Wikipedia:Reference desk/Archives/Science/2010 October 1

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October 1

Pthirus gorillae

Resolved

Can anyone, by any chance, supply a 'free to use' (ie Public Domain or Creative Commons commercial-permitted) picture of a Pthirus gorillae? For use on that article. I can't find one; thought possibly people here might know of other sources. Cheers,  Chzz  ►  00:29, 1 October 2010 (UTC)

Is this issue resolved? You seem to have found a picture Nil Einne (talk) 06:23, 1 October 2010 (UTC)

It is indeed; sorry for not marking it as such sooner. Someone else found a pic, which I was able to retouch a little. Nothing great, but it'll do the job. Thanks,  Chzz  ►  07:00, 1 October 2010 (UTC) (now marked as resolved)

Chemicals in inkjet photo paper

I've discovered that you can transfer the image from a normal sheet of inkjet photo paper onto another surface... I was experimenting with letting the photo prints soak in cold, warm, and boiling water when it turned out that boiling water allows the top, slimy layer of the photo to loosen enough that it can be burnished onto a sheet of watercolor paper.

The thing is that after boiling these prints for a while I noticed a smell, not overpowering but noticeable. Obviously some of the chemicals that hold the image to the page were being released into the air as they dissolved and evaporated.

The decayed appearance of the images that result from this technique are very well suited to the ideas I'm working with (I'm an art student), and the materials are much cheaper than a Polaroid camera and the film for it would be (as in a Polaroid transfer). This technique on a larger scale would be ideal for an upcoming project, but I have no idea what chemicals I'm exposing myself to in the process. Although I've done some basic checking on Google, no info seems to be forthcoming. Does anyone here have have any knowledge of the chemicals involved? Are they harmful on skin contact or if inhaled? Should I invest in a respirator?

I've contributed to Wikipedia articles often, but I've only used the ref desk a few times. Forgive me if this post is too forum-ish. Also, please don't link me to Inkjet transfer- those techniques involve specially made transfer paper and produce a flat and uninteresting image surface. Thanks, Lithoderm 02:24, 1 October 2010 (UTC)

Forgot to mention - I'm using an Epson RX680 with Claria Hi-Definition Inks and standard glossy inkjet photo paper from Staples. Lithoderm 02:30, 1 October 2010 (UTC)

My suggestion would be to look for the MSDS of the inks you're using. If they aren't available online, try asking Epson. Nil Einne (talk) 04:27, 1 October 2010 (UTC)

Thanks, I wouldn't have thought of that. Lithoderm 08:24, 1 October 2010 (UTC)

It is possible, of course, that the chemicals causing the smell are being released from the paper, though I expect that you have checked this. Dbfirs 10:03, 1 October 2010 (UTC)

Lithoderm did mention the type of paper so it may mean they're thinking of that too. However I don't know how well that can be examined more, I don't think there would be an MSDS for the glossy paper. The best option may be to try boiling printed normal white paper. If you still get the smell then you know the smell isn't coming from the paper. (Whether you can use it for transfers is irrelevant.) Of course you could get nasty stuff that you aren't smelling. However I have doubts there would be anything that bad in glossy paper. Nil Einne (talk) 12:13, 1 October 2010 (UTC)

The MSDS for the ink is here. It says that "intentional inhalation overexposure to ink vapors may result in respiratory tract irritation"- I suppose this means that I'd have to be huffing it for it to do any damage. Dbfirs is right to mention the possibility of the paper being the culprit - I have looked for information on that already, but as Nil Einne notes there doesn't seem to be an individual MSDS available for it. A controlled experiment would be a very good idea though. I may just end up borrowing a respirator from someone, or using a portable burner and doing the boiling outdoors. Lithoderm 15:18, 1 October 2010 (UTC)

Sounds like you figured that out on your own! Cheers! —Preceding unsigned comment added by 165.212.189.187 (talk) 15:34, 1 October 2010 (UTC)

biographical info about Agnes Stroud Lee

I am a librarian at a small school in Colorado and one of our students needs biographical information, contributions to scientific field, and a photo (if available) of Agnes Stroud Lee. We know she was Native American.75.173.217.192 (talk) 03:10, 1 October 2010 (UTC)

Well there's this booklet about her for starters. WikiDao ☯ (talk) 03:19, 1 October 2010 (UTC)

Her full name appears to be Agnes Naranjo Stroud-Lee. There is not a Wikipedia article about her, but typing her name into google brings up some promising results. For the record, it looks as though she may very well meet the guidelines at WP:BIO, which means there possibly should be an article at Wikipedia. There is at least one full book-length biography of her named Scientist from the Santa Clara Pueblo, Agnes Naranjo Stroud-Lee and Amazon appears to sell it. this page has a very short blurb about her. Near as I can tell, she was a biologist who worked for Argonne National Laboratory, studying the effects of radiation on the body. A google search turns up a few nuggets. --Jayron32 03:25, 1 October 2010 (UTC)

ppb

knowing that 1 ppb is 1 x 10 (to power of -9) how do I work out what 1200ppb is?Wyburn (talk) 04:59, 1 October 2010 (UTC)

Try 1200 x 10^-9 or 1.2 ppm. Dolphin (t) 05:19, 1 October 2010 (UTC)

Regarding "how", 1200 x 10^-9 = 1.2 x 10³ x 10^-9 = 1.2 x 10^3-9 = 1.2 x 10^-6 = 1.2 ppm.

See Scientific notation#Basic operations. -- 111.84.200.184 (talk) 14:02, 1 October 2010 (UTC)

Or 0.00000012% --Chemicalinterest (talk) 12:07, 1 October 2010 (UTC)

No, it's 0.00012%. Gandalf61 (talk) 13:44, 1 October 2010 (UTC)

For questions like this, Wolfram Alpha is quite good [1]. In this case the input '1200ppb' is converted to "1.2 grams per metric ton" which is easy to relate to if you have trouble with exponentials. EverGreg (talk) 13:35, 1 October 2010 (UTC)

Note that converting 1200ppb to "1.2 grams per metric ton" is only valid if the ppb is weight/weight (admittedly the most common), but not if it is volume/volume or weight/volume. -- 140.142.20.229 (talk) —Preceding undated comment added 17:27, 1 October 2010 (UTC).

If you have trouble with exponentials, slowing down and writing out intermediate steps can help. E.g.:

1x10¹ = 10
1x10⁰ = 1
1x10^-1 = 0.1
.
.
.
1x10^-8 = 0.000 000 01
1x10^-9 = 0.000 000 001

And now I find it helps to line up your 'columns', like when you used squared paper to write out problems in primary school, keeping your hundreds, tens and units straight!

So, if it were just 9 x 10^-9, you could write:

0.000 000 001
0.000 000 009

keeping your units lined up. So you'd know 9 x 10^-9 = 0.000 000 009

Whereas, if it were 90 x 10^-9, you'd write:

0.000 000 001
0.000 000 090

keeping your units lined up. And you know you can write that without the final 0, so 90 x 10^-9 = 0.000 000 09, or 9 x 10^-8

In the same way, 1200 x 10^-9 can be worked out:

0.000 000 001
0.000 001 200

same as 0.000 001 2

So, 1200 x 10^-9 = 0.000 001 2, so 1200 x 10^-9 = 1.2 x 10^-6 (a nice way to see it) or 12 x 10^-7. And, if you know that ppm is 1x10^-6, you can rewrite from ppb to ppm! As you do more of this sort of thing, you can start to skip steps.

I hope this helps with where you were confused. 109.155.37.180 (talk) 14:27, 1 October 2010 (UTC)

question regarding stars

what would happen if, someone having gotten the numbers slightly wrong, the stars Epsilon Eridani and Luyten 726-8 actually collide in thousands of years time, rather than just passing very close to each other?

148.197.121.205 (talk) 14:37, 1 October 2010 (UTC)

This is interesting because Luyten 726-8 is a binary system. There are many models of interstellar activity in which a binary system reacts to a collision by having one object fall into the collision and the other flung off into space (or at least a wide orbit). Star collision is considered rare (see note in star), but there are some theories that a star collision can create a blue straggler (also noted in the star article). -- kainaw™ 14:52, 1 October 2010 (UTC)

Yes, it is possible, but when you think of the word "close" as referring to two peas a mile apart, you can see that the chance of a collision is slim at best. --The High Fin Sperm Whale 17:35, 1 October 2010 (UTC)

Even without a collision, if there is any life in the Epsilon Eridani system, it could be disturbed by the perturbation of comets by the binary star close encounter. If two stars do collide, there is the chance for a supernova. However, a star actually colliding with an approaching star rather than just swinging by in a fractional orbit would be exeedingly rare, as evidenced by the future approach of Gliese 710. ~AH1^(TCU) 20:13, 1 October 2010 (UTC)

If they collide it won't be because someone got the numbers slightly wrong. The stars are not under navigational control of us humans – their trajectories became inevitable at the time of the Big Bang and ever since then, and into the future, they merely conform to what we now know as the laws of physics. Dolphin (t) 04:29, 2 October 2010 (UTC)

You are misinterpreting. If they collided, it would imply that someone had gotten the numbers wrong. --Anonymous, 07:13 UTC, October 2, 2010.

If two, or perhaps three, stars did collide, would they merge to form a single much larger star? And would that be so unstable as to explode, causing terrible destruction across a broad expance of space? And would the matter and energy thrown off from this explsion get drawn into other stars, causing them to grow to a less stable size and explode themselves, setting off a chain reaction and ending all life as we know it? 148.197.121.205 (talk) 20:14, 2 October 2010 (UTC)

Three stars colliding at the same time is almost impossible. However, the collision would rip both stars apart a fling the material everywhere, however, it would coalesce into a large star (although some material would be lost). And it depends on the type of star colliding; two small red dwarfs would probably just make a larger red dwarf, however, two blue supergiants colliding would probably go supernova. For them to go supernova, it takes some very special conditions. Most stars will never go supernova, so if a small group of very large, young stars were together, it might cause a chain reaction of two or maybe three stars. And you have to remember, a supernova is comparable to a pea causing a hundred foot long explosion. This may seem large, but when the next star is a mile or more away, then you can see there is little chance of any affect on one to the other. --The High Fin Sperm Whale 05:53, 5 October 2010 (UTC)

Ice as a murder weapon

Following on from the ice cube post above, is it practical to use Ice as a self-destructing untraceable murder weapon? Scenarios :-

1. Jamming an ice cube into someone's throat so they choke.
2. Using a large piece of ice to inflict blunt force trauma
3. Stabbing someone with an icicle

Would a forensic scientist (or equivalent) be able to detect the murder weapon used? It's harder to prove murder if you don't have a weapon so would this increase the chance of evading justice? Exxolon (talk) 19:14, 1 October 2010 (UTC)

(edit conflict)Depending on the length of contact, ice does cause damage to cells. An astute or particularly observant pathologist might see it, might look for it. I seem to recall something about murder via ice (an actual case) being discussed in one of Robert Ressler's books (true crime; he helped found the Behavioral Sciences Unit at the FBI) but I cannot for the life of me remember which one, and I no longer own the books. → ROUX ₪ 19:22, 1 October 2010 (UTC)

Not exactly what you're asking, but there's a Roald Dahl short story, Lamb to the Slaughter, about a wife who kills her husband with a frozen leg of lamb and then roasts it, feeding it to the detectives who come round to investigate. Mikenorton (talk) 19:21, 1 October 2010 (UTC)

Unless the icicle was particularly large and thick, I think it'd just snap. Method A seems a little impractical because you have to be able to get that close to the individual, and then enforce that they don't just bring it back up. The middle one is certainly possible if you can find a piece of ice heavy enough to hurt but light enough to lift, but I'm not sure from a forensic standpoint. I can't imagine any reliable DNA evidence could be found in a puddle of melted ice, or even if the ice stays at all (it may evaporate before the forensics guys get there). Regards, --—Cyclonenim | Chat  19:25, 1 October 2010 (UTC)

Well, for method A perhaps don't use an icecube, but you could cram a large amount of crushed ice down the intended victim's throat. Googlemeister (talk) 19:29, 1 October 2010 (UTC)

Tangent - why the hell has this question been tagged as "may be inappropiate"? I don't appreciate those kind of insinuations about me Ludwigs2, care to explain? Exxolon (talk) 19:31, 1 October 2010 (UTC)

• My guess is that it's tagged because it's a discussion of what would be a criminal act. Plus, answering the question arguably involves giving both medical and legal advice. --M@rēino 19:48, 1 October 2010 (UTC)
  • plus it could incite angry responses from people who are (rightfully) concerned that you are specifically asking about ways to murder someone. It wasn't about you, it was about your question (I assume you have sufficient perspective to recognize that the question could be interpreted in some very bad ways). --Ludwigs2 19:52, 1 October 2010 (UTC)

specifically asking about ways to murder someone... with an ice cube!--Aspro (talk) 19:57, 1 October 2010 (UTC)

I have removed that tag. There is nothing wrong with the question. The reference desk seems to be getting more useless with each passsing day. He's only asking and we have no reason to believe he wants to kill anyone.--92.251.134.225 (talk) 20:23, 1 October 2010 (UTC)

Aw-shucks! I could just see it now:

An' I humbly submit to you... you, the ladies and gentlemen of the jury; is it not incontrovertible?! That-the -only-reason-that-the-accused -----standing-before-you-now------had-a-fridge, was that he intended... he planed... he pre---meditated, that the ice cubes that this this fridge would produce, would choke the very breath...the very breath out of a poor unfortunate... a poor unfortunate, who had never heard,.. nor come across,.. nor expected,.. that there existed,. such an evil expository, which consisted of all the things that should be shared freely and without restriction. That seemingly bottomless expository, which is known to it followers –they who hid behind a anonymous nom de plume's as yes!.. I speak of WIKEE... PEEDEEAH .--Aspro (talk) 20:50, 1 October 2010 (UTC)

2) Using a large piece of ice to inflict blunt force trauma

Reminds me of Lamb to the Slaughter. A tv series called Tales of the unexpected re-did it with Susan George (looking like butter would not melt in her mouth). They never did find the murder weapon --even though it was very delicious.--Aspro (talk) 19:57, 1 October 2010 (UTC)

In scenario 1, there would be a certain amount of water aspirated into the lungs as the victim struggled to breathe, and a significant quantity of water left in the body unless you figured out a way to dry the throat. There would also likely be signs of internal bruising from jamming in the ice and the bruising process would be halted at or near death so it could flag up as a proximate cause of death. They might not get you for using ice, but they could easily just claim you drowned the victim. Franamax (talk) 20:45, 1 October 2010 (UTC)

What about spiked ice cubes?Smallman12q (talk) 21:58, 1 October 2010 (UTC)

There's the old melting-ice-bullet trick, but it seems that one has been dealt with on "MythBusters". WikiDao ☯ (talk) 22:11, 1 October 2010 (UTC)

There's a common misconception about (the American) legal system that is perpetuated by Hollywood and television: absence of murder-weapon makes conviction impossible. This is not true at all: it is quite possible to convict somebody of murder, even if no weapon is found. Depending on circumstances, jurisdiction, and other evidence available, it's not even valid to say "it's more difficult to reach a conviction if the murder weapon isn't found." The legal system is complex, and though the trope of getting away with a crime because of a missing piece of evidence probably makes for good drama, it is an inaccurate rendition of the way an actual trial is conducted. For an introduction to this concept, see our article on evidence (law). In many cases, presence or absence of a murder weapon is circumstantial evidence and is very often irrelevant to both the ability of the prosecutor to bring specific charges or of the court to yield convictions for specific charges. On the other hand, in California, proof of the presence of a firearm at the scene means that additional charges can be brought - (in supplement to other charges, including homicide), merely because a weapon was present during the commission of a crime - even if the firearm had nothing to do with any crime taking place. Law is much more complicated than movies would have it seem. Nimur (talk) 21:15, 2 October 2010 (UTC)

I may not be an expert on law, but I would find it shocking if additional evidence such as a murder weapon would not make prosecution easier (assuming the prosecution was correct to begin with). Googlemeister (talk) 15:20, 4 October 2010 (UTC)

A question I've never pondered

why do protons clump in the nucleus is they are all positively charged? Surely they would repel each other. I don't think this is taught at high school level...--92.251.134.225 (talk) 20:31, 1 October 2010 (UTC)

See Strong interaction (aka strong nuclear force). AndrewWTaylor (talk)

It's a super good question. The strong nuclear force basically makes nucleons (like protons) attract to each other. It's very powerful over short distances but weak once you start getting any distance in there at all. Understanding that the nucleus is always this balance of forces — strong nuclear vs. electromagnetic repulsion — makes things like nuclear fission make more sense, or the reason why you need neutrons. Neutrons don't have any effect on the electromagnetic forces, but do add strong force. So nuclei that would have too much positive electromagnetic repulsion become more stable when you add neutrons. Have too big of a nucleus (like uranium), and it starts to get unstable. Wobble that unstable nucleus a bit, and suddenly it is two very positively charged nuclei just outside the range of the strong nuclear force, which repel violently. (Most of the energy released by a fission reaction is in from this repulsion and is kinetic.) Nuclear fusion, by contrast, is hard to make work because you have to get two positively charged nuclei (repelling each other like mad) just close enough so that the strong nuclear force can kick in. --Mr.98 (talk) 20:44, 1 October 2010 (UTC)

Also see Nuclear force, but unfortunately these articles are not pitched at the elementary level. In fact, it is taught at high school level, in particular in elementary chemistry. Teenagers are taught that the isotopic mass of carbon-12 is arbitrarily assigned the number 12.000000. This is not surprising because a carbon-12 atom has 12 particles in its nucleus. But then they must learn that the isotopic mass of every other isotope is not equal to the number of particles in its nucleus. For example, the isotopic mass of oxygen-16 is not 16.000000 as one might expect — it is 15.9949146! The small amount of mass (0.0050854) that was lost when each oxygen-16 atom was assembled is related to the energy tied up in the strong interaction. The relationship between the lost mass and the energy tied up in keeping these repellant particles together is the familiar equation E = mc². Dolphin (t) 04:41, 2 October 2010 (UTC)

The wackyness of this is real. How do protons end up clustered together against tremendous repulsion? The answer is that everything we see and touch, except hydrogen, is the product of a supernova. It's said that we're star dust. The only way these nuclei exist is that they were forged together under the incredible pressures of a dying star. Wnt (talk) 00:30, 4 October 2010 (UTC)

Why weed is illegal

"Weed is illegal because when it was made illegal, alcohol prohibition had just ended and the government couldn't just liquidate that whole agency that was working for prohibition, this was backed by the paper companies as hemp was set to replace paper. "

I read this somewhere. Is it true? ScienceApe (talk) 22:24, 1 October 2010 (UTC)

We have an article that discusses the history of the legality of cannabis. See also the 1937 Marihuana Tax Act article. WikiDao ☯ (talk) 22:51, 1 October 2010 (UTC)

Marijuana is illegal because it is an intoxicating substance. Period. Theres about a million conspiracy theories that some unrelated industry was trying to put the kibosh on hemp production, or some sort. The reality is, hemp isn't all that special of a fiber, and the cannibis plant is pretty much mostly useful as a source of wacky-tobacky. Those silly arguements are basically a redirection, let's convince people that legalizing hemp isn't about the drug, it's about a wonderfiber that will revolutionize the industry. If only the wood-pulp lobby would let it go through! It's like claiming that heroin is illegal because poppy-seed muffin bakers wanted to control their stock of poppy-seeds. Now, that doesn't say that I am arguing against legalization. Just that if you are going to argue, at least argue from a place of truth. --Jayron32 23:40, 1 October 2010 (UTC)

Uh... if you're going to make statements about arguing from a place of truth, it would behoove you to avoid such blanket statements that are directly contradicted by well-sourced statements here. Part of the reason is intoxication, part of the reason is hemp production. → ROUX ₪ 23:48, 1 October 2010 (UTC)

I'm not too familiar with the evil-paper-company theory, but the article seems well-sourced about some of it:

• NAFTA & neocolonialism: comparative criminal, human & social justice.
• Understanding marijuana: a new look at the scientific evidence
• Under the influence: the disinformation guide to drugs

Though clearly if it weren't so wacky it wouldn't be illegal, whatever other factors might also be driving that illegality. ;) WikiDao ☯ (talk) 23:54, 1 October 2010 (UTC)

One reason for keeping such drugs illegal is so that law'n'order oriented politicians have something to campaign on. Appeal to the masses by condemning those others. HiLo48 (talk) 23:58, 1 October 2010 (UTC)

As I've heard it, the primary reason MJ is still illegal is that three major industries - tobacco producers, alcohol producers, and insurance companies - put a lot of money into lobbying against it. the first two are worried about competition, the last about changes in insurance payouts. The tobacco industry is mixed on it: they've had long-term plans to begin producing and marketing MJ if it ever becomes fully legal (and could adapt a lot of their current growth, harvesting, storage, and packaging systems), but I think they are worried that MJ is too easy to grow and prepare, and that they won't be able to compete effectively with small-scale cottage industries. --Ludwigs2 04:37, 2 October 2010 (UTC)

You quotation included the government couldn't just liquidate that whole agency .... This is a classic pointer to the existence of a conspiracy theory. Dolphin (t) 04:48, 2 October 2010 (UTC)

I've grown convinced that the major factor must be that the gangs lobby the government to keep it illegal, just as they lobby certain officials to keep it effectively legal for them to sell. There are many billions of dollars at stake in the illegal market which will go away if the drug is legalized. Some of the edge effects that point this out:

• bans on "look alike substances" (to prevent people from selling fake pot and poisoning the open market)
• "trading up for the big fish" (to allow corrupt officials to choose which producers to prosecute, and especially to preserve the demand while tightening the supply)
• Mexico's recent hurry to legalize (to make sure the price differential across the border doesn't go away entirely if California passes proposition 19)
• deliberate neglect of any kind of drug treatment by the government (and in Mexico, open attacks on it by gangs).

I honestly think that if you took all the gang corruption out of drug laws, there'd literally be nothing left — they'd be legal almost immediately. If that seems counterintuitive, consider that nobody bans henbane and nobody sells it. It's like how patents and copyrights are supposed to encourage the dissemination of inventions by prohibiting it. Wnt (talk) 06:57, 2 October 2010 (UTC)

Why would anyone waste their time banning something that no one is selling? (Or in general, why waste time and money outlawing things that no one does?) APL (talk) 19:19, 2 October 2010 (UTC)

Indeed. And why would a street dealer waste his time selling what no one is banning? But history tells us that China's 1729 ban on opium was passed when it was an obscure drug, which was taken up only as a substitute after they banned tobacco in 1644. In a bit over a century the drug dealers were the conquerors. America will be no different. Wnt (talk) 00:21, 4 October 2010 (UTC)

I understand that its illegal because it induces psychosis. 92.28.254.154 (talk) 20:19, 2 October 2010 (UTC)

• Rather than enter this circular debate: here is a link to: After the War on Drugs: Blueprint for Regulation. Title says it all really.--Aspro (talk) 21:30, 2 October 2010 (UTC)

According to the United States Department of Justice, "Illegal drugs are illegal because they are harmful." Understandably, this website has a known bias (it is operated by the Drug Enforcement Agency), but it presents a very clear, easy-to-read explanation from an authoritative source that exactly answers the original question. People are free to speculate as much as they like about subterfuge and unseen motives behind government drug policy, but the real reasons behind drug legislation is actually pretty straightforward. The question of whether it is worthwhile or productive to enforce these policies is a different issue altogether. Nimur (talk) 18:04, 4 October 2010 (UTC)

Increasing the range of the Strong Nuclear Force

I was just thinking that if this were possible, it might be easier to get hydrogen to undergo Nuclear Fusion. Is there any way to do it? ScienceApe (talk) 22:27, 1 October 2010 (UTC)

How do you propose to do so? By adjusting quantum physics? --The High Fin Sperm Whale 22:55, 1 October 2010 (UTC)

I was asking if it was possible. ScienceApe (talk) 23:04, 1 October 2010 (UTC)

At first glance, it doesn't seem outrageous. After all, you can focus the force carrier of electromagnetic radiation (i.e. with a lens), so if perchance there was some way to focus gluons in a similar manner. But alas, gluons travel only about a femtometer at the most, which is about the size of the atomic nucleus. There's simply no way to work with such a particle. --Jayron32 23:35, 1 October 2010 (UTC)

Well, there are nuclear isomers, which can have different properties. But if I look up "nuclear isomers of hydrogen" I get something unrelated (whether the nuclear and electron spins are aligned). I bet it's too simple to have any, but can someone knowledgeable confirm? Wnt (talk) 00:27, 4 October 2010 (UTC)

Microwaving a beetle

Here's hoping you all believe this is a genuine question! I've been housesitting and was kindly left money for some takeaways. Last night I ordered a pizza, ate some of it and put the rest in the fridge. On reheating a slice later in the microwave I opened the door to find a beetle (I think a Rove beetle) scurrying around :-( How did this critter survive when the pizza was piping hot? Could it simply have found a cool spot in the oven for 2.5 minutes? And does anybody know a good counsellor for my newly developed 'pizzaphobia' lol Spoonfulsofsheep (talk) 23:10, 1 October 2010 (UTC)

Had a similar experience a couple of years ago with small ants. Heated something in the microwave and found live ants in the oven when I open it. The Microwave article tells us that the actual wavelength of microwaves is typically in the range 1-10 cm, so if you're smaller than that, maybe the waves can't get you. HiLo48 (talk) 23:24, 1 October 2010 (UTC)

That's kind of a silly thing to say. You can microwave peas, for example, quite readily. → ROUX ₪ 23:44, 1 October 2010 (UTC)

Yep. OK. Next theory? HiLo48 (talk) 23:55, 1 October 2010 (UTC)

Thanks, I can see the sense in what you said. If the wavelength is large enough and the microwaves are focused at the central area of the oven (where the food would be) there could be 'safe' areas. No idea if you're right of course, and I'm not sticking my fingertip in an operating microwave to test your theory! Spoonfulsofsheep (talk) 00:13, 2 October 2010 (UTC)

From my recollections, HiLo48's original answer is basically correct. Due to the wavelengths of microwaves, there's something of a pattern of hot and cold areas in a microwave oven - and a small creature like an ant or a beetle can readily feel itself getting hot and move a few millimetres out of the hot spot - their comparatively large surface-area-to-volume ratio also allows them to shed unwanted heat very rapidly. A similarly small object like a pea will nonetheless be heated by a combination of (a) conduction and convection from its neighbors, (b) the spinning tray moving it into and out of hot-spots, and (c) its inability to move of its own accord. ~ mazca ^talk 00:58, 2 October 2010 (UTC)

Google Answers had a crack at explaining it here. HiLo48 is correct. So, to get rid of your bugs, what you need is for there to be a whole lot of them in there at the same time so you can microwave them as a group instead of hoping the waves will happen to hit the tiny individual. Matt Deres (talk) 01:16, 2 October 2010 (UTC)

Steve Baker liked to mention this sort of experiment [2] you can do with chocolate chips and by taking out the ring so the glass plate doesn't move which amongst other things shows the presence of 'hot' and 'cold' spots. Edit: I see the Google Answers actually suggests the same thing albeit with marshmallows Nil Einne (talk) 02:52, 2 October 2010 (UTC)

Might try putting one frozen pea in the microwave to see what happens. Clearly some research needed (and highly possible) here. HiLo48 (talk) 03:52, 2 October 2010 (UTC)

WP:OR per request I placed a ball of cheese 5 mm in diameter near the edge of a 32 cm diameter rotating plate in a 1650 W microwave oven. The cheese remained unaltered through about 270 degrees of plate-rotation, or about 11 seconds. Then it suddenly melted and sizzled at a mostly constant rate through 30 seconds. I repeated the experiment with an identical ball of cheese placed in the same start-position in the microwave, but this time the plate rotated in the opposite direction. After 90 degrees of rotation the second ball passed through the location where the first ball had melted, and then again continued up to about 270 degrees and 11 seconds before melting and sizzling as had the first. Conclusion: 5 mm seems sufficient for absorbing enough microwave radiation to cook food. WikiDao ☯ (talk) 06:16, 2 October 2010 (UTC)

I don't really understand why you let the plate rotate which seems to unnecessarily complicate any analysis Nil Einne (talk) 08:22, 2 October 2010 (UTC)

The plate rotates to more evenly heat food placed on it, because there are "cold spots" in a microwave oven. Presumably an insect could survive for a while if it remained in one of these poorly illuminated regions, but they tend to move around. I thought the experiment (with a "pea") was proposed to see if a bug-sized object might escape heating by virtue of its being too "tiny" for microwaves (1 mm to 1 m wavelength) to interact with it, but maybe I didn't understand it correctly. WikiDao ☯ (talk) 08:45, 2 October 2010 (UTC)

And reversing the rotation showed that it was not suddenly entering a "hot spot" that caused the cheese to cook, but average radiation intensity over time. So, any bugs surviving the amount of time it takes to heat a slice of pizza must have been hiding in a dark zone throughout that time -- unless it has to do with their water content. WikiDao ☯ (talk) 08:59, 2 October 2010 (UTC)

Well as the Google Answers said and is somewhat obvious, since bugs move around, they would likely move out of any hot spots, and if the plate is moving putting them in to hot spots they weren't in before they would likely move out of it quickly. Of course as Psychim as pointed out below, they may move off the plate anyway and it may not be just because they are trying to avoid the 'hot' spot they are feeling. And yes, you have it right about the plate, that's precisely why you stop it rotating when attempting to show the existanse of 'cold' spots and 'hot' spots but I think that wasn't what you were trying to show. (Actually I still don't understand what you were testing.) I would have thought it obvious that it takes a while for cheese to cook, but perhaps I'm not understanding something. Well I didn't really understand what the point of the pea experiment was for either. Nil Einne (talk) 10:18, 2 October 2010 (UTC)

I do think the existence of hot/cold regions is obvious. I thought it was about something like "absorption cross-section of a bug-sized object"! ;) WikiDao ☯ (talk) 11:14, 2 October 2010 (UTC)

Ah okay, I understand now. I'm not sure whether the ball of cheese is the best test subject though even if it's something easy to gauge. You could try some recently dead insects and see how long it takes them to cook. They will die before they cook of course. A perhaps better experiment would be if you have some sort of very quick temperature and resonably accurate for a small area temperature gauge. Quickly cut open the insect after it's been in the microwave and test the internal temperature. If it's more then say 50C I would say the insect would be dead if it were alive. Since microwave resonant heating works somewhat below the surface perhaps measuring the surface would work too. May be some sort of infrared thermometer? Do they work over such small areas? Nil Einne (talk) 16:59, 2 October 2010 (UTC)

Well an infrared thermometer is passively measuring infrared radiation emitted from the body. What would the difference be between the energy absorbed by the same 5 mm diameter object irradiated by microwaves with wavelength either 1 mm or 10 mm -- or even 100 mm? Any? WikiDao ☯ (talk) 19:28, 2 October 2010 (UTC)

Perhaps it is the water content (see Dielectric heating) of bugs that is "protecting" them from microwave heating relative to typical food material? WikiDao ☯ (talk) 06:29, 2 October 2010 (UTC)

Isn't it more likely that the food absorbs the microwaves and protects the insect? All the insects I've ever put in a microwave on their own have died quickly. Wnt (talk) 07:25, 2 October 2010 (UTC)

Well the more food there is in the microwave, the more microwaves are absorbed, so the lower the concentration in the "cold spots". Dbfirs 08:26, 3 October 2010 (UTC)

I'll go with the cold spot theory. The major cold spots in a microwave oven are along the edges and (especially) in corners, just the sort of place an insect would run too to try to escape. Physchim62 (talk) 09:24, 2 October 2010 (UTC)

Would it be possible (assuming enough materials and labor (!)) to make a stone tower so tall it CANNOT crack? (but instead deforms plastically)

And doesn't fall over? At the museum of natural history I once saw cylinders that show what rock would behave like at various depths and the more (man-made) heat and pressure endured the more they had to be glued afterwards to keep them together (for display) but after that it got "mooshed" with a crack and then "mooshed" with no cracks at all. So would pressure alone be strong enough and evenly distributed enough that it this would happen. (By tower I mean something skinnier than a mountain or plateau) What would happen to Earth's crust, by the way, since it is also rocks? If it's not strong or buoyant enough (due to the lack of a real mountain range's crustal "root"), would this be possible on a hypothetical infinitely strong surface? —Preceding unsigned comment added by 12.196.0.50 (talk) 23:38, 1 October 2010 (UTC)

Just imagine what would happen if you tried to build a tower out of Jello. It would goosh out laterally, right? This doesn't happen to the crust because it is so broad that it can't spread out. Looie496 (talk) 01:13, 2 October 2010 (UTC)

Rocks do behave like jello, but very very slowly. Solid rock will bend and flow, just on time scales on the order of millions of years. See Fold (geology). --Jayron32 01:48, 2 October 2010 (UTC)

No, I meant what would happen to the crust under a tower so tall it might flow plastically? Would it simply bend inwards like pushing down on a raft in a pool, would the preceeding happen and then tensile failure breaks it forming a microplate with the tower in the middle, or would the whole lot just fall into the mantle? Wouldn't this cause earthquakes?—Preceding unsigned comment added by 12.196.0.50 (talk • contribs)

I'm not sure such a tower could be built. Some natural structures which could approximate it may be something like Devils Tower National Monument, but I am unsure about what the rocks are like directly below the tower. Assuming you were just dealing with a very large, concentrated mass on the crust, it would depend on what kind of rock the crust under the tower is made of (sandstone is likely to react differently than basalt, for example), how heavy the tower is, on what time frames you are dealing with, etc. etc. Geology is far too complex, and there are far too many variables to just say "A big tower is on some rocks, and I want to know how it deforms them". --Jayron32 03:04, 2 October 2010 (UTC)

... and the time scale is very long! Here in the UK, the rocks are still rebounding from the effect of the ice sheets in the last ice age. Dbfirs 08:29, 2 October 2010 (UTC)

(ec) A series of very long term experiments have been carried out on granite beams in an effort to detect and quantify plastic deformation, see [3], the results indicate that granite has a viscosity of about 10 ²² poise. At that rate of deformation you would have to wait a long time (thousands of years) to see clear evidence of plastic deformation. Also your very large point load on the lithosphere would eventually (if large enough) cause an isostatic response as is seen in glacial loading. Finally, you would not be able to prevent a stone building failing by brittle fracture under its own weight if it was tall enough, even if the stone was literally 'flawless'. Mikenorton (talk) 08:44, 2 October 2010 (UTC)

Tower of Babel? ~AH1^(TCU) 15:37, 2 October 2010 (UTC)

Ha ha

You seem to be telling me cool rocks can't flow within a lifetime - ever, and that they would always break. If there's no way for it to break downwards then it would EXPLODE! Cool. —Preceding unsigned comment added by 12.196.0.50 (talk) 23:00, 2 October 2010 (UTC)

Weak equivalence question

Hello all:

I was reading about the weak equivalence principle when it said that a spring force accelerometer would register no force when attached to an object that is in free fall, hence free fall and inertial motion are equivalent and that gravity really isn't a force, but just a space time distortion.

My question is that, suppose the following two scenarios:

We know that by the weak equivalence principle the bottom scenario of the two masses attracting each other through gravity, the accelerometer for mass A would register 0 N.

However, for the top scenario, if the iron weight moves sufficiently to magnet for the magnet's magnetic "action at distance" force to pull iron weight until it sticks to the magnet. How many Newtons of force would the accelerometer register for the iron weight during the process of the magnet pulling the iron weight to itself?

If the accelerometer registers 0 N then wouldn't that also show that the electromagnetic force isn't really a force but is equivalent to inertial motion (which we know to be false)? If the accelerometer registers a greater than 0 N force then would gravity be the only "force" out of the four fundamental forces of nature for which the accelerometer would register 0 N for "action at distance"?

Thanks.

L33th4x0r (talk) 23:43, 1 October 2010 (UTC)

Not sure I understand. It seems obvious that the accelerometer will register a force in this scenario. Looie496 (talk) 01:09, 2 October 2010 (UTC)

You might get weird results if the accelerometer's mechanisms were made of iron, of course. APL (talk) 01:29, 2 October 2010 (UTC)

The weak equivalence principle only applies to point particles in a gravitational field. Real objects which exist in three dimensions experience tidal forces, and so given infinitely accurate accelerometer, you would, for example, be able to deduce your orientation in free fall. See Equivalence_principle#The_weak_equivalence_principle. Also, once you introduce other forces besides gravity, all bets are off... --Jayron32 01:45, 2 October 2010 (UTC)

Yes! Gravity is the only force for wich the equivalence principle applies. 174.58.107.143 (talk) 05:31, 2 October 2010 (UTC)

The difference is that in the magnetic case the registered force depends on what the body is made of:You get a force if it is made of iron, you get no force if it is made of plastic, say. The gravitational case is different in that the result is completely independent of that. This is why the geometric interpretation works for gravity but not for electromagnetism. --Wrongfilter (talk) 07:57, 2 October 2010 (UTC)

thanks. L33th4x0r (talk) 15:48, 2 October 2010 (UTC)

The gravitational force between two masses is (clasically) inversely proportional to their distance apart. There will therefore be a difference between the attraction on the mass and on the more distant accelerometer towards the left mass. This difference will result in a small force on the spring. (and of course there is a force between the mass of the accelerometer and the right mass also) 71.31.152.112 (talk) 16:53, 3 October 2010 (UTC)