Wikipedia:Reference desk archive/Science/2006 June 15

From Wikipedia, the free encyclopedia

Humanities Science Mathematics Computing/IT Language Miscellaneous Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above.

< June 14 Science desk archive June 16 >


Contents

[edit] Composition of Matter

In the Wikipedia entry "matter", matter is defined as everything that is composed of elementary fermions. It is also stated that matter is composed predominantly of atoms.

What else is it composed of?

Portions of atoms which do not form complete atoms?

Thank you.

--Ben

At a guess, the space between the atoms? Or the space between the electrons and the nucleus? Rockpocket 01:17, 15 June 2006 (UTC)
I don't think "space between things that doesn't contain things" counts as matter. However, the Fermion page notes that electrons, neutrons, and quarks are all fermions. By the definition on the matter page, those particles are all "matter", but are not atoms. DMacks 01:24, 15 June 2006 (UTC)
All everyday matter here on Earth is composed of atoms (and ions, if you say atoms have to be neutral). The Sun, however, is made of hydrogen plasma, which is protons and electrons that aren't associated into atoms. The core of a neutron star is probably not made of protons and electrons at all. —Keenan Pepper 01:49, 15 June 2006 (UTC)
Thank you very much, that answers my question exactly. -Ben
And dark matter is composed of who knows what. -lethe talk + 02:33, 15 June 2006 (UTC)
That's assuming it even exists. —Keenan Pepper 02:39, 15 June 2006 (UTC)
Don't forget neutrinos. Dar-Ape 03:15, 15 June 2006 (UTC)


See List of particles#Fermions (half-integer spin) for a list of particles. Of course, most of these are in the form of up and down quarks, combined into protons and neutrons, which are then combined with electrons to make atoms. As noted above, there are a considerable amount on Earth in the form of ions, which are basically atoms with extra or missing electrons (in a sense). Also, in stars, much matter is in the form of plasma, in which the nuclei (protons and neutrons) and electrons are not combined into atoms. As Dar-Ape notes, neutrinos are another fundamental particle, in addition to the up and down quarks and the electrons which probably occurs in large amounts. Then you have the other fermions listed (strange, charm, bottom, and top quarks; muons; taus), which occur much less frequently (the quarks always occur in combinations; they have never been observed in isolation). To that you can add any of the mysterious and hypothetical dark matter. — Knowledge Seeker দ 04:36, 15 June 2006 (UTC)


The way I always learned it, matter is composed of tiny eensyweensy little atoms surrounded by vast expanses of open space. Each atom is also mostly empty space with a positively miniscule nucleus in the center. So...my answer is empty space makes up most of matter. --M1ss1ontomars2k4 (T | C | @) 05:08, 16 June 2006 (UTC)
Thats not really matter is it, thats like calling the airspace in your garden part of you house. And also the quote said predominantly matter, and if you count space as the alternative, it is not predominantly matter it is only an absolutely minescule amount of matter, so clearly, the quote is refering to something else. Its probably some of the more exotic particles. Philc TECI 16:08, 16 June 2006 (UTC)
Interesting fact - it seems that the majority of the (non-dark) matter in the universe is in a state of plasma. It's the cold, dense atomic matter that makes up our earth that is the exception; we're just an unlikely island of weird fundamental physical interactions in a plasma universe.--Bmk 03:51, 17 June 2006 (UTC)
I have to say that matter is not just composed of fermions, some fermions and some bosons are matter, but not all of them are. Elementary particles are either fermions, or bosons, but that doesn't describe WHAT matter IS. That only describes what type of spin the particle has. The best way to explain what matter is is to talk about it's association with mass. The amount of mass an object has (and thus it's matter) is proportional to the amount of energy it requires to accelerate. If something requires no energy to accelerate it to light speed, it has no mass (Example: light). This is one of the defining charateristics of matter. More abstractly, it is not helpful to say that all matter is made of _____. Giving a name to something does not help understand what it is. You need to understand what matter does, and how it interacts with other things to really understand what it is. This, however, is easier said than done. You can study chemistry to understand how atoms interact, or physics to understand how smaller things interact. This gets you only close to the answer because physists aren't done figuring out what matter is yet. Hope this helps. Also, dark matter isn't what a physist would call matter yet. It is just a proposed explination for some gravitational effects that astronomers observe.

[edit] Java Image Editing

There's still some disagreement over which desk should get computer problems, so I'm going to go with this one and hope no one minds. I had a great snippet of Java code (I found it on the Internet somewhere) that could take bitmaps in, convert them to two-dimensional arrays, change the numbers however I wanted, and save the result to a bitmap. Unfortunately, the hard drive it was on died and I don't remember the details. Does anyone know how that works? Black Carrot 02:00, 15 June 2006 (UTC)

The BMP format in its common uncompressed variant is entirely trivial to parse; see that page and/or its external links for the file's format. In Java you'd just make a FileInputStream (or some other type of input stream) and read first the image size. Allocate the appropriate arrays, then read the image data into the arrays. Obviously you can do whatever you want with the arrays, and it's just as easy to write them back into a file with the appropriate header information. I've done exactly this, although (as it happens) with C++ instead of Java. Or were you asking for help in finding or reconstructing this code? --Tardis 04:28, 15 June 2006 (UTC)
The Portable pixmap bitmap format is trivially easy to write code to read and write, and there are a bunch of free utilities available to convert back and forth from other formats. --Robert Merkel 11:11, 15 June 2006 (UTC)
I never cease to be amazed at the infinite versatility of the English language. One person's "great snippet" is another person's "trivially easy". Pretend I'm dumb as a post. (I'm not, but I am profoundly uneducated, considering I was in CS for two and/or three years.) I don't know much about reading and writing files. Could you show me how to do that? Once I can get it into and out of array form, I know enough to make the pictures I want. Black Carrot 16:50, 15 June 2006 (UTC)
The easiest way in Java is probably using the ImageIcon class to load the image (this will work for jpg, png, gif & bmp files in most implementations), then create a BufferedImage in the format you want to use (e.g. 8 bit-per-channel), and draw the loaded image onto the BufferedImage using drawImage. Then you can use getRGB to get and manipulate the arrays as you want, then use setRGB to update it. To write it out again, use ImageIO.write() to save in the format you want. Very rough code:
ImageIcon icon = new ImageIcon(filename);
Image i = icon.getImage();
int w = i.getWidth(null), h = i.getHeight(null);
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics2D g = bi.createGraphics();
g.drawImage(i, 0, 0, null);
int [] data = new int[w*h];
bi.getRGB(0,0,w,h, data, 0, w);
// data now contains pixel data in (A)RGB format
// do stuff to data array
bi.setRGB(0,0,w,h, data, 0, w);
ImageIO.write(bi,"png", new File(newfilename)); // write in PNG format
Hope this helps. --Bob Mellish 20:16, 15 June 2006 (UTC)
It's claiming that ImageIcon, Image, Graphics2D, and ImageIO don't exist. What do I have to import? Black Carrot 20:36, 15 June 2006 (UTC)
At first glance, javax.imageio.*, java.awt.*, java.awt.image.*, and javax.swing.* --Bob Mellish 20:40, 15 June 2006 (UTC)
Thanks, you're a lifesaver. Black Carrot 23:49, 15 June 2006 (UTC)

It isn't working. It keeps throwing up an exception, claiming that the width and height of the image are -1. Black Carrot 22:40, 19 June 2006 (UTC)

[edit] can fireflies overwinter in warmer climates?

(I asked this on the talk page of the corresponding article, thought maybe I would try here as well) As far as I know there are no fireflies in warm dry areas (like on the west coast of the united states). Is this because fireflies prefer more humid climates or is temperature a factor? Would it make sense for an insect to overwinter in a warmer climate at all? --69.249.30.109 02:21, 15 June 2006 (UTC)

Well, you may be onto something regarding the dryness or humidity of the climate. But I can say for a fact that there are fireflies in Central Africa (Southeastern Cameroon, to be precise), and that's a pretty damn hot place. — BrianSmithson 18:11, 16 June 2006 (UTC)
There are also fireflies in Malaysia. Quite a lot of them in some areas in fact (see Kuala Selangor. That is a fairly whot place (but also very humid). However, as you always should do when asking questions on the reference desk, you might want to check out the Firefly article. I believe you're not realising that there are over 2000 species of fireflies Nil Einne 16:14, 21 June 2006 (UTC)

[edit] fever and bitterness?

when a person has fever why is the taste bitter?67.150.4.232 03:09, 15 June 2006 (UTC)

Which taste? Water will taste tasty if the fever is accompianied by a stuffed-up nose because the scent of the mucus will make the water taste like snot. If you mean the taste of the saliva in the mouth, I don't know, it never seemed bitter to me. Emmett5 03:35, 15 June 2006 (UTC)

Probably because an acid imbalance in your stomach, as your body attempts to fight off whatever its trying to fight off.  freshofftheufoΓΛĿЌ  04:05, 15 June 2006 (UTC)
I am not sure if food tastes bitter but I have experienced that it is kind of tasteless, probably because our tongue wil be covered by a kind of white layer of something (I don't know what it is) when you have fever -- Wikicheng 05:20, 15 June 2006 (UTC)
The taste page might be of use: its intro mentions the importance of smell, so consider stuffy nose→reduced olefaction→foods taste blander. Later on, the page mentions body temperature as having an effect, but doesn't seem to discuss the effect in any detail:( DMacks 06:21, 15 June 2006 (UTC)
You shouldn't eat people who have fever. Not only will they taste bitter but if not properly cooked you may contract their fever. AllanHainey 10:19, 16 June 2006 (UTC)
*sour face*  freshofftheufoΓΛĿЌ  06:04, 19 June 2006 (UTC)

[edit] IQ

Can anyone recommend a (relatively reliable) free online IQ test? If I'm looking to take the test for real, I'd like to have some indication on how well I'm likely to do, and though I've taken a bunch of them for kicks (such as [1] and a few of the ones on [2]) and the scores have been relatively consistant, since none of them are real and most of them are quite short, I can't be really sure if the scores I'm getting are realistic at all! Is there anything out there with a little bit more authority?  freshofftheufoΓΛĿЌ  04:12, 15 June 2006 (UTC)

Not a IQ test, but try [3] and their 'work out', should give you a idea on if you will do good or not. Stefan 13:12, 15 June 2006 (UTC)
Personally, I don't think that there are any reliable ones. With the quick ones I used to do online, I'd get scores of >160, which I don't think is accurate at all. My guess is that they inflate the scores to make you feel good about taking them. — Asbestos | Talk (RFC) 14:15, 15 June 2006 (UTC)
You have to keep in mind, an actual IQ test is a very sensitive tool, designed by professional psychologists for the use of professional psychologists. To be valid, it must conform to the many strict rules guiding scientific research. Tests over the internet, even home tests in hardcopy workbooks, cannot really do that. However, to get a ballpark figure, the free Mensa excercise is probably your best bet. Be careful to follow the rules, though, and don't go over the time limit. BTW, what was your score on the online tests? Black Carrot 15:58, 15 June 2006 (UTC)
Those online IQ tests tend to be rather rubbish; one gave me a score of 180, which is in the region of the top 0.0001%. But since it said the "average" score was 139 (on a normal IQ test, it should be 100), I'd take it with a pinch of salt. smurrayinchester(User), (Talk) 20:45, 15 June 2006 (UTC)
I've noticed that most online IQ tests tend to be coupled with ridiculous amounts of advertising, so my guess would have to be that they're trying to flatter peoples egos, so they'll be more likely to buy stuff, as a general rule (:205.188.116.74 21:14, 15 June 2006 (UTC)
Well, I would expect that those who would want to take IQ tests online are those who are more likely to feel that they will score highly on them, and so more likely to score highly, period.... 04:23, 16 June 2006 (UTC)
That's also very true. I tried to get my dumb friend to take one so I could compare our IQ figures and he absolutely refused : (.  freshofftheufoΓΛĿЌ  04:37, 16 June 2006 (UTC)
If you really want to know your IQ, you should see a...psychiatrist? psychologist? one of those psy people, for sure. That's what I did, but I took the WISC III in 3rd grade and scored too close to the top of the scale to get a good reading. --M1ss1ontomars2k4 (T | C | @) 05:06, 16 June 2006 (UTC)

[edit] Carbon Dioxide

Carbon dioxide gas and water vapor both absorb IR radiation. Do they also absorb visible radiation?

I don't know much about the subject, but I think that since humans can see dark smoke (carbon dioxide), it can't be letting all visible light pass through it. Some of it is getting absorbed, which is why the smoke looks dark. I assume that the explanation is similar for water vapour. -- Daverocks (talk) 13:13, 15 June 2006 (UTC)
Dark Smoke is not Carbon Dioxide, unless you know something I do not. Dark Smoke is unburned particles from a fire.
Carbon Dioxide says it's a colourless (sic) gas. This is a good article because it was obviously written by a Canadian :) --Zeizmic 14:00, 15 June 2006 (UTC)
Why is it obviously written by a Canadian? English people spell colourless colourless and we spelt it that way first. If anything should be given a (sic) it should be the American way of spelling it colorless. I'm sorry about that, but I really don't like American spellings, nor pronunciation. Anyway, back on the topic, I once saw a demonstration where carbon dioxide was poured out of a container and although you could not see the gas itself, you could see a very distinct shadow. This seems to indicate that it does absorb a small amount of visible light, although I am most probably wrong. --80.229.152.246 19:06, 15 June 2006 (UTC)
It's not a "shadow" in the conventional meaning (something blocking some light), but rather an effect of carbon dioxide having a different index of refraction than air. If an even level of light room light passes through side-by-side regions of high-CO2 and low-CO2, one will diffract the light differently than the other. That will make the image cast have different levels at the interfaces due to one region of light being shifted relative to the other. This is similar to how you see wavy effects if you look at an object across the top of a hot surface. DMacks 20:06, 15 June 2006 (UTC)
Dark smoke is unoxidized carbon, which iscreted when something is burnde in an oxygen lacking environment allong with carbon monoxide. This does not mean in oxygen low air, as any fire with a yellow flame is oxygen lacking. Hence if air is correctly introduced beofre burning, you get a blue flame, like on gas cookers. Philc TECI 14:36, 15 June 2006 (UTC)
Carbon dioxide and water vapor are both transparent at visible wavelengths. Automobile exhaust contains both compounds; notice how the exhaust is invisible under normal conditions. (If your car is burning too much fuel/not getting enough air, the exhaust turns black; those are particles of unburnt fuel: soot, the same sort of stuff that colours smoke. In cold weather, you can see a white cloud; this is because the cold air condenses some of the water vapour into liquid water droplets that scatter light like a little cloud.) TenOfAllTrades(talk) 13:46, 15 June 2006 (UTC)
I'm pretty sure CO2 does not absorb visible radiation (definition of colorless). But water vapor does absorb some, since it's simply water, and water absorbs visible wavelengths of light, particularly red. --M1ss1ontomars2k4 (T | C | @) 05:05, 16 June 2006 (UTC)

[edit] Question about Marine and Ship Designing.

I would like to know something about what subjects and areas are invloved in Marine and Ship designing. If possible, would like to have some website links which explain the various concepts involved in it.

Have you checked our article on naval architecture? — Lomn 14:39, 15 June 2006 (UTC)

[edit] Nuclear apocalypse

Let's assume there's a nuclear free-for-all in the northern hemisphere. China vs. USA vs. Russia vs. France vs. Britian... Israel vs. the rest of the middle East... India vs. Pakistan... basically every nuke that could fly, does.

Would this wipe out all life on the planet, or would the southern hemisphere be largely unaffected (apart from the massive economic collapse caused by losing the northern hemisphere)?

And speaking of which, would life up there be COMPLETELY gone? Because according to Threads, some people would survive, they'd just be living in an incredibly bleak and pointless world.

The southern hemisphere would be greatly affected -- the atmospheric patterns of the hemispheres are mostly isolated but not completely so (note that large volcanic eruptions have effected global temperature shifts). Even if fallout settled out first, nuclear winter would still wreck things fairly readily. As for complete annihilation, there would probably be survivors, at least initially. Brinkley's The Last Ship posits that the real problem would be one of repopulation. — Lomn | Talk 17:08, 15 June 2006 (UTC)
Ten females to each male... Sum0 14:54, 16 June 2006 (UTC)
The Nuclear Winter scenario was popular with Carl Sagan, but when the numbers were crunched, it was discoveredthe effect would not be as catastrophic as he predicted. Even if he were correct, there are organisms which would manage to survive.
Build Vaults... lots of them. -- Миборовский 22:18, 15 June 2006 (UTC)
I doubt that nuclear war could ever destroy *all* life on earth - insects and bacteria can be very tough and there are plenty of organisms in the depths of the oceans that would probably escape the worst of it. Mass extinction of mammal and bird species on land would probably be a given in the nuclear winter that followed but even then, I doubt that *everything* would be wiped out. Life has a funny way of 'getting on with things'. --Kurt Shaped Box 23:00, 15 June 2006 (UTC)
Life survived, amongst other things, the Chicxulub Crater impact. Nuclear war is small beer by comparison, unless we were silly enough to use the cobalt bomb. Even if we were to use them en masse and wipe ourselves out, microbes and insects would still probably survive. --Robert Merkel 23:42, 15 June 2006 (UTC)
Nevil Shute's novel On the Beach is about this very scenario. The last place on Earth is my city Melbourne. ("A perfect setting for the end of the world", according to journalist Neal Jillett, who mis-attributed the quote to Ava Gardner). JackofOz 02:14, 16 June 2006 (UTC)
Sorry, maybe I wasn't completely clear in my original question: I meant would any human life survive - after all, we're the only ones that matter ;). Basically, would the scenario described in John Wyndham's The Outward Urge (in which the southern hemisphere remains habitable after a nuclear war) at all plausible? (and sorry I didn't log in the first ime to ask) Battle Ape 04:44, 16 June 2006 (UTC)
In response to (and friendly rivalry with) JackofOz, I have to point out that one of Wyndham's other novels, "The Chrysalids" details remnants of a post-nuclear war North American society. In that, the one surviving society - and even then surviving with a few major alterations - is in the far south and called new Sea Land, "only spelt with a Z". Grutness...wha? 10:26, 16 June 2006 (UTC)
I disagree that "we're the only ones that matter" - just imagine if some bomb was invented that killed all other life & left humans, humans wouldn't last much longer before succumbing to starvation, disease, depression and other psychological problems (or you could wait 50 years and see the results of the 6th mass extinction to get an idea). On whether the southern hemisphere would be habitable, it would certainly be able to support a lot less life than it does now given the levels of radiation in the atmosphere, just look at the amount anf effects of the radiation released by Chernobyl, it's effects are still being felt in Wales (some sheep can't be sold as radiation is too high). AllanHainey 10:43, 16 June 2006 (UTC)

[edit] Orgasm

I always have ejaculation and orgasm while masturbating but never while fucking a woman, none of these two things. What's the matter? Johny Bill, 19:30, 15 June 2006 (UTC)

I suspect it's because you use to hold your jimmy tough as I do instead of up-down hand moving but I'm not sure :P --Brand спойт 19:35, 15 June 2006 (UTC)
Perhaps you aren't "concentrating" on what's avaliable at the moment, but while masturbating, are free to "concetrate" on whatever you please. There is a such thing as masturbating too much to a point where you become immune intercourse because it cannot satisfy you the same way your fantasies do. This may not be true in your case though. If you feel that your masturbation tendancies are not abnormal, then the problem could be something else. Do you have an intimate relationship with this "woman"? If not, do you experience this impotence with other women? Have you considered drugs such as Viagra, Cialis, or Levitra? --Chris 22:14, 15 June 2006 (UTC)
It could simply be the case that you're so used to 'flogging the dolphin' really hard and fast that a woman's vagina simply doesn't provide the same level of stimulation. Try cutting back on the wanking for a few weeks and see if things get any better for you... --Kurt Shaped Box 22:37, 15 June 2006 (UTC)
Read this article from Dan Savage about training your penis to get off on the "death grip." Here's the question that reminds me of your problem:
Remember how one time (or maybe two) you warned a guy (while remaining masturbation-positive) not to condition his body to come only in response to a particular kind of stimulation? I believe ('cause I looked 'em up) your exact words were, "If you hold your cock in a death grip every time, you may find it difficult to climax as the result of other, more subtle sensations."
Well, unfortunately, I read your excellent advice too late. About 30 years too late. So now, while women think it's cool that I can "stay hard all night," they eventually start to get a complex about the fact that, though they're having orgasms galore, they can't seem to make me come. It's not them, of course. It's the years and years and years of death-grip masturbation.
Help me, Dan. What can I do to climax in response to "more subtle sensations"?
While Viagra might help with getting an erection, it won't help you come. I have a similar problem, but getting the lady to close her legs helps by increasing the friction, as do ribbed condoms. --83.245.18.34 07:34, 16 June 2006 (UTC)

[edit] Speed of light changing?

According to Einstein’s general and special theories of relativity, this states that the speed of light cannot change.

However I am confused by this: The way I have always understood the theories of relativity is that time slows down to keep the speed of light constant relative to your own velocity. However if this is the case then moving at any speed will cause the speed of light to change relative to you, for example, the speed of light is moving at 2.998e10^8 but if we are moving at a velocity of 30 ms^-1 then the speed of light traveling towards you would be: 2.998e10^8ms^-1 + 30ms^-1. I knew that the speed of light could never change so I therefore thought that time would slow down to keep the speed of light constant but if this is the case then time would slow down to the point at which you would not move, because if you move at any speed then c, would change relative to you??

Thanks for any info,217.42.253.14 (talk · contribs) 19:44, 15 June 2006

I am kind of an amateur scientist, but here is what I understand.

1) When light passes through matter, like glass, it slows down, so the speed of light CAN change, irrespecive of relativistic effects. 2) When the velicity of an object increases, so does it's mass, this has the effect of slowing down observations, and this slowing is not noticed. This is because the reactions act more slowly on massive objects.-12.10.127.58 (talk · contribs) 20:12, 15 June 2006

  • actually no, the speed of light doesn't change in a refracive medium, rather, the thing that makes a medium refractive in the first place is it's ability to absorb and emit photons of a given wavelength, the excitation and emission process takes a finite amount of time, rinse and repeat a few million times, and the net amount of time for photons of a given type to pass through that medium is increased, without altering the fundamental velocity of light. The only thing special about vacuum is there's nothing there to emit photons, so c is always c--205.188.116.74 20:30, 15 June 2006 (UTC)


Let's talk about the speed of light in vacuum. As others have pointed out, the speed of light in a material can be less. Where the original question goes wrong is the assumption that you can still use the relative velocity formula of just adding two velocities when you get near to the speed of light. Actually what you need to do is start with the fact that the speed of light doesn't change, as this is the experimental observation (see Michelson Morley experiment). Then you can do various thought experiments about what the consequences of this will be. And purely through a series of carefully constructed thought experiments, you can end up deriving an expression for how to combine velocities. Specifically, if the two velocities are u and v, you get:
\frac{u + v}{1 + \left(\frac{uv}{c^2}\right)}
where c is the speed of light.
It turns out that if the two velocities are both much less than the speed of light, then it's very close to just adding up the velocities (as you'd expect). But if one of the velocities is the speed of light, then the combined velocity is still the speed of light. Arbitrary username 21:22, 15 June 2006 (UTC)
I'm not exactly sure what you are asking, but if you can move at the speed of light, time does indeed dilate to infinity. In other words, it will appear as if the clocks of other people has totally stopped. Similarly so, length contraction occurs, and the universe would appear to contract to a point. This suggests that, in your frame of reference, it takes no time at all to get anywhere. -postglock 03:54, 16 June 2006 (UTC)
Back to the original problem (changing speed of light), I've always interpreted it as being a wave in this case, and sound always travels at the same speed, so I never had any problems with this. Most likely I'm missing something, as I'm significantly better in chem and bio than in physics. --M1ss1ontomars2k4 (T | C | @) 05:02, 16 June 2006 (UTC)
sound always travels at the same speed Is that so?

Regardless, light and sound have so little in common that all but the most basic of analogues are misguided. Skip that. The problem with your question is that the speeds you reference are in units of distance AND time. Change the rate of time, and the numbers will have to change. It is hard to grasp without much study, but just trust Einstein when he says that you will never catch light in a vacuum going any speed besides C.


There's nothing in relativity that says the speed of light can't change. A popular idea in cosmology is that fundamental constants like the speed of light may be changing, though very slowly. The weak anthropic principle is the idea that the constants of nature vary from place to place in the universe, and we exist where we do BECAUSE the physical constants in this area are favorable for our type of life. Nifty, eh?

And to the orignal asker of the question, I would strongly recommend a special relativity course; it's the best way to understand this stuff. And it will blow your mind! Wheeeeee --Bmk 04:41, 17 June 2006 (UTC)

[edit] worms - destined for greatness?

hi, i was told by my primary school teacher that if you cut a normal, garden worm in half, the two halves will grow back into two new, fully functioning worms. my question is, is there a finite amount of times you can cut up a worm for this still to be true? if i cut a 10cm worm into 100, 1mm pieces, would i get 100 new worms or would the 100 pieces be too small to regrow and hence die? thanks! 87.194.20.253 19:49, 15 June 2006 (UTC)

If you cut a worm in half, both ends will continue to move for a short time, but both will die. If you cut it in a certain place, theres is a tiny chance that one end will survive. Dont believe primary school teachers on complex science. Philc TECI 20:18, 15 June 2006 (UTC)
Does the sadism of primary school teachers know no bounds? --83.245.18.34 07:37, 16 June 2006 (UTC)
Lol, poor innocent worms, victim of a primary school teachers plot to eradicate them all. Philc TECI 12:41, 16 June 2006 (UTC)
There is a worm (not an earthworm, though) that you can cut in half, and the halves will regrow, given time, into wholes. I think it might be the flatworm. The article agrees, at the end of the Body Functions section. Black Carrot 15:07, 17 June 2006 (UTC)
Just in case the article wasn't clear enough, the cut has to be lengthwise, across along the body from "head" to "tail", not separating the "head" from the "tail".--Tachikoma 15:31, 17 June 2006 (UTC)
Seastars also have this characteristic. -- Chuq 11:35, 20 June 2006 (UTC)
One thing to keep in mind is how much time you allow the surviving pieces to recover and re-grow after cutting! If you were to do it all in one shot, everything would probably die. But if you did it slowly - say, let each surviving piece live for a week between cuttings (presumably it would have food and be able to grow and heal), you could probably continue the cycle for a long time before everything died. Whether this would be infinitely sustainable is still up for question, though... it's almost like asking whether an asexually reproducing organism can ever die. Nimur 16:15, 22 June 2006 (UTC)

[edit] Excercise

Whats the best diet/excercise for maximum muscle build and fat loss in the shortest length of time (ie a few weeks) even if you can spend everyday working solidly. I was thinking maybe anaerobic excercises, but I dunno. And also what are some examples of them as I don't know any anaerobic excercises, if that is the right answer. Thanks dudes. Have an awesome summer everyone, or winter you unlucky southerners :-P. 195.93.21.8 19:55, 15 June 2006 (UTC)

Anaerobic excercises include activities such as weight lifting. These are best for muscle building, while aerobic exercises (those that a "fit" person can maintain for a long time) are probably better for fat loss because you can burn a lot of calories with sustained activity. A combination of the two is probably best for overall fitness. Add some stretches for flexibility. --Ginkgo100 talk · contribs 20:54, 15 June 2006 (UTC)

[edit] Outer Layer of Salmon Meat

I just baked a salmon before scaling it. So after cooking there is a thick section of pink coloured meat, on top of which is a thin layer of brown/pink meat which is easily scraped off seperate from the pink meat. On top of the brown/pink meat was the scales. The question is: What is that brown stuff? And more importantly: should I eat it? Thanks --Tacobake

You can eat the skin and all the meat, both the pink and the brown. In fact, in Japan salmon skin is considered a delicacy. Just don't eat the scales. The brown meat tastes like the pink meat to me, and is probably a different kind of muscle tissue. --Ginkgo100 talk · contribs 20:51, 15 June 2006 (UTC)
Isn't the brown meat saturated with omega-3-fatty-acids or am I just reading too much into my salmon?--205.188.116.74 21:00, 15 June 2006 (UTC)
I also thought that the thin brown layer was subcutaneous (or whatever it's called in a fish) fat. --vibo56 talk 21:09, 15 June 2006 (UTC)
No, subcutaneous fat in salmon is white, right underneath the skin. --ColourBurst 04:09, 16 June 2006 (UTC)
You can eat the scales too. If you fry the salmon, or roast it with some butter they're nice. AllanHainey 10:48, 16 June 2006 (UTC)

[edit] Unwanted shawdows behind icons

Hello. I am running Windows XP and I am having a desktop problem. There appears to be unwanted shadows behind the incons on my desktop (but here only). If the color of the background is white, and the color of the desktop is (right clicking the Desktop > Appearnce > Advanced), say, black, then the shawdows behind the icons on the desktop are black. The problem is that there is no option to not select "blank". When I create a new account on the computer, the solution is solve; but I don't want to keep two accounts. Do you know what the problem is? I can supply a picture if you want to email me, but I don't want to upload it to Wikipedia to illustrate a point when it won't be used in any articles. Thanks a lot. Kilo-Lima|(talk) 21:12, 15 June 2006 (UTC)

Right click on "My Computer" on your desktop and select properties. Click on "Advanced" and under "Performance" click on "Settings." Scroll to the near bottom of the list under "Visual Effects" and you'll see "Use drop shaows for icon labels on the desktop." Remove the check next to this box. -Quasipalm 00:50, 16 June 2006 (UTC)
This is unchecked, but the problem still exists. I also checked the preferences on the other account that I have created, and the only thing that is un-checked is "Smooth text on explorer windows" or something similar to that matter. Thanks. Kilo-Lima|(talk) 14:57, 16 June 2006 (UTC)

[edit] Lobsters

The earthworm question above have prompted me to ask this question: Why do lobsters (and other crustaceans) not die when they are dismembered, halved, or removed from water? How do they die in a pot: do they simply cook from the outside-in until there is not enough living flesh to sustain its life? Do they feel pain? --Chris 22:01, 15 June 2006 (UTC)

The enzymes necessary to maintain life denature. -- Миборовский 22:42, 15 June 2006 (UTC)
Feeling pain is notoriously heard to determine, even impossible. The nerve system of a lobster most certainly registers bodily damage and they are most certainly physically aware (e.g. their body is prompting them to make appropriate reactions in order to remove the cause of pain) that they are being dismembered or boiled, whether this constitutes pain or simply a reaction to a stimulus is highly debated. Adversely, some people argue that pain doesn't exist at all, evidenced by the amazing abilities of some people to do certain (disgusting) things to their bodies without feeling any need to counteract. But... that's another issue.  freshofftheufoΓΛĿЌ  01:48, 16 June 2006 (UTC)
There are some links at the Lobster Liberation Front (i mean, really!) page that may inform you:

Rockpocket 06:54, 16 June 2006 (UTC)

Whole Foods has just announed that they will no longer sell live seafood fish. It makes one wonder how they think their suppliers will produce the seafood body parts which they will continue to sell. User:Zoe|(talk) 16:08, 16 June 2006 (UTC)
Did they say "all live seafood"? I thought it was just lobsters and softshell crabs. Anyway, the issue is the nasty and long conditions in between capture and killing; I imagine the ones selling parts catch 'em and kill 'em (and probably freeze 'em) real quickly? --jpgordon∇∆∇∆ 02:42, 17 June 2006 (UTC)

[edit] Jogging at the speed of sound

I just read this question in a humorous context, but seriously what would be the answer to it? "If a jogger ran at [or above] the speed of sound, could he still hear his Walkman?" --Lph 22:17, 15 June 2006 (UTC)

Probably not, but simply because the roar of the wind rushing by would drown it out. The air between his ears and his headphones would be moving along with him. —Keenan Pepper 22:29, 15 June 2006 (UTC)
Assuming perfect conditions; e.g. he is jogging at the speed of sound and the wind is also blowing in the same direction at the speed of sound, then I believe the answer would be yes, he could hear his walkman. The speed of sound isn't a speed limit, and since the speakers emitting the sound are also moving at the speed of sound many of the sound waves would end up vibrating through the (small space of) air at a speed well above the speed of sound, and many would be well below it. I think.  freshofftheufoΓΛĿЌ  23:42, 15 June 2006 (UTC)
Can you talk to other passengers in a jet? Of course. If the air in between you is moving with you, and all other sound is muted (not the case with headphones), you'll hear just fine. Black Carrot 23:43, 15 June 2006 (UTC)
If you wear noise-cancelling headphones to drown out the air rushing past you (see sonic boom) you could hear your walkman. -- Миборовский 00:25, 16 June 2006 (UTC)
An iPod, on the other hand, would have disintegrated long before this.--83.245.18.34 07:43, 16 June 2006 (UTC)
Well the air between the headphone and his ear is probably trapped and therefore moving with him, so he should still be able to hear the walkman. (And even if not, there may still be enough sound conduction through solids to enable this.) A related question is if he was out running with a friend (i.e. the air between them is not trapped), would he be able to hear his friend? At exactly the speed of sound, she would have to be at least a little in front of him. (She could also be off to the side, but the sound energy she emits is anisotropic and he will receive comparatively more of the sound from her if she is more directly in front of him.) At higher speeds, she will have to be that much closer to being directly in front.
You could similarly consider the problem in terms of standing still in a wind tunnel. Of course not only is actually runnig at mach number 1 in still air ridiculous, so is even trying to stand up in a wind tunnel at that air speed. The wind force goes as the square of the air speed, and given the range of wind speeds defined as being a gale (see that page), the wind force would be several hundred times stronger than when standing in a gale. Arbitrary username 07:58, 16 June 2006 (UTC)

A more rational question is "do passengers on a supersonic jet hear engine noise" and the answer is, only if they are in the Mach cone behind the engine. moink 08:31, 16 June 2006 (UTC)

[edit] New question

All this speed of sound talk got me thinking: if I run at twice the speed of sound, and have a large speaker playing a song real loud for several seconds. Then about 50m after that I come to a full stop, will I hear the song backwards? VdSV9•♫ 14:40, 19 June 2006 (UTC)

At best you would hear it delayed. There is no good reason why you should hear the song backwards. Anyhow, I think the largest problem with these questions is a sort of imprecise definition of sound and speed of sound:
  • Sound is a vibration of air. When our ears detect these vibrations, our nervous system and brain work to decode them.
  • Sound travels as a transverse wave in air; and this means that vibrations of the air propagate by pushing the air back and forth.
    • Now, if you are running (flying, jogging...) at the speed of sound this means that you are physically moving faster than the air in front of you - which means you must push that air away from your body (airplane, etc) faster than it would normally be able to move. This act of pushing air away will create its own set of vibrations (e.g. sonic boom, rushing air sounds, etc). But, it will form a shockwave through which other air will not be able to penetrate. It is extremely unlikely that you will hear anything from the outside of your air-cushion. Nimur 16:26, 22 June 2006 (UTC)

[edit] The end of the world...

Following on from the 'nuclear apocalypse' thread, I find myself wondering about humans literally causing 'the end of the world'. While we are certainly capable of causing the extinction of our own (and other) species, be it via nuclear war, a manmade virus, poisoning the air and seas, destruction of the ozone layer, etc. - is there anything that humans could do/cause that would literally 'destroy the world' (i.e. result in the complete anihilation of the Earth)? I can't think of anything offhand - even if all the nuclear weapons in the world were set off in a huge global pissing war, the net result to the planet would only be a few craters and scorch marks on the surface, right? Would I be right in thinking that the only kind of event capable of destroying the planet itself would be one of extraterrestrial origin (e.g. a gigantic asteroid/planetoid collison, the expansion of the sun into as red giant, etc.)? --Kurt Shaped Box 23:16, 15 June 2006 (UTC)

Yep. About the only thing I can think of that could destroy the entire planet would be an unlucky collision with a stray interstellar planet, or a near miss close enough to significantly change the Earth's orbit. A sufficiently massive intruder could also destroy the Earth indirectly, by perturbing the solar system enough to cause another planet to collide with the Earth — but if the intruder was big enough to retain significant primordial heat and close enough to be a short-term threat, there's a good chance we would've seen it already. —Ilmari Karonen (talk) 23:34, 15 June 2006 (UTC)
I've heard of scientists making tiny, unstable (meaning they disappear immediately) black holes in a lab. I think they're so small they instantly radiate out their entire mass, or something like that. Could they make a bigger one that would eventually swallow the earth? Black Carrot 23:42, 15 June 2006 (UTC)
No, a black hole has the same amount of gravitational force acting outside of it as whatever went into creating it. They create small black holes with tiny bits of matter. That tiny bit of matter can't pull the Earth inside of it any more than a bit dust could. --Dan 19:44, 22 June 2006 (UTC)
You may be interested in Sam Hughes’ “How to destroy the Earth”, reposted in part at LiveScience. — Knowledge Seeker দ 23:58, 15 June 2006 (UTC)
Impossible (at least in the next thousand years or so). The energy required to shatter earth would be astronomical. -- Миборовский 00:23, 16 June 2006 (UTC)

[edit] Gull identification...

What kind of gull am I?
What kind of gull am I?

I'm coming to the aid of a fellow Wikipedian here - I found this question posted at Talk:Gull.

Does anyone know what type of gull this baby is? I'd actually be quite interested to know myself, being an avid gull fanboy... --Kurt Shaped Box 23:19, 15 June 2006 (UTC)

Googleimages thinks it's a plain western baby gull (searched for ... baby gull). Do you need some western latin name ? [She gulps sea gull on the sea. Whore!] --DLL 19:31, 16 June 2006 (UTC)

The photo is from Norway, so it almost certainly isn't a Western gull. It could, however, be just about any of the gulls found in Norway, which include the Common gull, the Herring gull, the Lesser and Greater black-backed gulls, the Glaucous gull and the Black-headed gull. Based on the photos I could find on the web, Black-headed gull chicks don't seem to have an orange beak tip, so we can probably rule that one out — but the others all do, and look pretty much identical in all other respects too. —Ilmari Karonen (talk) 15:24, 18 June 2006 (UTC)
That makes sense. Herring, Glaucous and LBB gulls are all quite closely related. Thanks anyway. --Kurt Shaped Box 11:27, 19 June 2006 (UTC)
I've copied this discussion over to Image talk:Baby gull.jpg. —Ilmari Karonen (talk) 21:18, 21 June 2006 (UTC)

[edit] tremors

How likely is a person to develop tremors from the poisons in a flea collar? Are these tremors permanent?

If you are experiencing tremors, particularly if you think you have been exposed to a poison, go and see a doctor quickly. Skittle 08:58, 16 June 2006 (UTC)