Wikipedia:Reference desk/Archives/Science/2012 May 8

= May 8 =

Speed of Light and Black Holes
If the speed of light is constant, then how is it that a black hole has a gravity force so strong that light cannot escape? Before the collapsing star becomes a black hole light will be emitted. At some point, will light that has left slow down, stop, and then reverse back into the hole? If so, then how is the speed of light constant? 209.197.169.54 (talk) 02:31, 8 May 2012 (UTC)


 * The light doesn't reverse, instead it would be going in the direction of the singularity right from the start. Inside the event horizon, nothing can move in the positive radial direction, it is a bit similar to how everyting in flat space is forced to move in the forward time direction, inside the light cone. Count Iblis (talk) 02:58, 8 May 2012 (UTC)


 * The speed of light isn't constant either. It has a maximum, but the speed of about 300 million meters per second or whatever it is, is the ideal speed of light in a vacuum. Light's been successfully slowed to the speed of a car. Shadowjams (talk) 03:27, 8 May 2012 (UTC)


 * That's a little misleading; the speed of light is constant in a vacuum. But ideas of speed, direction, and even time break down past the event horizon. In fact, we really can't say for sure anything about physics inside the event horizon, because it is causally separated from the rest of the universe. - Running On Brains (talk) 03:56, 8 May 2012 (UTC)
 * It's constant given whatever medium it's in.... it'll always be the same speed given the same medium... but I think the OP's thinking the speed of light is always constant, when in fact it's quite variable depending on what it's passing through (hence mirages and lenses). Shadowjams (talk) 04:13, 8 May 2012 (UTC)
 * Well there are really two separate concepts here which are the speed that photons move at through a given medium, and the universal constant called "the speed of light". While the former can vary, the latter is hard-coded into the geometry of space-time. Rckrone (talk) 04:21, 8 May 2012 (UTC)
 * Actually, as I understand it, photons never move at any speed other than c. When light is passing through a refractive medium, if you want to describe it in terms of photons, you have to describe them as being absorbed and re-emitted in random ways.  For this to come out with the observed orderly behavior of the wavefront, you have to sum over all possible Feynman diagrams, the so-called Feynman path integral, which is unsatisfying to a philosophical realist because there can be no answer as to which Feyman diagram is the one that "really happened" (but this is true of QM in general; nothing special here).
 * There is a sort of compromise description which quantizes the particles' interaction with the medium into a particle called a polariton. I don't know much about those.
 * As a practical matter, though, if you want to know how light moves through a medium, it's generally best to forget about photons entirely and use the wave formulation in terms of electric and magnetic fields. --Trovatore (talk) 01:09, 9 May 2012 (UTC)
 * Right, I just had a beef with your wording Shadowjams; you made it sound like the speed of light varied, which it does not. It is just different depending on what it is passing through; and since we're really talking about the speed of light in a vacuum, I wanted to make sure the OP understood that. - Running On Brains (talk) 22:28, 8 May 2012 (UTC)


 * Every object floating around out there in space has an "escape velocity". For the earth, it's about 25,000 miles per hour. The more massive the object, the greater the escape velocity will be. If a black hole or any other object is sufficiently massive that its escape velocity is greater than the speed of light, then light can't escape from it. ←Baseball Bugs What's up, Doc? carrots→ 04:08, 8 May 2012 (UTC)


 * It's a bad comparison, though. In a low gravity environment, such as Earth, an object launched straight up with insufficient velocity will slow down and then fall back to the surface. Light, however, can't slow down. So the analogy completely fails to say what would happen, for instance, should someone inside the event horizon aim a flashlight away from the singularity and turn it on. The light doesn't slow down and fall back, and I'm not comfortable enough with general relativity to try and explain what actually happens. Someguy1221 (talk) 05:03, 8 May 2012 (UTC)


 * I think the answer is that you can't be inside the event horizon aiming a flashlight away from the singularity. I'm not an expert on this, but going on Count Iblis's response I think whatever you did in there, everything including the light from the flashlight would always be moving toward the singularity from the start.  Addressing the OP's scenario where the light is emitted before the star becomes a black hole, I think the answer is that the event horizon expands no faster than the speed of light, so light emitted by the star directly away from the singularity is never overtaken by the event horizon and will escape. Rckrone (talk) 05:49, 8 May 2012 (UTC)
 * It's true that everything is always moving toward the singularity, but until you get too close to the singularity everything in the local reference frame behaves normally. In fact, the infalling observer doesn't experience anything peculiar as he crosses the event horizon. Someguy1221 (talk) 05:52, 8 May 2012 (UTC)
 * The escape velocity of a black hole is higher than the constant speed of light in a vacuum. Since light cannot go faster than its own limit, it can never attain escape velocity of a blackhole. Gravitational isobars travel at the speed of light, thus any light that is travelling ahead of the expanding isobar will escape. Any light trapped within the critical isobar will be trapped and move towards the singularity of the blackhole. Plasmic Physics (talk) 06:05, 8 May 2012 (UTC)
 * (EC)Spaghettification is not "anything peculiar"? ;) I'm just kidding, i know it's not directly related to the event horizon and depends on the size of the black hole. Vespine (talk) 06:08, 8 May 2012 (UTC)
 * I don't approve of 'spaghettification'. I think that 'gravitational extenuation' is a more cromulent term. Plasmic Physics (talk) 12:49, 8 May 2012 (UTC)


 * How about pancakeification or crepeification.165.212.189.187 (talk) 13:00, 8 May 2012 (UTC)
 * I don't think so. Spaghettification refers to how spaghetti is made - by pulling it into long, thin strands. In the process, all positions along the axis of action are pulled apart, while all positions perpendicular are pulled together. In 'pancakeification', all positions along the axis of action are compressed together, while all positions perpendicular are pushed apart. Do you see? Plasmic Physics (talk) 02:09, 9 May 2012 (UTC)
 * Yes, that is before the event horizon. I'm talking about after it.68.83.98.40 (talk) 04:54, 9 May 2012 (UTC)
 * It should still behave under the spaghettification model, until even the quarks are stretched appart into preons. Who knows what happens after that, or even what happens when it finally collides with the singularity. Some even doubt that it can reach the singularity, they suppose that the information gets snapped to the future after the black hole has evaporated. Some also doubt that there is a singularity. This being said, pancakeification would be an applicable term for an object smashing into a neutron star and pooling over the surface, before becoming part of it. Plasmic Physics (talk) 10:52, 9 May 2012 (UTC)
 * Well i dont think so.165.212.189.187 (talk) 13:55, 9 May 2012 (UTC)

There's something I don't understand here. I thought light isn't matter, so how can it be sucked into the black hole in the first place? Do black holes suck up everything or just matter? I'm confused. Narutolovehinata5 tccsdnew 13:20, 8 May 2012 (UTC)
 * Although photons have no rest mass, they have gravitational mass proportional to their energy. Gravity, including from black holes, affects everything not just stuff with rest mass.  This is an important part of mass-energy equivalence. Rckrone (talk) 14:40, 8 May 2012 (UTC)
 * Gravity affects photons in accordance with gravitational redshift and gravitational lensing. --Modocc (talk) 19:52, 8 May 2012 (UTC)
 * Indeed, one of the first confirmations of Einstein's work on relativity was the observation during a total solar eclipse that the sun was bending the light from stars, making them appear displaced. See Tests_of_general_relativity - Running On Brains (talk) 22:28, 8 May 2012 (UTC)
 * True, but I've always been intrigued by how wrong conclusions can nevertheless give correct results, sometimes spectacularly so, yet still entail equally wrong conclusions, because models often only need to be self-consistent to be useful predictors. --Modocc (talk) 23:21, 8 May 2012 (UTC)
 * Light isn't matter, but it exhibits wave-particle duality, ie. it behaves as if it were both a wave and a particle. &mdash;  The Hand That Feeds You :Bite 22:52, 8 May 2012 (UTC)
 * By that reasoning matter also isn't matter, since everything exhibits wave-particle duality. Someguy1221 (talk) 00:01, 9 May 2012 (UTC)

Clarification from original poster: I'm not asking about light from an already existing black hole. I was thinking more of a collapsing star before it becomes a black hole -- moments before -- for at some point it needs to come into existence; and then the moment it becomes one; and then after it is one. Before it is one, light will be emitted since the escape velocity is less than the speed of light. But at the moment the density becomes such that the escape velocity is greater than the speed of light, no more light will escape from the (now) black hole. What happens to the light that has already left? Will any of it slow down and reverse back in as the black hole becomes even more dense? Or is it that once the light has escaped, even with the increase in gravitational pull, it has already made it out and will never return? I understand if the gravitation pull is constant, then the light would not return, but if it is increasing, will it not pull back some of the light that left earlier but had not travelled very far away yet? If it did, then those photons would have to slow to zero before reversing back to the hole?

Thank you to everyone who has contributed to this question.209.195.82.45 (talk) 00:03, 9 May 2012 (UTC)


 * The idea that "gravity gets stronger" as a black hole forms is actually a common misconception. Look at the equation for Newtonian gravity. You can also look at the significantly more complicated Schwarzschild metric. In either case, the density of the source of gravity is irrelevant. You experience the same force regardless, so long as your distance to it and its mass are the same (and in the case of general relativity, the shape and rotation also matter).


 * Anyway, what's actually happening when the core of a star collapses into a black hole is that although nothing beyond the core notices a difference, gravitationally, gravity does get stronger inside what used to be the core. Put yourself inside the core. Per the shell theorem, you only feel the gravity of the portion of the star that is closer to the center than yourself. As the core gets denser, that portion gets heavier. So there is a region that used to be inside the core that is now experiencing increased gravitational pull, but everything beyond the core still doesn't see a difference in gravity (at least, not because the core is shrinking. Other drastic things tend to be happening at the same time). The core of the star becomes a black hole the moment it achieves a critical density for its size, but at that moment, the event horizon forms right at the edge of the black-hole-forming mass. It's not like it shrinks down, and then all of a sudden the entire region around it is inside a black hole. So once again, in the initial moments the black hole forms, only the mass that created the black hole is contained by the event horizon. The event horizon thereafter only grows as stuff falls in. Someguy1221 (talk) 00:12, 9 May 2012 (UTC)


 * I think what you're asking is, can an expanding event horizon outrun the speed of light? Certainly it could outrun light moving perpendicularly to it.  But any change in the distribution of mass takes time to propagate (the Earth circles where the Sun was, not where it is "now") so I think that there's no way for the news that you're in an event horizon to outrun the light.  Except... if the light is close to a big event horizon and there are masses just a little behind it and off to either side, then maybe they could add up?  Hmmmm.  I think you need a better answerer. ;) Wnt (talk) 00:17, 9 May 2012 (UTC)
 * The light emitted just before the black hole forms will be intensely red-shifted, the photons being very low energy. At the critical instant a hypothetical photon would have zero energy.  (Disclaimer: I am not a physicist.  A real physicist will be along to tell you that's all rubbish in a moment.) Rich Farmbrough, 01:31, 9 May 2012 (UTC).


 * Perhaps, there is a minimum wavelength for light, based on the fact that energy could be quatisised. A photon with with zero energy is meaningless to me, it is equivalent to no photon. If I'm walking at 0 m/s, then it's safe to say that I'm not walking at all. Plasmic Physics (talk) 02:27, 9 May 2012 (UTC)
 * "Equivalent to no photon" was exactly what I meant. Rich Farmbrough, 13:42, 9 May 2012 (UTC).


 * Energy is quantized, but frequency and wavelength are not (so far as we know). You can always red-shift a photon further. The energy gets smaller but does not go to zero.--Srleffler (talk) 16:31, 9 May 2012 (UTC)
 * How is that possible, I thought that λ = hc / E? Plasmic Physics (talk) 22:29, 9 May 2012 (UTC)
 * It's the energy of light at a particular wavelength that is quantized. Without altering wavelength, you can only change the energy of a light wave by adding/removing quanta of energy (aka photons). But wavelength itself (and therefore frequency) can vary continuously. Or at the very least, no one has demonstrated that such is not the case. Someguy1221 (talk) 22:39, 9 May 2012 (UTC)

How harmful are the expected failure modes of London subway congestion?
After reading multiple reports that the London Underground subway will almost certainly become congested beyond operational capacity during the 2012 Summer Olympics, and perhaps several times so, I would like to know the extent to which its expected failure modes involve injury. E.g. suggests that even moderate passenger congestion on platforms occasionally leads to people being pushed or falling onto the live tracks. What London agency is responsible for this risk assessment, and where are their reports? Per it appears that measures, which seem almost certain to increase congestion, are being taken against "Terrorism, Serious and organised crime, Domestic extremism, Public disorder, and Major accidents and natural events," but the effects of ordinary congestion are simply not considered. "Public disorder" is taken to mean intentional disruption by individuals, and not the results of crowds. Do stations have the ability to limit their occupancy? If so, is spillover expected to streets or other holding areas? 71.215.84.127 (talk) 07:11, 8 May 2012 (UTC)


 * There has been a documentary series about the London underground system recently on UK TV and there are indeed mechanisms used to limit the overcrowding on stations. They close the gates to people entering the station. We saw several examples of this happening during regular rush-hours. There was a predictable build up of angry people in the street but they were much easier to deal with than bodies on the line. Richard Avery (talk) 07:26, 8 May 2012 (UTC)


 * Yes, London's Underground stations have the ability to prevent overcrowding on platforms. All the large Underground stations have CCTV systems and manned control centres, and they close gate lines if platforms become overcrowded - at some stations this happens several times a week. We could raise our umbrellas high and march on City Hall, but as we are British, we tend to stand around and grumble instead. Gandalf61 (talk) 11:01, 8 May 2012 (UTC)


 * I take it from the Q that those subways have a platform open to the tracks. I've never understood this.  For a modest cost, they can build a wall between the platform and the tracks, with doors that slide open only when a train is present.  Why don't all subways have this safety feature ? StuRat (talk) 16:05, 8 May 2012 (UTC)


 * The Jubilee line does. I guess it's more expensive to retrofit than to build in from new. --TammyMoet (talk) 17:01, 8 May 2012 (UTC)


 * I wouldn't expect it to be. After all, you don't have to remove what's already there, just bolt the new wall to the existing concrete floor, walls, and ceiling (if it goes all the way up).  I'm assuming that the dimensions are the same at each station, but, if not, then you'd need to either custom fit each one (at additional expense) or leave a gap. StuRat (talk) 17:15, 8 May 2012 (UTC)


 * At some stations it would be difficult (although not impossible) due to curved platforms. Even at the straight ones, it would probably be more than a weekend's work and it isn't something you can really do a bit at a time. That means they would have to close stations during the week, which is something they try extremely hard to avoid. Most of the problems they have with renovating and upgrading the underground is that they still have to transport millions of people every day while they're doing it. --Tango (talk) 20:06, 8 May 2012 (UTC)


 * Why couldn't they do it a bit at a time ? I assume the wall is in sections, so install one at a time. StuRat (talk) 20:14, 8 May 2012 (UTC)


 * How many people actually die from falling onto the tracks? If it's one drunk dude in 30 years, it makes no sense to spend millions of dollars adding a safety feature to prevent it when that money could be spent improving the system's capacity and coverage.  --140.180.5.49 (talk) 22:19, 8 May 2012 (UTC)
 * According to Suicide on the London Underground and Safety on the London Underground, most fatalities are suicides, of which there seem to be 50-100 a year. AndrewWTaylor (talk) 11:10, 9 May 2012 (UTC)


 * The Jubilee line didn't have it when it was new. Or even quite some decades after. Rich Farmbrough, 01:34, 9 May 2012 (UTC).


 * Platform edge doors are a feature of the new Jubilee Line Extension stations from Westminster to Stratford, which were opened in 1999. I don't think they were retrofitted to any of the older stations on the line. Gandalf61 (talk) 06:02, 9 May 2012 (UTC)


 * That article describes a fatality from those under crowded conditions - I really would expect more of this type, actually, unless the trains have some advanced system of sensors. Wnt (talk) 13:24, 10 May 2012 (UTC)


 * One of the reasons that these doors couldn't be retro-fitted to older London stations, is that for ventilation, they rely on air being forced through the tunnels by the movement of the trains. If you put a screen up, you lose your ventilation. Many of London's deep "Tube" stations are more than 100 years old and excavating a new ventilation system for them is going to be a difficult and expensive job. As I understand it, most US metro systems are quite close to the surface, so the same problems don't apply. Alansplodge (talk) 23:44, 10 May 2012 (UTC)


 * Hmmm, if that were the case, couldn't they just make the barriers out of a fine-grained steel mesh? Wnt (talk) 15:42, 11 May 2012 (UTC)
 * Maybe they could. Another solution could be waist-high barriers. You'll have to ask Transport for London. Alansplodge (talk) 17:08, 11 May 2012 (UTC)

Putrescine
Putrecine is a foul-smelling chemical emitted by putrifying flesh. Plasmic Physics (talk) 10:02, 8 May 2012 (UTC)
 * 1) Which plant genus contains a species with the higher average putrescine content: Medicago or Lathyrus?
 * 2) Is there another organism with a higher content than either one of these?


 * Your search might be more fruitful if you use "putrescine". Brammers (talk/c) 11:12, 8 May 2012 (UTC)
 * Sorry, I meant to spell it that way. (I used the correct spelling when I searched for it.) I have corrected it. Plasmic Physics (talk) 11:38, 8 May 2012 (UTC)

The question is still open. Plasmic Physics (talk) 23:49, 9 May 2012 (UTC)

Real-life applications of Pokéballs
If Pokéballs were actually invented, what would likely be their applications? That would assume that Pokémon don't exist, but the actual balls did. I would imagine that they would probably find great applications in transporting very large cargo and make transportation of cargo much easier, possibly even replacing cargo containers. But would that be the case? Narutolovehinata5 tccsdnew 11:20, 8 May 2012 (UTC)


 * All powers plants would be replaced by Pokéball powered perpetual motion machines since the balls can readily alter mass. Cheap infinitely sustainable energy would pretty much change the world. 173.32.168.59 (talk) 11:37, 8 May 2012 (UTC)
 * Why do you ask us? anyone is qualified to speculate about the hypothetical applications of a fictional device. Basically, what answers do you want us to feed you? Plasmic Physics (talk) 11:45, 8 May 2012 (UTC)
 * As in, how the functions of the Pokéballs as seen in the anime can be used in real-life. For example, how the Pokémon is somehow transformed into energy and put into the ball, and that the ball can shrink or expand with a press of a button. Can these technologies, especially the one of energy convertion have real-life applications? Would Pokéballs as cargo containers be feasible or practical? Narutolovehinata5 tccsdnew 12:13, 8 May 2012 (UTC)
 * You tell us. Plasmic Physics (talk) 12:28, 8 May 2012 (UTC)
 * We don't know the capacity or limitations of these fictional 'technologies', so they can be applied in any way you deem fit. Plasmic Physics (talk) 12:30, 8 May 2012 (UTC)
 * It's like asking, if I had a genie in a lamp, what could I wish for? Plasmic Physics (talk) 12:33, 8 May 2012 (UTC)

Ammonia is gaseous at STP, but can be a ligand bounded to certain metal ions. --84.61.181.19 (talk) 11:28, 8 May 2012 (UTC)
 * That is completely unrelated to the question. Plasmic Physics (talk) 11:45, 8 May 2012 (UTC)
 * As an answer to this nonsensical trollish question it is just as valid and reasonable as any other string of characters. Roger (talk) 12:50, 8 May 2012 (UTC)
 * This is actually a serious question you know. Being a Pokémon fan since childhood, I'm genuinely interested in the science of Pokéballs and how they can be used in real-life. Yes it is fictional so we can't say for sure exactly how they work, but the actual concept of a Pokéball, a device that converts matter into energy for storing: how would they probably be used in real life? This question means "How can the concept of a Pokéball be used in real-life?" Narutolovehinata5 tccsdnew 12:56, 8 May 2012 (UTC)
 * There is no science behind them. You're not listening, we can't make any scientific predictions about a fictional device that doesn't follow real world physics. Plasmic Physics (talk) 13:06, 8 May 2012 (UTC)


 * Airliners could use them instead of seats to get alot more people on each flight who wouldnt complain or have to use the lave or ask for peanuts and soda.165.212.189.187 (talk) 13:14, 8 May 2012 (UTC)
 * I want one that converts energy into steak and beer! Roger (talk) 14:38, 8 May 2012 (UTC)


 * You could have such a thing in a simulated reality but not in a universe with constant laws of physical reality. And if you had a functional one that would be strong evidence that you were in such a simulated reality – so theres that. Sky Machine   ( ++ ) 15:50, 8 May 2012 (UTC)


 * It would depend on what the underlying technology was capable of. Can it turn any matter into energy, and back as required? So, could you extract as much energy as you wanted by converting seawater, at the cost of permanently reducing the ocean? A rising sea-level double win, although also likely to backfire. Can you use it to turn energy into any matter, or only the matter it was originally? And you could use it to 'store' ill people in the hopes of finding a cure and returning them to life. And like the techniques in Orson Scott Card's book Capitol, you could use it to effectively elongate your life at the cost of dipping in and out: if you left your pokeball one month per year, you'd live 12 times longer, although miss most of it. Useful for watching investments grow, but bad for social mobility and societal engagement. You could use it to send people to distance planets, without having to spend a lot on ships with the life-support for a long journey, or even having to spend fuel on the full weight of the people. You could use it to go far into the future. You could use it to contain people you wanted out of the way, or people you wanted to take somewhere against their will. You could use them as a weapon, throw them onto the battlefield to capture the enemy. You could use them to 'evacuate' civilians from an area, before bombing it: given that normal pokeballs are most successful on the weak, someone could argue that anyone who wasn't caught was strong enough to have left the area themselves. People could use them to store pets or even children to make them easier and more convenient to care for, as well as maximising the amount of growing-up time you personally get to spend with them, even if it takes them 10 years to reach their first birthday.
 * Sorry if some of that gets a bit weird: I blame Capitol. 86.140.54.3 (talk) 23:39, 8 May 2012 (UTC)
 * That's actually very interesting.. If anyone could just hibernate for 10-20 years to capitalize on investment, I imagine our economy would devalue such a scheme to the point of making it not very worth while. Perhaps actually DOING work would become the most valuable activity again, as opposed to the thinky veiled gambling and larceny (otherwise known as the stock market) which underpins our current economy Vespine (talk) 00:51, 9 May 2012 (UTC)
 * Yes but if such devices were rare only the very wealthy oligarchs could afford them / steal them in the first place. Sky Machine   ( ++ ) 01:26, 9 May 2012 (UTC)
 * http://xkcd.com/989/ Rich Farmbrough, 01:41, 9 May 2012 (UTC).

Newly discovered pathogen in Roundup Ready crops
This and other sites has a letter pronouncing the discovery of an "electron microscopic pathogen that appears to significantly impact the health of plants, animals, and probably human beings" isolated from Roundup Ready soybeans. It only provides very scant details on this supposed pathogen which makes me slightly suspicous. Can anyone find anything about this is any reliable sources? SmartSE (talk) 13:08, 8 May 2012 (UTC)


 * "Emeritus" is a word, which, in biology, foretells many wonders... the notion of a fungus the size of a virus is ... interesting.  Note that a fungus by definition is a eukaryote.  It has mitochondria and a cell nucleus.  To make it appear the size of a virus on EM, a lot of structures have to be eliminated or scaled down to teeny weeny little versions of themselves.  And he mentions nothing about DNA tests to back up his ideas.  That said, he is a scientist who has written about diverse fungal pathogens ( http://books.google.com/books?hl=en&lr=&id=WeR23VTJE64C&oi=fnd&pg=PA169&dq="Don+M.+Huber" ), and ..... nothing is impossible in biology.  But a lot is unlikely, I think.  Search Google for "livestock" and "spontaneous abortion" and most of the hits come back to this guy.  If he were telling the truth about the sudden rise in this, wouldn't we be reading stuff about it from a thousand sources as farmers lose their livelihoods? Wnt (talk) 13:38, 8 May 2012 (UTC)


 * Yeah, that's kind of what I thought... It just annoys me to see this stuff is used as an example of why "GMO=evil" online, when it seems as if there is zero scientific evidence to back it up. Sigh... SmartSE (talk) 14:18, 8 May 2012 (UTC)


 * Reminds me of the supposed fossil found in the Mars meteorite. It was also at the wrong scale to be the type of organism supposed.  In the end, they decided it was likely just an inorganic formation.


 * That said, I would expect nature to "fight back" at some point. That is, if the GMO foods are more tolerant of pesticides and thus aren't infected with the usual pests, this will put evolutionary pressure on those beasties to adapt.  So, we should expect pesticide resistance to also develop in them.  StuRat (talk) 15:58, 8 May 2012 (UTC)


 * Yep. 71.215.84.127 (talk) 20:43, 8 May 2012 (UTC)


 * RR crops are normal plants which have had a certain molecule in a particular amino acid pathway slightly modified in shape so that RR molecules cannot attach and inhibit the pathway. A claim that these RR crops are a major threat to humanity due to a never before seen type of organism is extremely suspicious, particularly knowing that there is a community fighting against all GMOs largely with unsubstantiated claims of great peril, similar to this. If the retired prof has actual proof he can easily show it to other scientists. Until there is a significant number of scientists backing the idea I would pay it no mind what so ever. Unique Ubiquitous (talk) 23:14, 8 May 2012 (UTC)
 * Further inspection of the website shows that it is indeed full of deception. The article Roundup and Birth Defects is sillyness, it rejects RR crops as "glyphosate causes malformations in experimental animals at high doses". That reasoning would mean we would ban vitamin pills because if someone used 100x the appropriate rate it would hurt them. It is also silly as glyphosate's use generally replaces the use of more dangerous pesticides. Continuing to read from such a poor source would only hurt my brain and is not worth anyone's time. Unique Ubiquitous (talk) 23:34, 8 May 2012 (UTC)


 * These crazy stories are typically rooted in a hatred of "corporate" farming, coupled with astonishing ignorance. There is no glyphosate in RR soybeans. RR soybeans are "glyphosate tolerant", meaning that they won't die when Roundup is sprayed on them. If "super weeds" do eventually come along, Monsanto will invent something else. Or maybe figure out a way to turn those super weeds into sileage. The original article cited by the OP indicates these alleged scientists can't even figure out if it's Roundup or the RR gene that's the "culprit". Maybe they had best get back to the lab and get their story straight. ←Baseball Bugs What's up, Doc? carrots→ 00:21, 9 May 2012 (UTC)


 * The whole point of them being "glyphosate tolerant" is so they can be sprayed with large quantities of glyphosate. So, RR and glyphosate exposure must be considered together. StuRat (talk) 01:08, 9 May 2012 (UTC)


 * Roundup is the commercial name of a pesticide containing glyphosate. There is trace levels of glyphosate upon RR produce though the level is of a level to be of no concern even if one's entire diet was of RR produce. Unique Ubiquitous (talk) 01:30, 9 May 2012 (UTC)


 * And were the studies which concluded that funded by the makers of Roundup ? StuRat (talk) 16:30, 11 May 2012 (UTC)


 * The levels of glyphosate in the environment and food, after more can be used, are indeed worth asking about. Undeniably some people do suffer glyphosate toxicity, but generally by ingestion  which is a risk we typically write off when considering consumer products, and doesn't specifically apply to Roundup Ready farm crops.  But it can also enter groundwater (but when? How much? how often? PMID ,  etc.)  The total impact of Roundup Ready crops may be hard to figure out .  I'm not pretending to have the answer to this one - there's a combination of precise and extensive data and philosophical attitude that together produce a person's decision.  It would be easier for me to reject such crops if no one ever went hungry, but it is not really a lack of farm production that is to blame for that... Wnt (talk) 21:22, 12 May 2012 (UTC)

Light bulbs
I think I notice that when changing a light bulb, incandescent or fluorescent, the new bulb is brighter than a bulb that has been in use for awhile (identical manufactured product). What would account for this? The outside could be dirty on the older bulb. Or maybe the components inside the bulb don't give off as much light after being in use for a long time? How would this be explained? Bus stop (talk) 16:33, 8 May 2012 (UTC)


 * I don't know what the mechanism is for fluorescent, but in incandescent bulbs, some of the tungsten from the filament evaporates and is deposited on the inner surface of the glass bulb, where it absorbs some of the light that would otherwise escape from the bulb. Jc3s5h (talk) 16:37, 8 May 2012 (UTC)


 * And yes, the bulb can be dirty. Specifically, grime seems to accumulate on the top.  In the kitchen this can be greasy and in a house with a smoker, it can be yellow tar.  Thus, cleaning off the bulb (and any dead bugs from the fixture) can help.  StuRat (talk) 16:52, 8 May 2012 (UTC)

From our incandescent light bulb article, I found this section of "The Great Internet Light Bulb Book, Part I", which contains a nice plain-english description of the time-evolution of incandescent bulb filaments. For fluorescent bulbs, there are several long-timescale failure-modes: failure and degradation of the Ballast electronics; diffusion or leakage of the gas mix; deposition of metals and mercury on the bulb glass; and other phenomena discussed in this section of our article. Nimur (talk) 16:54, 8 May 2012 (UTC)


 * Thanks. This is great information...I just haven't read it yet. Bus stop (talk) 16:57, 9 May 2012 (UTC)


 * I agree with darkening caused by material from the filament deposited in the inside of the glass globe, as an explanation of why incandescent bulbs get darker at the end of their service life, A secondary explanation might be increased resistance in the filament due to decreased cross section, causing lower current and lower temperature. Certainly and obviously dirt and dust deposits on the bulb would decrease light emittance. Edison (talk) 03:46, 13 May 2012 (UTC)

How long do adult flies live ?
I trapped a fly in my storage room in Detroit. Assuming it was a young adult (because of how active it is), how long will it live at room temperature ? I don't want to open the door again until it's dead. StuRat (talk) 23:18, 8 May 2012 (UTC)


 * Three weeks. Or a day in Detroit if it can figure out a way to get to the suburbs. 71.215.84.127 (talk) 23:35, 8 May 2012 (UTC)


 * Unless that storage room is airtight, there's a good chance yon fly has fled. ←Baseball Bugs What's up, Doc? carrots→ 00:13, 9 May 2012 (UTC)


 * I'm not sure about that - Bugs are pretty stupid. present company excluded . Someguy1221 (talk) 00:17, 9 May 2012 (UTC)


 * Agreed. They pretty much stay in the window until they die, unless disturbed, in my experience. StuRat (talk) 00:19, 9 May 2012 (UTC)


 * If it appears to be dead you should poke it with something to see if it leaps over a couple of metres, flies will often play dead when low on energy as a survival behaviour. Sky Machine   ( ++ ) 00:26, 9 May 2012 (UTC)


 * And that's why you never hear about Schrödinger's fly. Blakk   and ekka 12:40, 9 May 2012 (UTC)


 * Flies are not bugs, and I agree with the IP, about a month at most. Though I must ask, why do you care so much about the fly's possible escape? Unique Ubiquitous (talk) 00:21, 9 May 2012 (UTC)


 * It can't do much harm in the storage room. But, if it gets into the rest of the house, it can land in my food, fly in my face, wake me up by buzzing in my ear and landing on my face, etc.  Best case scenario, I manage to swat it, then I have fly guts to clean up. StuRat (talk) 00:39, 9 May 2012 (UTC)


 * Did you try flypaper? ←Baseball Bugs What's up, Doc? carrots→ 02:23, 9 May 2012 (UTC)


 * I tried it once. It was a disaster.  The brown glue got all over me and the walls.  To me, this is a desperate measure you take if your house is overrun with flies, not what you do if you have one safely locked in a storage room. StuRat (talk) 16:56, 9 May 2012 (UTC)


 * ...I want my time and effort back :P Unique Ubiquitous (talk) 01:33, 9 May 2012 (UTC)
 * The word bug came before any formal classification system, it is still ok to use bug to refer to insects in general in nonformal contexts. Sky Machine   ( ++ ) 00:30, 9 May 2012 (UTC).
 * Tell that to my old IPM prof...Unique Ubiquitous (talk) 01:33, 9 May 2012 (UTC)
 * Probably the same guy that claims dinosaurs are birds. ←Baseball Bugs What's up, Doc? carrots→ 02:23, 9 May 2012 (UTC)
 * Nearly - birds are dinosaurs. Not all dinosaurs are birds. (That's if you define "dinosaur" to refer to a clade, which scientists and pedants sometimes do, but nobody else does.) --Tango (talk) 19:40, 9 May 2012 (UTC)
 * Birds are no more dinosaurs than are humans marmosets. ←Baseball Bugs What's up, Doc? carrots→ 01:41, 10 May 2012 (UTC)

StuRat, as you are getting bored, I have a more interesting problem you should investigate in your lab in Detroit: How long would it take to create giant flies by selective breeding in a high oxygen atmosphere? Count Iblis (talk) 15:21, 9 May 2012 (UTC)


 * Would giant flies be able to fly without major physiological changes? While one may put pressure upon a population to grow simply larger, it would be much harder, and close to impossible due to low genetic diversity, to also bring the physiological changes required as the fly loses its surface area to volume and food source benefits....I suggest high doses of radiation...or at least genetic engineering for the less adventurous. Unique Ubiquitous (talk) 16:51, 9 May 2012 (UTC)


 * Presumably the high oxygen environment is to allow the fly to continue to get enough oxygen, despite the higher mass-to-surface-area ratio. The next size related problems would probably be an inability to fly, as their wings are designed for small insects, and an inability to stand on walls and ceilings, do to their foot design.  Thus, you'd end up with a "fly" which could only crawl on the ground.  Then, at some point, the exoskeleton would be insufficient to support it's weight.  It's circulatory system might also need to add an extra level (capillaries), which is a major change.  With all of these changes, you might get a fly the size of a Goliath beetle. StuRat (talk) 17:04, 9 May 2012 (UTC)
 * Might as well splice a few of the more interesting fly's genes with one's own to get a really exotic and much larger "fly"... And barring anything that interesting, a fly bottle  or two might help spare you another visit from the one you have trapped or any of its vengeful kin. ;) --Modocc (talk) 21:35, 9 May 2012 (UTC)