Wikipedia:Reference desk/Archives/Science/2009 April 11

= April 11 =

Blowing out a candle
When you blow out a candle with your breath, what causes it to go out? Bubba73 (talk), 01:23, 11 April 2009 (UTC)


 * A flame is maintained by A) combustible material, B) sufficient oxygen, and C) sufficient temperature. For any flammable fuel, burning is an exothermic reaction; that is, it produces excess heat (that heat maintains the temperature necessary for more fuel to burn, continuing the process). When you blow on a candle, your breath is separating the heat of the flame from the combustible material. Without that heat the candle cannot continue to burn. The more heat that is generated by the fire, the harder it is to "blow out" (which is why you can't blow out a campfire, for instance). –   7 4   02:46, 11 April 2009 (UTC)


 * Thanks. Bubba73 (talk), 02:48, 11 April 2009 (UTC)


 * Specialized firefighters usually use explosives to blow out Oil well fire (think of a 500 ft tall Bunsen burner) so that they can be sealed. 65.121.141.34 (talk) 13:58, 13 April 2009 (UTC)


 * Indeed. But the principle there is to eliminate all available oxygen for the fire (much like a candle snuffer), not to separate the heat from the fuel. Your link does lead (indirectly) to fire triangle, which is an official version of my flame requirements listed above that also optionally includes a fourth component: D) chemical reaction. –  7 4   15:53, 13 April 2009 (UTC)

New born animals cute
Is there a reson why new some born animals are cute like puppys. Why are only some new born animals cute while some are not so cute such as birds. --Sivad4991 (talk) 01:24, 11 April 2009 (UTC)
 * Scientists have identified and researched a phenomenon known as "cute response" (see cuteness). Essentially, humans have an innate response to particular infant features: oversized head, large eyes, shorter limbs, rounder figure, less pronounced nose, etc. This response carries over to some other mammals (like puppies, kittens, and pandas) which share similar newborn traits (and some even theorize that common pets have evolved to retain infantile features in adulthood for maximum advantage from our cute response; see neoteny). –  7 4   02:28, 11 April 2009 (UTC)
 * It also conveniently explains why many larvae, lacking features that could be considered "juvenile" are always given such a hard time, whereas fish and crustacean larvae are considered by some as "cute", and their bodies reflect juvenile proportions. 124.154.253.25 (talk) 06:35, 11 April 2009 (UTC)
 * Are you talking about "the spectres or spirits of the dead", Lemurs or the larvae of animals (like tadpoles or caterpillars)? Nil Einne (talk) 12:30, 11 April 2009 (UTC)


 * Some new-born birds are cute (IMO) - some of the precocial ones, at least. On the other hand, the tiny, blind, bald youngsters remind me of premature foetuses. --Kurt Shaped Box (talk) 01:57, 12 April 2009 (UTC)

Physics of "Knowing"
I just caught the movie "Knowing" tonight and have two questions. First, what are the chances of a "super flare" (as described in the movie) being accurately predicted (or even occurring), and, second, if such a super flare were to occur, would it cause the kind of global annihilation as shown in the movie? —Preceding unsigned comment added by 216.154.22.157 (talk) 04:53, 11 April 2009 (UTC)


 * I haven't seen the movie, but big flares have caused some havoc on Earth. See, e.g. Solar storm of 1859. But no annihilation... yet! --98.217.14.211 (talk) 11:00, 11 April 2009 (UTC)


 * Bad movie alert! Imagine Reason (talk) 11:57, 11 April 2009 (UTC)

Thanks. Let me re-phrase my query: How probable is it that there could be a solar flare of such magnitude that the Earth as we know it would cease to exist? —Preceding unsigned comment added by 216.154.19.87 (talk) 17:13, 11 April 2009 (UTC)


 * Are you referring to the biosphere or the planet itself? If you mean the planet, IIRC, it's believed that the Earth will survive the sun becoming a red giant, so I'd say about zero. — DanielLC 18:01, 11 April 2009 (UTC)


 * The Earth is actually expected to plunge into the Sun, as depicted by computer models showing orbital fluctuations. However, the Earth is expected to become too hot for life in only about 500 million years. As for solar flares, a particularly massive one could leave the power grid damamged and 150 million North Americans in the dark. They're nowhere near large enough to destroy the Earth, but leaks have been found in the magnetic field that protects us from these flares, so this could be a problem. The Sun does periodicly undergo severe solar flares and Coronal mass ejections, and this sunspot cycle usually repeats every 11 years, with the next peak in activity arriving about 2012. The last solar maximum was pretty intense as well: 2001 saw a flare that ranked X22 on an intensity scale between 1 and 20 (this was even bigger than the flare that caused the 1859 "Carrington" event, but fortunately it wasn't pointed at Earth), 2003 saw a series of strong flares and CME's never before seen (one of them hit Comet NEAT as it approached the sun), and 2005 saw a flare that produced aurorae as far south as Florida. It's therefore possible to predict the approximate timing of flare activity (although 2006 - 2009 saw an unusual period of solar quiet), but your prediction may be off on the order of years. ~ A H  1 (TCU) 18:26, 11 April 2009 (UTC)
 * I'd never heard that 500 million years number before. It would be sad to think that life is 88% finished.  --Sean 01:00, 12 April 2009 (UTC)
 * According to our Sun article (and also my recollection of my books, but I haven't looked anything up), the 500 million year figure is incorrect. In the life cycle section it says the Sun will become a red giant and swallow the earth in 5 billion years.  This is not the same as "plunging into" the sun, its more a case of the sun coming out here to meet us.  However, life will cease to be viable long before that, the temperature will be too high for liquid water at around one billion years.  Sean, this does not mean that life is 88% over (or even 79% over), it mean that life on earth is 88% over.  A billion years is plenty of time for us to be somewhere else when it happens.  Our technology has moved from basic agriculture to what we have today in only 10,000 years.  That is only 0.001% of the remaining time for earth.  Sp in ni  ng  Spark  10:32, 12 April 2009 (UTC)
 * I'm optimistic that one of two scenarios will resolve this matter:
 * We may ultimately be able to make habitats on the scale of sci-fi tradition (Rendezvous with Rama, etc) where thousands of people can live in earth-like conditions in large, spinning cylindrical space stations. With fusion power and sunlight where available - we can (in principle) make these things self-sustaining.  When the sun is due to go bye-bye - we have to slowly propel these things to some other star.   The speed at which such fragile, gargantuan structures could be moved would be unbelievably slow - but since people would have been living and dying in these habitats for generations - then spending generations to get someplace else would be no big deal.  This process can be repeated over and over until we either bump into alien civilisations - or take over the entire galaxy.
 * We will do "The Matrix" thing - scan our brains into computer memory and live our lives in virtual worlds. The physical computers that would run this thing could readily be shipped from star to star without problems - and even as the energy of the stars begins to run down, we can simply run the computers more and more slowly so that they consume less and less energy.  The "inhabitants" would notice the universe seeming to speed up as this happened - but time does not appear to be a finite resource.
 * However, in order for this to be possible - we REALLY have to be careful to look after the only place we can live until one or other of these things becomes possible. SteveBaker (talk) 15:40, 12 April 2009 (UTC)


 * Coming back to the original question. Yes, the sun does (rarely) put out solar flare 'jets' that could severely disrupt life on earth if they hit us.  But seen from the perspective of the surface of the sun, the earth is a tiny little dot - the probability of one of these very rare super-powerful jets being aimed precisely at us is incredibly small.  Imagine coming along once a decade or two and firing one round from a rifle in a totally random direction (including upwards, downwards, behind you) - hoping to hit the bullseye on a target a mile away purely by chance...it's about that unlikely.  So these things are even less likely than gigantic meteor strikes or other crazily improbable things.  That's not to say that they can't happen (just ask the dinosaurs!) - or that we shouldn't at least try to think about how to survive them - but we can't go around assuming this will be our ultimate fate. SteveBaker (talk) 15:40, 12 April 2009 (UTC)
 * Over a billion years, shot at once every 10 years, works out at a probability of a hit of p=0.04. (Other assumptions radius of earth (target) 6400 km, radius of sphere target is on (earth sun distance) 150 million km)  Sp in ni ng  Spark  19:06, 12 April 2009 (UTC)

rutherford model
Rutherford sent alpha and beta particles to a sheet and gold and most of the particles passed the sheet, how can we prove that most of the volume of an atom is empty? There may be a large distance between atoms and alpha particles are passing through them. How we can prove that these particles are passing through atom itself? Besides why we do not imagine that electrons are making nucleolus and protons are turning around them? —Preceding unsigned comment added by Logicman112 (talk • contribs) 11:25, 11 April 2009 (UTC)
 * I'm not sure I fully understand your question, but may I recommend that you read Geiger-Marsden experiment. — Cyclonenim | Chat 11:37, 11 April 2009 (UTC)
 * The Geiger–Marsden experiment involved alpha particles, not beta particles. Although Rutherford did not know about protons and neutrons in 1909, he did know a lot about the properties of the alpha particles used in the experiment - he knew their charge, their mass and their velocity. He understood that they were basically doubly ionised helium atoms He2+. It was not surprising that most of the alpha particles passed through the gold foil with little or no deflection - the plum pudding model of atomic structure predicted this. The surprise was that a small proportion of alpha particles were deflected through angles of 90 degrees or more, with no collision debris appearing on the far side of the gold foil. To explain this, Rutherford proposed the Rutherford model of atomic structure in which all of the positive charge and most of the mass of an atom is concentrated in a small region, which we now call the nucleus. Our article on Rutherford scattering shows how the size of the nucleus can be estimated. A nucleus that consisted only of electrons would have been too light to deflect the alpha particles. Gandalf61 (talk) 12:41, 11 April 2009 (UTC)

Prilosec as diet drug?
How effective would proton pump inhibitors be as a diet drug? I'm asking purely out of curiosity as I would rather gain than lose weight at this point. Imagine Reason (talk) 11:59, 11 April 2009 (UTC)

Legality of encryption
Our article Steganography states: "and may in themselves be incriminating in countries where encryption is illegal". However, I've been unable to find the legal status of encryption worldwide. In which countries is it illegal? --Taraborn (talk) 12:29, 11 April 2009 (UTC)

basically legal where there is free speech (seriously). no source sorry 79.122.103.33 (talk) 16:38, 11 April 2009 (UTC)


 * According to an ACM digest, the presence of encryption software may be treated as de facto evidence of criminal intent in Minnesota, much the same as burglar's tools. This Washington Post article sums up the history of the legality of encryption in the USA. The US government has forbidden export of large key encryption software on the grounds that it is a "munition", and other countries limit its import and use. Network World claims encryption in China is illegal if it does not provide the government access. You might find a more comprehensive answer in the Crypto Law Survey, including this handy graphical summary, though it focuses on restrictions instead of complete illegality. –  7 4   06:00, 12 April 2009 (UTC)


 * I know that encryption was technically illegal in France for many years - despite 'free speech' being allowed. Although the French laws started to be relaxed in the late 1990's, I believe that use of hard-to-break encryption by individuals is still illegal without some kind of government permission .  There is a comprehensive survey of cryptography laws around the world here. SteveBaker (talk) 06:13, 12 April 2009 (UTC)


 * Great, thanks! --Taraborn (talk) 18:28, 12 April 2009 (UTC)

Too hungover to masturbate
TenOfAllTrades(talk) 14:34, 11 April 2009 (UTC)


 * The talk page discussion about whether this medical advice is here: Wikipedia_talk:Reference_desk. StuRat (talk) 15:21, 11 April 2009 (UTC)

Identiy this water beetle
I saw this large water beetle in a pool beneath a waterfall at Chapada Diamantina in Bahia, Brazil on Christmas day, 2007. I've been very curious about what this critter could be for some time, but have just been sitting on this picture for over a year. Recently I read an article that mentioned Belostomatidae, and the possibility that I may have narrowly escaped an excruciating flesh-dissolving bug-bite has renewed my curiosity in this image. You can see a few more here. --Shaggorama (talk) 14:41, 11 April 2009 (UTC)


 * It certainly looks like a giant water bug, its similar in shape to some of the water scorpions but lacks the tube at the back. Mikenorton (talk) 15:13, 11 April 2009 (UTC)

Global warming, axial shift, sea level rise, seismic activity, and solar eclipses
Hi. First of all, the melting of ice sheets such as the West Antarctic and Greenland Ice Sheets are predicted to have an effect on the Earth's poles, moving them perhaps 500 metres every-which-way. This is also expected to have an effect on surface gravity in some regions, as well as the amount of light reflected from Earth, which could perhaps minutely affect the Moon's orbit on a negligible scale. Now, could all this conspire to ever-so-slightly drift the paths of future predicted total solar eclipses? For example, London, England, doesn't seem to have any predicted totality from total solar eclipses between now and 3000 CE, but this could be very different should eclipse paths shift (or if sea level rise floods the area, driving the city inland, if it remains intact).

Also, why is it that climate change experts always seem to refute any possible connection between global warming and seismic activity, past, present, or future (this isn't really an argument, just a basic question)? There are already sources linking increased seismic activity to global warming. I don't mean an increase in the observed number of global earthquakes or earthquake damage, which would probably be caused by better observational equipment, a higher population in earthquake-prone zones, or recent large disasters such as the 2004 Indian Ocean tsunami. What I mean is a regional increase in seismic activity over the span of several years. For example, a NASA press release about 5 years ago reported an increase in the the earthquakes around the Alaskan mountains, attributed to the melting of glaciers and permafrost, un-depressing the land (while subsiding it) over mountains near a seismic boundary. Here are some more examples of evidence and scenarios related to seismic activity (this isn't nessecarily from reliable sources, and some of it may involve speculation):
 * Volcanic flank collapses in the past, such as those at Mauna Kea in Hawaii, which triggered megatsunamis, have been linked to periods of warmer climate, higher rainfall (thus more erosion), and higher sea level.
 * The melting of methane clathrate deposits in the past have triggered subsea landslides, notably the Storegga slip, which caused tsunamis on the British Isles and Norway. If these landslides occur near a seismic boundary, it may be enough to trigger seismic activity.
 * Following the 2008 Sichuan earthquake, some people speculated that the Three Gorges Dam, which sits near an active seismic fault, may have been responsible for the quake. However, since this was largely a hypothesis made by anti-government sources, it is more of a conspiracy theory than anything. However, the point is that the melting of glaciers and sea level rise could create plenty of situations like this, where large amounts of water suddenly sit on a seismic fault, because ice jams and rock ahead of rapidly filling glacial lakes could allow them to form in mountainous areas, often where seismic faults lie.
 * West Antarctica has many active volanoes, particularly the one near the Pine Island Glacier, responsible for the largest eruption in Antarctica in the past 10,000 years. This is the area where scientists proposed could allow a destabilization of the West Antarctic Ice Sheet, which is largely anchored below sea level, if water encroaches into the region. Considering the seismically-stressing forces that would come with such a destabillization, which could happen in the span of only decades or centuries, sudden isostatic rebound would occur caused by a sudden lifting of pressure, many trillions of tons of seawater would flood these volcanicly-active basins within years, and cold water could contact sources of magma (this is what triggered the sonic boom and ensuing tsunami at Krakatoa). Since these forces are enough to shift the pole by a few hundred metres, it should be enough to trigger some level of seismic activity.
 * A sea level rise of about 25 metres could flood the Caspian Depression, which would increase the volume of the Caspian Sea by about 40% in about one year (by the way, is there an adequate formula for calculating how quickly water fills a depression?). Since this is a large area, and there are many neighbouring plate boundaries and mountainous regions, this could potentially trigger new seismic activity as well.
 * The Ethiopian volcano Erta Ale sits in a depression, surrounded completely by a basin below sea level. Seeing that sea water could quickly flow into this basin accompanying a sea level rise of about 15 metres, this might stress the active volcano, which sits on the active African Rift Valley.
 * Sudden pressure changes accompanying severe storms, such as the typhoon that struck the area during the 1923 Great Kanto earthquake, are hypothesised to stress seismic faults, due to the severe storm surge (a sudden increase in pressure) and low air pressure (a sudden decrease in pressure). Melting of glaciers near seismic areas, sea level rise in certain regions, severe rapid isostatic rebound, surface gravity fluctuations, and severe storms influenced by climatic change may be capable of this as well.
 * New York City is believed to be at risk from a magnitude 7 earthquake. Sea level rise could widen river and sea channels in the area, in fact a few metres could flood past Albany. This increases the risk of large storm surges, which again, may be capable of triggering an earthquake.

Now, after those exhausting scenarios, here's a related question. If the West Antarctic Ice sheet were lifted from the ground, also meaning if it melted but not considering the sea level rise associated, about how much sea level "drop" would occur worldwide as a result of this, when water floods into areas that are below sea level, notwithstanding the effects of isostatic rebound that are likely soon to follow? What about for the Caspian Depression, if the sea level rise required brings the area under water at that level, thus exacting a drop in global sea level, which would probably mean that, notwithstanding the effects of erosion, the sea levels could probably drop far enough that it would require more sea level rise to continue to flood the area? Also, when sea level rise turns coastal underground aquifers saline and this water encroaches inland, could this flood an inland low-lying depression from water seeping underneath, or does this depend heavily on the pourousness and permeability of the rock, and the extent of the bedrock? Thanks. ~ A H  1 (TCU) 18:08, 11 April 2009 (UTC)
 * Probably too many "what if's" for a meaningful answer? (I note that our articles don't seem to agree with your description of Krakatoa (Plinian eruption). Rmhermen (talk) 18:31, 11 April 2009 (UTC)
 * AH1, your enthusiasm just overflows sometimes. I don't see how anyone can answer all that other than by pointing you to a book (or writing one on the ref desk).  You need to ask shorter questions, or ask a lot of questions under separate headings.  Sp in ni  ng  Spark  09:29, 12 April 2009 (UTC)
 * ...or better still, simply condense all of the 'back-story' down and ask a simple question. The general thread of this "question" appears to be "Is there any possible way I can remain skeptical about global warming?" and the answer is an unconditional "No".  All of the things you've described have undoubtedly been considered by the armies of scientists who are investigating this phenomenon - and (with the exception of the more dubious ones paid by coal-related industries) they have not changed their minds as a result. SteveBaker (talk) 15:13, 12 April 2009 (UTC)
 * I don't understand the point you're making here. I'm in no way trying to refute global warming, I'm simply asking a series of hypopthetical and physics questions. The questions are simply about global warming and solar eclipses, seismic activity, and the physics of water filling into a depression, and I'm not discussing this as a cause of global warming, but as an effect. ~ A H  1 (TCU) 14:30, 13 April 2009 (UTC)