:There is a big misconception circling around here - that gases "reflect" visible light or IR radiation. They do not - gases can scatter and absorb, but there is not mirror-like reflection unless there is a flat surface of some sort (which gases don't have). Gas molecules with polar bonds (e.g. C=O, C-H, O-H, C-F, etc.) tend to be good at absorption of long-wave IR radiation (The same gases also emit a lot when warm) which makes them greenhouse gases. An "anti-greenhouse" gas would need to be poor at absorbing long-wave IR (so it must not contain such polar bonds) and good at scattering or absorbing visible light. However, the common gases with nonpolar bonds such as N<sub>2</sub> and O<sub>2</sub> are transparent. Gases without polar bonds can be colored/non-transparent such as Cl<sub>2</sub>, but it is toxic, harmful and unstable so clearly we shouldn't be pumping it in massive quantities into our atmosphere. I am not aware of any gases which i) have no polar bonds, ii) are not transparent to visible or short-wave-IR, and iii) Could be released in massive quantities necessary to achieve a substantial cooling effect without disastrous side effects. However, if you remove the restriction to gases, sulfate aerosols might work (see [[Geoengineering]].) [[Special:Contributions/129.2.46.178|129.2.46.178]] ([[User talk:129.2.46.178|talk]]) 01:02, 28 July 2010 (UTC)Nightvid
:There is a big misconception circling around here - that gases "reflect" visible light or IR radiation. They do not - gases can scatter and absorb, but there is not mirror-like reflection unless there is a flat surface of some sort (which gases don't have). Gas molecules with polar bonds (e.g. C=O, C-H, O-H, C-F, etc.) tend to be good at absorption of long-wave IR radiation (The same gases also emit a lot when warm) which makes them greenhouse gases. An "anti-greenhouse" gas would need to be poor at absorbing long-wave IR (so it must not contain such polar bonds) and good at scattering or absorbing visible light. However, the common gases with nonpolar bonds such as N<sub>2</sub> and O<sub>2</sub> are transparent. Gases without polar bonds can be colored/non-transparent such as Cl<sub>2</sub>, but it is toxic, harmful and unstable so clearly we shouldn't be pumping it in massive quantities into our atmosphere. I am not aware of any gases which i) have no polar bonds, ii) are not transparent to visible or short-wave-IR, and iii) Could be released in massive quantities necessary to achieve a substantial cooling effect without disastrous side effects. However, if you remove the restriction to gases, sulfate aerosols might work (see [[Geoengineering]].) [[Special:Contributions/129.2.46.178|129.2.46.178]] ([[User talk:129.2.46.178|talk]]) 01:02, 28 July 2010 (UTC)Nightvid
:Some people think that there may be a way to protect the earth via a gas [http://www.wired.com/science/planetearth/magazine/16-07/ff_geoengineering?currentPage=all (See this article)]. Basically, a relatively small amountof SO2 in the stratosphere could 'reflect' some of the light that would have entered the atmosphere. Not sure if it really reflects (see above regarding gases absorbing or scattering light), but it is possible that it would exist as a fine particulate, maybe sulfates as mentioned above, that would reflect. As for cheap sources, there is quite literally tons of sulfur sitting in the Alberta tar sands that some people would love to find a use for...[[Special:Contributions/24.150.18.30|24.150.18.30]] ([[User talk:24.150.18.30|talk]]) 02:50, 28 July 2010 (UTC)
== There is not enough darkness in all the world to put out the light of even one small candle ==
== There is not enough darkness in all the world to put out the light of even one small candle ==
Revision as of 02:50, 28 July 2010
Welcome to the science section of the Wikipedia reference desk.
The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
All of us have heard about a pair of spectacles that can supposedly enable one to see people naked even when they are not naked i.e. see-through their cloths. Do such things exist for real ? Jon Ascton (talk)01:24, 23 July 2010 (UTC)[reply]
That's a fairly common joke in the United States. They are not real - and I question how you could think they could be real. About a year ago there was a big thing about modifying digital cameras to allow you to barely see through certain fabrics. I don't know if it was actually real, though. --mboverload@01:32, 23 July 2010 (UTC)[reply]
Yeah, mboverload, that rings a bell! Is it right that certain kind of digital cameras can be modified to become "x-ray" ?
I have read about applications for mobile devices that make it possible to see thru the clothes. Even saw a demonstration video of such application. Twilightchillt03:56, 23 July 2010 (UTC)[reply]
The modification that you asked about involves removing the infrared (IR) filter in a camera. It doesn't really give you X-ray vision, but some fabric that's opaque to visible light is not so opaque to infrared, and a digital camera with the IR filter removed may see through it. I've seen a pretty dramatic demonstration in which a modified camcorder saw through two layers of dark-colored trash bags, as if they were transparent. --98.114.146.237 (talk) 04:36, 23 July 2010 (UTC)[reply]
Oops, my mistake. The dramatic demo I was referring to was actually done using some kind of thermal imager, not a simply modified camcorder. --98.114.146.237 (talk) 04:54, 23 July 2010 (UTC)[reply]
Under the right lighting conditions - and with the IR filter removed from a digital camera (removed...not added!), it is possible to see IR light that is passing through some kinds of thin fabric. It's exceedingly tricky though - and it wouldn't (yet) fit into a pair of spectacles. However, there are many YouTube videos that claim to demonstrate this effect. A camera that's designed to be sensitive to just the right IR frequencies can see "heat" (well, technically, the IR radiation that comes from hot objects) coming from the body through even moderately thick clothing - but because warm air is trapped between clothing and body - you don't see a clear outline of the skin because the difference in temperature between different parts of the body is much greater than the difference between skin and trapped warm air - so you see something through the clothing - but it's not remotely like watching someone who is naked! SteveBaker (talk) 13:14, 23 July 2010 (UTC)[reply]
The night-vision/x-ray trick often requires adding a IR-pass filter, (ie: A filter that looks opaque-black to the naked eye, but is crystal clear to IR) and running the camera in "night vision" mode in bright sunlight.
Some cloth is remarkably transparent to this kind of photography, almost like saran wrap. But that's rare. Most cloth looks about like you would expect.
(The best cloth I've seen to demonstrate this effect is the black cloth covers used in front of certain large (older?) speakers. It's amazing. Looking through the camera you'd swear someone took cloth off your speaker.) APL (talk) 15:25, 23 July 2010 (UTC)[reply]
A cheap webcam with the IR filter removed will make a bottle of Coca-Cola seen transparrent and allow you to see objects placed behind it. Most clothing however is quite opaque to IR. --NJR_ZA (talk) 13:52, 27 July 2010 (UTC)[reply]
If light only had wave-like properties, one would expect a gradual drop-off in the effect. The sudden stopping of the effect under a certain frequency indicates that light energy is quantized, rather than continuous, with regards to frequency. If light were just a continuous wave, then as electrons accumlated energy, they would eventually accumulate enough to be knocked free of their orbitals. Higher energy light would remove electrons faster, and lower energy light would remove them slower, but light of any energy should work, since a continuous energy model would imply that the light is able to accumulate on the electrons until they are knocked free. The sudden cut-off below the threshold frequency indicates that it isn't a continuous wave of light which is "energizing" the electrons, rather it is a single particle of light which is energizing a single electron; below the threshold frequency, no single photon has enough energy to excite the electron to leave its orbit. Since this is a particle-like behavior, it confirms the particle nature of light. --Jayron3203:02, 23 July 2010 (UTC)[reply]
Sure. You can mix anything. Just place them together. I suspect nothing much exciting will happen, as ammonium bicarbonate is just as soluble as sodium bicarbonate, so you'll just get a basic solution with sodium, hydroxide, bicarbonate, and ammonium ions floating around. --Jayron3203:57, 23 July 2010 (UTC)[reply]
It won't react dangerously; actually the baking soda will neutralize the ammonia to form ammonium carbonate (provided the ammonia is in solution form.) --Chemicalinterest (talk) 11:25, 23 July 2010 (UTC)[reply]
Liquid household ammonia (smelly) will react with sodium bicarbonate to form a mostly odorless ammonium carbonate. It is probably dissolved in the liquid. BTW, sodium carbonate is produced too. See ammonium carbonate for more details. --Chemicalinterest (talk) 17:54, 23 July 2010 (UTC)[reply]
Hang on , carbonate is much more basic than ammonia, so the reaction above and below doesn't happen:
NH3 + HCO3- >> NH4+ + CO32-
Explanation:
[HCO3-] <> [H+] + [CO3--] K = 4.8x10-11[1]
[NH4+] <> [H+] + [NH3] K= 5.7x10-10
So the equiilibrium constant for the reaction:
[HCO3-] + [NH3] <> [NH4+] + [CO3--] is 3.8x10-11 / 5.7x10-10 = 0.07
Ammonia solution and sodium hydrogen carbonate combined stays mostly completely as ammonia, sodium ions, and bicarbonate ions. Ammonium carbonate is not produced.
I was just going to correct you. So you are saying that the equilibrium tends to lean toward the bicarbonate and the ammonia rather than the ammonium and the carbonate? --Chemicalinterest (talk) 21:28, 23 July 2010 (UTC)[reply]
We cannot give medical advice. If you have concerns about your acne, you should see a qualified physician, likely a dermatologist. Wikipedia has articles on Adolescence and Acne vulgaris. However, any specific problems you may be having should be discussed with the proper doctor. --Jayron3205:06, 23 July 2010 (UTC)[reply]
Tut, Jayron32. You know this isn't a request for medical advice; it's a request for medical information. 190 is not asking for advice or anything involving a diagnosis. As our Acne vulgaris article states, the condition often lasts into adulthood, often disappearing after the early twenties but sometimes remaining into the thirties or beyond. There are some very effective treatments for it — for which, of course, you need a doctor's advice. Comet Tuttle (talk) 07:01, 23 July 2010 (UTC)[reply]
Of course this is a request for medical advice. Do you really think the OP is asking out of idle curiosity? The OP wants us to diagnose whether they have an underlying condition or if this is just regular teenage acne, which we certainly cannot do. The information you and Jayron have provided should be useful, but if the OP wants anything more specific to their case they need to see a doctor. --Tango (talk) 09:15, 23 July 2010 (UTC)[reply]
The above conversation makes me laugh. To answer the question, it's not abnormal, but still undesired. See a doctor and you can discuss options to clear it up. Regards, --—Cyclonenim | Chat 09:53, 23 July 2010 (UTC)[reply]
You can't know if it is normal or not because you haven't seen it. That is one of the reasons why we don't give medical advice. You don't have anywhere near enough information. --Tango (talk) 11:04, 23 July 2010 (UTC)[reply]
Doh.. Acne vulgaris aka 'teenage acne' is a common disease in teenagers. There are other forms of acne some more servere, others about the same - if you have acne it's a medical condition which a doctor (or possibly pharmacist) can help with.
Actually the article just says (uncited) there is "some evidence" that it contributes to "increased risk" of liver cancer. That's a considerably more precise and less straightforward statement than saying it "causes" it. The liver cancer article doesn't mention anything about smoking or tobacco — the primary causes of liver cancer are elsewhere. --Mr.98 (talk) 12:57, 23 July 2010 (UTC)[reply]
As a pure layman here, I'd note that small cell lung carcinoma, which is caused by smoking, is pretty likely to metastasize, and if it does so into the bloodstream then the cancerous cells may end up in the liver, as the liver performs its blood-filtering function, and the smoker ends up with metastasized lung cancer growing in his liver. He's in pretty bad trouble by then anyway. Comet Tuttle (talk) 17:02, 23 July 2010 (UTC)[reply]
but does the liver process nicotine from the blood (and additives) as it does alcohol? Or do other organs (kidneys etc) do that? 85.181.51.2 (talk) 19:22, 23 July 2010 (UTC)[reply]
I think I see where you're going with this, and I guess the answer would be 'yes'. There's a cost involved in having an immune system. Were such a system unnecessary, then organisms could be relieved of its cost. Whether or not that amounts to "better" is a value judgement. --Tagishsimon(talk)10:22, 23 July 2010 (UTC)[reply]
...and without bacteria, we'd have no gut flora and be in deep trouble for that reason. When you have to take a large dose of antibiotic, this can kill off a lot of gut flora - causing diarrhoea and all sorts of other unpleasant digestive problems. (Trivia: There are 10 times as many bacteria in your gut than there are human cells in your entire body - and 60% of your poop is dead gut bacteria!) Also, consider that the "Seneca Valley Virus" has been found to kill some kinds of cancer cells vastly more effectively than chemotherapy - and without the associated toxicity.[2] Since we don't yet fully understand the role of viruses - this kind of result suggests the possibility that we'd be unable to survive without them. Over the very long term, periodic additions of viral DNA into our DNA drives evolution - so eliminating them could also cause problems over very long timescales. SteveBaker (talk) 12:55, 23 July 2010 (UTC)[reply]
Bacteria and viruses are not the only things that our immune system protects us from either. There are also fungi and molds that can be harmful to people. Also, without bacteria, the world would be very different because things would not really decay in the manner they do today, so there would probably be dead plants and animals everywhere. Googlemeister (talk) 13:29, 23 July 2010 (UTC)[reply]
I'm not sure if this is the immune system per se, but if you get a splinter or something your body will often kick it out. I don't know if that's caused by associated infection, though. --Sean15:52, 23 July 2010 (UTC)[reply]
The real cost of an immune system isn't the energy expenditure or whatever -- that's quite minimal. The adaptive immune system is supported by a ridiculously small number of memory cells. The real cost is autoimmune disease. In fact, I wonder what white blood cells evolved from -- I somehow get the idea that they evolved from a rather maverick predecessor, what with slipping between interstitial spaces and ambushing bacteria hiding in deep tissue. Like a spy movie almost. John Riemann Soong (talk) 16:15, 23 July 2010 (UTC)[reply]
evolution of the mammalian red blood cell
Are there any nonmammalian ancestors whose RBCs lacked nuclei? What was the main advantage of the loss of nuclei -- deformability, speed, or being unable to be infected by viruses? John Riemann Soong (talk) 16:06, 23 July 2010 (UTC)[reply]
Also the amount of oxygen 30 trillion RBCs can carry astounds me. When we run and become out of breath, but not so much that we start running anaerobically, I suspect the limiting factor is not actually oxygen transport, but decreased blood pH and rising CO2 levels. Also what is it that makes your chest feel painful? We don't feel light-headed or dizzy, so we must not use that much oxygen when running, right? John Riemann Soong (talk) 16:11, 23 July 2010 (UTC)[reply]
No idea either, but since the number of cabs seems to be equal to, or greater than, two times the number of floors served, you'd be talking about one for only two floors. One wonders what the point would be. Deor (talk) 20:37, 23 July 2010 (UTC)[reply]
entry of gold nanoparticles into the cell nucleus
My boss tells me that when gold particles are tagged with DNA and incubated with cancer cells, over 50% of them can be seen inside the nucleus (versus the 2-10% I've been seeing when they are coated with just carboxylate groups).
Originally I thought the only way for these things to get inside the nucleus was during mitosis when the nuclear membrane dissolved and reformed around some of the particles.
However, my boss says that active transport of gold particles into the nucleus is possible. But it surprises me that it can be done so easily (and statistically favourably) -- since wouldn't cells want to curb the introduction of foreign DNA as a safeguard against viruses? Or is this some mechanism left over from our bacterial days? Previously I thought maybe when the nuclear membrane, DNA-carrying gold simply got "tugged" by the forming nucleus inside the membrane, thinking the DNA was one of its own. John Riemann Soong (talk) 17:27, 23 July 2010 (UTC)[reply]
Custom color urine
What is the mechanism as to how asparagus can your urine green, and beets can turn it red? How can we make artificial compounds such that, when consumed, will produce any color of urine we desire?--70.122.112.145 (talk) 17:33, 23 July 2010 (UTC)[reply]
Colored urine means that there is some compound that is not metabolized by the body, but is excreted via the kidneys. Most compounds are metabolized into base elements, but some are not and are excreted unchanged (or are partially metabolized, and the metabolite is excreted). The compound doesn't necessarily have to be colored, but can react with something in the urine to make it colored. What specifically is in beets and asparagus I don't know. Eating too many carrots can cause carotenemia which makes a person orange (the skin). And silver can cause Argyria, which turns skin grey, there is also Chrysiasis from gold the turns skin blue or gray, and lycopenodermia from tomatoes which is deep orange. Presumably there are others, but I don't know them offhand. Ariel. (talk) 20:54, 23 July 2010 (UTC)[reply]
Yes, it can. However, it is not easy to do. If you burn magnesium and dunk it in water, the water will cool the magnesium and make it stop burning. However, if you put an effort into limiting the cooling effect of the water, you will see that the magnesium will continue to burn. -- kainaw™18:45, 23 July 2010 (UTC)[reply]
Just the water itself. Even cold magnesium is oxidizing enough to reduce water to hydrogen (and magnesium oxide). The reaction is slow at normal temperatures, but would certainly work if there were already a heat source to get it going. Physchim62(talk)20:11, 23 July 2010 (UTC)[reply]
How can an oxidizing agent reduce?. I was wondering about the tightly bound H+ ions in water, whether they were the oxidizing agent, but even more reactive metals do not actually burn under water, the H2 burns above water. --Chemicalinterest (talk) 20:39, 23 July 2010 (UTC)[reply]
As I understand the alkali reduction reaction, the magnesium (or other alkali metal) drags oxygen out of the water to form magnesium oxide, and/or magnesium hydroxide, releasing energy and hydrogen. Hydrogen, plus heat, then undergoes a second ("unrelated") reaction with the free oxygen (O2) in the air, yielding flame (and resulting in water vapor). If this reaction is correct, the flame can't exist underwater - all that will happen is formation of warm water and hydrogen bubbles. I recall performing an experiment in a chemistry lab some years ago (WP:OR) where we used this process to isolate pure H2 (trapping gas under water). Can somebody find a source that says otherwise? The MG + H2O reaction will yield MgO (or Mg(OH)2) + H2 + heat, but no flame; and the H2 will bubble up to the surface (by which time it is probably too cold to ignite). Nimur (talk) 20:47, 23 July 2010 (UTC)[reply]
Isn't it just a redox reaction involving the hydrogen and magnesium? The oxygen is along for the ride (H/Mg exchange on the O in a molecular sense). Lots of metals do this at various rates, sometimes requiring added heat, pH changes, or other initiators to get a noticeable reaction rate. More active metals (potassium) don't require being ignited to cause the reaction. DMacks (talk) 18:00, 24 July 2010 (UTC)[reply]
As pointed out - it does - but the cooling effect of the water tends to halt the reaction. On the other hand the reaction with steam works always (even with no air) - in fact even iron reacts with steam and glows like it is burning. Aluminium reacts even better. I think there are videos on youtube of both of these.83.100.252.126 (talk) 03:58, 25 July 2010 (UTC)[reply]
It should be pointed out that Magnesium does burn readily in both pure carbon dioxide and pure nitrogen (forming Magnesium Carbonate and Magnesium Nitride, respectively). It's one of the rare substances that does. You can look up YouTube videos or Magnesium burning in Dry Ice; its quite cool. I've seen it live in person, and its always interesting. If it were molten magnesium, it may react readily with water. Molten iron will react with water to form iron oxide/iron hydroxide, and liberate hydrogen gas. --Jayron3204:40, 25 July 2010 (UTC)[reply]
I suspect the highest temperature would be even higher than 100 degrees; if a storm is triggered by a cold front displacing a warm front with thermal inversion in the fronts, then the temperature at ground level as the rain began would be just as hot as it was before the rain arrived. I guarantee you that even somewhere with relatively pedestrian weather like New York City will have had the occasional 100+ degree day that suddenly turned into a thunderstorm, and during the early part of the storm, it would measure above 100 degrees. —ShadowRanger(talk|stalk)20:29, 23 July 2010 (UTC)[reply]
It can easily be way above 100 when the rain starts, but it won't stay that way for long. Note that if the rain water itself was above 100, you could easily get heatstroke from being out in it, because your body would have no effective way to cool itself. Rain water in fact never gets anywhere close to that hot. Looie496 (talk) 20:53, 23 July 2010 (UTC)[reply]
You would only have heatstroke if you were out in it for a significant amount of time. Your average hottub water can easily be 105F, and you people are often in that water up to their neck. Googlemeister (talk) 21:01, 23 July 2010 (UTC)[reply]
The temperature can be hotter than 100F during thunderstorms around the start of the monsoon season in the Indian subcontinent, the Sahel and parts of the Middle East and even in Southern China. ~AH1(TCU)22:57, 23 July 2010 (UTC)[reply]
What do you retain from textbooks read years ago?
I've read a lot of textbooks in my time, I still do. If you do not recall the contents word for word, then what is the form of the knowledge that gets imprinted in your memory? How do words on the page get transformed into knowledge (which you may not even remember from which textbook or lecture it comes from) which you may make use of many years later? Do even books read ten years ago leave a trace on the brain? 92.15.3.219 (talk) 19:32, 23 July 2010 (UTC)[reply]
Psychologists have distinguished between "Semantic memory," which is things you maintain as part of your general knowledge, without linking it to a particular book, lecture, TV documentary, or life experience, versus "Episodic memory," which is in fact linked to such a specific source. Certainly we may remember in some cases a particular textbook, lesson, encyclopedia article, TV documentary or personal explanation whereby we learned a particular nugget of knowledge. Edison (talk) 20:06, 23 July 2010 (UTC)[reply]
This is merely an anecdote, but I was recently asked a question about a particular part of history. I could recall the exact layout of the page it was on in my high school textbook, but could not for my life remember what the sentences actually said. ?EVAUNIT神になった人間06:44, 24 July 2010 (UTC)[reply]
Yes, I have a similar peculiarity of memory in that I can often remember where on a page I read the information, but I cannot read the page. People with true photographic memory can (disputed claim). Most of your knowledge, however, is a synthesis of what you have read - processed by your brain to become understanding and recalled in a different form. Dbfirs07:24, 25 July 2010 (UTC)[reply]
I suppose it might be theoretically possible, if the bullet was extremely soft lead, and you basically fired the bullet at the edge of the katana. But no, no matter how much training you have, you can't move a sword fast enough or precisely enough to get it in the way of a bullet moving at several times the speed of sound. You might be able to move the sword into the path of the gun while someone was aiming (extremely difficult, but possible), but if they adjust the angle of the shot by fractions of a degree, your sword will be out of place, and human reaction times aren't fast enough to correct. And of course, even if they don't change their aim intentionally, the slight changes in angle triggered by the force they exert pulling the trigger, the recoil, etc., all combine to make it effectively impossible. —ShadowRanger(talk|stalk)20:09, 23 July 2010 (UTC)[reply]
I should point out that this would depend greatly on the structural integrity of the katana, and even a good katana would probably be irreparably damaged. A lot of things marketed as katanas are just plain stainless steel; hard, but brittle, and would likely shatter if hit by a bullet. Traditional katanas have more flexibility, but the edge is still hardened steel and would suffer badly. —ShadowRanger(talk|stalk)20:15, 23 July 2010 (UTC)[reply]
Here is some video of shooting a sword edge-on in laboratory conditions, and here is a guy who tried it in the real world. An important thing to consider is that you can't see bullets. For fun, take the fastest a human can move a limb (the fastest baseball pitch is probably close), the speed of a .22 bullet, and the width of your body you want to protect and see how far away you'd have to see the bullet to get your hand to the right place in time. --Sean20:19, 23 July 2010 (UTC)[reply]
So if the Japanese guy had Superman quality reflexes and held the sword in front of him just so, it would have split the bullet into two pieces which would each have hit him. Two small wounds instead of one big one, and less kinetic energy due to what was absorbed by the sword. A possible improvement. Holding an iron skillet, an anvil a sadiron or a manhole cover between oneself and the shooter might be preferable. Edison (talk) 01:35, 24 July 2010 (UTC)[reply]
The meteorologists are telling us it will be 96 degrees F (36 C) with heat indexes over 100 F (38 C) today in North Carolina. What they almost never tell us is that this is totally unrelated to being out in the sun. How much hotter would it be out in the sun, and would the heat indexes also have an effect on that?Vchimpanzee· talk·contributions·19:53, 23 July 2010 (UTC)[reply]
I think the heat index is just taking into account the humidity; the sun would be determined by several more factors, such as the color of your clothes, how much you sweat, how much wind there is, how much shade you are in, how much exertion you do, how you are positioned in relation to the sun, etc. --Chemicalinterest (talk) 20:56, 23 July 2010 (UTC)[reply]
It's so variable that there's no point in trying to say anything. Did you ever see one of those pictures of somebody frying an egg on a hot sunny sidewalk? Looie496 (talk) 21:02, 23 July 2010 (UTC)[reply]
Surface temperatures are measured in the shade because the thermometers would give inaccurate readings in the sunlight. For example, the air temperature (often measured in Stevenson screens, which can still have an error of a few degrees) could be 35°C but the thermometer under intense sunlight could read 45°C or even 50°C. ~AH1(TCU)22:28, 23 July 2010 (UTC)[reply]
It's impossible to say anything about the temperature "in the sun" in general. The difference in air temperature between sun and shade is negligible, since convective and turbulent movements of the air will quickly equalize any temperature gradient. However, when you place a thermometer in the sun, it invariably spikes by several, if not dozens of degrees. Why is this?
It's because an opaque object such as a thermometer or your skin will absorb certain wavelengths of light from the sun; this will heat the surface of a thermometer or your skin by some significant amount. Because this varies strongly among different objects made of different materials and of different colors, it's impossible to make a general statement about how hot it is "in the sun". I suspect the color of your skin greatly affects how hot your skin actually gets. Would certainly make for a good science project! (with the proper sunscreen, of course :D) -RunningOnBrains(talk)05:17, 24 July 2010 (UTC)[reply]
add that the body is a self-regulating temperature system, so the effects of direct sunlight on the body change the perception of temperature without actually changing the surface temperature of your body significantly. It's much like watching ice melt: ice melts faster when the temperature is hotter, but the surface temperature of the ice (by definition) never strays far from 32° Fahrenheit during the entire melting process. --Ludwigs206:10, 24 July 2010 (UTC)[reply]
what is inside of a pepper, a gas or air? and how does it get in their?--Horseluv10 20:40, 23 July 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
Pepper skins are not airtight. The gas inside wouldn't be 100% ordinary atmosphere, but it would be pretty close. (Small differences in CO2 concentration, presence of a bit of ethylene, higher concentration of water vapor, etc.) Looie496 (talk) 20:48, 23 July 2010 (UTC)[reply]
I think it is a pretty good question. What's surprising to me is that the inside is neither solid nor liquid. Why did the pepper even bother to grow larger than necessary to actually deploy its seeds? Does the air-space somehow improve the seeds' chance of growing, does it serve some other evolutionary purpose, or is it just a vestigial artifact of the way that pepper biology forms its plant-tissue structure? Nimur (talk) 21:45, 23 July 2010 (UTC)[reply]
The bell pepper is a member of the Solanaceae family, also known as the nightshades. Another member of that family is the tomato. If you imagine a tomato with all the parenchyma-y goop inside gone, you've got something not unlike a pepper. Check this picture for a visual comparison. And given the variety of tomatoes (beefsteak, cherry, plum etc) no doubt a lot of cultivation has gone on for peppers too, like Bugs has said. Brammers (talk/c) 07:59, 24 July 2010 (UTC)[reply]
(EC) It seems most likely to me the size & shape of the fruiting body relates to it's purpose, to attract birds. (The same is believed for the colour after all, as it is for most brightly colour fruits.) To put it a different way, to claim that it's larger then necessary to actually deploy its seeds is most likely wrong, it isn't anymore then a watermelon is. The fact that there's no liquid or solid inside likely arises somewhat from the evolutionary history and also the fact it isn't needed as the external skin already provides enough for the birds that eat it. After EC: Of course as BB has mentioned we also need to distinguish from completely naturally occuring chillis and those that have been cultivated at some stage in their hisotry, which can be rather difficult for something which has been cultivated as long as chillis have... Nil Einne (talk) 22:02, 23 July 2010 (UTC)[reply]
I would expect some although I have my doubts we'd see the very large sort of things like some modern capsicum for example. These [3][4][5] have some discussion of wild capsicum including some pictures. Bear in mind as I mentioned above determing if something has been influenced by cultivated varieties is usually rather difficult even with genetic analysis. In this case the refs all suggest the history has not even been well studied anyway. Nil Einne (talk) 22:33, 23 July 2010 (UTC)[reply]
Those big tails would have been hard for the females to curl out of the way, and their multi-ton weights would have made problems for the male mounting (especially in cases like the brontosaurus and brachiosaurus). The little forearms of the tyrannosaurus would have made it hard for the females to get down on her "elbows" and for the males to "hold on". And in the case of the stegosaurus, well, between the weight, the spines, and the big tails, they pretty much hit the anti-mating trifecta. 71.161.45.103 (talk) 22:49, 23 July 2010 (UTC)[reply]
Short answer: although we can draw inferences from the strategies of various modern reptiles and from birds (which technically are dinosaurs), we don't really know; for example, soft tissues like penises are almost never preserved by fossilisation, and although it's commonly assumed that (male) dinosaurs didn't have them, some of them may have (just as some modern birds do and some don't).
I believe some broken bones in dinosaur tails are ascribed to the problems they had mating. They obviously went n for S&M :) Dmcq (talk) 14:14, 24 July 2010 (UTC)[reply]
Many of the larger sauropods are believed to have lived much of their lives in or near water, even though they didn't swim. Their enormous size is believed to have made living on dry land difficult. This is not settled theory; there are others that claim that their structure would have made breathing and maneuvering in the water difficult. But there are some credible theories that some of the largest dinosaurs did live a partially aquatic lifestyle. Also, be careful asking "how did dinosaurs mate". Its like asking "how do mammals mate". Dinosauria was a massive, diverse clade which existed for hundreds of millions of years (and still does, in the form of birds). There was likely a huge diversity in the manner in which dinosaurs mated, considering they ranged in size from the perhaps 60-meter long Amphicoelias to some that were only a meter or smaller. They were two-legged or four-legged, and came in two very different types of hip configurations (Ornithischia and Saurischia). Making definitive statements over how such a diverse group of animals may have behaved is practically impossible. --Jayron3204:32, 25 July 2010 (UTC)[reply]
I would assume a millipede, but it's hard to tell what species it is, as it's so blurry. However, it is not poisonous unless you eat it (even then it may not be). Where do you live? Perhaps that would help identify it. --TheHighFinSpermWhale03:41, 24 July 2010 (UTC)[reply]
I have now seen commercials for both paint and sunglasses claiming their products to somehow be related to high definition. It seems completely bogus to me (HD is about resolution on a monitor, not how bright colors are to the eye), but am I missing something? ?EVAUNIT神になった人間06:49, 24 July 2010 (UTC)[reply]
Well for paint I would assume that the HD means "heavy duty" rather than High Definition. Sunglasses wise i think they're definitely using HD as 'short hand' for high quality because consumers associated HD as being high-quality so they want you to associate your sunglasses with that. Can't see there being a genuine application of HD in sun-glasses but you never know! (Oh and the paint company may be doing the same as the sunglasses one just instant assumption was 'heavy duty' when you say HD and paint). ny156uk (talk) 10:12, 24 July 2010 (UTC)[reply]
No, it's not "heavy duty". I've also seen paint marketed as "high definition", which in that case really just meant they were trying to sell bright, bold and "vibrant" colors. Obviously it has nothing to do with HD displays, and would seem they are just trying to ride the coattails of the larger awareness about HD. I don't know about the sunglasses, but I would suspect that is also a marketing ploy. Dragons flight (talk) 16:57, 24 July 2010 (UTC)[reply]
Well, at least that statement is objectively true — there really isn't any fat in mineral water. I agree that it's meaningless in the sense that it fails to distinguish the product from any other brand of mineral water (or any water...), but I'd say it's a grade of meaningless one above the "high definition" paint. In a similar vein, I saw a box of microwave popcorn proudly announcing that it is "100% whole grain". Well, yes — it won't pop otherwise.... TenOfAllTrades(talk) 19:41, 24 July 2010 (UTC)[reply]
Well arguably most paint is fairly high definition since you can't see any pixellation or lines except perhaps when you look at it very closely. Of course if you use multiple paints the result may not be very high definition Nil Einne (talk) 21:13, 25 July 2010 (UTC)[reply]
If you know English and only English...
...what are you missing in the field of science/technical developments? Is something out there of importance that is not being published in English?--Quest09 (talk) 13:29, 24 July 2010 (UTC)[reply]
Well, it seems so that all scientific innovations are monopoly of English using world, but it is not so. For example Japanese are actually ahead in many a field. Likewise the Germans were far ahead of us durning WW2 etc. Jon Ascton (talk)14:27, 24 July 2010 (UTC)[reply]
Yes the English speaking world (especially the US) is falling behind in most scientific achievements and manufacturing; just see where most things are made. The US is on a declining slide. --Chemicalinterest (talk) 14:54, 24 July 2010 (UTC)[reply]
I am sure Chemicalinterest is not joking and that the proportion of new US patents granted to various countries is evidence for what he/she says. Cuddlyable3 (talk) 15:40, 24 July 2010 (UTC)[reply]
That compares the two countries, but does it say anything for the information available in the language? Do the Chinese (for example) have a load of knowledge which has never been translated into English? Vimescarrot (talk) 16:29, 24 July 2010 (UTC)[reply]
And citation needed anyway. Chemicalinterest, you've managed to give a number of GIGANTIC generalizations lately on here — could you please either spend some time elaborating on your own sources for this information, or provide some? Because otherwise this whole thing degenerates into Yahoo! Answers very quickly, and it is not helpful. --Mr.98 (talk) 16:30, 24 July 2010 (UTC)[reply]
As Vimescarrot has hinted at, a large amount of scientific research is published in English, no matter the native language of the researchers. And colloboration largely happens in English. There are frequently postdoc programmes in countries like Japan which require no Japanese (although some basic level may be recommended/required so the people can live in Japan, e.g. [7]). This isn't to say there are no non English scientific journals, e.g. as discussed in Academic publishing in China there are. However many countries even those where English is not the native language may also have local English journals. And generally speaking if a researcher feels their research is particularly significant, they're going to try to publish it in a reputable international English journal as in the China case. In other words, while there is a fair amount of stuff out there that isn't in English, it won't generally be major breakthroughs that are missed.
Note that an even without a language barrier, the poor regard of some of the journals, lack of indexing, lack of interest etc means that a fair amount of stuff may not be considered or well known among researchers in other countries. An example, I was looking in to cloud seeding a while back when it came up in an RD discussion. This is something widely praticed in China and from my searches, I found there was a fair amount of published research in English and more in Chinese however the state of play in Chinese research wasn't generally reflected or well discussed in more Westernised things I read. Another example, in Malaysia where English is largely the scientific language, various issues means from my experience many academics have rather poor publishing records particularly when it comes to internationally recognised scientific journals. They do publish somewhat in local journals which are usually in English but (well this was ~2-5 years ago) they were barely known or unknown, often not indexed nor easily available (well I'm sure you could get them via interloan) and I do wonder about the quality of the peer review (some of them may not even have been peer reviewed). Of course a lot of this is fairly applied research, relating to tropical plants and the like which isn't generally of that much interest to people in temperate countries. (Bearing in mind I have somewhat of a biological background so my greatest experience is there.)
In the 15th and 16th century did scholars who read Latin but not English, German or French miss out on all the scientific and mathematical development, since folks in Germany, France and Britain were making breakthroughs in math, chemistry and physics? Not all that much, because Latin was a common language of publication then, just as English is now. English might even be a common language of publication researchers in different regions of China might or different regions of India, whose local dialect is not that intelligible nationally. Edison (talk) 19:58, 24 July 2010 (UTC)[reply]
I know my answer above does not have anything to do with the question. The trend has been that way. China used to be a poverty-stricken, backward country... now it rivals the US. --Chemicalinterest (talk) 23:16, 24 July 2010 (UTC)[reply]
As a rule, if people make a discovery that they think the world should know about, they will make every effort to publish it in English. There is also significant science published in French, Russian, Japanese, and Chinese. Many of these journals, though, are abstracted in English or even fully translated. A person competent only in English will have no difficulty following developments in virtually any modern science. Looie496 (talk) 23:44, 24 July 2010 (UTC)[reply]
There was a time a few decades ago where, if you were a chemistry major in the U.S., you were usually required to learn German. That's because most of the major players in the chemisty industry that weren't in the U.S., like DuPont and Dow and Gen Chem, were in Germany, like BASF and Bayer and IG Farben and the like. That's because, in the early 1900's, Germany had a near monopoly on the coal-tar dye industry, and that was at the time a major source of research in pure chemistry. Over time, petrochemicals became more important, but historically the two most important languages for a chemist to know were English and German. Even in the mid 1990's, when I was in school, it was still highly recommended to learn German as your required second language. (I chose French as my langauge, as I already had 7 years of it under my belt at that point). The rationale was that, although most modern literature was availible in English, much of the historical literature was in German, and if you wanted to get to the original paper on something, you had to read it in the original German. Today, however, almost everything is in English. It has become the lingua franca of most scientific literature. Even foreign journals often (but not always) publish an English version, and lots of research from non-English speaking countries is published in major English-language journals. --Jayron3204:15, 25 July 2010 (UTC)[reply]
Yes. As an undergraduate Science student in Australia 40 years ago, I was required to demonstrate my skills in a "Science Language". One had a choice of French, German or Russian. Given my current (lack of) ability in any of those languages, I am thrilled that almost everything is very quickly published in English these days. I've seen a couple of writers recently refer to Globish, reflecting the takeover of English in the science/tech world. HiLo48 (talk) 04:20, 25 July 2010 (UTC)[reply]
It is probably accurate to say that English is sufficient. Any new development that were published in Chinese, for example, would quickly be translated to English. It's also reasonable to say that a foreign language skill is more relevant in business than academia. Most non-English-speaking academics will be more likely to translate their research papers into English. However, outside of "research", I often find schematics, datasheets, parts catalogs, and so on, written only in Chinese or Japanese. Not being able to read those documents does inhibit some knowledge transfer; but mostly about specific implementations, and not about general ideas. This is sort of the distinction between "research" and "development" - it is highly unlikely that a Chinese researcher would invent a new type of device and not tell the English-speaking world about it. But, it is very common for a specific implementation to remain untranslated. Nimur (talk) 00:02, 26 July 2010 (UTC)[reply]
poison ivy
if somebody got poison ivy in their eyes, would they get blind?--Horseluv10 15:16, 24 July 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
We have several articles on the general topic of Toxicodendron species and their effects, the big three being poison ivy, poison oak (mainly Toxicodendron diversilobum), and the particularly brutal but luckily less common poison sumac. We also have a general article on urushiol-induced contact dermatitis, which is where the information on the medical effects should probably be centralized. Unfortunately it appears that the information on contact with the eye is somewhat limited; maybe that should be fixed. --Trovatore (talk) 00:00, 25 July 2010 (UTC)[reply]
Or maybe it's just a curious kid wondering how careful you need to be around poison ivy. I'd say the question is ill defined. Do you mean around the eyelids? in which case there would very likely be temporary blindness due to the swelling of the lids. Or do you mean damage to the cornea? - in which case temporary blindness would occur and the possibility permanent blindness would be significant but not certain. Richard Avery (talk) 07:35, 25 July 2010 (UTC)[reply]
I realize this is personal research, but I've had poison ivy all over my face, and in my eyes. They were swollen shut but I could still see if I pried open my eyelids. No permanent damage, although I was treated by a doctor to reduce the swelling. -- JSBillings13:27, 25 July 2010 (UTC)[reply]
Here is an 1893 medical journal which lists two men made blind by poison ivy: [8]. Given the prescientific methods used by medical doctors in those days, the blindness might have been a consequence of ill-advised treatments, or it could be due to infection caused by scratching.Edison (talk) 17:16, 25 July 2010 (UTC)[reply]
It must be pretty common to get urushiol (the active agent) in the eyes, at least in small quantities, because if you get any on your fingers, it will take hours for even the smallest effects to show up, and you'll get it on everything you touch. Looie496 (talk) 17:57, 25 July 2010 (UTC)[reply]
oh thanks for the information. i was just curious, and i was asking about getting it actually in your eye. Horseluv10 10:55, 26 July 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
This is the sort of thing if you have to ask then the answer is likely no. Working with mains voltage can be very dangerous and you should not try it unless you know what you're doing. If you really are determined, make sure you connect everything before you turn on the mains switch. Do not touch the meter or cords while the switch is on. If you are trying to measure because you think something is broken then again you probably shouldn't do it at all. Nil Einne (talk) 16:20, 24 July 2010 (UTC)[reply]
There will generally be a sticker somewhere on the meter (on that photo it's clearly visible around the sockets) that describes what safe range of voltages, currents etc you can work with. I would suspect 220v mains may be outside the recommended range of most normal multimeters. ~ mazcatalk16:48, 24 July 2010 (UTC)[reply]
Actually, even $20 multimeters are usually rated for voltages above 220 AC. I'm not sure I have ever seen a multimeter that could not measure wall voltages. That said, I agree with Nil. If you aren't sure what you are doing, then you probably shouldn't be doing it. Dragons flight (talk) 17:07, 24 July 2010 (UTC)[reply]
Or US$3 ones [9]. Okay that's actually measuring 110V but it looks like this [10] which is $9.99 not $5 but does have a 750V setting. I actually don't think I've seen one that doesn't have a similar setting although I've only seen a few (largely cheap) ones Nil Einne (talk) 18:05, 24 July 2010 (UTC)[reply]
Clockwise of the off position on the dial is the setting for 750V ac - this is the one you would use - if you knew what you were doing.. As you have to ask about this I'd suggest getting some more experience on using multimeters (is there someone you can ask who can show you?) before plugging yourself into the mains. 83.100.252.126 (talk) 17:22, 24 July 2010 (UTC)[reply]
I would never connect a cheap meter to a mains circuit at voltages of 480 volts or higher, unless the probes had fuses capable of interrupting a fault at the voltage level in question and at the maximum available fault current. The clearances and insulation levels are likely to be inadequate. Even so, the operator might need protective high voltage gloves, eye protection, and perhaps special protective garments. High voltages can sustain an arc which can incinerate everything for several feet around. A cheap meter could have leads which short, or could have an internal short. I am personally not as scared of 220, but I would treat it with respect. The suggestions of connecting the meter with the circuit dead are good if you are not experienced. Just because a voltage rating is on a meter does not automatically make it a safe operation to test at that voltage. Edison (talk) 19:48, 24 July 2010 (UTC)[reply]
Yes. Set the switch to just right of the OFF position to the setting for 750 VAC. Do not use any other setting and take good care not to come in contact yourself with the mains that you are probing. The warnings above are well intentioned but overblown. The probes, cables and meter are adequately insulated for 220V measurements and the notion of having fuses in the probes and special garments for a domestic mains voltage measurement is frankly ridiculous. Cuddlyable3 (talk) 23:09, 24 July 2010 (UTC)[reply]
Cuddlyable3, Per your comment that special precautions for testing voltages at 480 and above are "frankly ridiculous:" We were talking past each other a bit, regarding 220 versus the higher voltage shown on the meter. I addressed the consequences of a short in the meter or faulty insulation on a test lead, when there might be over ten thousand amps of available fault current from the utility. If testing a vacuum tube radio, or a fused circuit in a house, there is an upstream fuse or breaker which would limit the fault current. If testing on the high side of the main breaker panel in a house, or a utility transformer secondary, such upstream protection may not be there. A premises might well have over 10,000 amps of available fault current on the high side of the main breaker or fuse panel, and a large flash could occur even at 220 or 240, though not likely a prolonged arc lasting minutes. A short at the meter even at 220 can cause a very large explosion, with injuries from heat and blast, worse than a short at an outlet or a toaster. If 480 volt leads from a large power transformer were inadvertently shorted, as by test leads or a multimeter, persistent and deadly high temperature arcing at can result. Note that I wrote about 480 volts and higher (the cheap meter illustrated has a 750 volt range), which can sustain an arc capable of incinerating the switchgear and everything in the vault. A meter, especially a cheap offbrand one, can have an internal short, a test lead can develop frayed insulation, and a plug can pop out of a meter and short to ground. A cheap meter is not necessarily safe to use at the highest voltage level selectable. Even a quality digital meter, with a high voltage probe, might not be safe to test utility primaries, even if the probe is rated to step down 30 kv to 300 va low meter input. A utility tester would use a meter the probe on a long stick which places him several feet away if there is a flash, and might be required to wear a facemask and protective clothing. Even at 240, a utility would require personnel to wear flame resistant clothing and protective glasses when testing voltage. It is all too easty to inadvertently short a test lead to ground, or for a wire to get pinched by a cover. I personally would not hesitate to test domestic 220 or 240 volt outlets with the meter shown. But a careless or inexperienced person could get into serious trouble touching test leads to such a meter to a high fault current source at the highest voltage level shown on the dial. Another problem area is that if a meter shows no voltage the circuit is not necessarily dead, since a test lead may have developed an open circuit or the meter might have a blown fuse or other problem. Ideally one would test on a live source, then test the "dead" circuit, then retest the live circuit. Edison (talk) 04:27, 25 July 2010 (UTC)[reply]
I think Edison is right here. The probes should have fuses capable of interrupting the maximum available fault current at the voltage level in question. —Preceding unsigned comment added by 88.104.95.35 (talk) 23:23, 24 July 2010 (UTC)[reply]
All the words of caution given here are most appropriate. My first Multimeter was an analogue machine - moving coil galvanometer etc. I was excitedly measuring everything I could find, including the resistances of all my electrical appliances and the mains output (240 V). After measuring a resistance I moved on to check the output from one general purpose outlet but I forgot to reset the Multimeter from "Resistance" to "AC voltage". Instantly one of the resistors in the Multimeter fused! I think it is still an open circuit to this day, so that is one "Resistance" setting that doesn't function. Don't bother measuring mains output until you have gained a lot of experience with your Multimeter and you are supremely confident you are following all the precautions you have been given here. Dolphin(t)00:51, 25 July 2010 (UTC)[reply]
Check whether the meter is certified as IEC 61010 CAT-III 600V (yes, six hundred) or better.[1][2][3] Don't use it on mains equipment unless it is. (Merely been rated at 220V or 600V, or even higher is not sufficient. It must be CAT-III.) Even if the meter is correctly rated, electricity can kill. If you had to ask the question at all you should call a licenced electriction. Mitch Ames (talk) 04:21, 25 July 2010 (UTC)[reply]
Is there any real animal that has an actual metal shell or exoskeleton? Or something close to that? I know that shells contain calcium but I was thinking more of something that eats minerals and then secretes pure metal on the outside. --95.148.106.219 (talk) 16:29, 24 July 2010 (UTC)[reply]
Many arthropods (and some worms, maybe Nereis - not sure) have increased metal (Mn, Zn, Fe) concentration in the parts of their exoskeleton that must be most wear-resistant. For insects that would be primarily the mandibles. Concentration of metals can reach over 10% by mass (!) according to the literature. What is not known, though, is whether those metals are incorporated in the chitin & protein matrix as nanoparticles, as mineral inclusions, or as ions. It is only pure, elemental metal (particles or nanoparticles) that you are asking about, AFAIU. --Dr Dima (talk) 18:21, 24 July 2010 (UTC)[reply]
Is it that difficult to detect? Just put the insect part under a high-res DIC microscope and use an appropriate wavelength corresponding to the plasmon resonance of the metal. As long as the particles are not much smaller than 50 nm in diameter, they should be easy to detect. John Riemann Soong (talk) 18:48, 24 July 2010 (UTC)[reply]
Beats me, too. If you can do it conclusively and in reasonable time, it could be a good paper. Just make sure you (a) ask your boss first if he or she doesn't mind you spending time on this, and (b) search the literature thoroughly to see if no-one has tried this before. I am a neuroscientist, so my knowledge is not exactly on the cutting edge of the insect mandible research, no pun intended. --Dr Dima (talk) 19:03, 24 July 2010 (UTC)[reply]
Am I the only person here thinking about mantises (manti?) with hardened bio-metallic blades now? That would be an extremely fearsome mini-beast. --Kurt Shaped Box (talk) 22:52, 24 July 2010 (UTC)[reply]
Last year after a particularly long organic chemistry lab I spilled a test tube and wiped it up with a towel. 2 weeks later at checkout, the towel had gone black, brown and blue and crumbled to dust when you touched it. 1 day later after touching the towel, I suddenly noticed my fingernails and parts of my hand had been stained black.
Now in that lab I had worked with sulfuric acid and silver nitrate. Silver nitrate seems likely for staining my hands (the skin recovered within a week...the fingernails took several months to grow out) ... but would it eat cloth? It seems unlikely I would have worked with both in the same test tube (doesn't the combination make an especially strong oxidiser? how strong of a Lewis acid is Ag+ anyway)? John Riemann Soong (talk) 18:43, 24 July 2010 (UTC)[reply]
Description of a "white Horse" wind wave. The Wikipedia listings of the Beaufort wind scale use the term "white horse" to describe a white cap at low wind velocity. There is no clear definition or illustration. What exactly is a "white Horse" in this context? Science Searches lead nowhere or to the color of horses. —Preceding unsigned comment added by RManns (talk • contribs) 21:03, 24 July 2010 (UTC)[reply]
A white horse is just the breaking cap of a wave. Once the wind reaches about 7 knots (Force 3), a few white horses become visible, by the time the wind speed has reached about 22 knots (Force 6), white horses are everywhere. The photos of sea states from the NOAAhere are not great but they may help. Mikenorton (talk) 23:19, 24 July 2010 (UTC)[reply]
Doesn't seem to be a scientific term, but Google Web and Google Books searches find usages. The term was defined as long ago as the Encyclopedia Americana of 1829. Looie496 (talk) 23:25, 24 July 2010 (UTC)[reply]
Pocket Monsters Special Yellow (final battle): Lava surfing?
Assuming you could make a surfboard that could withstand the heat, and you could withstand the heat, then yes, you could. Because even the lowest-viscosity lava (flood basalt) is more viscus than water, than it might be easier to surf on it. Now, some lava is too viscous, like rhyolite lava (about consistency of toothpaste), so surfing may not work on that. On the plus side, it's cooler in temperature... QFL 24-7 bla bla bla ¤ cntrb ¤ kids ¤ pics04:31, 25 July 2010 (UTC)[reply]
Well, both seem likely interpretations of what they wrote to me, although the former is more suited to this desk, and a more interesting question. For the latter, I'm pretty sure there's no surfing on lava, but I never had this edition myself. I don't see it mentioned in any walkthroughs. Of course, there weren't really any colours on the screen in those early versions, so it would be possible to interpret some body of water as lava. 86.164.66.83 (talk) 18:47, 25 July 2010 (UTC)[reply]
Anyone that's ever owned a budgie will probably have seen this - they seem to have an ability to recognise even the smallest and most fractured reflection of itself as another bird with which to interact. For example, a budgie can see another budgie and recognize it as another budgie (speaking from personal experience) in items such as a tarnished, scratched-up Zippo lighter, the wooden top of a speaker cabinet, a metal clip used to hold cuttlefish bone (reflective bit can be no more than 2mm square), fingernails, the scratched-up screen of a mobile phone, a bit of clear plastic shrink wrap from a CD...
How does this work, exactly? As a human, I can *barely* make out a reflection of *something* in these things - yet the budgie will sing his little heart out and do his little display dances as though it's a brand new friend. --Kurt Shaped Box (talk) 23:01, 24 July 2010 (UTC)[reply]
Are you sure they think it's another budgie? Maybe they just like shiny things. But birds have much better (day) vision than humans. Ariel. (talk) 03:19, 25 July 2010 (UTC)[reply]
July 25
Ultra violet rays
Do ultra violet rays penitrate water? Any differnce between fresh water and salt water? Can a person get sunburned while swimming under water? —Preceding unsigned comment added by Wsccj8 (talk • contribs) 00:00, 25 July 2010 (UTC)[reply]
Yes. In fact many water purification systems depend on UV light. I don't think there is a difference between fresh and salt water, but murkiness makes a difference. You probably wouldn't get sunburned if you were more than a few feet down, but I get the worst sunburn of my life while snorkeling in the Caymans -- you don't have to spend much time at all near the surface for it to get you. Looie496 (talk) 00:37, 25 July 2010 (UTC)[reply]
Ultraviolet radiation can be sub-divided in several ways. One way is to sub-divide the ultraviolet family of radiation into ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). See Ultraviolet#Subtypes. UVA and UVB are the ones we are most familiar with, and they do not penetrate water for any significant distance. So sunburn is not a risk while underwater, but we mammals can't stay underwater continuously, and when we come up for air then we are vulnerable. UVC penetrates water and has application in disinfecting water because it is lethal to any living organism. See Ultraviolet germicidal irradiation. Fortunately UVC is not present in our environment because solar UVC is eliminated by the Earth's atmosphere! Dolphin(t)01:06, 25 July 2010 (UTC)[reply]
You are mistaken. For wavelengths longer than ~200nm, i.e. UVA and UVB, there is little difference between the absorptivity of UV in liquid water than the absorptivity of visible light [12][13]. So, in practice, the UV is diminished by about the same amount that sunlight appears diminished. Hence, for most swimming scenarios, water offers very little protection. The one correction to this is that waters rich in organic matter and/or microorganisms, will attenuate UV faster than visible light, but that won't be common among the waters people usually choose to swim in. Dragons flight (talk) 07:29, 25 July 2010 (UTC)[reply]
I may be wrong, but I've always heard that water can act as a magnifying lens (or water droplets can) and focus UV rays on your skin, increasing the chances of getting a sunburn if you are wet as opposed to being dry. This may be urban myth though. – Kerαunoςcopia◁galaxies16:01, 25 July 2010 (UTC)[reply]
Odd chemical reaction?
While on the road this afternoon, I ate a can of pineapple chunks packed in pineapple juice. Finding the fruit rather warm (it had been sitting in the car, unopened, for quite a while), I bought a bottle of Pepsi. After drinking most of the bottle, I returned to the pineapple; for the rest of the afternoon, I'd take a little of one, wait several minutes, take a little of the other, wait several minutes, take a little of the first, etc., until both pineapple and Pepsi were gone. Since that time, I've had an odd taste in my mouth; could a mix of the two substances produce an odd chemical reaction that would be responsible for this unique and long-lasting taste? Whatever it is, I know it's not harmful, so I'm not asking for medical advice. Nyttend (talk) 00:08, 25 July 2010 (UTC)[reply]
The taste is metal. You are not supposed to leave the pineapple in the metal can once it's opened. Pineapple juice is acidic enough to eat some of the metal in the can, and you can taste that. It'll be either zinc or steel (usually zinc). It's not toxic in low amounts, but don't do it often. I bet if you looked, you would see something like "After opening, store unused pineapple in a glass or plastic container in the refrigerator."[14] printed on the can. Ariel. (talk) 02:32, 25 July 2010 (UTC)[reply]
After doing some research, now I'm not sure about the zinc. I'm still pretty sure tin isn't used much in cans anymore. They seem to be steel coated either with plastic, or enamel. But no tin or zinc. Ariel. (talk) 03:16, 25 July 2010 (UTC)[reply]
There really isn't such a thing as a zinc coated food can. Zinc is too reactive. 'Lacquers' of various types are also used. A tin can is tin coated steel, aluminium, or coated steel. Just read Tin can. Tin is still used extensively.83.100.252.126 (talk) 03:18, 25 July 2010 (UTC)[reply]
Here's a proper reference (from 2005) [15] "Steel cans, often called "tin" cans because of their micro-thin tin coating, comprise more than 90 percent of the food can market" —Preceding unsigned comment added by 83.100.252.126 (talk) 03:23, 25 July 2010 (UTC)[reply]
Ariel, do you have a reference for that? I understand that many foods should be refrigerated once opened to prevent spoilage, but your reply suggests that the acid in the pineapple doesn't begin to leach metal from its container until opened. Is this because that reaction requires oxygen? Please explain. -- Scray (talk) 03:10, 25 July 2010 (UTC)[reply]
Maybe tin in the pineapple and phosphate in the coke reacted to make insoluble tin phosphate which has stuck to your tongue? What is the taste like anyway? fizzy, metallic, fruity ??? 83.100.252.126 (talk) 03:52, 25 July 2010 (UTC)[reply]
Sorry, I can't really say: I've never tasted anything like it before, and I didn't really experience it when my mouth was empty. I should clarify — (1) I was done with the pineapple perhaps 30 minutes after I opened it; and (2) I didn't notice the taste with either Pepsi or pineapple in my mouth; it was only 1½ hours later, once I reached home and drank milk from my normal cup, that I noticed anything. Nyttend (talk) 04:23, 25 July 2010 (UTC)[reply]
Surprisingly no one has asked the obvious question that I've noticed; have you eaten that much pineapple that quickly before? Nil Einne (talk) 07:25, 25 July 2010 (UTC)[reply]
I'd guess it's something to do with taste bud burn out or overload, maybe someone can explain more.. Did the milk lack taste or 'wetness' - this is something I've occasionally experienced - my usual solution is to drink more milk until it tastes like milk again...83.100.252.126 (talk) 13:49, 25 July 2010 (UTC)[reply]
Nil — I ate it somewhat slower than I normally do; a complete can of pineapple, eaten out of the can, is a common part of my lunch. IP — the milk seemed as wet as normal, and it had a distinct taste; it's just that it didn't taste like milk normally does. Nyttend (talk) 00:11, 26 July 2010 (UTC)[reply]
I'm still pretty sure it's simply metal, and not some more complicated reaction - metal has a pretty distinct and very strange taste. Maybe a test. Leave some pineapple juice in the can in the fridge. A few times a day take some out and taste it (put some in a cup and let it warm up - it's easier to taste when it's room temperature). Also some vitamins have a metallic taste. Maybe you've eaten some and can compare? Ariel. (talk) 03:31, 26 July 2010 (UTC)[reply]
Okay I wondered if it may be some sort of allergy (several people in my family have some sort of oral allergy syndrome to pineapple which causes a funny tongue, I myself have some sort of mild reaction to prawns which gives what I describe as a metallic taste) but guess not Nil Einne (talk) 21:47, 27 July 2010 (UTC)[reply]
Absolute certainty
Is absolute certainty possible in science? For example, one of the fundamental axioms of relativity is that the speed of light is the same for all observers, but do we actually know this to be true beyond any doubt, or do we simply assume it to be true because we have never found a counterexample? Also, is absolute certainty possible in mathematics? For example do we know that is true for all a and b, or do we assume it to be true because we have never found a counterexample?--220.253.172.214 (talk) 03:14, 25 July 2010 (UTC)[reply]
Science is empirical. We gain evidence through observation, and extrapolate laws from the patterns we see in the evidence using inductive reasoning. This strategy can't tell things with absolute certainty, but for a lot of scientific claims we can be confident enough that for all practical purposes we can be certain. On the other hand it's been argued that induction has inherent flaws as a foundation for predicting how things will behave in the future (see Problem of induction). The math question is a bit trickier and I don't feel qualified to give a thorough answer so I will leave that to someone else. Rckrone (talk) 03:36, 25 July 2010 (UTC)[reply]
Absolute certainty is impossible. Are you absolutely sure you exist? Are you absolutely sure that what you are experiencing now is real and not a dream or a hallucination? Why are you so sure? How can you be so sure. At some level you must trust your own perception as reliable. Insofar as science is little more than the collective perceptions of humanity, organized into a certain system, we trust it. Science is as absolutely certain as it can be, given the limits of what certainty can be. It is also a flexible certainty, science at once expects its results to be reliable, and is also able to overturn past conclusions in the face of new, contrary evidence. --Jayron3204:04, 25 July 2010 (UTC)[reply]
I contend that the empirical nature of science means that absolute certainty within science is impossible. However, I also contend that absolute certainty within mathematics is possible, because mathematical laws are derived from axioms which are defined such that they are true. For example, the equality operator "=" is defined such that is true for all x, and otherwise false. We can therefore be certain that for all x. This then becomes one of a set of axioms from which all other mathematical laws are derived, including for instance . This means that we can be certain that . Does anyone object to this or have anything more to add?--220.253.172.214 (talk) 04:17, 25 July 2010 (UTC)[reply]
No, you're talking about semiotics and not mathematics. You're defining the meaning of symbols, and declaring their absolute certainty. The definition of the equals sign is a linguistic issue, not a mathematical one. Again, your certainty with mathematics is still subordinate to your certainty of your own ability to trust your thoughts and perceptions, as well as the ability for the symbol to define the concept. You can trust mathematics to work only insofar as you can trust your perception of its own working. You still cannot escape your own mind, and so you must have faith that what you are experiencing in mathematical proof is really what exists. Furthermore, mathematics is not absolutely certain. All mathematical systems must be incomplete, and thus cannot be said to be completely certain. See Gödel's incompleteness theorems for more on these inherant incertainties in mathematics. --Jayron3204:46, 25 July 2010 (UTC)[reply]
All right, absolute certainty is impossible, even in mathematics. However, some hypotheses must be more likely than others, otherwise science is pointless. Is there a way to quantify the probability that a particular hypothesis is true?--220.253.172.214 (talk) 05:09, 25 July 2010 (UTC)[reply]
"Absolute certainty" only exists within religions. The fact that their "certainties" vary from religion to religion is ironic, to say the least. The way to "quantify" a hypothesis is to perform experiments to see whether the hypothesis holds true. Science is a lot like math in that it relies on the concept of "if A is true then B follows". Consider geometry. The concepts of Euclidean geometry are absolutely true within that geometry. But you can create other geometries which have different truths. The likelihood of a given hypothesis being "true" would depend on the quality of the observations that support the hypothesis. ←Baseball BugsWhat's up, Doc?carrots→ 05:20, 25 July 2010 (UTC)[reply]
By the way, I am familiar with bayes theorem which states that , where H is a particular hypothesis and E is some new found evidence. This is generally the method used to quantify the probability that a hypothesis is true. However, how do we know that bayes theorem is correct if we don't have absolute certainty in mathematics? It would be ludicrous to use bayes theorem to quantify the probability that bayes theorem is correct.--220.253.172.214 (talk) 05:31, 25 July 2010 (UTC)[reply]
The "absolute certainty" you're seeking in math is based on "axioms" or "laws" which define the specific mathematics. IF those laws are considered to be true, THEN the mathematical theoreoms follow. If you want a "universal" absolute, science and math are not the places to go. The theories are subject to change based on new observations. As would be the above equation, I expect. If you want "absolutes", you need to find a religion that works for you. ←Baseball BugsWhat's up, Doc?carrots→ 05:39, 25 July 2010 (UTC)[reply]
The truth of a mathematical statement is completely determined by the meanings of the symbols in it; it has no factual content and cannot be falsified by empirical observations. If a mathematical statement has a well-defined truth value, its truth value is independent of any minds perceiving it. I think Jayron's answer is confusing two questions of "certainty", namely (1) whether a subjective feeling of being convinced of the truth of a mathematical statement necessarily means that the statement is true, and (2) whether a mathematical statement involving an infinite number of cases is only true to the extent that no counterexamples have been discovered. I think the OP's question is about the latter, and the fact is, some mathematical statements can be demonstrated to be true under the intended interpretations using sound inference rules. Strictly speaking, Gödel's incompleteness theorems do not say that all axiomatic systems are incomplete—only those whose language is sufficiently expressive, but that's a technical detail that's not very important to the discussion here. It is important to understand the implications of Gödel's theorems correctly. Incompleteness only means that some statements are true yet not provable with a given (decidable) set of axioms; it doesn't mean that no true statements can be demonstrated to be so by means of a formal proof. --96.227.54.59 (talk) 06:54, 25 July 2010 (UTC)[reply]
I just want to add something regarding the Bayes Law question. There's an important distinction to make between the mathematical endeavor of proving theorems from axioms and definitions, and the scientific endeavor of tying to connect the math results to a physically meaningful description of the world. So for example "2 + 2 = 4" is a mathematical result, but "2 + 2 = 4" alone doesn't imply that if I have two apples and I acquire two more then I'll have four apples. First we have to establish empirically that this mathematical structure of integers and addition that we invented tends to reflect the physical process of gathering up discrete items, and that's a scientific problem. (Of course in practice the math concepts tend to arise to represent empirical properties rather than the other way around.) So the truth of Bayes Law as a mathematical theorem is separate from the idea of probability as a measure of certainty of empirical facts. Rckrone (talk) 07:14, 25 July 2010 (UTC)[reply]
Actually, you kind of answer your own question by saying "we simply assume it to be true because we have never found a counterexample." Science does not concern itself so much with what's "true" but with what works. There was a question here recently about the relative motions of celestial objects. It's possible to construct a geocentric model of the universe, and it worked for hundreds and hundreds of years. And in practical, everyday life, it still pretty much works. The current model of the solar system, the galaxy and the universe in general are based on what we know so far. Unless we become God, we can't ever say that a theory is "absolutely right". But we can say that it "works" - the model constructed from that scientific theory provides consistent results. Hence, it's "good enough" for now. If we find inconsistencies, we make more observations and more hypotheses. ←Baseball BugsWhat's up, Doc?carrots→ 05:47, 25 July 2010 (UTC)[reply]
In Kantian terminology, the mathematical fact is an analytic a priori, whereas the physical law is a synthetic a posteriori. Nothing is ever completely certain, but the only doubt about the mathematical fact comes from doubt about the ability of thousands or millions of humans to judge the validity of a mathematical proof. Looie496 (talk) 05:58, 25 July 2010 (UTC)[reply]
I would dispute that. I consider mathematics to be synthetic rather than analytic. The assertion that it's analytic is the fundamental premise of logicism, which is essentially a failed approach to mathematical foundations. --Trovatore (talk) 07:19, 25 July 2010 (UTC)[reply]
Well, I don't want to be dogmatic, but it would clearly be wrong to say that we believe only because we don't know any counterexamples. There is some kind of distinction in there somewhere, however you would prefer to frame it. Looie496 (talk) 17:49, 25 July 2010 (UTC)[reply]
How absolutely certain are you that this conversation between us is really happening, and not an elaborate hallucination? --Jayron3207:16, 25 July 2010 (UTC)[reply]
No, but you can assume some things are true for convenience sake. And, if these assumptions are not contradicted by your continuing experience, nor do they cause problems later that undermines their convenience, then you can continue to assume they're true. Just make sure you continue to gather experience, and occasionally examine these assumptions in the light of it. You might also want to have a couple of back-up explanations that currently seem less likely, to compare with as you aquire more experience, and be ready to find another explanation that fits your experience better, if necessary. That's basically how science works.
That would be an excellent rejoinder to a claim that no one has made, namely that we can be absolutely certain that nothing can be absolutely known. --Trovatore (talk) 00:42, 26 July 2010 (UTC)[reply]
Given the title and discussion, it may be more accurate to say we can find enough evidence to show something is extremely unlikely to be true/correct, but we can never say with absolute certainty it isn't Nil Einne (talk) 21:52, 27 July 2010 (UTC)[reply]
Type of Current in Landline
What type of current is there in telephone line. I tried to measure, I think it's something near 48 volts DC. Our article POTS, I think, says that too. I can light up a LED with it. But why can't I run a DC motor with it ? Jon Ascton (talk)04:44, 25 July 2010 (UTC)[reply]
According to the POTS article the "subscriber loop typically carries a "load" of about 300 Ohms" - that would mean the current would always less than about 0.16A .. what sort of motor where you trying to use ? - a small can motor should still work on 0.16A 83.100.252.126 (talk) 13:37, 25 July 2010 (UTC)[reply]
This would be a good time to use the multimeter you mentioned above. The 200mA setting should be ok if the current is going to be less than 0.16A (that's 160mA) 83.100.252.126 (talk) 13:37, 25 July 2010 (UTC)[reply]
Bear in mind that a lot of places, especially the United States, have "pseudo-POTS" backed by VoIP on the service-side. In those cases, there may be a 48V ringer-circuit provided locally (via power supply fed by the utility electric grid), but not actually provided by the telephone distribution wire. In fact, in many parts of the United States, the only reason POTS still exists is because of legal mandate from the FCC; when possible, the service is replaced by cheaper VoIP equivalents, which do not distribute meaningful quantities of power on the signal lines. Nimur (talk) 00:13, 26 July 2010 (UTC)[reply]
That was a simple DC motor (taken from a toy car) that normally runs even on one cell (1.5 volt), but runs on as high as 12 volt also. I am in India. And my landline has actually DSL service also, that's I use it for internet as well. It is that type of service where awhile using internet you can use phone also i.e. the "voice" will not interfere with internet-process. Is that what you called "psuedo-POTS" ? Jon Ascton (talk)14:07, 26 July 2010 (UTC)[reply]
It sounds like you are describing DSL, which often indicates that your phone-line has been upgraded (but in and of itself, DSL doesn't guarantee anything about the actual distribution-line hardware). You probably shouldn't be trying to draw power out of the phone line, either way; whether the power comes off the telephone distribution line or a local power-supply, the equipment is not designed to sustain a steady power draw. Why can't you run off a DC power supply or a battery, instead of the phone line? Nimur (talk) 16:35, 26 July 2010 (UTC)[reply]
Many years ago, in what was probably the summer I took a year of chemistry I retained very little of, I remember being shown a graph of a smooth descending(?) curve that had an unexpected spike in it. It looked something like the graph here but I think(?) it dropped to zero at the origin. The quantity being measured was something absolute and objective, like specific heat versus the elements or something (forgive me if that is gibberish). The story was that for years people would do these experiments/measurements and due to the smoothness of the graph everywhere else they would disregard the spike that appeared at one data point, assuming it was an error. Then someone thought about what it meant if it wasn't an error, and discovered some new property. My prof was trying to make a point about the right way to do bias-free experiments, as well as possibly teach us something important, but apparently that last bit didn't work in my case.
I realize this is close to nothing to go on, but it might be one of those things that is blindingly obvious to someone in the right field and it's been itching my brain for years.76.105.238.158 (talk) 05:51, 25 July 2010 (UTC)[reply]
Not related, but a very famously wrong graph was the Ultraviolet catastrophe, a name given to the expected results when you calculate the wavelength of light emited by a blackbody radiation source compared to the intensity of the light. Classical physics predicts that blackbodies would emit light of infinite power in the ultraviolet range (hense "catastrophe", since infinite power is meaningless). It's one of the cornerstones in the development of quantum mechanics, which is a theory that much closely matches actual results in this realm. Another sort of "unexpected" result from graphs is the so-called Island of stability, which predicts that certain superheavy elements (not yet synthesized) would actually be more stable than lighter counterparts. The general trend is that heavier elements are progressively less stable than lighter ones. The island of stability is someone counterintuitive based on the trends of most of the transuranium elements. Again, not the answers you were looking for, but some examples of how unexpected results from graphs can be used to push forward scientific thinking. --Jayron3206:25, 25 July 2010 (UTC)[reply]
Not really. Remember that most of the really big transuranium elements have half-lives on the order of microseconds or shorter. That means that you could have an element which is 1 billion times more stable, and it would have a half-life on the order of a few hours. That's the scales were talking about here. Long compared to most transuranium elements, but not truly "stable" --Jayron3207:14, 25 July 2010 (UTC)[reply]
You get graphs of the sort you describe if you plot heat capacity (often called "specific heat" in older texts) against temperature and your sample undergoes a phase transition. They're important, because you're probably measuring the heat capacity at low temperature to calculate the standard entropy of the substance and, if you miss the phase transition, all your results will be out by a fixed error (the entropy change at the phase transition), which means that your thermodynamic equations won't "add up", even at normal temperatures. It could well have been a determination such as this that your professor was referring to – preferably some really important compound like water where you want the data to be as accurate as possible! Physchim62(talk)11:26, 25 July 2010 (UTC)[reply]
Pretty sure that's it, and it just got messed up with other things in my head. When I read your post I suddenly remembered the prof talking about how that extra energy had to go somewhere, which is where steam power comes in. How, if this thing didn't happen, the Industrial Revolution wouldn't have turned out the way it did for lack of the steam engine - no trains, no big mills. Thanks, Physchim62. (no idea how to mark a question 'resolved'...) 76.105.238.158 (talk) 06:36, 26 July 2010 (UTC)[reply]
The point your prof was trying to make (I assume) was about the objective assessment of data and how it relates to theory. A graph is just a visual representation of some aspect of a data set, a data set if just the observations made from a particular run of experiments, and an experiment is just an operationalization of a particular aspect of a theory. Now, what every scientist does is deduce - they start with a theory, operationalize it (i.e., construct a pragmatic, real-world situation in which the theory ought to be valid), and try to produce the outcomes they expect from the theory. The reason I say that's deduction is because that's what it is: the syllogism looks like this - theory A says X will always happen; condition Q is a case of theory A; X will happen in condition Q. What good scientists don't do is get blinded by their theoretical expectations. So, if a theory predicts a smoothly decreasing output function, and data produces a smoothly decreasing output function with an odd spike, a lot of scientists will assume that the theory is valid and the spike is a random phenomenon, and give it no further thought. A good scientist will step back and take the question "is that spike a random phenomenon or a real effect"' as a separate question and investigate it. Sometimes it will prove itself to be random, but sometimes it will prove itself to be real, and either way a lot of knowledge is generated. --Ludwigs212:53, 25 July 2010 (UTC)[reply]
Skyscraper cost
An interesting thought. Burj Khalifa is the tallest building with 828 metres height and 160 floors, Taipei 101 is second tallest with 509 metres height and 101 floors. But the second costs more ($1.8 billion) while the first costs $1.5 billion. Why a building with less height costs more than a building with more height, floors and architectural challenge? Any idea?? --Galactic Traveller (talk) 11:05, 25 July 2010 (UTC)[reply]
And I have a similar interesting and well thought out question: My Ford Super Duty sits more than 2 meters high (4WD), my neighbors Mercedes SLK is only 1.2 meters high. Yet my truck cost a 1/3 of the price of his car. Why a vehicle with less height costs more than a vehicle with more height, metal, and load carrying ability? Any idea? 68.28.104.251 (talk) 12:20, 25 July 2010 (UTC)[reply]
Why the cheap sarcasm? My question is a valid one. You cannot compare a luxury car with a general truck. But Burj Khalifa/Taipei 101 are different things than Ford Super Duty/Mercedes SLK. --Galactic Traveller (talk) 12:31, 25 July 2010 (UTC)[reply]
You have answered your own question Travellller, you cannot compare the cost of the 2 buildings on height alone. As with my cheap, sarcastic analogy your comparison is non-logical. 68.28.104.232 (talk) 12:55, 25 July 2010 (UTC)[reply]
The question is almost impossible to answer - it involves too wide an assortment of factors. for example, if we assume to otherwise equal buildings, one built in an earthquake zone will be more expensive than one built in a different location; different kinds of soil structures require different techniques which will produce differential costs; different local economies will provide labor forces with different standards of living and different pay scales as well as divergent costs of materials. and in this case there is no reason to assume that these are otherwise equal buildings. This is on a par with asking why it costs more to raise a child in the US than it does in Guatamala - the obvious answer really isn't all that obvious at all. --Ludwigs213:05, 25 July 2010 (UTC)[reply]
Indeed. Some more factors: TP101 is mostly a box whereas the Burj is a spire, so while the Burj is much taller, the two have almost the same floorspace. So TP101's cost-per-square-yard isn't so bad as the cost-per-floors number would suggest - but then again high floors and spaces with greater proximity to windows rent for more, so that complicates an economic comparison of the two. TP101 has more elevators (but in different configurations, again confounding easy comparisons). Both are in hot, humid places, so both are going to need impressive AC systems, but which will cost more (again the shape and ratio of window to floorspace is a factor)? TP101 has to withstand typhoons, whereas the Burj has a rather tamer wind environment (and I guess much less rain). How much did the capital for each cost (that is, how much interest did the two construction companies have to pay to borrow the money to build the things). In addition to the differential labour costs Ludwig2 cites, there are different compliance burdens (healthy and safety, fire risk, security, structural redundancy). And then there's the downright risks of construction - I'd bet you could build two skyscrapers next to one another at the same time, using two high-quality contractors, and end up with final bills on the two that differ by at least 5%. -- Finlay McWalter • Talk19:29, 25 July 2010 (UTC)[reply]
Our article, Construction of the World Trade Center, has some discussion of costs. Interestingly, the decision to build a duplicate building, with the same design across the street from the first did not strictly multiply the expected cost by a factor of two. The economics of large projects like a skyscraper are very "nonlinear." Nimur (talk) 00:29, 26 July 2010 (UTC)[reply]
TP101 also has to withstand strong earthquakes due to its location along one of the more active faultlines in the world, as such more sophisticated planning in structural engineering have to be done. As well the fact that Taipei is located on an ancient lake bottom also poses additional challenges. -- Sjschen (talk) 23:01, 25 July 2010 (UTC)[reply]
A more valid way to compare cost is by cost per square meter/foot, since the floors are certainly not equal in area or extent between buildings. In point of fact, Taipei 101 is more or less the same all the way up, while the Burj Khalifa gets narrower as it goes up. Construction costs in Taipei may be different, and the overall level of finish can vary by 50%. Further, are we comparing the same things? Construction cost vs. sale price? Finished throughout, or just shell space? Soft costs (financing, design fees, furnishings) vs. hard costs? There's no way to make a valid comparison without knowing all this. Acroterion(talk)00:51, 27 July 2010 (UTC)[reply]
Why is it that a vaccine protects dogs against rabies but humans who have PEP (pre-exposure prophylaxis) still have to get more shots after a possible exposure? Is it the case that both vaccines provide partial protection, but that we're more cautious in the case of humans? Rodney Boyd (talk) 14:44, 25 July 2010 (UTC)[reply]
In the human case, the virus potentially has a head start, and it may take a larger immune boost to suppress it. If rabies vaccine were given to dogs after a bite, they also would probably require larger doses. Looie496 (talk) 17:31, 25 July 2010 (UTC)[reply]
I think he's getting at the fact that in most cases, humans bitten by a rabid animal have not had prior rabies shots. In many cases (in the United States) pet dogs have had prior rabies shots before they are bitten. Therefore, the rabies virus has more of an opportunity to replicate itself in humans before you get the injection, and your immune system (hopefully) learns how to recognize it. The question that I have though is that, in my understanding, if I have a dog that has had its immunizations dutifully kept up to date, and it gets bitten, it requires no further treatment - it is immune. Yet, even humans that have had prior immunizations (people who work in jobs that carry a higher risk of contacting rabies get a shot even without having previous contact with rabies) have to have shots after being bitten. What would the difference be between the human and the dog? Falconusptc00:19, 26 July 2010 (UTC)[reply]
You're dealing with two different risk groups. For pet dogs, you are essentially vaccinating the whole population regardless of individual risk of contracting rabies; for humans, you only vaccinate people who have a higher than average risk of coming into contact with rabies, and you revaccinate those people who could have come into contact with the virus. Because the risk factor for rabies is higher for the humans whom we choose to vaccinate, the use of a more aggressive protocol is justified. No vaccine provides 100% protection, and all vaccines have potential side-effects – if they didn't, we'd all be vaccinated against everything we can vaccinate against! Physchim62(talk)00:58, 26 July 2010 (UTC)[reply]
Some medical sites--perhaps erroneously?--state that if you're bitten by a dog that has its shots up to date, then no worries. Is this meant to imply that the canine shots are ~100% effective, or just that the probability that the dog was exposed to rabies x the probability that the shots *didn't* protect it are infinitesimally small? Rodney Boyd (talk) 01:46, 26 July 2010 (UTC)[reply]
I would go for the latter explanation. I don't have any figures for the effectiveness of the canine vaccine, but there's always some variation between individuals (and vaccine batches) so you never get to exactly 100% effectiveness. The latter explanation works better: most domestic pets will never be exposed to rabies, and those that are should be immune, so you would have to be extremely unlucky indeed to be bitten by a "double exception". If we were really so risk-averse as a society, private motor vehicles would be banned ;) The major risk to humans is from wild-animal bites, which is why people who regularly come into contact with wild mammals are vaccinated. Physchim62(talk)17:28, 26 July 2010 (UTC)[reply]
Don't forget expense: the rabies vaccine is very expensive! (though I seem to recall that there's an older kind of rabies vaccine that's cheaper but very painful) The nearly-100% mortality rate of rabies once symptoms appear makes it more attractive, though... [edited to rephrase] Paul (Stansifer)05:13, 26 July 2010 (UTC)[reply]
You have to weigh up the expense of the vaccine with the expense of treating rabies victims (and the lost benefit to society of those who die). As for side effects, you weigh up a "cost" of side effects (which might include a small risk of death) to the "cost" of not being even partially immune to rabies. The balancing act is not always devoid of controversy when you're talking about an entire population... Physchim62(talk)17:28, 26 July 2010 (UTC)[reply]
I suppose on a windless day, we can all hear the sound of a jetliner flying overhead, a steady drone rumbling high above. That rumble will increase in volume as the plane passes by, and decrease in volume, the sound dragging along far behind, not unlike an aural "chip log". But sometimes—and I'm assuming it's wind currents playing heavily—the sound of the plane reaches our ears at a compressed rate; the plane will be farther along in its travels and the sound still won't have reached the ground just yet. But when it does, the incidental sound resembles a loud engine throttling down, from high frequency to low frequency in a matter of only a few seconds. I don't know how else to describe it. It could be like the sound of a semi-truck's engine and wheels on the road as it comes to an abrupt stop. One could almost think it's a fighter jet (less screeching) approaching quickly, but as the frequency of the sound reaches that familiar low droning, it's like it has uncompacted and "caught up" with the jetliner's regular sound, and the plane will fly off sounding normal as usual. My two questions are—if I've made myself clear—how is this sound caused, and does there happen to be a word for it? Thank you! – Kerαunoςcopia◁galaxies15:56, 25 July 2010 (UTC)[reply]
I am in love with glassware sonication. Why hasn't it taken off for household use -- to wash dishes in a sonicating sink? It would seem very antimicrobial too -- you could lyse any biofilms. Most laboratory units seem to go for over a thousand dollars but I bet costs would drastically decrease with mass production. John Riemann Soong (talk) 16:10, 25 July 2010 (UTC)[reply]
You mean like these google shops or google shops - spot the 1000-10000% mark up on the ones for scientific use. ok so they house-hold ones are only big enough for jewelry or 1 glass.
Why hasn't it taken off? - maybe it doesn't work on a tub full of plates and pans with pasta on - too heavily loaded. They are used industrially for cleaning metal components etc in engineering - but loadings are not the same as people expect in a dishwasher or hand washing bowl.83.100.252.126 (talk) 16:31, 25 July 2010 (UTC)[reply]
It seems to me more of an engineering problem than a concept problem. Do sonicators use a narrow range of frequencies? Do they alternate the frequencies up and down for maximum effect? Do they try to employ resonance? John Riemann Soong (talk) 16:42, 25 July 2010 (UTC)[reply]
One possible barrier is that sonication requires the dishes to be totally immersed in water - that would be a lot of water for a dishwasher , even before rinsing.
At least one manufacturer uses variable frequency as an option [18]
Resonance is (I think) the way in which the cleaning cavities are produced, but resonance of the object to be cleaned can be a problem [19], also standing resonance can produce areas which are constantly cleaned can cause cavities and pitting of the thing to be cleaned.83.100.252.126 (talk) 21:06, 25 July 2010 (UTC)[reply]
Evolution
Evolution says that organisms should do whatever it takes to ensure that their genes are passed on, so doesn't this mean that, if evolution is true, then rape is not only acceptable, but desirable? --138.110.206.101 (talk) 16:11, 25 July 2010 (UTC)[reply]
That would be a naturalistic fallacy, see also appeal to nature. The acceptability or desirability is an ethical question. Though we might be able to use the theory of evolution to explain certain animal behaviour such as rape, the theory cannot be applied to the (im)morality of rape committed by humans. ---Sluzzelintalk16:16, 25 July 2010 (UTC)[reply]
From an evolutionary perspective, it's also great to take others' spouses, food, housing and belongings and perhaps even kill the previous offspring of the spouses that you snatch. Plead innocent on the basis of evolution and let me know how that goes :) DRosenbach(Talk | Contribs)16:33, 25 July 2010 (UTC)[reply]
DRosenbach, that's not really true, anyway. Human beings are social animals. We cannot survive on our own, we depend on at least a tribe, and ideally a larger civilization. Natural Selection will tend to select against people who don't properly participate in that society. APL (talk) 18:09, 25 July 2010 (UTC)[reply]
All you're doing is utilizing the present circumstance of human society to justify the present circumstance of human society -- circular logic indeed. We may choose what we like, whether it be more evolutionarily efficacious or not. Lions are pretty social animals, and it's reported that adult males may kill off offspring of other males. We certainly can survive on our own and even if we prefer to live in a tribe consisting of more than one male with a harem of females, that says nothing of the treatment one tribe would offer another tribe. DRosenbach(Talk | Contribs)18:26, 25 July 2010 (UTC)[reply]
Lions sorta lack the level of sophisticated thought, memory, communication and action we do therefore what works well for them doesn't necessarily work well for us. For example, if a lion kills the offspring of other males, the females will still usually fairly willing mate with it when they enter heat. They aren't likely to hold a 'grudge' against that lion forever more. If you kill a woman's children because they were with other males, you'll likely get locked up and there's a very good chance that woman and most other women who are aware of what you did aren't going to be particularly happy to mate with you unless perhaps you convince them it was a mistake in your past. (In the past, you'd may have been kicked out of the tribe and forced to live on your own or find another tribe, or even killed.) If you force them, you may be locked up again and the woman even if she gets pregnant may have an abortion. Even if she doesn't the children of rape will often be raised by solo mothers, given up for adoption or enter foster care, or otherwise in a less likely to be successful environment then the children of a happy relationship (or even the children of an affair with a woman in such a relationship). In other words, none of this is particularly good for you when it comes to spreading your genes. A smart judge may point out the fatal flaws in your logic if you do try to plead 'evolution', perhaps a simple 'well we'll see whether being locked up in jail is good for your genes from an evolutionary perspective' or 'thanks for agreeing you should be locked up'. BTW 'preference' has nothing to do with it. Humans have apparently evolved to live in a societal manner, presemuably because this was the most successful pathway as we evolved. Perhaps we could have evolved to liveout our lives primarily as individuals, but we didn't. Nil Einne (talk) 20:27, 25 July 2010 (UTC)[reply]
I don't claim that our society has to be exactly like it is now, or even that our ideals of ethics and morality have to be exactly like they are now. That would be a foolish statement. I claimed only that human beings instinctively try to survive in groups, and that such behavior is selected for. The details of how we organize those societies falls largely to the logical section of our brain, which is a good thing, because tribal life doesn't scale well. APL (talk) 21:05, 25 July 2010 (UTC)[reply]
Evolution doesn't say anything about what organisms should do, it just explains what they do do. It says that animals that do everything they can to pass on their genes are more likely to pass on their genes, so the next generation is more likely to be made up of animals that do everything they can to pass on their genes.
It's not even necessarily true that evolution will select for rape. You don't just need to have children, you need your children to survive to have children of their own. Since, in the case of rape, the female hasn't chosen a male that she thinks will provide good children (I am assuming we are discussing a male raping a female, but the sexes can be reversed without harming the argument) she may conclude that it is better to not waste effort on this child and to have other children with a chosen mate instead (she may even abort the pregnancy). That means the male may have a better chance of having successful children if he works to convince a female that he is a good mate.
Also, rape will usually involve the female having (or potentially having) multiple sexual partners, which makes determining the father of any child difficult. That means males are not likely to be involved in the upbringing of children (since they can't be sure it is their child they are using resources for), which reduces the likelihood of those children surviving to adulthood. --Tango (talk) 16:37, 25 July 2010 (UTC)[reply]
Don't also forget things like the action of other males towards the children (which is bad enough in most species even without rape as an issue), or, as a point to hit home with in the human example, the action of other males and females towards would-be rapists. (Rape amongst humans, for example, would probably result in your genes being selected against in any society with accessibility to abortions and rigorously enforced anti-rape laws. Prison isn't a place to pass on one's genes, generally speaking.) --Mr.98 (talk) 17:13, 25 July 2010 (UTC)[reply]
(edit conflict) similar to above : No. Evolution does not say that organisms should do whatever they can to pass their genes on. Organisms do whatever they want.. which ever behaviour results in them succesfully passing their genes on in the long term is evolutionarily successful.
The human aspect has been pointed out above - for animals (for which sex can often be violent) other factors are important - such as caring for offspring in higher animals, and general survivability. Being a 'rape machine' might be one way to pass genetic material on, but is not necessarily linked to success. - any beast can reproduce itself - but 99% of life involves escaping from enemies, feeding oneself, reaching higher branches, catching mice etc. 83.100.252.126 (talk) 16:48, 25 July 2010 (UTC)[reply]
I also recommend this article as a good starting point to the logic: while I'm not sure I'd often use that site, the author of this particular article and the links given within it make it helpful. And, of course, even if rape were evolutionarily advantageous (which I don't think it is), that wouldn't mean you should do it. 86.164.66.83 (talk) 16:56, 25 July 2010 (UTC)[reply]
To take your point further, evolution is antimoral. There are no ethics if man is the highest animal and therefore does what he wants. Ethics only exist because of someone higher than man who dictates what is right and what is wrong. --Chemicalinterest (talk) 18:49, 25 July 2010 (UTC)[reply]
In hunter-gather societies you depend on your fellow group members. You must trust them and they must trust you. If you are caught cheating (stealing food, not taking a big enough part in the hunts), you will likely be shouted/snarled at. Keep doing it and you will be thrown out of the group. You are likely to starve to death as a result. That selects genes for detecting cheating and against cheating, at least at cheating enough to be caught. 62.56.49.134 (talk) 19:19, 25 July 2010 (UTC)[reply]
Certain big cats fight over what they catch all the time, with sometimes one "stealing" what another caught. Certain lazy animals just eat what the hard-working ones catch. --Chemicalinterest (talk) 10:49, 26 July 2010 (UTC)[reply]
Ethics does not require a god or gods to dictate it. Atheists can be just as moral and ethical as theists. You could consider "society" to be "something higher" that dictates what is right and wrong, but there is certainly no need for a "someone higher". --Tango (talk) 20:04, 25 July 2010 (UTC)[reply]
It is indeed society (or inbuilt god given guidance) that makes ethics exist: a single human being has no need for ethics/morality since they have nothing to apply it to. Some philosophers such as Mencius are interpreted as saying that humans have inbuilt good morals. Others (see Legalism (Chinese philosophy) also Xun Zi) say that humans are intrinsically bad, and it is society that prevents evil. The bible presents evil as an abuse of man's free will on the instigation of the devil; which I think is somewhere inbetween. Biologically it's easy to interpret ethics as an extension of a built in natural instinct not to kill and eat things that look like you - which even some very simple animals respect. 83.100.252.126 (talk) 20:37, 25 July 2010 (UTC)[reply]
Tango, I'm not sure you even need that. It seems like some combination of humans' natural instincts for empathy and cooperation combined with our ability to ponder the logical question "What if everyone did this?" would come up with a usable, if not perfect, system of ethics. APL (talk) 21:14, 25 July 2010 (UTC)[reply]
Ah, but if morality was a natural consequence of human nature then all humans would have the same sense of morality, but that isn't the case. We consider slavery to be highly immoral now, but humans in the same countries not all that long ago felt differently. Since different societies have different moralities, society must come into it somewhere. --Tango (talk) 21:46, 25 July 2010 (UTC)[reply]
Chemical, that does not "take [my] point further". You just responded to what I said with canned religious dogma that was pretty much the opposite of what I said. Evolution has no more to do with morality (good or bad) than any other scientific explanation of the world around us. (Say, electromagnetism, Or atomic theory.) APL (talk) 21:04, 25 July 2010 (UTC)[reply]
Matthew 5:9,22,46 7:3-5 10:14 22:20-21 23:5 And, of course, Ecclesiastes 3:15 is why the internet sets up FAQs like you can find at the talk.origins archive, rather than trying to draw people into yet another rehash. 86.164.66.83 (talk) 23:46, 27 July 2010 (UTC)[reply]
Refusing to consider and discuss something because we find it morally objectionable is not a good way reach the most effective conclusions about things. --Tango (talk) 21:46, 25 July 2010 (UTC)[reply]
(Edit Conflict) Disagree, 82; although we can't mindread the OP, who might have had trollish intent, the question is a perfectly valid one in evolutionary, biological and sociological terms and, on the principle of assuming good faith, should be addressed. 87.81.230.195 (talk) 21:48, 25 July 2010 (UTC)[reply]
The fact is that there are animals where rape and killing the children of other males and all manner of "nasty" behaviors have been evolutionarily effective - but then there are other animals (like Meerkats, for example) where a remarkably human-like society has evolved. The reason why one strategy works for (for example) lions and a different one works for humans and meerkats is complicated. It is in the interest of a gene to produce an animal (or plant or whatever) that not only reproduces itself effectively - but also avoids killing off other copies of itself. In many small-society animals, there is sufficient inbreeding that killing off the offspring of another pack member is more likely to reduce the spread of the 'murderer's genes than to increase it by relieving competition. Humans are pack animals - and it's very likely that we've evolved our sense of moral outrage for precisely this kind of reason. Lions have a very different life-style though. The male offspring of a pack go off on their own as 'loners' into the wilderness for many years before finding a pride that he can take over by beating off the incumbent male. Having done that, killing all of the cubs of the previous male is a worth-while strategy. Using the word "rape" to describe what happens to the females of the pride is a little contentious because it's a very loaded word...but I suppose you could apply it there.
The point is that our system of instinctive morals has evolved as a result of what works best for our society...and we very often viciously attack members of our species who have any kind of alternative moral sense.
That's an unfortunate example: I saw a documentary a few weeks ago in which a female meerkat killed the young of another female in order to force the group to concentrate its efforts on her young instead. --Tango (talk) 02:26, 26 July 2010 (UTC)[reply]
There was a scholarly paper written on this within the last few years that attracted a lot of the same political attention. I agree with the moral fallacy arguments above, and would point out too that part of why these sorts of aggressive evolutionary mechanisms aren't prevalent today is probably a good reason why they weren't prevalent (or at least acceptable) in pre-industrial times: there are very severe consequences for them. In pre-industrial times it probably meant the victim's family punishing the perpetrator. In modern times we've outsourced that function to the state, but the end result is similar. Shadowjams (talk) 07:04, 26 July 2010 (UTC)[reply]
"Morals" in animals are the result of instincts, while morals in humans are not. Humans decide what they do by their own free will. God gave us a plan of morals. Over the years, man has violated it. Seeing that God has grace on men and so generally does not punish violations in this life, they make bigger violations, thereby defining their moral code. So at first it was life for life in the case of murder. Then it became just imprisonment. Then the killing (yes it is killing) of unborn infants became legalized in expanding proportions. Then the killing of old people became legalized in some countries. Sometime it might be the killing of anyone you do not like is tolerated. Saying that since God is not existent (and therefore it is safe to violate him) is like standing in front of an old cracked dam bulging with water and saying that since the water is not visible, it is safe to live there. --Chemicalinterest (talk) 11:01, 26 July 2010 (UTC)[reply]
(EditConflict) CI, I can see that you have deeply-held religious views on this matter. However, I contend that humans' innate sense of morality is from our genes, not a supernatural being. Just as we have a far greater emotional response that other animals, we have a greater moral code, and can contend subtleties more. These are part of our ability to put ourself in another's shoes, i.e. theory of mind, and empathise with them. I can't remember the technical term just now. IIRC, 3 year-old children, chimps and some dogs and cats can tell if a person they are interacting with is 'playing fair', which is part of a moral code, "Thou shalt not cheat". CS Miller (talk) 11:53, 26 July 2010 (UTC)[reply]
We can place ourselves in another's shoes, and know what it would be like to be on the receiving end of our actions. By understanding we wouldn't like this, we know that we shouldn't do that action on another. CS Miller (talk) 12:20, 26 July 2010 (UTC)[reply]
OK I might have got it wrong. Atheism does not mean there is no morals; it means that you are your own god and you make your morals for yourself. Whatever feels right to you goes. Which I consider a lack of morality because humans can dull their consciences to accept things that they used to not feel right doing, thereby changing their moral code. I am presenting my beliefs beside yours so people can have a choice as to which they will believe. --Chemicalinterest (talk) 12:45, 26 July 2010 (UTC)[reply]
I'd still contend that some morality is innate. Moral universalism states that basic morality is the same for all societies, which is probably based on the golden rule, which itself comes from empathy. However, short of raising a group children with no adult contact, there is no easy way to prove it. Such an experiment would be highly unethical. CS Miller (talk) 12:57, 26 July 2010 (UTC)[reply]
This is a popular mistake, and I don't blame you for making it, but you seem to be confusing 'atheism' (a lack of belief in the existence of a deity or deities) with a lack of an ability to follow (or establish) a fixed moral framework. Our article on secular humanism – which is one of the organized frameworks or creeds one might choose to live within as an atheist – has this to say:
Fundamentalists correctly perceive that universal moral standards are required for the proper functioning of society. But they erroneously believe that God is the only possible source of such standards. Philosophers as diverse as Plato, Immanuel Kant, John Stuart Mill, George Edward Moore, and John Rawls have demonstrated that it is possible to have a universal morality without God. Contrary to what the fundamentalists would have us believe, then, what our society really needs is not more religion but a richer notion of the nature of morality. - Theodore Schick, Jr.
On the flip side, all Christians are supposed to be reading (literally) from the same books, but we have the loose-nut wackjobs of the Westboro Baptist Church ("God hates fags!" "God: USA is terrorist!"), the Roman Catholic Church (which treats the sexual abuse of minors and the attempted ordination of women as equally serious matters), and the United Church of Canada (Canada's second-largest church, which has ordained women since 1936, supports women's access to safe abortion, and endorses same-sex marriages) who are somehow all in the same tent. Should you eat meat on Fridays, or shouldn't you? Is alcohol a sin? What about dancing? How about women wearing trousers? There is a centuries-old tradition of forking existing religious frameworks when one gets tired of particular tenets (or wishes to impose new rules or interpretations). If it is immoral for an atheist to establish his own moral principles to live by, it must surely be equally immoral for a theist to elect to change denominations or convert between religions — he would be making a principled decision that the previous rules he lived by weren't correct, just like that dirty, self-guided atheist. TenOfAllTrades(talk) 14:44, 26 July 2010 (UTC)[reply]
That may be a problem for Christians, I don't know: I guess it must be hard, as so many Christians so obviously fail to follow what they claim to be the inspired word of God. That has nothing to do with the evolution of morality, however. If morality were a Christian invention, we would have blatently different moral codes between human societies, and yet we don't. Not only are basic moral codes remarkably similar among human societies, we can also find partial parallels among other species, and not simply among primates, or even simply among mammals. Physchim62(talk)18:08, 26 July 2010 (UTC)[reply]
That is not true. Moral codes vary widely. Examples: Honor killings, Bride burning, killing unwanted children by exposure, abortion, bride kidnapping, different laws for different social classes, human sacrifice, slavery, elder suicide, euthanasia, there's tons more. Ariel. (talk) 18:41, 26 July 2010 (UTC)[reply]
I can't think of one issue on which all members of any major religion agree on. Hell, Christians can't even agree on what makes a person a Christian. 67.243.7.245 (talk) 19:35, 26 July 2010 (UTC)[reply]
To support Physchim62's point, the peoples of the world started as one. They then split up at the building of the Tower of Babel, where each group (i.e. language) has the same ideas but a different language. Each group (and their morals) gradually change over time, supporting Ariel's point. --Chemicalinterest (talk) 21:39, 26 July 2010 (UTC)[reply]
Chemicalinterest, this is the SCIENCE Reference Desk. You have made statements on this thread such as:
what God has stated in his word
the peoples of the world started as one
They then split up at the building of the Tower of Babel
These are obviously things that you believe. I suggest you believe them because authoritative and influential people have told you these things. You are an obedient young man and you believe what these people have told you. But that does not make them science. Science requires evidence from more than one source. Please confine your comments on this Desk to ideas that can be independently verified from more than one source. That will be appreciated. Dolphin(t)22:49, 26 July 2010 (UTC)[reply]
ChemInterest, I wish you'd stop saying things like "To support so-and-so's point" or "expanding on what-his-name's remark" and then going off on an unrelated religious diatribe that the poster whose name you've invoked would obviously not agree with. APL (talk) 01:30, 27 July 2010 (UTC)[reply]
APL, I was corrected by the first user I referred to. The second one had a different meaning. I didn't say that they would agree with my point; I just was showing how the Bible corresponds perfectly with history. Dolphin51, to respond to your point; people give evolutionary explanations because authoritative and influential people have broadcasted these things in scientific journals and the like. I was also saying that the Bible's account of the history of man corresponds perfectly with the evidence of man's past, which means that science and the Bible are friends, not enemies.
I thought it was only the old Catholics that hated being told that the earth was round, not the modern day squelchers of belief. Even the creationists allowed Darwin's point in, though not without debate.. Morals and origins--neither of those are sciences. They are both philosophy, which is not science. Philosophy vs. science is like thinking vs. how you think in your brain.
End note. I have not had anyone help me with any of these discussions, give me suggestions, etc. This is just what logically occurs to me when I think of the world. --Chemicalinterest (talk) 10:47, 27 July 2010 (UTC)[reply]
The Bible and science do not agree. I won't enter into an argument about this, though, it's too close to arguing about whether 2+2=4 anyway. I will, however, point out that religious morality, at least of the type found in most religions, is just an extension of egoism. It basically orders you to do X, because a certain boss will reward you for it, and to refrain from Y, because a certain boss will punish you for it. This becomes an issue of your own self-interest rather than caring about others. Atheist morality is, in the typical case, about doing X and refraining from Y out of empathy or benevolence towards other human beings, even though you don't expect any rewards or punishments for yourself, ever (altruism). There's another thing - while atheist morality, being based on empathy and benevolence, can only include principles that are based on empathy and benevolence towards other beings, religious morality, being based on the whim of a certain boss and not on any objective principle, can include any arbitrary command, including things that are indifferent or harmful to other human beings. Christianity seemingly incorporates real morality (love thy neighbour), but still dominated by the framework of religious morality, with rewards and punishments (love thy neighbour or else the good boss will torture you for all eternity), as well as arbitrary commands (do nothing on Saturday Sunday, don't be gay, recognize that Jesus existed, was born of a virgin, is the Messiah of the Jews, is son of God, is coeval with and equal to his own father, etc.). --91.148.159.4 (talk) 14:13, 27 July 2010 (UTC)[reply]
And then there's another point - not only do most forms of religion exclude real morality (i.e. unselfish morality) for its worshipers, but they also exclude morality for the god they worship. I mean, of course, the issue of theodicaea, God himself being omnipotent and yet allowing bad things to happen. God can't be both all-good and all-powerful - and most religions opt for the second alternative, the all-powerful one (the only theistic religion I'm aware of that doesn't do that is Zoroastrianism, most clearly in its mediaeval form). The god of most religions is (all-)powerful, hence clearly not good - indeed he has an unspeakable, unfathomable amount of guilt on his shoulders - yet he hypocritically requires to be considered good, thereby introducing a most perverted, Orwellian, sacrilegious notion of goodness. Saying it is possible, in this world, for a creature to be both omnipotent and all-good is a blasphemy against goodness - against morality. If you worship this putative creature, you really worship absolute Power despite the fact that it is amoral. Basically, this means you worship Satan. It's not atheism that is amoral; it is religion. The reason many people reject religion is not that it is too moral for them; it is that it is, among other things, too amoral for them. It is paganism.--91.148.159.4 (talk) 18:28, 27 July 2010 (UTC)[reply]
Achilles tendon humans vs animals
The other day I was watching my dog. I observed that he has a small "foot" (i.e. toes) with the "ankle" higher up. This got me wondering if the tendon between the "foot" and the "ankle" was the equivalent of the human Achilles tendon (same with horses, cows, goats, sheep, cats, etc.). If so, what is the "evolution" of this difference in anatomy? —Preceding unsigned comment added by 99.250.117.26 (talk) 16:29, 25 July 2010 (UTC)[reply]
The evolution of humans and horses diverged in the split between Laurasiatheria and Euarchontoglires, probably about 90 million years ago. The bones of the legs can still be matched up, but the muscle and tendon arrangements have diverged so radically that there is really no way of matching any part of horse anatomy with the human Achilles tendon. Looie496 (talk) 17:14, 25 July 2010 (UTC)[reply]
Triple Slits, Born's Rule, and Sum over Histories
There's been recent news reports (e.g. [20]) of the results of the triple-slit version of the classic double slit experiment. These write-ups all tout the results, showing interference between pairs of slits but not all slits simultaneously, as confirmation of Born's Rule. However, reading that Wikipedia article there doesn't seem to be any indication that, as claimed in the ars technica article, Born's Rule implies "quantum interference can only occur between pairs of probabilities". Additionally, my lay-man's understanding of quantum mechanics, specifically the Sum over histories approach as presented in from Richard Feynman's QED: The Strange Theory of Light and Matter, would seem to indicate that the particle can and should move through all three paths simultaneously. Could anyone provide a (non-technical) explanation as to why Born's Rule, as presented in the Wikipedia article, would imply that quantum interference would only occur between pairs of particles, and what this implies for the sum over histories approach? Specifically, if the sum over histories view is still valid, why doesn't it imply that interference should occur for all paths, rather than just two? Thanks. -- 174.24.222.181 (talk) 18:17, 25 July 2010 (UTC)[reply]
So, I'll admit that I didn't read all of the article but I think this is just a problem of terminology. The article looks at 3 slits (labelled ) and imagines a wavefunction associated to the photon passing through each slit (). Now the probability of observing a photon at the detector, , can be composed via Born's rule as
where they've defined When they say that interference only occurs between pairs of probabilities they just mean that each term only couples two paths together. They go on to define
and their experiment confirms that is (to the accuracy of their experiment) zero. Just like we expect from good-old quantum mechanics. Martlet1215 (talk) 22:46, 25 July 2010 (UTC)[reply]
Since you've read QED you know that the amplitude of finding the particle at a location is given by the square of the length of the sum of a bunch of arrows, one for each path. Mathematically, the angle through which one of these arrows turns is called S(γ) (where γ is the path), the arrow is ei S(γ) (a complex number), and the square of the length of the sum is
Since |z|² = z z* (where * is complex conjugation), this can be written
You can measure cos (S(γ1) − S(γ2)) with a two-path interference experiment, and once you know its value for all pairs of paths you have everything you need to compute all multi-path interference probabilities. The nice thing about this approach is that it deals entirely with physical, measurable quantities. You can't measure S(γ) or ei S(γ) or ∑ ei S(γ)—they contain "unphysical degrees of freedom"—but you can measure p and the cosine. The same trick works elsewhere in the Standard Model and also in general relativity (in GR, you look at the relative precession of a gyroscope transported along two different paths). If you like this stuff (I know I do), you might be interested in my post in Wikipedia:Reference_desk/Archives/Science/2010 February 13#magnetic vector potential actual meaning?. The twisting circles I talk about there are closely related to Feynman's rotating arrows. You can think of the arrow as pointing from the center of the circle to a point on the circumference. It tries to retain its orientation like a gyroscope, but because of the twisting of the circles, when you transport the same arrow along two different paths it ends up pointing in two different directions.
All that said, I can't understand why Science published this paper. Nothing that I said above is new, and while you can always retest the basic principles of quantum mechanics, I don't see what they could expect 80+ years into the game with an accuracy of only 1% (!). I've only read the abstract, though. -- BenRG (talk) 23:56, 25 July 2010 (UTC)[reply]
Question about effects of lightning
Why doesn't people's hair stand on end, or some sort of effect on other things similar, before a nearby lightning strike? If lightning were to strike, wouldn't that mean that there is a bunch of negative charges in the clouds, thus attracting a bunch of positive charges together in the ground? I would think that with the amount of charge required to create dielectric breakdown given the large distances involved, such an effect would be noticable? 68.160.243.61 (talk) 20:36, 25 July 2010 (UTC)[reply]
Despite the similarity to a joke, it is actually good advice. Spikes (which a person standing on the ground is) tend to concentrate charge, making them likely targets for lightning strikes. Since your backside is quite round, it's a good idea to stick it in the air. --Tango (talk) 21:51, 25 July 2010 (UTC)[reply]
When lightning hits a tree or the ground, there is a strong potential gradient around the spot, such that two points several feet apart may have several thousands of volts between them during the strike. If your head and your feet touch the ground 6 feet apart, more current will flow through your body than if the only ground contact is your feet a few inches apart. A contortionist who could form a low ball balanced on one foot might fare better yet. Edison (talk) 04:38, 27 July 2010 (UTC)[reply]
again, personally experience, no proof - yes it does - I've seen it coming off bushes on tops of hills prior to a strike - it's not clear to me whether in this case "St. Elmo's Fire" and "Positive Streamers" are the same thing - I think they are.87.102.43.171 (talk) 13:58, 26 July 2010 (UTC)[reply]
There was a famous 1976 photo of hikers who thought it was funny that their hair was standing on end. Supposedly a lightning strike soon thereafter killed some of them [23]. Edison (talk) 04:45, 27 July 2010 (UTC)[reply]
Sealing in juices; frying meat
Hello! It is me again. =)
I desire a once-and-for-all answer on a topic I see is debated... namely sealing in juices in meat. Some authorities I've read state that it is simply not so that juices stop escaping, backing this up with claims about experiments showing no difference when pieces of meat are cooked one way or the other, by measuring their weight, ie no juice escaping. Others say they do, once you've created an impenetrable crust on the outside of the meat, that is through searing/caramelization. If I fry a piece of meat, is it in fact juicier by cooking correctly in this manner? Thank you in advance. 88.90.16.109 (talk) 23:12, 25 July 2010 (UTC)[reply]
If published authorities say different things, why do you imagine you can get a once-and-for-all answer from the anonymous non-experts who answer questions on Wikipedia? Looie496 (talk) 00:34, 26 July 2010 (UTC)[reply]
A lot of cookery shows and cook books show that the experts all seem to do this. If the experimental evidence is that the meat doesn't weigh any different cooked one way or the other - then all that says is that the REASON that doing this improves the final product may not be what is claimed. Perhaps, for example, the juices leave the meat later in the cooking process if it's 'seared' first - the final weight would be the same - but the ability of the liquid to keep the temperatures lower for a little longer before they boil away might be enough to change the flavor or texture. The chemistry involved in cooking and flavor are stupendously complex...this is not a simple thing to analyze. So it's very possible that the science isn't there yet. But for sure simply cooking the same exact cut of meat using two different techniques and then weighing the final product is a pathetic experimental test to prove whether searing the meat is or is not a good idea. SteveBaker (talk) 01:50, 26 July 2010 (UTC)[reply]
However, cauterization does stop bleeding. It's not the same thing, of course (unless the rest of the cow is still attached to the steak) but there may be some effect of searing on how fast the "juices" escape the steak. --Dr Dima (talk) 02:54, 26 July 2010 (UTC)[reply]
Try this experiment: make two identical weight hamburgers. Leave one with an uneven (porous) surface with nooks and crannys, and make the other one with a very smooth surface with almost like a coating of meat goo. Then cook the two the same. The one with the smooth surface will be substantially more juicy. —Preceding unsigned comment added by 165.212.189.187 (talk) 12:53, 26 July 2010 (UTC)[reply]
That's not actually an experiment which is just about 'sealing' the surface, though. First, the uneven surface with nooks and crannies will have a significantly greater surface area; even if there was no difference in the rate at which moisture escapes through seared versus unseared surfaces, the uneven burger would lose moisture faster because of its greater exposed surface. Second, the cooking of the 'rough' burger will be less uniform. Small exposed bits of meat on the surface (which will have a very high surface area in proportion to their volume) will dry out rapidly and may even char. These dry, crunchy bits are apt to have a disproportionate effect on the perceived moistness and doneness of the meat — particularly when the experimenter is looking for a particular result.
Doing a proper, controlled experiment – instead of just looking for an outcome to confirm a particular chef's biases, which often is the preferred outcome – is actually pretty challenging. It might go something like this. 1) Obtain a large amount of ground beef; mix until fairly uniform throughout. (Each burger should have the same fat and protein content.) 2) Prepare burgers of standard shape (using some sort of mould or press) from equal masses of meat per patty. 3) Cook burgers using an assortment of time-temperature profiles to desired degree of doneness. 4) Weigh the burgers after cooking to determine mass loss during cooking. (Incidentally, I strongly suspect that just these experiments have been done, if someone familiar with the food sciences literature knew how to search for them...?)
Note that there is wiggle room in step 3 — how should you determine doneness? I suspect that you'll be able to get two different results, depending on your methodology here. If you use a measure of internal temperature to determine when the meat is cooked, I suspect that you'll find searing has an advantage. It's not because searing 'seals in juices'; it's just because that quick pulse of high heat up front means that you will be able to employ a shorter overall cooking time. On the other hand, if you sear one batch of patties and not the other, and then cook for the same duration over medium-low heat, the unseared patties will be moistest. All that said, of course, proper searing will almost always greatly improve the flavor of the final product, and deserves to be done for that reason alone. TenOfAllTrades(talk) 14:01, 26 July 2010 (UTC)[reply]
That's all very well - but this isn't anything to do with burgers - they are so full of holes, you couldn't hope to 'seal' all of the surface area anyway! The technique is for solid cuts of meat - steaks, that kind of thing. SteveBaker (talk) 14:09, 26 July 2010 (UTC)[reply]
Agreed - by the time meat is ground, I don't think any culinary expert talks about "searing" it. Searing only really applies to solid meats. Nimur (talk) 16:38, 26 July 2010 (UTC)[reply]
OP here. Thank you for all your answers, some of which were exceptionally informative. In particular TotoBaggins', which I must admit had me rather credulous. I am not hesitant to ask for more evidence that searing seals no juices (which I shall get that book, right certainly), but I'll understand if the minds here concerned with cooking have been exhausted on this subject. Until anything else, I will not speak of sealing the juices when I fry my beefs (which there was never a question of doing or not doing in a pan! Oh no, for the outwards effect we -must- have), but I shall not educate others until an example of the aforementioned book has come into my hand, and I can lecture them the very details. Well, perhaps I am not entirely honest. I will surely tell them to not think of the juices. 88.90.16.109 (talk) 23:32, 26 July 2010 (UTC)[reply]
What you want to trap juices is to denature the proteins in such a way that they "trap" the juices within their structure. Which is why I use kosher salt...it also lowers cooking time somewhat. You can sear to caramelise then turn the heat down low to complete the cooking since some of the denaturation has been done for you. See Jaden's very enlightening article "Steak: How to Turn Cheap “Choice” Steak into Gucci “Prime” Steak". John Riemann Soong (talk) 00:03, 27 July 2010 (UTC)[reply]
Ok you're right Its not an experiment - its a fact that the smoother burger is more juicy! But, hello, what I'm trying to say is that if the meat is prepared properly searing does, in fact, seal in the juices, if the meat is not prepared properly then it does not! —Preceding unsigned comment added by 165.212.189.187 (talk) 13:57, 27 July 2010 (UTC)[reply]
No, that's completely incorrect. Here is the transcript of a show where a professionally trained chef performed the experiment with at least a modicum of scientific rigour and came to the exact opposite conclusion - searing meat causes it to lose more juice. Our searing says the same thing with an independent reference. Matt Deres (talk) 17:26, 27 July 2010 (UTC)[reply]
Juices sealed or not sealed, the justification for searing is that it makes meat taste good. Any chef worth his salt will tell you this. The followup question is now, "how can meat taste good if it has less juices?" I think the answer is obvious - any "juices" in meat are mostly water. What flavorful components of meat are water-soluble and would "leave" the meat if any juices leaked out? Nimur (talk) 20:15, 27 July 2010 (UTC)[reply]
I'm having trouble finding a ref about flavorful compounds, but this site lists some water-soluble nutrients (mostly B vitamins) that would logically be reduced with the loss of water. This paper looks promising, though I'm not familiar enough with the terminology used to be sure. In any case, nobody is claiming that searing doesn't increase flavour or improve mouth feel. Matt Deres (talk) 21:43, 27 July 2010 (UTC)[reply]
I think I remember reading something, perhaps Readers Digest a long while back where they had some semi-scientific cook or something who showed what's said above, i.e. it make the meat lose more of its juices, he suggested the juices which come out cook (and I guess adhere to the surface) & help to give the meat flavour IIRC. Nil Einne (talk) 22:08, 27 July 2010 (UTC)[reply]
The very first Google hit for "Smardale bridge" shows a photo of the bridge, with the caption "Smardale Bridge crosses Smardale Gill.... Behind the bridge are 'Giants' Graves,' archaeological features of uncertain origin that date to prehistoric times." There are lots more links beside. Looie496 (talk) 05:45, 26 July 2010 (UTC)[reply]
No.No. You misunderstand, I know where it is. My question is: why is/what is it geologically important and how can I find more about the geological features that are important. Sf5xeplus (talk) 11:23, 26 July 2010 (UTC)[reply]
I think your best bet is to simply ask the Cumbria RIGS Group what the criteria for the listing were (there's a "Contact us" link at the bottom of the page). Alternatively, since the group says that "site details are logged with local authorities and the County Council", you might try the county council. Deor (talk) 15:58, 26 July 2010 (UTC)[reply]
Many (most?) gay males don't exhibit any more effeminacy than straight males do. Many gay males gravitate towards the hyper-masculine, others might be 'bears', others don't behave any different from anybody else. It's largely a social thing, mixed with whatever makes the person comfortable. So if we narrow your question down to "what causes effeminacy in the small percentage of gay males who exhibit a marked tendency towards effeminacy?", then Cuddlyable3 and LarryMac's answers have it covered. 76.105.238.158 (talk) 00:32, 27 July 2010 (UTC)[reply]
They purposely do that so people know their gay. there is no other explanation.--Horseluv10 11:55, 27 July 2010 (UTC) —Preceding unsigned comment added by Horseluv10 (talk • contribs)
Why do straight effiminate males do it then? And why don't the other gay males bother? And why do some gay effiminate males stay in the closet for so long? And what's wrong with the plenty of other explainations like the ones above? Nil Einne (talk) 21:34, 27 July 2010 (UTC)[reply]
What possible meaningful scientific answer do you imagine you could get for the above questions? Ask your self why YOU behave the way you behave? Why you are attracted to (presumably) girls instead of boys? If you can come up with a more meaningful answer then "because they're hot", and you aren't allowed to cheat by saying "millions of years of evolution" because that's something you are told by others, I'm sure you aren't thinking "I'm sure glad evolution has made me attracted to girls so we can have lots of offspring" when you admire someone you fancy. Human behavior is probably one of the most complex subjects you can study and people spend lifetimes trying to understand and explain it, often getting it totally wrong. It doesn't help that there are a LOT of errors and misconceptions in "common wisdom" about psychology. Vespine (talk) 23:30, 27 July 2010 (UTC)[reply]
A 100 W light bulb emits light with a wavelength of 575 nm
How many photons leave the filament of the globe in 1 second?
Basically I have no idea how to do the question. I can convert the wavelength to frequency and then I can convert that to energy if that helps --220.253.172.214 (talk) 10:10, 26 July 2010 (UTC)[reply]
I think this is just a homework question ;) You're right that the situation is not physically realistic, but the same goes for many such problems. Physchim62(talk)10:35, 26 July 2010 (UTC)[reply]
Don't leave out the units! Besides being a requirement for physics calculations, making sure the units match is an excellent way of checking that your calculations are right. (In many cases if you don't know the formula, simply making the units correct will automatically give you the correct formula. This doesn't always work, but it works often enough to be a good first try for an unknown calculation.) Ariel. (talk) 13:47, 26 July 2010 (UTC)[reply]
There's some basic figures at the bottom of this page [24] , other sources quote a figure of 10-20% of total weight (presumably for a non obese person).This [25] gives 13% of body weight. 87.102.43.171 (talk) 13:39, 26 July 2010 (UTC)[reply]
Living human, or dry bones? (Not that I know the answer, but there is a large weight difference between the two.) Ariel. (talk) 13:49, 26 July 2010 (UTC)[reply]
I'm talking about the objects that make up quarks, not the things you use to tie your shoe with. Since they are 1 dimensional structures, it made me think if they are really matter or energy. Of course I'm aware that matter and energy are related (E=mc2) but, is it fair to say that the line is kind of blurred at that level? 148.168.127.10 (talk) 14:04, 26 July 2010 (UTC)[reply]
First of all, it is important to note that string theory doesn't have any significant evidence in favour of it (so it's a bit of a stretch to even call it a theory, it's just an idea). Assuming string theory is correct, then it doesn't really make sense to distinguish between matter and energy at the scale of individual strings. Photons are made out of strings in the same way quarks are and there isn't really any difference between those strings other than the way they vibrate. --Tango (talk) 14:35, 26 July 2010 (UTC)[reply]
What determines wether the particle has mass is the vibrational pattern of the string, not the string having mass itself, for example a photon is massless because it has a different vibration than quarks do even though they are both 1 dimensional vibrating strings according to string theory.--74.67.89.61 (talk) 14:50, 26 July 2010 (UTC)[reply]
Just to comment on the distinction between matter and energy: One shouldn't say that "something is energy" as if energy were something material or substantial; it is not. The correct way to put it is "Matter has energy", and the (misnomed) equivalence between matter and energy means that matter has energy even when it is at rest. So photons and strings will have energy, but they are not energy. Whether you want to call photons and strings "matter" depends on whether you want matter to be made of particles with mass or whether you accept massless particles, too. --Wrongfilter (talk) 10:02, 27 July 2010 (UTC)[reply]
Oh sure, I know about that. I just meant within the context of what he was saying. I suppose we can't call any object energy then. Photon is not matter or energy, but it has energy. What about the four fundamental forces? Can we call any of those energy? 148.168.127.10 (talk) 15:53, 27 July 2010 (UTC)[reply]
Actually photons ARE energy. So is mass - mass does not contain energy - it is energy (and energy is mass, they are not just interconvertable they are two words for the same thing, but each has a different emphasis). The forces are not energy, but they do transmit energy, so while in transit they could contain energy. Ariel. (talk) 01:25, 28 July 2010 (UTC)[reply]
soundwaves
Is it possible to view a soundwave in 3D? So for example would it be possible to develop a software that shows a soundwave from front on? —Preceding unsigned comment added by 91.103.185.230 (talk) 15:51, 26 July 2010 (UTC)[reply]
You could have software that shows 2d sections through a soundwave. More complicated solutions could include using transparent colour or exaggerated refractive index to visualise the soundwave. However note that high frequency sounds have short wave lengths eg 3.3kHz has only a 10cm wavelength. The problem with 3d visualisation of room full of soundwaves is that it would be looking through fog - also from front on you would be looking through pressure wave peaks and troughs - as the sound wave propagates itself there would be very little or no difference over time in the appearance (from front on). 87.102.43.171 (talk) 16:28, 26 July 2010 (UTC)[reply]
Showing 'isobars' of soundpressure level would be a lot easier - again using transparent (coloured) surfaces to visualise the sound level at different positions in space.87.102.43.171 (talk) 16:31, 26 July 2010 (UTC)[reply]
We regularly encounter this problem during full wave equation modeling for seismic imaging. (I'm sure RADARs and SONARs could have similar visualizations, but their data is less commonly visualized in a full 3D sense - in seismic imaging, the final desired result is a visualization of the entirety of a 3D volume, including its interior). Because the 3D wavefront is, well, three-dimensional, trying to render it on a 2D screen means you have to makes some tradeoffs. Many options exist for displaying the actual wavefront - you can pick an isosurface (i.e., interpolate one surface such that each point (X,Y,Z) has the same acoustic amplitude or phase) and render it in 3D; you can render a cube, and use a unique user-interface to select planar cross-section views; you can render an animated movie that traverses through one or more axes. Or, you can process the results of the acoustic wave, and instead of visualizing the wavefront, you can image some derived parameter - e.g. reverse time migration, where the results are correlations of the acoustic wavefront with a time-reversed version of the recorded echos. You can visualize the 3D acoustic wavefront in the fourier domain, or some other transform domain, where its 3D characteristics collapse along one or more dimensions. Every one of these approaches comes with difficult tradeoffs that boil down to, ultimately, you can't completely represent a complicated 3D structure on a 2D viewing screen. We have some peripherally related articles, volume rendering, tomography, and so on, that explain the difficulty of imaging a 3D structure. Nimur (talk) 20:15, 26 July 2010 (UTC)[reply]
Thermodynamics what-if
You have a box made out of a material which is very rigid and has a low thermal expansion coefficient. It is filled to the brim with water at room temperature. Suddenly you thrust it out of the airlock of your spaceship into the vacuum of space which is a couple of degrees above absolute zero. Because the box material conducts heat, the heat energy of the water leaves through the box and the water starts to cool down. When the temperature of the water gets to the freezing point, since water is one of the different materials that is less dense as a solid than it is as a liquid, the water begins to be under pressure as it pushes on the box. Say the box held rigid. It seems to me this pressure would have an effect of increasing the water temperature so it would go back to liquid. So would the water in the box in that frigid environment stay liquid or form some denser-than-normal ice? 20.137.18.50 (talk) 16:35, 26 July 2010 (UTC)[reply]
It would stay liquid for longer, i.e. at a lower temperature, but eventually it would still freeze. Keep in mind that the lower density of ice is only around the freezing point. Eventually it starts contracting like other materials, this article suggests that that temperature is 200K (about -70c) - see the graph. But keep in mind this graph was made at ambient pressure. Inside your box the pressure will be much higher which will influence things. Ariel. (talk) 16:48, 26 July 2010 (UTC)[reply]
Freezing point doesn't vary much with pressure (unlike boiling point), so it wouldn't stay liquid at a significantly lower temperature. --Tango (talk) 17:02, 26 July 2010 (UTC)[reply]
If you increase the pressure on a gas, it warms up, but I'm not sure the same is true of a liquid. Liquids are pretty much incompressible, so I don't think they would change temperature much. Regardless, as Ariel says, the water would eventually cool to the point where ice is denser than liquid water, at which point it would definitely freeze. --Tango (talk) 17:02, 26 July 2010 (UTC)[reply]
At equilibrium, the pressure inside the box will be lower than when you started, because the density of (normal) ice is higher than that of liquid water at low temperatures. While the water is cooling down, the pressure will be very much higher (but I'm assuming you want us to consider an infinitely rigid box). Physchim62(talk)17:15, 26 July 2010 (UTC)[reply]
I think I need to slightly correct what Tango said above - freezing point does change with pressure for materials like water that change volume on freezing. Since water initially expands on freezing increased pressure lowers the freezing point (described in general by Le Chatelier's principle) .. Since both water and ice are very incompressible even a small amount of (normal) ice formation would cause a very massive increase in pressure.
There are denser forms of ice - I don't know if the conditions here would be sufficient to cause its formation over normal ice - though I would guess it's likely.87.102.43.171 (talk) 17:34, 26 July 2010 (UTC)[reply]
Generic phase diagram - the dashed green line shows water, the solid green line shows typical substances. This phase diagram seems to show that the freezing point of water changes less with changes of pressure than typical substances (although water does at least change in the right direction). Both the solid and dashed green lines are pretty close to vertical, so the change is pretty small. --Tango (talk) 18:08, 26 July 2010 (UTC)[reply]
water expands about 10% on freezing, the bulk modulus of ice is ~1010Pa - so to compress ice to the same volume of water would require about 1000MPa of pressure. In fact this is beyond the pressure for which normal ice exists - so one of the more dense forms of ice is formed. There's a similar discussion (from which I got the compressability data from) here [26]
The same link references this page [27] which has a phase diagram which extends beyond that given right - It looks like ice V or VI would be formed at 0C at these pressures. However if the cooling was rapidly to 0K and not 0C all this is not relavent.87.102.43.171 (talk) 19:34, 26 July 2010 (UTC)[reply]
I got a very rough figure of 1degree change in freezing point per MPa (ie 0.1 degree C per bar/atmosphere) - no idea how accurate that is.87.102.43.171 (talk) 20:44, 26 July 2010 (UTC)[reply]
That will only be accurate near a specific temperature (probably 0 deg C). It can't be accurate everywhere, otherwise the freezing point at 300MPa would be below absolute zero, which is obviously nonsense. --Tango (talk) 21:39, 26 July 2010 (UTC)[reply]
You are essentially asking about freezing water at constant density (i.e. by not allowing the water expand as it freezes). Assuming an sufficiently rigid container to counter the large pressures involved, I would expect to see a combination of normal ice and one of the high density ices such that the density of the mixture stayed constant. Dragons flight (talk) 18:28, 26 July 2010 (UTC)[reply]
Right. Note that below about 250K there is no stable liquid form at any pressure, so the result is bound to be ice of some type. Looie496 (talk) 18:34, 26 July 2010 (UTC)[reply]
Looking into this further, what would happen, I believe, is that the water would remain liquid as it cooled down to 250K, with the pressure rising steadily to over 200 million atmospheres. Then it would freeze into a mixture of ordinary ice and altered phases of ice. As it continued to cool, it would evolve through several combinations of phases, with the pressure slowly dropping but remaining in the hundreds of millions of atmospheres. As it approached absolute zero, you would end with a mixture of about two parts ice XI to one part ice IX -- assuming that the container was totally filled with water at the start and totally nondeformable. Looie496 (talk) 19:55, 26 July 2010 (UTC)[reply]
I think that is almost but not quite right - ice can form at -1C and the pressure increase. At 20% normal ice (at -1C) the pressure would be 200MPa and then other forms of ice could form.the figures in the last sentence may be quite far out Nevertheless there would definately be normal ice in the box below 0C below 200MPa (above 250K) 87.102.43.171 (talk) 20:07, 26 July 2010 (UTC)[reply]
The scholarly consensus (e. g., PMID 20504748) is still that humans can't detect the Earth's magnetic field, the cited article notwithstanding. MRI involves fields stronger by many orders of magnitude, so a moderate sensitivity to them wouldn't mean all that much. Looie496 (talk) 18:17, 26 July 2010 (UTC)[reply]
A human would be able to magnetically detect a magnetar from a good long distance off, since at 1000km away, the magnetic field is lethal. It's not strictly relevant; I just mention this fact whenever I can. Paul (Stansifer)03:00, 27 July 2010 (UTC)[reply]
I think my group is using conductive indium tin oxide cover slips for electric field experiments. However, my group doesn't know what happens if you culture epithelial cells on it -- any predictions? Would poly-L-lysine coating -- used for helping cells adhere -- ruin the conductive properties, or no? John Riemann Soong (talk) 18:53, 26 July 2010 (UTC)[reply]
The issue I can see would be if polylysine (basic) reacted with the indium tin oxide - if the indium tin oxide film is very thin (ie 1 atom) you could end up stripping that film by complexation with the polyamine... However I imagine the film will be much thicker.
I have no idea about culturing cells on indium tin oxide - if indium or tin is toxic to your cells then that could be a problem - beyond that no idea. It's not clear why a conductive glass slide is needed - wouldn't anodised aluminium be just as good for culturing cells and doing field experiments?87.102.43.171 (talk) 21:28, 26 July 2010 (UTC)[reply]
Thank you so much. I feel a little dumb because we have some impatiens in our yard, but this looked a little different to us. I appreciate your time in answering. Alanraywiki (talk) 22:00, 26 July 2010 (UTC)[reply]
Help me identify these intercellular bridges, follow-up?
I've put up some of my images at User:John Riemann Soong/intercellular bridges. I'm trying to puzzle out what kind of intercellular bridges these are. These bridges are between A549 lung cancer cells. Help is appreciated!
for background, most of the white things that don't appear to change appearance with rotations are vesicles, not gold nanorods. Particles that go black-white-black or "wobble" are gold nanorods. I excluded most of the video of course as they are much too big, but I can upload huge (~30 MB) animated gifs if necessary. A brief description of what happened on each day is on the page I linked to.
I've been reading this paper to try to help me identify these bridges. Do any of them consist of membrane nanotubes at least internally? I don't think I have any "tunneling nanotubes" right? Am I observing type I epithelial bridges, or just mere filopodial bridges? John Riemann Soong (talk) 23:52, 26 July 2010 (UTC)[reply]
July 27
Can a gas shield the Earth?
Can we release a gas which will shield the Earth from sun rays and reduce global warming? (That would be the equivalent of CO2 but reflecting heat instead of absorbing.)--Mr.K.(talk)11:17, 27 July 2010 (UTC)[reply]
The sun emits most of its energy in the visible range of the spectrum. I don't know of too many gases that significantly reflect in the visible, are stable in the atmosphere, and are mostly harmless to the ecosystem. Also, of course, it would seem to be more rational to do less meddling with a large, complex, critical system, rather than more. --Stephan Schulz (talk) 11:34, 27 July 2010 (UTC)[reply]
(Actually, you have it wrong - the whole problem with CO2 is that it DOES "reflect heat" - thereby trapping the heat in our atmosphere instead of letting it radiate harmlessly out into space!)
The tricky part is that you need to find something that's able to reflect visible and UV light - but be transparent to infrared. That's because it would have to bounce away the frequencies of light where the sun is injecting energy into the planet - but not prevent the planet from radiating away waste heat as infrared light. The Greenhouse gasses like CO2 that are causing all of the problems are quite the opposite - they are transparent to visible light (letting sunlight into the planetary atmosphere) and reflect infrared (preventing waste heat from escaping).
So the material you're looking for wouldn't be a transparent substance like most gasses - because those aren't reflecting visible light - they are transmitting it. The material you're imagining would have to be bright white to look at - yet transparent to IR light. Clouds are somewhat like that - but they are tricky to manage. Water vapor is a greenhouse gas, like CO2 - but when the water droplets are just the right size and temperature to form clouds, they become opaque and reflect away sunlight. But it's tough to control water vapor - to have it form clouds and reflect light without becoming a greenhouse gas.
You'd also need something that was very cheap and non-damaging to manufacture (if, for example, it took a lot of energy to make - it might cause more problems than it solved). You need an ungodly amount of 'stuff' to fill all of that atmosphere densely enough. It would also have to not damage ozone, not be poisonous, etc. Ideally, you'd want something that would break down naturally - at just the right rate so that we could control it's effects - you wouldn't want something where some small misunderstanding of the Earth's environment caused us to use too much of the stuff and plunge the planet into a massive cooling spell. Overall, this kind of approach is very dangerous...it's hard to imagine that doing this would be sufficiently non-risky to be acceptable. The politics of doing this would be very tough to negotiate too...suppose one country decided to do this kind of risky planetary engineering without the agreement of all of the other countries on Earth?
The earth has natural cycles of heat and cold, and our industry only makes a small difference to the temperature of the earth. Yes, the risks and expenses of making such a system would make it completely impractical. --Chemicalinterest (talk) 12:02, 27 July 2010 (UTC)[reply]
In any case, if the earth is only 7000? years old it's questionable how we can know whether the earth has natural cycles or not and these natural cycles must be so short that we better be bloody scared. Nil Einne (talk) 21:31, 27 July 2010 (UTC)[reply]
Clouds reflect a lot of visible light, but don't they also reflect IR? That's why it's generally warmer at night if there is cloud cover. --Tango (talk) 14:19, 27 July 2010 (UTC)[reply]
If you have an infrared thermometer you can actually measure this. If on a day with some clouds in the sky you point your thermometer in the direction of clear sky you get a very low reading (like -50 °C), if you point it toward a cloud you get a much higher reading (e.g. 0 °C). Count Iblis (talk) 15:38, 27 July 2010 (UTC)[reply]
Isn't that detecting the thermal radiation from the cloud, rather than reflected thermal radiation from the ground? --Tango (talk) 21:59, 27 July 2010 (UTC)[reply]
There is a big misconception circling around here - that gases "reflect" visible light or IR radiation. They do not - gases can scatter and absorb, but there is not mirror-like reflection unless there is a flat surface of some sort (which gases don't have). Gas molecules with polar bonds (e.g. C=O, C-H, O-H, C-F, etc.) tend to be good at absorption of long-wave IR radiation (The same gases also emit a lot when warm) which makes them greenhouse gases. An "anti-greenhouse" gas would need to be poor at absorbing long-wave IR (so it must not contain such polar bonds) and good at scattering or absorbing visible light. However, the common gases with nonpolar bonds such as N2 and O2 are transparent. Gases without polar bonds can be colored/non-transparent such as Cl2, but it is toxic, harmful and unstable so clearly we shouldn't be pumping it in massive quantities into our atmosphere. I am not aware of any gases which i) have no polar bonds, ii) are not transparent to visible or short-wave-IR, and iii) Could be released in massive quantities necessary to achieve a substantial cooling effect without disastrous side effects. However, if you remove the restriction to gases, sulfate aerosols might work (see Geoengineering.) 129.2.46.178 (talk) 01:02, 28 July 2010 (UTC)Nightvid[reply]
Some people think that there may be a way to protect the earth via a gas (See this article). Basically, a relatively small amountof SO2 in the stratosphere could 'reflect' some of the light that would have entered the atmosphere. Not sure if it really reflects (see above regarding gases absorbing or scattering light), but it is possible that it would exist as a fine particulate, maybe sulfates as mentioned above, that would reflect. As for cheap sources, there is quite literally tons of sulfur sitting in the Alberta tar sands that some people would love to find a use for...24.150.18.30 (talk) 02:50, 28 July 2010 (UTC)[reply]
There is not enough darkness in all the world to put out the light of even one small candle
Is this true?
Namely, if you had a small unobtrusive clear container of STP air in a remote and (perfectly?) dark region of space with a small wax candle burning inside, would black-body radiation drop the temperature low enough to extinguish the flame? -Craig Pemberton18:16, 27 July 2010 (UTC)[reply]
I assume you're thinking of something like the fact that water left outside on a clear night can freeze even if the air temperature is above freezing, because it loses heat to space, and air (not being very efficient at radiating heat) does not radiate enough heat back to the water to compensate. Whereas if the night is cloudy, it won't happen, because the clouds will radiate enough heat to keep the water liquid.
I am quite sure that effect cannot put out a candle flame. The limit of the effect is the heat that would otherwise be transferred by radiation from the air to the candle wick, if air followed the black-body law. But that's a pretty trivial amount of heat compared to what a candle generates. --Trovatore (talk) 18:23, 27 July 2010 (UTC)[reply]
Let's try some back-of-the-envelope calculations and see what they reveal. Let's assume that the container is a cube 10cm on each side, that the space is at absolute zero (actually, cosmic microwave background radiation makes it about 3K, but that's close enough to zero), that the container is a perfect black body and that the candle continues to have enough oxygen to burn by magic. The relevant law is the Stefan–Boltzmann law, which states that the power lost is , where A is surface area, T is temperature and . According to candle, a typical candle emits about 40W. We can now rearrange the Stefan-Boltzmann law and find the equilibrium temperature. . The candle will have no problem burning with the container at 56C (the air right next to the candle will be hotter). If we increase the size of the container, then the equilibrium temperature will be lower, for example a cube 1m on each side would have a temperature of -170C, which is probably too low for the candle to keep going (the air in the centre would be much hotter, but the outside would be very close to the point where oxygen condenses, which would cause problems). --Tango (talk) 18:47, 27 July 2010 (UTC)[reply]
As a minor aside, I will note that bringing liquid oxygen together with a combustible material in the presence of a spark or other ignition source is actually a very effective way of making a very impressive fire. While I have not tested this personally – and I would discourage any but the most qualified from making the attempt – I strongly suspect that dropping a lit candle into liquid oxygen would be very...exothermic...indeed. Making interesting reading (and viewing) are the numerous accounts of people lighting charcoal barbecues using a lit cigarette, a pile of charcoal, and a bucket of liquid oxygen — attached to a very long pole. TenOfAllTrades(talk) 22:03, 27 July 2010 (UTC)[reply]
(ec)A candle can burn as hot as 1930K - i.e. a temperature rise of 1637K, even if you froze the whole thing to absolute zero the candle would still release enough energy to burn (at least once you managed to ignite it). Ariel. (talk) 18:50, 27 July 2010 (UTC)[reply]
I quite like Tango's analysis above, but I fear that once the box gets large (and the corresponding mass and volume of air around the candle become significant) we will no longer be able to approximate the system as reaching a uniform air temperature. Instead, we will have a gradient of air temperatures ranging from 'quite hot' adjacent to the candle flame down to 'very cold' at the walls of the box. Assuming the box is under gravity then convection currents will also play a role. (If the box is not under gravitational or other acceleration, then we might have problems with the candle depleting the oxygen around itself and going out for that reason.) Conductive and convective heat transfer will become increasingly important in larger boxes. TenOfAllTrades(talk) 22:03, 27 July 2010 (UTC)[reply]
Indeed, my calculations are for the container, rather than the air. The air will have a temperature gradient, from the temperatures I gave at the edge to thousands of degrees at the candle itself. The exact details of that gradient are beyond my ability to calculate. --Tango (talk) 22:13, 27 July 2010 (UTC)[reply]
Per Fourier's law, the gradient will tend towards a linear isotropic temperature falloff after a long period of time. In other words, dT/dr = constant, where r is the vector from a test point to the candle heat source. In reality, two factors confound this calculation; there is not spherical symmetry (if the box is a "cube"), so depending on whether we have "imaginary nonconductive walls" or some walls with real thermal characteristics, that will break the linear isotropic assumption. We could call the walls "very conductive" and therefore at constant temperature at all locations along the wall, in which case they would serve as a boundary condition for the heat flux equation. Or, we could call them "very non-conductive" (much less conductive than air), in which case they would simply truncate an otherwise spherically symmetric solution. The realistic case, where the conductivity is "comparable" but non-equal to that of air, would be a complicated boundary value problem. The second problem is that air will convect and turbulence will exist; if the candle burns for an "indefinite period of time", we can assume a steady-state will be reached eventually, but it may be a very long time before that is the case. Tiny fluctuations in initial conditions of the momentum and angular momentum of each air particle will persist in a very unpredictable way. I agree with Tango, any realistic solution for the air temperature that does not rely on trivial-solution assumptions are extremely difficult. (Not surprisingly, these are the same calculations used to determine planetary energy-balance and surface-temperature equations in planetary science. The results can provide bounds on material composition, internal seismicity or radiogenic heat, and so on. There is good coverage in de Pater and Lissauer's Planetary Science text). The scenario described above is a lot like a miniature "hot gas planet" with an internal heat source. Nimur (talk) 02:34, 28 July 2010 (UTC)[reply]
Blood gives a typical volume of 5 liters, which is in sync with the 4.7–5.7 L range given in circulatory system. Of course none of this is specifically cited. Anyone with a medical text or similar ref handy? DMacks (talk) 19:41, 27 July 2010 (UTC)[reply]
How much paneer cheese would I get per litre of milk?
Having read the paneer article I'm intrigued by the idea of making some myself, rather than buying salt-laden fetta cheese from the supermarket. What weight of paneer cheese would I get from a litre of milk please? Is it possible to make low-fat paneer cheese by using skimmed milk? Thanks 92.29.116.34 (talk) 23:19, 27 July 2010 (UTC)[reply]
It is not specific to paneer, but this website [30] describes turning 5 gallons (roughly 40 pounds) of milk into 6 pounds of cheese. So, using that ratio, 1 liter of milk should make about 150 grams of cheese. Dragons flight (talk) 23:42, 27 July 2010 (UTC)[reply]
July 28
Phlebotomy Laws
Where would I look things up about Canadian Phlebotomy Laws. What about patient consent ?. Can the Dr. make me take blood fr
om a patient, consenting? , or non-consenting? —Preceding unsigned comment added by Dean J Taylor (talk • contribs) 00:10, 28 July 2010 (UTC)[reply]
I don't know about Canadian law specifically, but I'm pretty sure it's the same as other similar legal systems in that sticking a needle in someone without their consent is an assault (or, maybe, a battery, depending on the terminology used in the jurisdiction in question). There are exceptions made for people trying to help someone who cannot consent (eg. they are unconscious, insane, a child, etc.). The exact details of those exceptions will depend on the jurisdiction and, as I say, I'm not familiar with Canadian law. --Tango (talk) 00:15, 28 July 2010 (UTC)[reply]
![{\displaystyle T={\sqrt[{4}]{\frac {40}{0.06\cdot 5.7\times 10^{-8}}}}=330\mathrm {K} =56^{\circ }\mathrm {C} }](https://wikimedia.org/api/rest_v1/media/math/render/svg/6ac502e1cbd29450d18217b5bd9f0e9275edfea2)
![[12]](http://excalibur.110mb.com/watopt.gif){kind=link}
