Wikipedia:Reference desk/Archives/Science/2008 February 4

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February 4

Genetic code

When using letters to represent bases, as well as A, T, G and C, there are also letters to represent various possibilities, e.g. X and N among others, where each letter might represent A, T and G but not C, A or T but not G or C, G or C but not A or T and so on. Where can I find a list of these letters and the bases that the represent? Thanks ----Seans Potato Business 00:36, 4 February 2008 (UTC)

See Degenerate bases. (EhJJ) 02:21, 4 February 2008 (UTC)

And I've cleaned up the list of symbols into a much neater table. TenOfAllTrades(talk) 04:25, 4 February 2008 (UTC)

High-pitched TV sound

From the time I was a child until this very day, I can hear a high-pitched sound coming from television sets. My sister can also hear it. People are often surprised when we can tell whether the TV is on even when it is on mute and we are not in the same room as it is. What exactly is this sound? Where does it come from? Why can't everyone hear it? Wrad (talk) 00:41, 4 February 2008 (UTC)

I used to hear it, too. It's the horizontal deflection, which runs at about 15,000 cycles a second (15,575 if I remember right [BZZZZT! 15,735]). This is well within the normal range of audibility for humans. --Milkbreath (talk) 01:04, 4 February 2008 (UTC)

This gets me thinking though...is the actual source of sound the deflection coils or the gun itself? I don't see it being the gun, since the tube is a vacuum and the gun doesn't move (only the beam)... Trimethylxanthine (talk) 01:10, 4 February 2008 (UTC)

This seems to provide some insight: http://www.repairfaq.org/samnew/tvfaq/tvwhine.htm - Marcio —Preceding unsigned comment added by 71.211.231.102 (talk) 01:22, 4 February 2008 (UTC)

Note the part about how as you get older you lose the ability to hear frequencies this high. The people who are surprised you can tell the TV is on are older than you, right? --Anon, 01:39 UTC, February 4, 2008.

Most of them. My brother is a few years younger but listens to louder music... Wrad (talk) 01:40, 4 February 2008 (UTC)

A side note: A mobile telephone ring tone that has been popular here in Norway (and probably elsewere) features a very high piched note. To teenagers, it is intensely unpleasant, while their teacher cannot hear it. So they amuse themselves by irritating their classmates by playing it in class, without their teacher noticing. I'm in my 50's, and was able to hear it only when holding my ear quite close to the phone, but at that distance it was almost nauseating. --NorwegianBlue ^talk 14:08, 4 February 2008 (UTC)

That sounds like the same principle as the device to disperse troublesome teenagers. AndrewWTaylor (talk) 13:29, 4 February 2008 (UTC)

Another possible source of audio-frequency squeal is resonance in a power supply. Often these circuits involve switching capacitors or some other circuitry which might inadvertently ring. Nimur (talk) 03:47, 4 February 2008 (UTC)

The squeal comes from the line output transformer, which is a sort of power supply, or from related circuitry. --Heron (talk) 13:16, 4 February 2008 (UTC)

Yes, it is the flyback transformer. Flyback transformers are often switched using a feedback winding, making them resonate at their resonant frequency, which is typically around 20 Khz. The flyback transformer is what generates the HV for the electron guns. Ilikefood (talk) 22:13, 6 February 2008 (UTC)

I've always been able to hear it too; never quite knew where it came from or if I was just imagining things until now. But now we have an LCD Bravia, so no more sounds for me :(. --M1ss1ontomars2k4 (talk) 01:49, 8 February 2008 (UTC)

Non-Irish joke “travelling to sun” sci fi short story - details required

Looking for details of story of space ships which work inside the sun(!). This short story is not related to the novel “Sundiver”, which has an article in WP.

It’s a golden age (1950s I think) work in which a team of intrepid astronauts go to the sun, in a craft of a kind known as “sunskimmers” (I think – I read this a long time ago). The craft design was ingenious, though it wouldn’t really work. First, to counteract the enormous heat, they had pumps putting out a continual intense spray of liquid hydrogen (or some such) down the sides of ship, continually draining off the heat. Neat, huh? Well, if you think that’s neato, then listen to what they used to counteract the gravity. They had a huge cyclotron above their heads in the ship. This massive particle accelerator was so powerful, the spun particles became massive gravitational objects in their own right. And this cancelled out the gravity of the sun. In reality, it would probably mean that the crew would have their top halves pasted to the cyclotron, and their bottom halves to the deck. The purpose of the mission was to subtly alter some “vectors” or such (vectors are the term to use when you don’t know what you are talking about) in the maelstrom of the sun, in order to change the weather on Earth for a special reason. (Shades of Sunshine). And it does. In the final scene, an old and dying scientist, waiting to see it rain just one more time on his ranch, is granted his wish when a SINGLE cloud comes out of nowhere, and rains down right on his small bed of petunias. Now that makes you want to get the old hanky out, doesn’t it guys? But what was the story? And does anyone think Sunskimming could work. Myles325a (talk) 02:54, 4 February 2008 (UTC)

I remember the story that you're looking for—I remember the bit about the counter-gravity cyclotrons clearly. A story that seems like it might fit the bill is "The Weather Man", by Theodore L. Thomas. If I recall, the goal was to bring snow to somewhere unusual, rather than rain; other than that the description is bang-on. I'd appreciate it if someone could check that result for me, though. TenOfAllTrades(talk) 03:57, 4 February 2008 (UTC)

OP myles325a here. Thanks TenOfAllTrades. The story obviously struck a chord with you too. It was certainly unusual because of the rarity of ideas of people exporing environments so extreme as to be normally considered unbroachable, even by sci-fi writers. But I STILL can't locate the book in Google. It MIGHT be Weather Man by Theodore Thomas, or another of his called Weather on the Sun" (he obviously had a thing about solar exploration) but I can't find anywhere where the works are described. Does this ring a bell with anyone at all? Myles325a (talk) 23:37, 4 February 2008 (UTC)

There's one sentence in the article Sun in The Encyclopedia of Science Fiction: "The weather technicians of Theodore L. Thomas's 'The Weather Man' (1962), however, skim across the surface of the Sun in 'sessile boats' in order to control its radiation output". --ColinFine (talk) 00:28, 6 February 2008 (UTC)

OP myles325a here. Thanks ColinFine. Yes, it comes back to me now. "Sessile boats" it was, yes indeed. Myles325a (talk) 23:41, 6 February 2008 (UTC)

A lot of empty space

I hope I can formulate this question clearely. The universe we see is mainly made of empty space (talking volume). The constituents of molecules are widely seperated, and again, between them is a lot of empty space (please correct anything inacurate). Each particle that makes up matter has a energy/mass and therefore it is possible to (gu)estimate the weight of the universe. Do these particles also have a size so that if we ignored the immense volume of void we could estimate the volume of all the matter in the universe? In other words do particles occupy a volume in space or are they only energy/mass points that have spatial relations to each other? I hope it makes sense. Keria (talk) 11:34, 4 February 2008 (UTC)

In the Standard Model of particle physics, elementary particles are assumed to be point-like objects with no size. In various alternative (and currently speculative) theories such as string theory, elementary particles have extension and are not dimensionless points. However, "empty space" is, in fact, a sea of transient virtual particles, so I don't think it is possible to phrase a question about the "total volume" of particles in the universe in a way that has a meaningful answer. Gandalf61 (talk) 13:12, 4 February 2008 (UTC)

The universe is a pretty empty place, is it not? Ignoring electrons and other low-mass particles, and considering only protons and neutrons, if these particles where evenly distributed throughout the universe, how far apart would they be? Edison (talk) 01:31, 5 February 2008 (UTC)

According to the Lambda-CDM model, which is the leading theory about what the universe is made of, the density of normal matter (baryonic matter) is 4.17 * 10^-28 kg/(m^2). If we assume the universe is about 70% hydrogen and 30% helium, then the average weight of the particles in the universe is about 1.9 AMU. That gives...an average interparticle distance of 2.76 meters! Note again that this neglects any dark matter which may or may not exist. --Bmk (talk) 13:39, 5 February 2008 (UTC)

Terminator

Their time travel technology doesn't allow you to bring back weapons or clothes, that's why they had to send back engineers to build weapons in the past.. so how can they send back terminators? :D\=< (talk) 11:34, 4 February 2008 (UTC)

You know, that always bugged me. I think it's something of a conceit. -mattbuck 11:37, 4 February 2008 (UTC)

They're lying, of course. They can send back whatever they want. The question is why are they lying? Hmmmm??? --Milkbreath (talk) 12:44, 4 February 2008 (UTC)

In the original movie, they said the machinery had to be surrounded by living tissue. I always wondered as a kid why they didn't put an "M-27 Plasma Phase Rifle" inside a pig and send it back along with the person. --Sean 14:34, 4 February 2008 (UTC)

OH that explains why the teacher/terminator cuts open his leg and pulls out a pistol in one of the Sarah Connah Chronicles episodes.. I just thought he was doing to be completely awesome and because he can, not because he had to or anything, like casually yeah that's how I carry my guns around :D\=< (talk) 12:02, 5 February 2008 (UTC)

You have to take this with a grain of salt, like most science fiction. The official explanation is that the Terminators are covered in organic material, allowing them to go back. However, this leaves the questions of A.) How are the ones covered in metal nanomachines sent back? B.) How come the time machine ignores the insides of what it is sending back? 206.252.74.48 (talk) 14:48, 4 February 2008 (UTC)

I looked in some old Cyberdyne systems manuals (from before they were taken over by Micro$oft) and found some things that might explain:

Series 800 m 101 owners manual

Congratualtions on buying your new Cyberdyne Systems Series 800 Model 101 Version 2.4 anthropomorphic battle robot / lawn sprinkler device. By following the instuctions in this manual you'll experience centuries of trouble-free operation.

The 800 series lawn sprinkler device features comprehensive support for a wide range of modern weapons systems, including pulse-cannon and laser weapons systems, together with device drivers for operating spacecraft, hovertanks, and anti-gravity surfboards - as such it is an ideal choice for late-twentieth century operation. Limited backwards-compatability capabilities cover shotguns, uzis, and pointy rocks, although use of such items may invalidate your warranty. Note that some late Model 101s were accidentally shipped from the factory with Krautweld(tm) Comedy Bavarian Theme Park Character voice PROMs, which should be swapped out for a mission-appropriate selection prior to reployment (unless the required termination will take place in a Bavarian theme park).

CSI T-1000 application note 1044 - differences with earlier models.

The T-1000 runs Windows Vista Basic Edition and replaces outmoded weapons systems such as guns and bombs with highly effective knives and stabbing weapons with a lethal range of over two feet! Improvements in the T-1000's locomotive subassembly allow it to run almost as fast as a rusty old pickup truck!!

Weapons-use plugin modules you may have purchased for other Cyberdyne products under the "Kills For Sure[tm]" logo will not work in T-1000 models due to incompatabilities between the platforms' respective DRM subsystems.

For legal reasons, it is not permitted to configure the T-1000's mimetic polyalloy chameleon function to impersonate any living person or copyrighted fictional character; doing so will cause the T-1000 to close down unexpectedly.

Care should be taken to avoid use in dusty or sandy environments, as this may cause the inlet manifold to become blocked. Keep your T-1000 away from x-ray machines, MRI scanners, and plugholes. Avoid exposing your T-1000 to spirit levels, mercury-vapor lamps, or those naff mercury mazes everyone had in the '80s, as inadvertent interbreeding may occur.

Cyberdyne systems lawn sprinkler model T-X - important product recall

If your model T-X "Terminatrix" lawn sprinkler resembles a Swedish underwear model, please return it to your Cyberdyne dealer for a full refund. No matter how badly it acts, no-one thinks it's scary, and what's the point of buying a multimillion-credit robot if it just looks like a sleazy hooker? Replacement T-Y and T-Z models are reassuringly covered in chrome and feature lots of flashing blue LEDs.

Hope this helps. -- Robotard (talk) 15:06, 4 February 2008 (UTC)

Quite humourous. Anyway, I bring up another question. In the first episode of Sarah Conner Chronicles, the "substitute teacher" Terminator is blown up just as he enters the range of the time machine, with all his flesh burned off - and yet he makes it to the future. I'm starting to think that Reese truly was lying. 206.252.74.48 (talk) 19:27, 4 February 2008 (UTC)

Again, it's all a conceit. You have to look past the flaws in the argument and just accept it for the betterment of the story. -mattbuck 20:04, 4 February 2008 (UTC)

That's true, but I believe that fans were made for the sole purpose of pointing out these flaws and making logical (or illogical) explanations when the writers can't. 206.252.74.48 (talk) 20:31, 4 February 2008 (UTC)

What? I'm pretty sure he didn't make it into the future. He got de-molecularized by the safety deposit box gun.. Then everyone was naked on the road and they walked off awkwardly, not fighting :D\=< (talk) 12:06, 5 February 2008 (UTC)

Pretty sure?! Have you seen ANY of the episodes after the pilot? He obviously made it! 206.252.74.48 (talk) 13:36, 5 February 2008 (UTC)

The body didn't make it at all, it just got buried in the bank's wreckage and sat in a dumpster for 10 years.. the head made it through though and reactivated the body --:D\=< (talk) 14:12, 5 February 2008 (UTC)

Yes, I realised that from this topic. I don't know why I didn't make this connection before.

You don't happen to have the manual for the femme-bot in TSCC (whatever model she is) handy, do you? She's obviously a more advanced model than your standard T-800, as she has blue LED eyes (which is far more of a giveaway than the enhanced AI). ;) Unless of course, female-type Terms come with blue optics as standard (the T-X had them too) in order to differentiate them from the male-type endoskeletons on the factory floor before the flesh coating is applied. --Kurt Shaped Box (talk) 01:34, 7 February 2008 (UTC)

I'm really liking the show thus far, pity it had to be on Fox. I take great care to avoid the horrible commercials 206.252.74.48 (talk) 14:39, 5 February 2008 (UTC)

Thomas Dekker is cute. But his head makes it, and body goes the long way. -mattbuck (Talk) 12:14, 5 February 2008 (UTC)

Wrong thomas dekker, and the modern one is annoying cause he's somehow a 'ril legit hacker' yet doesn't think the idea of machine rule and superhuman AI is freakin cool?! --:D\=< (talk) 14:28, 5 February 2008 (UTC)

Meh, didn't bother checking the link. Also just realised how my statement could be misconstrued. Bugger. Oh crap, that's another one. -mattbuck (Talk) 17:26, 5 February 2008 (UTC)

AMERICAN IS THE ORIGINAL ENGLISH :D\=< (talk) 19:12, 5 February 2008 (UTC)

Actually, English comes from the language of the Anglans, which of course are angles, which are important in triangles, which were invented by the Greeks, who were created by the Gods. Therefore, English is the language of the Gods passed down through geometry. 206.252.74.48 (talk) 19:43, 5 February 2008 (UTC)

Yeah, Americans. That's what I said. :D\=< (talk) 20:27, 5 February 2008 (UTC)

Human reproduction without an intercourse

In some areas,the spouses don't indulge in sexual intercourses and still their co-habilitation causes a baby birth. How does that occur? And in this case how do the sperms fertilize the ova? —Preceding unsigned comment added by 202.125.143.68 (talk) 15:17, 4 February 2008 (UTC)

I'm unaware of this phenomenon. Could you be a little bit more specific about the areas you refer to, in which you believe that this occurs? --NorwegianBlue ^talk 15:24, 4 February 2008 (UTC)

They're probably having intercourse and claiming that they are not. When in doubt, suspect a lying human, especially when it comes to sexual matters. Co-habitation without intercourse of some sort will not result in pregnancy, unless we are talking about various artificial means of insemination, which are fairly rare. --24.147.69.31 (talk) 15:25, 4 February 2008 (UTC)

I didn't know House had a wikipedia account! On a side note, I distinctly remember my 6th grade "health teacher" telling us that if a guy sleeps in the same bed as a girl, their sperm can swim across the bed and get her pregnant. There may be some recall error, as it's been about 12 years. -- MacAddct  1984 ^{(talk &#149; contribs)} 16:04, 4 February 2008 (UTC)

Not only can sperm swim across the bed, but masturbation will also cause hairy palms!

Er, on a more serious note, even in the absence of penetrative intercourse, there are still ways for sperm to get to egg. For example: she manually masturbates him, accumulating some semen (containing live and happy sperm) on her hand. She then masturbates herself, transferring semen to her vagina. The vigourous and virile little swimmers head north in search of the Promised Land. Presto—pregnancy with no intercourse. There are many possible variations on this theme; all involve the inadvertent transfer of semen from the male to the female's genital area. Luck, gravity, fluid dynamics, and determined swimming cover the rest. TenOfAllTrades(talk) 17:22, 4 February 2008 (UTC)

Right, but that's a rather complicated series of actions. It can happen but it's not as likely as them just having plain old vanilla penetrative intercourse.--24.147.69.31 (talk) 22:21, 4 February 2008 (UTC)

I'm surprised sperm can make it through the vagina without the help of an "injection" device. I would have thought sperm needs to be close to the cervix and propelled out, in order to make it into the uterus. On a related note, how exactly does sperm "swim" to the ovaries? What kind of fluid are the uterus and fallopian tubes filled with? -- MacAddct  1984 ^{(talk &#149; contribs)} 22:29, 4 February 2008 (UTC)

Believe it, ask Boris Becker. Richard Avery (talk) 20:47, 4 February 2008 (UTC)

Remember Occam's razor! --S.dedalus (talk) 21:32, 4 February 2008 (UTC)

Right. The odds are that if they are cohabitating and a baby is born then they probably had intercourse in one form or another. (Sorry Mary, I don't buy it!) --24.147.69.31 (talk) 22:21, 4 February 2008 (UTC)

The guy didn't shoot himself in the testicles whilst stood in front of the woman (with the bullet passing through his nuts and penetrating her lower abdomen) did he? I may be wrong, but I'm sure I read somewhere that at least one child has been conceived in this manner... --Kurt Shaped Box (talk) 22:52, 4 February 2008 (UTC)

The story you mention involves an American Civil War soldier (shot through the testicles, but by an enemy rather than by himself; the woman in question was a field nurse). Some people believe the story, but it's far from proven - and let's face it, it's much more likely that the soldier and the nurse got it on. There was a 1989 case report in the British Journal of Obstetrics and Gynaecology ("Oral conception: Impregnation via the proximal gastrointestinal tract in a patient with an aplastic vagina." Volume 96, page 501), describing a young woman with a congenitally absent vagina who performed oral sex on a lover. She was then stabbed in the abdomen. Several months later she was found to be pregnant, presumably by an intraabdominal transfer of sperm between the gastrointestinal tract and uterus. This is a bit more believable than the Civil War story, because without a vagina, vaginal intercourse is pretty much impossible.... - Nunh-huh 23:06, 4 February 2008 (UTC)

Here's Snopes on the bullet-assisted pregnancy: [1]. --Sean 23:49, 4 February 2008 (UTC)

Oho, that's interesting: the story was a joke in the first place! --Anonymous, 07:18 UTC, February 5, 2008.

They did that ^^ on mythbusters can't remember if it was bustered or not... Also I think there are cases of insemination off a toilet seat.. Again unlikely but possible. Shniken1 (talk) 23:06, 4 February 2008 (UTC)

It was bustedZrs 12 (talk) 00:47, 5 February 2008 (UTC)

There was a guy arrested around here a couple of years ago after he was caught sneaking into public (ladies) toilets and masturbating on the seats. I can see how it *might* happen. --Kurt Shaped Box (talk) 23:19, 4 February 2008 (UTC)

Just some points.

1. Shniken1 avers

They did that ^^ on mythbusters can't remember if it was bustered or not... Also I think there are cases of insemination off a toilet seat..

I wanna know which one of the dudes on Mythbusters shot themselves in the balls and splattered his semen on his coworker’s vagina?

In any case, whatever they did, all they could demonstrate was that it didn't work on that occasion. It's impossible to prove it could never happen under any circumstances. Still, it seems very unlikely. -- JackofOz (talk) 00:53, 5 February 2008 (UTC)

2. Kurt Shaped Box (talk) 23:19, 4 February 2008 (UTC) alleges:

There was a guy arrested around here a couple of years ago after he was caught sneaking into public (ladies) toilets and masturbating on the seats. I can see how it *might* happen.

Over here is unusual for women to straddle toilet seats side saddle. Just like regular guys, the only parts of their bodies to touch the seat are thighs and buttocks.

3. Occam’s Razor is a methodological rule of thumb, it does NOT guarantee that the more complex and unlikely supposition is ALWAYS wrong. Just about every crime and trial movie ever made is based on the idea that what appears to be an “open and shut” case is anything but that, so each of them is a negation of the absoluteness of Occam’s Razor. Consider the following scenario. Husband does not want girl friend to get pregnant, so he uses a condom. For whatever reason, girl friend wants a child. She smuggles out and disguises the used condom, leaving it in the fridge. When boy friend is not around, she injects the semen as per well-known procedures, and has a child by boy friend. Plausible? Certainly.

(Inserted) Hmm, I seem to recognize the latest episode of Boston Legal here! --Anonymous, 07:18 UTC, February 5, 2008.

4. Finally, there used to be a tradition amongst country folk that on “bath night” for the kids, the girls would always get the tub first before the boys, to prevent the possibility of super powerful sperm being in the water and making their way to sister’s uterus. Myles325a (talk) 00:23, 5 February 2008 (UTC)

Whoa, pardon me, I thought for a minute I had wandered into Yahoo. Richard Avery (talk) 08:01, 5 February 2008 (UTC)

Nobody claims Occam's Razor is guaranteed. However in most cases when we are not talking about one-off random flukes it's a good way to rule out the "plausible-but-unlikely" from the vast majority of the "probable". As has been said, statistics and probability tell us almost nothing about any individual case but over the aggregate of cases they make it almost into a scientific law. The OP seemed to be referring not a one-time, exceptional case, but some sort of general trend, which leads one to think the most simple answer is probably correct. Each of the above "possible" methods require great luck to pull off; they're not the sort of thing that would be happening on any sort of mass scale. --24.147.69.31 (talk) 16:51, 5 February 2008 (UTC)

and oddly enough, many times the baby resembles the next door neighbor, or the mailman, rather than the husband. Gzuckier (talk) 19:56, 6 February 2008 (UTC)

Storing food in cans after they have been opened

Twice recently people have told me that they have worked in restaurants that strictly forbade storing food in the can, after the can had been opened. One of these people told me that storing food that way leads to botulism. Now, I know enough food microbiology to know that this in nonsense, but I am wondering if there is some other reason that this practice could be dangerous. ike9898 (talk) 20:52, 4 February 2008 (UTC)

From Food Science Australia [2]:

Once cans are opened some foods, especially fruit, fruit juices, and tomato products, should be placed in a clean plastic or glass container, covered and stored in the refrigerator. When these foods are stored in the opened metal can, tin and iron will dissolve from the can walls and the food may develop a metallic taste. Food containing high concentrations of tin can cause nausea, vomiting, diarrhoea, abdominal cramps, abdominal bloating, fever or headache. These symptoms pass quickly and there seem to be no long term effects of high tin exposure. However, repackaging food once a can is opened is a good practice to adopt for all foods packaged in metal cans.

So it's more a metal-poisoning issue than a microbiology problem. I gather that some cans have a liner made of some inert material, but it's still quite easy to damage this lining when the can is opened or when contents are scooped out. TenOfAllTrades(talk) 21:33, 4 February 2008 (UTC)

The thing about damaging the lining sort of makes sense. Otherwise I don't see how opening the can starts the corrosion process. I'm not convinced that modern food cans have much tin in them. Maybe at the seams. ike9898 (talk) 22:06, 4 February 2008 (UTC)

Our article on tin cans isn't much help. It only really states that no cans are made primarily from tin anymore. It does say, however, that modern cans do not require any solder at the seams - I had though there might be tin in the solder. ike9898 (talk) 22:12, 4 February 2008 (UTC)

Once the can is opened, oxygen from the air can oxidize metal atoms into soluble metal ions. The low pH of the particular foods listed in the above quote speeds the oxidation process. --169.230.94.28 (talk) 02:16, 5 February 2008 (UTC)

According to Brittanica [3]: "Unlike steel, tin is not affected by the acids in food, so that a layer of tin placed on steel sheet protects the steel in the can from corrosion." This seems to argue against tin ions leaching into the food. ike9898 (talk) 22:07, 5 February 2008 (UTC)

Wouldn't there also be the problem that food in an open can is now exposed to the air, and all the lovely pathogens in it? Confusing Manifestation(Say hi!) 22:08, 4 February 2008 (UTC)

Well, that would happen just as much (or more) if you transfer the leftover food to another container such as glass or tupperware. ike9898 (talk) 22:10, 4 February 2008 (UTC)

But if it's a sealed container, then you at least minimise the exposure to the air. It's a lot harder to re-seal a can than a glass jar or tupperware container. Confusing Manifestation(Say hi!) 04:14, 5 February 2008 (UTC)

You can easily put plastic wrap and if necessary a rubber band. Potentially not quite as airtight as a tupperware container perhaps but good enough if all your worried about is pathogens on a short term Nil Einne (talk) 13:45, 6 February 2008 (UTC)

Keeping the food cold is much more important for controlling pathogen growth than covering. The greatest oppurtunity for pathogens to get into the food is while you are handling it. If you get fecal coliforms in the food while handling it, covering it is irrelevant but keeping it cold will at least limit their growth. ike9898 (talk) 16:41, 6 February 2008 (UTC)

Yeah, it's the question of leaching metal from the can into the food, and tin was used specifically to prevent this. The problem with soldered cans is lead, not tin. As for the microbiology, of course once you open the can it's not sterile by definition; but as the last guy said, you're more likely to inoculate the food with bacteria in the process of transfering it into another container than if you just removed what you need and left the remainder mostly undistrubed; and at any rate, consider it nonsterile, and cold is what keeps bacteria from growing. Gzuckier (talk) 19:54, 6 February 2008 (UTC)

Uranus

Is the surface of Uranus filled with things such as craters and fissures? How about cracks and valleys? Bellum et Pax (talk) 21:17, 4 February 2008 (UTC)

Phil, is that you? --Milkbreath (talk) 21:35, 4 February 2008 (UTC)

Given the windspeed, I'd expect it to be quite smooth due to erosion. -mattbuck 21:28, 4 February 2008 (UTC)

It apparently has no solid surface. From Uranus: "The fluid interior structure of Uranus means that it has no solid surface. The gaseous atmosphere gradually transitions into the internal liquid layers." -- MacAddct  1984 ^{(talk &#149; contribs)} 22:17, 4 February 2008 (UTC)

...and it's called a gas giant.--Shantavira|^{feed me} 08:27, 5 February 2008 (UTC)

So then a lot of gas comes from Uranus? Bellum et Pax (talk) 16:14, 5 February 2008 (UTC)

Ugh I can't wait for the year 2620 :D\=< (talk) 20:29, 5 February 2008 (UTC)

Hmm, depends on what you consider to be a "solid surface". Uranus does have a solid core. The sheer pressure forces would force the matter to be solid eventually. Malamockq (talk) 01:57, 6 February 2008 (UTC)

Stop, please, stop! :D\=< (talk) 03:53, 6 February 2008 (UTC)

PHYSICS MAGAZINE QUESTION THOUGHT

Hey,it`s Me the Physics Magazine guy. I have a question for you from the magazine,a sort of MIND-WARMER.How does,the thing with the elevator as well as the thing with the pennies demonstrate NEWTONS SECOND LAW. —Preceding unsigned comment added by Yeats30 (talk • contribs) 23:06, 4 February 2008 (UTC)

What things would these be? Algebraist 23:19, 4 February 2008 (UTC)

Hey, PMG. I'm curious: what is the name and country of publication of the physics magazine these questions come from? Thanks. --Sean 00:10, 5 February 2008 (UTC)

Since you didn't initially provide enough information in the elevator question (as noted in the first response to said question), and never returned to the question to append the missing information, we can't answer this question either. Best I can do is link you Newton's Second Law. — Lomn 14:25, 5 February 2008 (UTC)

OMFG. I can't believe your back. I really thought you wouldn't be back until the middle of the month since that seems to be when your magazine comes out Nil Einne (talk) 12:02, 6 February 2008 (UTC)

Phisical/chemical changes

good evening wikipedia volenteer, I'm currently doing a prodject on chemical an phisical changes —Preceding unsigned comment added by 71.72.242.212 (talk) 23:13, 4 February 2008 (UTC)

Do you have a question related to your project? Algebraist 23:20, 4 February 2008 (UTC)

Perhaps you should take a gander at physical change and chemical change. Our articles on heterogeneous substances and homogeneous substances may interest you also. If you still have any questions, please ask us. --Emery (talk) 03:39, 5 February 2008 (UTC)