)? Maybe they want the resources, the slave labour and the lebensraum? Maybe they want to 'save our souls'? --84.65.149.111 00:37, 19 January 2007 (UTC)[reply]

I would think that a species that had developed such high technology would also have a highly-developed sensibilities and ethics. This has certainly been the case in human history; as technology improves, so does morality. Vranak

Has it? The 20th Century was the cruelest and bloodiest in human history. It doesn't look like the 21st is going to be much better the way things are going. As technology improves, we just find ways of using it to kill people more efficently. --84.65.149.111 00:50, 19 January 2007 (UTC)[reply]

I understand your pessimism, but consider some of the tortures that used to be commonplace but are now unthinkable: brazen bull, Pear of Anguish, Hanging, drawing, and quartering. Vranak

High technology does not correlate with high values. The Soviet Union developed incredibly sophisticated military technology under a system of slave labor. They couldn't keep people fed but they could make ICBMs. High technology is no guarantee of civility, there is no correlation at all. And I don't think any of those tortures you named were "commonplace". The only one which seems to have been used with any regularity was the latter, and even that was reserved for a very small number of offenses. And I'm not sure that getting ones limbs blown off by artillery is any more humane. Napalm does not feel better than being boiled in oil. --24.147.86.187 02:04, 19 January 2007 (UTC)[reply]

I am thinking from a historical perspective, not a geographical one. Anyway, the tortures I listed require someone being right there with their victim, condoning a continuing anguish. An arm blown off by an artillery shell is certainly gruesome and inhumane, but it's not like the person firing the cannon means to do it. Burning someone at the stake or cruxifying them hardly leaves any doubt as to intent. Vranak

This thought has occurred to me before, and I thought, what if we gave medieval European countries nuclear weapons? Even if we also gave them the knowledge of radiation poisoning, I bet Europe would have been a nuclear wasteland in a month. Imaninjapirate^{talk to me} 23:17, 20 January 2007 (UTC)[reply]

I don't know whether to point out the impossibility of this proposition (unless you know something about time travel we don't), or to say that humans were never so stupid as to pointlessly obliterate themselves. Vranak

Why is it often assumed that alien technology, if it exists, exists for aggressive and hostile purposes? JackofOz 00:30, 19 January 2007 (UTC)[reply]

Because if everyone assumed that the aliens were peaceful, they could attack us and we'd never expect it? I know for certain that if a fleet of alien spacecraft entered the solar system on a course for earth, every single ICBM on the planet would be locked on and waiting - just in case - even if they were broadcasting messages of peace beforehand. --84.65.149.111 00:41, 19 January 2007 (UTC)[reply]

The Earth won't get attacked. Signals from early transmissions of Walker, Texas Ranger will have gone quite far into space by now, and they are doing a fine job as a deterrent. Readro 00:45, 19 January 2007 (UTC)[reply]

Even if we were attacked, we wouldn't be enslaved. Slavery in a modern civilization is very inefficient, even if you don't consider the enormous amount of training required to adapt us to their technology/language/culture. So we'd just be disposed of - feel better now? Clarityfiend 07:11, 19 January 2007 (UTC)[reply]

I recommend you all to read some Stanislaw Lem novels. It could help to imagine aliens who are really different, not like us just with slightly different organs or skin color. The idea that they need our resources is just a setup for some stupid action movies. In reality, considering the scarcity of life in the universe, why would the aliens need to travel hundreds and thousands of light years just to battle us, when there are a lot of uninhabited planets on the way to be conquered more easily without a war. --V. Szabolcs 08:35, 19 January 2007 (UTC)[reply]

This question has been on many minds for decades now, popularized by War of the Worlds since the 50's. If we are invaded our technology and defence would be far inferior to the invaders, as they would already be a spacefaring race. Even Star Trek scenarios of grandiose space battles are very unlikely as the level of technology would be hugely different if you consider the odds... the universe is billions of years old and modern man is barely 2,000 years old, imagine what a 100,000 year old race would have achieved? What about a million-year old race? Highly advanced and probably evolved or transcended into beings of energy or whatever your imagination can muster. The question is, would it be likely they would want to invade and exterminate us like bugs? This depends on a number of factors. Are they genetically aggressive or expansionist? Do they need to expand for living space? Do they need natural resources or worlds that can support life? My personal hope is that there is some sort of galactic council of aliens and they are waiting for us to evolve so that we can be invited to join the council. Probably some sort of non interference policy being adhered to. Maybe we are being monitored (UFO's). So much more to say but so little time to type. Sandman30s 08:44, 19 January 2007 (UTC)[reply]

Who says aliens are advanced? They might be some form of microscopic life form that no one will ever notice. Stupid science-fiction films are to blame for misinforming (probably) millions of people. They should make a good movie for once... | AndonicO ^{Talk · Sign Here} 12:05, 19 January 2007 (UTC)[reply]

Infinite universe. Infinite number of stars. Infinite number of stars with orbiting planets. Infinite number of life-bearing planets. Infinite number of life-bearing planets with intelligent life. Infinite number of advanced civilizations. QED. ;) --Kurt Shaped Box 12:23, 19 January 2007 (UTC)[reply]

"Infinite universe" is certainly not known for a fact, nor is "infinite number of stars". Maelin (Talk | Contribs) 07:24, 25 January 2007 (UTC)[reply]

We would send Sheriff Bush out to defend us, Mano-a-thingo. My money would be on the thingos, though.

Atlant 12:47, 19 January 2007 (UTC)[reply]

The US, Russia, and this week China have sent up missiles and destroyed satellites, just to show they can. These coiuntries could take down spy satellites to blind their opponents, weather satellites to deny that modern benefit, and communication satellites (the horror!). The Bush administration does not look favorably on China having that capability, but I'm not sure what remedy he will apply. Stop paying out debts to them or stop buying all our manufactured goods from them maybe. So if they attacking space aliens would stay in simple orbits and not deploy any countermeasures, they could get whacked. Edison 21:10, 19 January 2007 (UTC)[reply]

Have you already thought that aliens could like to keep us as pets? Mr.K. 21:42, 19 January 2007 (UTC)[reply]

In the very unlikely event that an intelligent alien race could and would come to our planet, and in the unlikely chance they would attack us for no apparent reason, I have no doubt that we could defend our selves very effectively no mater there level of technology. This is because the laws of physics still work the same all over the galaxy. For instance earths nuclear weapons can be built just as strong as any alien nukes could. No mater whether you have ray guns or not a nuke is still an extremely powerful deterrent. Actually I would be more afraid of humans destroying the aliens than vice versa. S.dedalus 23:18, 19 January 2007 (UTC)[reply]

There's no reason to think that a civilization that advanced doesn't have extremely advanced point-defence capabilities. -- Consumed Crustacean (talk) 23:44, 19 January 2007 (UTC)[reply]

Perhaps, however considering how little armor and materials have developed over the entire coarse of human history I think it is statistically unlikely that even the most advanced of races would be shielded from the effects of a Tsar Bomba. Also I think most carbon based life forms would be adversely effected by that much radiation. Because of the finite speed of light, interstellar travel is also apt to be very slow. This would give us another tactical advantage as reinforcements might take centuries to arrive, and logical communication would be all but impossible. In any case, I’m not saying there’s not a chance of invasion but I suspect ET’s would try to talk first. S.dedalus 06:45, 20 January 2007 (UTC)[reply]

Good point. We launch the missiles, they shoot them down in the upper atmosphere with particle beam technology, the things break up and scatter radioactive material over half the globe. If it was a computer game, the 'BAD END' screen would come up at this point... --Kurt Shaped Box 22:04, 20 January 2007 (UTC)[reply]

Live by the sward. Die by the sward. ;-) S.dedalus 03:51, 21 January 2007 (UTC)[reply]

Animal Tracks

It has finally snowed here in Monmouth County, New Jersey. But just a dusting. I went to bring the trash out and noticed strange animal, possibly bird tracks on my driveway. Here are two photos: [1] [2]. They are quite large, 2 or 3 inches across. Any ideas? --Russoc4 00:21, 19 January 2007 (UTC)[reply]

Ski polls? They aren't a bird, birds have at least one claw facing back. --liquidGhoul 03:00, 19 January 2007 (UTC)[reply]

I see a curved mark facing backwards in at least some of the prints. StuRat 01:40, 20 January 2007 (UTC)[reply]

Hehe, you might want to read the above post. :) --liquidGhoul 03:01, 19 January 2007 (UTC)[reply]

What post? Edison 06:34, 19 January 2007 (UTC)[reply]

Aliens...still, they are really weird. The closest I can find is here [3], third row, third from the left. No clue what it is though. --71.250.199.10 14:51, 19 January 2007 (UTC)[reply]

The alien post. Don't worry, my joke didn't work :( --liquidGhoul 16:02, 19 January 2007 (UTC)[reply]

It's a Wild Turkey track. -- Sturgeonman 00:41, 26 January 2007 (UTC)[reply]

Anamorphic widescreen

If I watch an 'anamorphic widescreen' DVD on a TV with a 16:9 aspect ratio, what difference would I see from watching an ordinary widescreen DVD? Would the 'anamorphic' picture fill more of the screen (i.e. produce smaller black bars)? Or would both DVDs take up the same amount of space on the TV screen, but with the anamorphic one offering a clearer image? I've been wondering about this. Thanks!

Anamorphic and aspect ratio are two different things. A movie filmed in 16:9 will play with no black bars on a 16:9 TV, a movie filmed wider, like 2.2:1, will have black bars, anamorphic or not. The anamprphic will have a better picture however. Vespine 02:49, 19 January 2007 (UTC)[reply]

Basically, an anamorphic DVD just has the movie picture with no black bars, it contains instructions that tell the DVD player "if it's a 4:3 TV, put some black bars on it". A non-anamorphic DVD has a square picture with black bars included, so the bars are a part of the image. Because of this, the movie itself is somewhat lower quality. Anamorphic is preferable. Pesapluvo 22:48, 24 January 2007 (UTC)[reply]

A compressed virtual disc

"'Moved to Computing desk

Amplitude of EM waves

The energy of an electromagnetic wave is related only to its frequency (or wavelength), as given by E = h×nu. I hadn't thought until recently about the amplitude of the wave. I would have thought that a wave with a larger amplitude would have more energy than a smaller wave of the same frequency and wavelength. Can this situation exist? What controls the amplitude of EM waves? Or, do all EM waves have the same amplitude? --BenC7 02:02, 19 January 2007 (UTC)[reply]

Actually, E = hv gives the energy of a photon, not of the electromagnetic wave. Take a look at radiant energy. Basically, you can think of amplitude as the "amount" of photons of a wave, each photon carrying a bit of energy proportional to their frequency. — Kieff 02:30, 19 January 2007 (UTC)[reply]

Hmm, perhaps I should rephrase. Clearly, constructive and destructive interference will change the amplitude of a wave at a particular point in space. But what about a single wave? For example, does a single gamma ray (or one photon, if you want to think of it that way) have the same amplitude as a single radio wave? --BenC7 10:57, 19 January 2007 (UTC)[reply]

All EM radiation involves the photon; even radio waves. This wasn't fully realized until the development of quantum mechanics and particle physics. Skim through photon. As was mentioned before, EM radiation (say, the plane wave solution to Maxwell's equations) usually comprises many interacting photons. If you're talking about the energy of a single radio-frequency photon compared with a single gamma-radiation frequency photon, you already gave your answer: E=hv. Note that energy is not the same quantity as EM field magnitude, which is usually considered (at least for the plane wave case which is used for RF engineering) in terms of the electrical field, in V/m, and the magnetic field, in A/m. See electromagnetic field for a pretty good explanation of all this. Some of the derivations from Maxwell's equations there may help you understand the amplitude concept if you're okay with the mathematics. P.S. - A physicist may be able to offer a little better explanation of exactly how Maxwell's theory relates to QM and GR. I'm not a physicist, so I only know that the Kaluza-Klein theory verified Maxwell's equations using GR in the early 1920s. -- mattb @ 2007-01-24T20:33Z

Heats of combustion of common alkanols

In a recent experiment at school I calculated the molar enthalpies of combustion of four common alkanols: methanol, ethanol, 1-propanol and 1-butanol. Butanol seemed to be somewhat of an outlier as the result I obtained was ten times what I got for the other alkanols. I was just wondering where I can find information listing molar enthalpies of combustion of common alkanols and what the reason is for differences between each alkanol in terms of heat of combustion? thanks Wbchilds 03:32, 19 January 2007 (UTC)[reply]

You obviously need to redo your calculations. This famous practical is supposed to show that there is a regular rise in molar enthalpies of combustion, which is ascribed to each one having an extra -CH₂- group. --G N Frykman 07:20, 19 January 2007 (UTC)[reply]

I love you more than....

Ok fairly frivolous question but bare with me. As inspired by Sarah Silverman's funny song, I'm making up a list of things that love things which are scientific or academic in nature. The best way to explain is to give you a couple of examples I already have:

I love you more than:

hydrogen loves oxygen (currently my favourite one)
positive loves negative
protons love electrons
entropy loves increasing

I'm sure you get the idea. I also thought 'black holes love light' but that's a bit, I don't know, dirty sounding ;). So no stupid ones, I'm sure we could make a list a million long of really crap things like "Balls love rolling down a hill becuase of gravity", but that's not really clever or anything, so I'm looking for as clever or cute as you can think of, any ideas? I promise these will be used for good not evil, thanks in advance. p.s. no this isn't homework!;)Vespine 04:01, 19 January 2007 (UTC)[reply]

(from a health point of view)...more than:

cavities love sugar

plaque loves teeth

dentin loves bonding agent

gum loves braces

I recognize that I may be the only one that finds this amusing. - Dozenist talk 04:16, 19 January 2007 (UTC)[reply]

Mice Love Rice? -- 我♥中國 04:44, 19 January 2007 (UTC)[reply]

Sorry to rain on your parade, Vespine, but I am not at all sure that hydrogen does love oxygen, certainly not in any exclusive sense. Sure, the relationship starts with a bang, but that whole water molecule thing is a ménage à trois. Plus hydrogen has some very intimate extra-molecular relationships - see hydrogen bonding. As soon as hydrogen sees a more attractive partner or a bit of electricity, it abandons poor old oxygen (hydrolysis, electrolysis). In fact, hydrogen will bond with more or less anything that will take its electron or give it one - see Hydrogen compounds. So maybe this isn't such a good example after all ! Gandalf61 08:03, 19 January 2007 (UTC)[reply]

I wasn't trying to imply hydrogen won't bond with anything but oxygen, but it takes more energy to break the chemical bonds in water than to make them. Vespine 01:28, 20 January 2007 (UTC)[reply]

Heh i dont know but i like this its cute. so Gandalf61 says that hydrogen is a cheat eh. he couldnt be more right. bad hydrogen heh. maybe hydrogen is just misunderstood maybe it needs to experiance more love ok thats enough of that. as for a love thingy how about

Hydrogen, you ignorant slut!. Clarityfiend 23:03, 19 January 2007 (UTC)[reply]

stains love shirts food love floors cars love speed Maverick423 16:53, 19 January 2007 (UTC)[reply]

WE ALL LOVE THE INTERNET! Ovation plz. Vitriol 22:21, 19 January 2007 (UTC)[reply]

Fat kid loves cake? :> -O bli (Talk)^? 22:45, 19 January 2007 (UTC)[reply]

Odd color perception with a tone of violet

There's a particular tree around here from the genus Tibouchina (Tibouchina multiflora, in particular) which flowers have a color similar to this violet\purple tone. But, I'm not quite sure why, the color has a completely different effect on me than any other.

It really burns my vision, in the sense that I see afterimages and sometimes trails of the petals for quite a while afterwards. Another curious thing is that the color seems to "blur" everything else, and leaks out to the rest of my vision (particularly when I see several petals scattered on the floor.) It's like the color blinds all others. It also seems to be the last color I can perceive with my photopic vision (it's as if I could see it with the corners of my eyes.) It's quite an interesting feeling overall. It can be distracting, but nothing worth worrying about.

So, I was wondering what could this be... I wanted to know if there is such thing as color hypersensitivity? Maybe my cone cells and rod cells are all affected by high energy photons of the violet light in a different way? Or maybe the petals are particularly good reflector of an usually invisible part of the spectrum, which I happen to be a more sensitive to?

Well, I don't know. Any ideas of what's this? I asked other people if they have the same thing, but I couldn't find anyone else who admitted perceiving this tone differently from the others. Even the ophthalmologist I go routinely never heard of this sort of thing. — Kieff 10:40, 19 January 2007 (UTC)[reply]

The way you describe it as burning an afterimage into your sight probably indicates that photons of this particular frequency for some reason have an abnormal effect on the reformation of the rhodopsin molecule in your photoreceptor cells (the article Retinal explains the process). Maybe you have an abnormal form of the molecule, due to some genetic mutation? Does any of your parents/grandparents report the same hypersensitivity? —LestatdeLioncour t 11:25, 19 January 2007 (UTC)[reply]

I already theorized it could be genetic. If so, then it's either recessive, since my parents deny any such effect, or a specific mutation of myself. Since violet photons are more energetic than the others in the visible spectrum, maybe a slightly different molecule is having a whole new reaction against this higher energy? — Kieff 11:58, 19 January 2007 (UTC)[reply]

It's much more probable that a point mutation resulted in a slightly different, less efficient version of your opsin (in the sense that high-energy excitation prevents it from reassuming cis form), than for you to have synthesized a whole new molecule and developed a whole new method of perceiving color. The mutation doesn't have to be inherited, either. It could have taken place in the gametes of your parents, in which case it would more likely be dominant, and none of your parents would have it (see the mutation article, which might be helpful). If you can't find anyone in your family with a similar condition, then this is the more likely scenario. —LestatdeLioncour t 13:37, 19 January 2007 (UTC)[reply]

I think so... But it'd be nice to know of anything of the sort on record, and to look more into it. — Kieff 14:00, 19 January 2007 (UTC)[reply]

We are not able to provide you with medical advice. If you are concerned for your health or safety, you should seek professional medical attention. Hipocrite - «Talk» 13:22, 19 January 2007 (UTC)[reply]

I think Kieff is just trying to understand the biochemical/genetic origin of his peculiar condition. Based on how he describes it, it doesn't seem to be a medical condition warranting professional medical attention. —LestatdeLioncour t 13:37, 19 January 2007 (UTC)[reply]

Oh please, I'm well aware of the RD policies, but what I'm asking is not medical advice, at all, I'm not concerned or anything. I just want to know if anyone out there ever heard of this sort of thing, and just so I can look more into it. And I've been to an ophtamologist already, he never heard of anything like this, and didn't seem to be very interested on it either. — Kieff 13:30, 19 January 2007 (UTC)[reply]

Kieff your not the only one that has this experiance. I too have it even right now while i was typing and reading i still see the after image of the color that you displayed. It can be quite annoying and kinda hazardis when your driving. I personally dont know what this condition is called but i do know that im the only one in my family to have such problems with colors like this. so it cant be genetic. I do however wear Glasses if that can explain anything (although i doubt thats the problem) however i had this problem even before the glasses. well in anyways i also want to know what this is calledMaverick423 15:51, 19 January 2007 (UTC)[reply]

I don't have such a strong effect as you describe, but this shade does seem to be rather more insidious than your average colour. D aniel (‽) 21:21, 19 January 2007 (UTC)[reply]

Well, the color in a monitor doesn't do anything to me, and I don't think it should. The monitor is sending red and blue photons giving me the violet perception, but still they're not violet photons. — Kieff 02:25, 20 January 2007 (UTC)[reply]

Great White shark and sea lion

The article about the Great white shark states that "[..] This tactic allows the animal to avoid combat with dangerous prey, such as sea lions". I can't imagine how a sea lion can be dangerous for such a huge and well armed shark. Any ideas? Thanks. --Taraborn 10:53, 19 January 2007 (UTC)[reply]

That was probably vandalism; I've seen tons of footage of sharks attacking sea lions. | AndonicO ^{Talk · Sign Here} 12:09, 19 January 2007 (UTC)[reply]

Perhaps it's trying to express the concept "Prey which can themselves potentially do damage to the shark"? I'd imagine a sea lion is more dangerous to the shark than, say, j-random 1/2-metre fish.

Atlant 12:52, 19 January 2007 (UTC)[reply]

Some sharks, but not Whites. Their hide is as tough as aluminum siding. Pretty much the only animals that can do damage to whites are people, orcas (and maybe other toothed whales if they were interested), and other whites. Anchoress 13:04, 19 January 2007 (UTC)[reply]

So, do you think that a great black-backed gull defeat a great white in combat on land? :) --Kurt Shaped Box 13:24, 19 January 2007 (UTC)[reply]

If you attached the gull to a jackhammer or a harpoon, definitely. Anchoress 13:48, 19 January 2007 (UTC)[reply]

On land, unless the great white is related to the lungfish, the gull wouldn't have to do anything. All hail the mighty gull. (Deduct 20 points.) Clarityfiend 16:00, 19 January 2007 (UTC)[reply]

Even if it was, the gull could just go for the eyes (they're good at going for eyes) and incapacitate it - no aluminium siding there. --Kurt Shaped Box 18:41, 19 January 2007 (UTC)[reply]

Radioactive poisoning and possible cures

Dear Sir/Madam

Please name some radioactive isotopes that if consumed can poison and kill a person?

Also, are there any possible or hypothetical cures for radioactive poisoning?

Please submit an answer as soon as possible as it is for a school research project and the deadline approaching fast!

Thank You 222.165.183.45 13:00, 19 January 2007 (UTC)[reply]

You probably aren't going to find anyone on Wikipedia willing to do that much work for you. Why don't you start by reading some of the Wikipedia articles in THIS SEARCH and come back with some specifics? Editors on WP are more friendly and helpful when you 'show your work', so to speak, and let us help you fill in the blanks. Also, I took the liberty of fixing the wikimarkup and moving your signature. Hope that was OK.Anchoress 13:09, 19 January 2007 (UTC)[reply]

Polonium 210? The isotope of choice if, for example a government or government agency (allegedly) wishes to make an example out of a well-known dissident... --Kurt Shaped Box 13:16, 19 January 2007 (UTC)[reply]

Look at the half life of the isotope and take only isotopes with a half life of less than a year and you are on the safe side. If you want to be really sure take alpha emitting substances or even better transuran isotopes which do multiple emissions during the decay path! Most of the stuf is not readily available!--Stone 13:49, 19 January 2007 (UTC)[reply]

And for the cure look at the star trek medical advisary hompage, you will get plenty of antiradiation pills from Leonard McCoy or Beverly Crusher.--Stone 13:51, 19 January 2007 (UTC)[reply]

Although not a cure per se, see potassium iodide. Laïka 14:08, 19 January 2007 (UTC)[reply]

Bone marrow transplant? Though if you're unfortunate enough to be contaminated internally with alpha-emitters, the only real 'cure' is to place a pistol to your own head and pull the trigger whilst you still have the strength to do so. --Kurt Shaped Box 14:36, 19 January 2007 (UTC)[reply]

Well then as far as radiation poisioning, the only thing that i know that can cure that is a long visit to a hospital and alot of prayers. sure there are some cures out there but they are not fast enough or probable enough to get you fully cured. once damage is done to your body from radiation its either live or die. I have seen cases where the only thing doctors can do is just watch the patient slowly die. as far as a radioactive isotope try americium (~~sorry cant spell that one right so someone correct it plz~~ - done — Kieff) in any ways you will find that that element is located in most fire detectors in the house! yes you heard right! you can even pull down your fire dectector and read the back of it and it will state on most of them "this detector contains americium a radioactive isotope". go ahead and check it! also if you want to find out how radiation works try going to www.howstuffworks.com and search for radiation and everything you want to know about it. Maverick423 16:18, 19 January 2007 (UTC)[reply]

Remember kids - do not under any circumstances eat the contents of a smoke detector, no matter how tasty they may appear... ;) --Kurt Shaped Box 18:45, 19 January 2007 (UTC)[reply]

I saw a TV program a few years back where a kid tried to make a nuclear reactor using smoke detectors and I think it was lithium batteries. I can't remember the details, can anyone else? Theresa Knott | Taste the Korn 00:59, 20 January 2007 (UTC)[reply]

Ah here it is - David Hahn. 01:02, 20 January 2007 (UTC)

Radioactivity, radiation poisoning, radioactive decay... We have lots of articles on the subject already, take a look! — Kieff 18:36, 19 January 2007 (UTC)[reply]

If the radioactive isotopes happen to be heavy metals, perhaps chelation therapy could be used. StuRat 01:08, 20 January 2007 (UTC)[reply]

Could some sort of nanotechnology be developed that can prevent most radiation damage, or rebuild afterward:) What about rewriting someones DNA so they can prevent the damage themselves, although this could be considered unethical for some reason:)Hidden secret 7 13:48, 21 January 2007 (UTC)[reply]

I don't think that anything you did to the DNA would affect the body's reaction to radiation - it's about physical cell damage from high energy particles. Imagine that a watermelon represents a cell from somewhere in your body. Pretend that you are The Jackal from "The Day of the Jackal". Blast the melon with a shotgun at close range for an idea of what an alpha particle does to a cell. Use a .22 pistol for a beta particle and a pellet gun for gamma. --Kurt Shaped Box 23:01, 21 January 2007 (UTC)[reply]

DNA is also the way it is for a reason. Strengthening it externally somehow would cause "difficulties" in cell division and DNA replication. --W o o ty Woot? contribs 23:04, 21 January 2007 (UTC)[reply]

Also, remember that mutations in DNA are an important element in evolution. Any species which had unalterable DNA would not evolve and would eventually die out to competitors which did evolve. StuRat 06:38, 22 January 2007 (UTC)[reply]

If our DNA didn't mutate, we could do it ourselves and evolve as we wanted:)Hidden secret 7 18:46, 22 January 2007 (UTC)[reply]

Arun S. Bagh

what is the name of the sign used just above the Angstroms's short-form "A"

See the second paragraph of Å --bmk 15:43, 19 January 2007 (UTC)[reply]

Hydrogen storage and burning

Can hydrogen leak out from the walls of a typical, plastic 500-mL water bottle? Also, is it safe to ignite a bottle-full of hydrogen using a match? --Bowlhover 17:27, 19 January 2007 (UTC)[reply]

I have seen this before. it appears that when burned in a bottle all that happens is that the fire crawls up the bottle its a pretty awsome sight! as far as safty is involved well it was performed in a school when i saw it so it might be safe as long as you take proper measures.Maverick423 17:40, 19 January 2007 (UTC)[reply]

If the bottle were completely full of hydrogen, the match would extinguish due to a lack of oxygen. I'm not sure I would try this though, due to the chance of finding the right ratio of hydrogen and oxygen, and blowing yourself to smithereens. After all, you are dealing with rocket fuel. If curiosity gets the best of you, I'd be sure to fill the bottle by first filling it with water, then bubbling the hydrogen in to ensure only hydrogen is in the bottle, and always keeping the bottle sealed and/or upside down. I'm not sure about the gas going through the bottle, I'm not sure. You could experiment by weighing the bottle on a sensitive balance, then waiting for a while (overnight) and doing it again. Presumably if hydrogen escapes (or another gas enters) you will see a rise in weight. -anonymous6494 17:43, 19 January 2007 (UTC)[reply]

Pressure builds up inside the weak water bottle, bottle bursts, oxygen gets in, boom. -- Consumed Crustacean (talk) 17:54, 19 January 2007 (UTC)[reply]

Never attempt such an experiment without observing all the safety procedures which would be followed in a well run school lab, such as eye protection, adequate distance from the thing and maybe bulletproof glass between you and it (see how Mythbusters handles explosions). A small amount of hydrogen is capable of an explosion which would sound like a cannon. I saw/heard/felt such a demo at a chemistry department open house when a balloon about 10" diameter full of hydrogen was ignited, which might have held 2 to 3 liters. It literally shook the room. It probably burned faster than a pop bottle full of hydrogen would. A half liter bottle with an explosive ratio of H2 and air or O2 ignited by a spark would be a different story. The ignition in a plastic bottle probably often occurs with a mixture too rich or lean to be at the peak of the explosive mixture ratio. Beware the temptation to think that if some chemical reaction makes a nice "pop," then bigger will be more satisfying. Remember the Challenger and the Hindenberg. Edison 21:03, 19 January 2007 (UTC)[reply]

As Edison notes, be very careful with this sort of experiment. If your bottle contains pure hydrogen, combustion will only occur at the opening of the container, at the point where the hydrogen can mix with available oxygen. The combustion will occur at a fairly moderate rate, and all will be well.

However, if you uncap the container and wait for a while (a short while) then the (denser) oxygen in the air will fall into the bottle and displace some of the rising (less dense) hydrogen gas. The net effect will be to mix the hydrogen with oxygen, resulting in a mixture which will burn rapidly (explosively!) if ignited. In the experiment Edison describes (involving a balloon full of hydrogen gas) hydrogen from the balloon is forcefully and rapidly mixed with air as the balloon bursts, resulting in rapid combustion. I've seen this demo too; it's quite impressive. I recommend using a match or other ignition source attached to a long stick, otherwise the explosion could be deafening.

Over a reasonably short period of time, hydrogen won't leak through the walls of a plastic bottle, however it may escape by following the threads around the bottle's cap. TenOfAllTrades(talk) 02:24, 20 January 2007 (UTC)[reply]

Thanks everybody. For my first attempt at burning hydrogen, I'll probably tape the bottle to a wall, light a candle beneath it, and run for cover. I might deliberately add some oxygen to the bottle to make the fire more spectacular.

Don't worry about hydrogen escaping through the bottle's top, because I will add some water and invert it. Also, TenofAllTrades, how long is a reasonable amount of time? A month or two?

By the way, this is not a school lab. That's why I'm asking for the safety precautions here. --Bowlhover 05:01, 20 January 2007 (UTC)[reply]

vegetables cooking

What cooks faster at the same tempature, frozen vegetables or raw vegetables?

Raw. They need less energy to cook. — Kieff 18:28, 19 January 2007 (UTC)[reply]

Remember, though, that many frozen vegetables sold in the states at least are "pre-cooked", these may "re-heat" quicker than cooking fresh. --Cody.Pope 18:53, 19 January 2007 (UTC)[reply]

And even if not, the freezing process breaks down the vegetables. I don't know if that process is enough to counteract the extra time (not much, BTW) it would take for the frozen veggies to catch up to the raw. Anchoress 18:57, 19 January 2007 (UTC)[reply]

Tritium oxide

Since tritium is radioactive and tritium oxide is similar to water, would an ice cube of tritium oxide melt itself over time? 66.214.220.134 19:30, 19 January 2007 (UTC)[reply]

Not if you keep it cold enough. Tritium has a fairly long half-life, at 12.32 years, and based on that and the decay energy, I'm sure someone can figure out how much warmer than ambient temperature a tritium ice cube would be. What is certain to happen is that the ice cube will decompose over time into helium and oxygen gas as the tritium decays. --Carnildo 20:30, 19 January 2007 (UTC)[reply]

The size of the block would be critical, as well. Beyond a certain size, there would be no amount of cooling that could be provided at the surface which would keep the interior frozen, much as the core of the Earth remains molten due to radioactivity (as well as tidal forces). StuRat 01:00, 20 January 2007 (UTC)[reply]

Thermal Nuclear Rocket

I am unclear about the last bit at the end of the Nuclear Thermal Rocket article about risks. Do these rockets release fallout at all I would think they do but how much?68.120.226.193 20:26, 19 January 2007 (UTC)[reply]

A properly-designed nuclear-thermal engine will release no more fallout than any other nuclear reactor. --Carnildo 20:32, 19 January 2007 (UTC)[reply]

Which is to say, "none" for all intents and purposes. --24.147.86.187 00:46, 20 January 2007 (UTC)[reply]

So if its where launched from an isolated area fine but one of these rockets fying over a city probabely a bad idea?

Well the biggest worry is that it'll pull a Challenger and spread the core materials over a wide area. Disintegrating rockets can spread debris over a very wide area, and depending on what stage of lift-off it came apart in, it could spread the debris over an area very different from where it took off from. But you could probably minimize these risks in a variety of ways (different types of fuel pellets, containment vessels, plotting very specific trajectories) and make them manageable. The real difficulty is the political will and the public distrust of official statements on radiation matters (the US gov. has a pretty bad track record in this respect), among other things. --24.147.86.187 18:44, 20 January 2007 (UTC)[reply]

Would fallout be reduced if the rocket where launched from a high altitude in case of explosion?

fallout would be the same as the rocket would be the same size, but it would spread out over a larger area, and be affected by wind more:)Hidden secret 7 18:00, 21 January 2007 (UTC)[reply]

Unless, of course, it was only producing αradiation, which could only travel a short distance from the rocket:( I am not sure what it would produce as I am not a rocket:)Hidden secret 7 18:03, 21 January 2007 (UTC)[reply]

No, the radioactive materials will still spread, and will continue emitting whatever they emit. The "fallout" isn't the radiation itself, but the radioactive leftovers and by-products from the explosion. -- Consumed Crustacean (talk) 18:39, 24 January 2007 (UTC)[reply]

Thanks for all the answers.68.120.81.177 06:09, 22 January 2007 (UTC)[reply]

Wikipedia:Reference desk/Archives/Science/2007 January 19

Contents