Wikipedia:Reference desk/Archives/Science/2011 October 31

= October 31 =

Colliding black holes
So I was wondering what it would be like if two black holes collided and so I decided to search YouTube which is where I go for most of my astrophysics animations. I found, , , , , and. Which do you think most accurately depicts colliding black holes? Dualus (talk) 00:25, 31 October 2011 (UTC)


 * The second one is definitely the best of them all. The first one isn't very good (low resolution). The third one is a galaxy collision (nice graphics). The fourth one like the first has low resolution. The fifth one has only a very brief scene of a simulation (most of the time is taken showing interviews). The last one also has very good graphics, it shows the collision of neutron stars (with the eventual formation of a black hole as a result). In short, the second video is clearly the best choice. Dauto (talk) 02:22, 31 October 2011 (UTC)
 * I think the last one may be the best, but I haven't decided yet. Dualus (talk) 04:34, 31 October 2011 (UTC)
 * The last one is showing the collision of neutron stars. That's not the same thing as the collision of black holes which is what you were asking about. I agree that it shows an interesting simulation but it is slightly off topic. Dauto (talk) 14:34, 31 October 2011 (UTC)
 * Well, a black hole is produced, so in a way it's like when we say "a tree collision" we mean the tree even if it isn't there anymore after the collision. Dualus (talk) 20:22, 31 October 2011 (UTC)

Scientific integrity
Recently I was reading http://scienceprogress.org/2011/10/overdue-and-underdone/ on the White House Office of Science and Technology Policy scientific integrity initiative. I have questions: Dualus (talk) 04:34, 31 October 2011 (UTC)
 * 1) Will scientific integrity in the Environmental Protection Agency mean fuel synthesis? I.e., http://windfuels.com + http://www.greentechmedia.com/articles/read/guest-post-kicking-oil-addiction-permanently-with-windfuels/ + http://www.pnas.org/content/early/2009/06/19/0904101106 + http://dodreports.com/pdf/ada530365.pdf + Wind power + http://www.dtic.mil/cgi-bin/GetTRDoc?Location%20=U2&doc=GetTRDoc.pdf&AD=ADA299090 + http://www.youtube.com/watch?v=fiK5-oAaeUs#t=10m00s + http://www.youtube.com/watch?v=ocBBrYYYYqg + http://www.youtube.com/watch?v=TlRavcMZpX4 + http://www.youtube.com/watch?v=Cjf3gRq32eo ?
 * 2) Will scientific integrity in the National Institutes of Health mean single-payer health care?
 * 3) Will scientific integrity in the Office of Management and Budget mean more progressive taxation and an end to tax havens?


 * I am unable to understand your question. Perhaps you could explain your question better please? Dmcq (talk) 07:17, 31 October 2011 (UTC)


 * Answer to 1.,2.,3.: NO. From the article you linked to: "the focus appears mostly on ensuring the proper conduct of agency scientists." It does not imply to follow a specific policy. 88.9.210.218 (talk) 09:30, 31 October 2011 (UTC)
 * Are policy recommendations not the proper conduct of agency scientists? Dualus (talk) 01:44, 2 November 2011 (UTC)


 * I suggest you read the definition of integrity (the first one on that page is the one being used here). You seem to have be misunderstanding the word. --Tango (talk) 20:16, 31 October 2011 (UTC)


 * Or allowing your own political biases to override your powers of critical thinking. 67.169.177.176 (talk) 23:30, 31 October 2011 (UTC)


 * How so, Tango and 67'? Dualus (talk) 01:43, 2 November 2011 (UTC)


 * By thinking/claiming that a person/group that follows the principles of "scientific integrity" would inevitably conclude from available evidence that the particular policies you happen to support are in fact the right ones for the country, while in reality someone who approaches the evidence impartially may reach a different conclusion. In fact, the way you framed your question not only clearly shows your political biases, but is at the very least a case of begging the question and may even be indicative of cherry-picking evidence (either consciously or unconsciously, I have no way to tell).  This is what I call the "If you were as smart/honest/well-informed as I am, you'd see things my way" type of fallacious argument -- believe me, I've seen (and argued against) this kind of fallacious thinking during political debates more often than I can count! 67.169.177.176 (talk) 02:24, 2 November 2011 (UTC)


 * I don't think it is biased to assume that scientists would reach the reality-based policy conclusions. Dualus (talk) 10:24, 2 November 2011 (UTC)


 * ...For an accepted ideal outcome, where the evidence is good enough. Science can't decide what is ethically right, or whose campaign is getting funded with money saved from taking advantage of a tax haven. Teshmanesh (talk) 14:13, 2 November 2011 (UTC)


 * Scientists don't set policy, they provide the evidence around potential benefits and disbenefits to inform political debate. Policy is set by politicians, who will (in theory) include the analysis of benefits and disbenefits into their decision making.
 * You're indicating your own bias by assuming that the evidence supports conclusions that you agree with.
 * ALR (talk) 14:32, 2 November 2011 (UTC)
 * Reasonable scientific integrity in the government is where they don't threaten scientists with the loss of their jobs or worse if their conclusions differ from what a politician wants them to be, good scientific integrity is allowing their conclusions to be published even if the politicians don't like them. Dmcq (talk) 18:29, 2 November 2011 (UTC)


 * (un-indent) @Dualus -- what evidence do you have that wind-powered fuel synthesis, single-payer healthcare and progressive taxation are "reality-based"? (Not to mention that your third question belongs to the realm of tax policy, which IN GENERAL actually belongs to the realm of ECONOMICS and is therefore OUTSIDE the purview of the natural sciences.) 67.169.177.176 (talk) 23:11, 2 November 2011 (UTC)
 * I believe it is within epidemiology. Dualus (talk) 21:40, 4 November 2011 (UTC)
 * The one about healthcare is, but not the one about taxation. That one is exclusively within the realm of economics. Besides, my question is what evidence do you have at your disposal to show that the policies you support are the best ones for the United States of America. 67.169.177.176 (talk) 01:10, 5 November 2011 (UTC)

Firecracker pollution
What chemical residues do firecrackers leave in the air and on the ground? What effects do those residues have on the natural environment? How do city street cleaners dispose of these chemicals? —Wavelength (talk) 04:50, 31 October 2011 (UTC)
 * On the ground they mainly leave paper. In the air you will find sulfur dioxide, carbon dioxide, potash and smoke. Graeme Bartlett (talk) 05:01, 31 October 2011 (UTC)


 * ...Which are all found naturally in the environment, (excluding the paper) and since they are suspended in the air, they are readily dispersed and diluted. Plasmic Physics (talk) 10:58, 31 October 2011 (UTC)


 * Paper is found naturally in the environment in some places. (User:Vespine should know this.) 67.169.177.176 (talk) 23:32, 31 October 2011 (UTC)
 * Yes, i did know, just by the way:) Vespine (talk) 00:12, 2 November 2011 (UTC)

Fireworks discusses pollution from fireworks. In the context of my three questions, are there important differences between firecrackers and fireworks? —Wavelength (talk) 16:50, 31 October 2011 (UTC)
 * Qualitatively, not much at all. The difference is purely quantitative; its a rather large quantitative difference, maybe on the order of 2-3 orders of magnitude given that a firecracker weighs a few grams at most, and some fireworks can exceed a kilogram.  -- Jayron  32  17:56, 31 October 2011 (UTC)


 * Fire works are usually coloured. This colouring comes from small quatities of metal compounds like salts, and often contains heavy metals, but it is still dispersed over a large area. Plasmic Physics (talk) 22:39, 31 October 2011 (UTC)


 * I suppose that the quantity of people who explode firecrackers on Halloween is thousands of times as large as the quantity of people who explode fireworks on New Year's Eve and the Fourth of July.
 * —Wavelength (talk) 05:59, 1 November 2011 (UTC)


 * Here is a picture of street sweepers cleaning up firecracker litter.
 * —Wavelength (talk) 06:04, 1 November 2011 (UTC)

Dubois and Fernholz
I noticed some red links at Nutrition:

"Eugene Floyd Dubois showed that work and school performance are related to caloric intake. In 1938, Erhard Fernholz discovered Vitamin E."

Does anyone know anything about Dubois and Fernholz? Does anyone know who discovered magnesium is vital? Dualus (talk) 06:22, 31 October 2011 (UTC)


 * There's lots online about Dubois, e.g. . Fernholz is a little less well-known, but there's still information if you Google.  He seems to have mysteriously disappeared in 1941. --Colapeninsula (talk) 14:05, 31 October 2011 (UTC)


 * Thanks! Dualus (talk) 01:48, 2 November 2011 (UTC)

Australia's beaches
Australia seems to have a much higher proportion of its coastline adorned with sandy beaches than any other landmass. (I haven't been able to find figures, but there seem to be many thousands of miles of sand. It even has the world's largest sand island.) Is this true and is there something about its geography that predisposes it to endless beaches? I couldn't find anything in the relevant articles.--Shantavira|feed me 09:10, 31 October 2011 (UTC)


 * As an Aussie I've wondered the same thing myself. (And yes, we do laugh at those rocky places called beaches in Europe.) My suggestion is that it would be somehow related to the fact that Australia is one of the oldest land masses on Earth, and/or has been largely unaffected by glaciation. HiLo48 (talk) 09:27, 31 October 2011 (UTC)


 * You may laugh at our beaches, but at least we don't have quite such an unnecessarily malevolent fauna. Equisetum (talk &#124; contributions) 10:32, 31 October 2011 (UTC)


 * I have been told by several Australians that there aren't ANY sandy beaches in Britain. This seems to stem from Aussies who stay in London and hop on the train to Brighton, which has (unusually) a pebble beach. My two childhood favourite British sandy beaches are Whitsand Bay in Cornwall and Oxwich Bay in South Wales. There are many, many others besides. Alansplodge (talk) 13:49, 31 October 2011 (UTC)

Maybe it is related to its many coral reefs? Plasmic Physics (talk) 10:22, 31 October 2011 (UTC)


 * My brief visit to Australia a while ago, left me with the impression that the whole landmass is almost entirely composed of sand. Most of the exposed rocks I saw appeared to be sandstone and the soil seemed to have plenty of sand content too. This is a completely arbitary observation and I wait to be shot down in flames by someone better acquainted with Australian geology. Alansplodge (talk) 11:50, 31 October 2011 (UTC)


 * I can think of several contributing factors. Reflecting some other comments, Australia has had relatively little impact by geological processes (mountain formation, volcanism, etc) for hundreds of millions of years making it's exposed rocks and soils very ancient, fragile, and easily eroded. Being the world's driest continent (excluding Antarctica) also contributes to the sandy soils. Additionally it is very flat (again significantly related to the lack of geological activity) making it more susceptible to beaches, compared to say more mountainous coastlines that plunge steeply down into the sea, although we do see that in some parts of Australia (consider the Great Australian Bight for example). It's also been quite exposed to oceanic erosion for a long time, having separated from what was left of Gondwana as much as 80MYA, and having existed as an island ever since. The coastline is also reasonably open and exposed, i.e., long open coastlines tend to be more sandy compared to say coasts with lots of little bays and inlets. I kind of like the coral reef suggestion too, but I'm not sure Australia has relatively greater reefs than elsewhere to make that a reality. --jjron (talk) 14:39, 31 October 2011 (UTC)


 * I think Australia does have more coral reefs than, say, Europe. I attribute this to the shallow water, warm weather, and lower population and industry density, since corals are particularly sensitive to pollution, etc.  Many corals in the Mediterranean may have been hacked away in antiquity, for use as decorations, etc. StuRat (talk) 19:40, 1 November 2011 (UTC)


 * Yes, yes, that's true - I was meaning more in terms of places at similar latitudes, such as tropical locations. For example there's the nice big Great Barrier Reef up in the tropics off Queensland, but not really anything substantial down around Victoria for example. But your point about (historically) lower human impacts is also valid, as we see with the GBR now dying off mainly due to human impacts like increased pollution over the last hundred years or so, and climate change. --jjron (talk) 01:09, 2 November 2011 (UTC)


 * And if the GBR disappears, this may reduce the rate of sand production off the coast. Since the amount of sand on a beach is a balance between new sand being introduced and old sand washing away, this may eventually lead to less sandy beaches, too.  As for similar climates, I'd think the Mediterranean Sea would be fairly close to that where the GBR is located, although the Med may have smaller waves (I wonder if those are important for coral reefs). StuRat (talk) 04:16, 2 November 2011 (UTC)


 * Well it's over 20 years since I did any (basic) research on coral reef formation, but I do seem to remember that wave action is important in continually supplying new nutrients to the reef, and to clear wastes. Hmm, perhaps also interesting to note that Fraser Island, the world's biggest sand island (mentioned in the OP's question) is not far south of the main body of the GBR, although that article states "All of the sand, which originated in the Hawkesbury, Hunter and Clarence River catchments in New South Wales has been transported north by longshore transport", which I guess rather relates back to my original reasoning to do with erosion of the soils and rocks of the continent itself, rather than it originating from the reefs. Regarding the locations, even the most southern parts of the Mediterranean, around north Africa, are well and truly north of the tropics, and coral reefs are really a tropical phenomenon. And in similar latitudes to the Med, well away from coral reefs, Aust certainly has immense sandy beaches. --jjron (talk) 12:26, 2 November 2011 (UTC)


 * Climate isn't solely due to latitude, however. The Gulf Stream/North Atlantic Current and being surrounded by large land masses likely both contribute to warmer water there than would be expected otherwise, perhaps with temps close to that of the tropics. StuRat (talk) 15:57, 2 November 2011 (UTC)


 * Quote from the article Geology of Australia: "A thin veneer of mainly Phanerozoic sedimentary basins cover much of the Australian landmass (these are up to 7 km thick). These in turn are currently undergoing erosion by a combination of aeolian and fluvial processes, forming extensive sand dune systems". Dauto (talk) 14:46, 31 October 2011 (UTC)

Thank you all for your observations.--Shantavira|feed me 14:12, 2 November 2011 (UTC)(OP)


 * I can't find any figures to answer your question either, but for what it's worth, our articles on Cox's Bazaar (Bangladesh) and Praia do Cassino (Brazil) both claim their subject is the world's longest beach. 81.98.38.48 (talk) 22:16, 3 November 2011 (UTC)


 * The classic fractal problem from "How long is the coast of Britain?" may come into play here. That is, the length of a beach is entirely dependent on the length of the ruler you use to measure it. StuRat (talk) 21:32, 4 November 2011 (UTC)

Accurate test for mercury poisoning
When I was in school (about 12 years ago) I played with some open mercury a few times not realizing the danger - I might have breathed in quite a bit. I'd like to undergo a test to see if my body still has excess levels of mercury but doing a search on the internet there seems to be a lot of scams out there, with most types of test being disputed (including hair test and chelation challenge). Is there a kind of test that I can request at my GP or a hospital that is generally considered accurate in the medical world? 41.164.7.242 (talk) 10:34, 31 October 2011 (UTC) James


 * Have you read mercury poisoning? I think that mercury is automatically removed from the body, since it is naturally present in very small amounts in certain food anyways. I don't think that you would find any mercury above background levels. Just a note, don't decide whether or not to have any medical tests done based on coments made on Wikipedia. If you are genuinely considering this, then you should ask a professional. Plasmic Physics (talk) 10:47, 31 October 2011 (UTC)


 * I always thought mercury was not automatically removed from the body, quite in contrary. I was sure it bio-accumulates with time. Quest09 (talk) 13:58, 31 October 2011 (UTC)


 * Mercury poisoning discusses diagnosis. The reference desk does not offer medical advice, so if you are worried about mercury poisoning, you should consult a doctor. --Colapeninsula (talk) 14:13, 31 October 2011 (UTC)


 * If someone plays with elemental mercury, as in a thermometer, there's not much danger. As our article says: "Quicksilver (liquid metallic mercury) is poorly absorbed by ingestion and skin contact. It is hazardous due to its potential to release mercury vapor."  What it doesn't say is that the amount of mercury that becomes vapor at room temperature is negligible.  This would only be a concern if someone worked with mercury at elevated temperatures, or over many years, or were reacting it with other chemicals. StuRat (talk) 17:22, 31 October 2011 (UTC)


 * Hence, for example, Mad hatter disease. {The poster formerly known as 87.81.230.195} 90.193.78.35 (talk) 18:39, 31 October 2011 (UTC)


 * The whole point of doctors is that they know how to treat you. You don't need to find out what test you need and then ask for it. You just go to the doctor and let them decide what tests you do (or don't) need. --Tango (talk) 20:13, 31 October 2011 (UTC)


 * How I wish this was my experience. Sometimes, you really do need to ask. GPs in the UK only tend to be proactive about testing you for things that people have run media campaigns for: everything else, you have to be a bit more on the ball, do your research, and ask them about it. Unless you've found a really good GP, in which case I envy you. 86.163.1.168 (talk) 22:55, 31 October 2011 (UTC)


 * Agreed. Research clearly shows that patients who take charge of their own health do far better than those who put themselves wholely in the hands of a doctor.  Why ?  A doctor typically can only spend a few minutes or maybe hours diagnosing each patient, whereas the patient may be willing to spend days, weeks, or years researching their condition.  The doctor doesn't know if the patient is exaggerating trivial complaints or really is experiencing something unusual for them.  The patient knows.  The doctor has other patients, so can only spend so much effort on any one.  Last week I saw a TV program on Cushing's syndrome which stated that most people went undiagnosed until they insisted that doctors test them for it. StuRat (talk) 22:29, 1 November 2011 (UTC)


 * Just as a matter of perspective, note that there is a practice, actually rather common in herbal shops in the Chicago Hispanic community (probably others) of selling capsules of mercury (about 9 grams) for ingestion. This perturbs many health professionals but hasn't generated a lot of ER casualties for them to write home about.  Also, to quote from an EPA report about this, "Overall, the amount of mercury contained in a thermometer is small and does not present an immediate threat to human health. However, to avoid a health risk over time, the mercury should be cleaned up and disposed of properly."  (You may want to save that file and open it in a PDF reader - it apparently crashed my PDF plugin in Netscape)  I'm not really recommending anyone to play with mercury but I did it as a kid and I survived, and I'm loath to take the wonder away from others. Wnt (talk) 23:16, 31 October 2011 (UTC)


 * I think that if no problems have turned up after 12 years it is not unreasonable to believe that the mercury has caused you no harm. Personal curiosity about the amount of possible mercury in your body should not be a reason to use valuable medical resources. I also played with mercury many times as a child (many years ago) and had no ill effects. Richard Avery (talk) 08:36, 1 November 2011 (UTC)


 * Yes, it's not elemental mercury, but rather things like methyl mercury, which are highly toxic. Unfortunately, both the public and lawmakers seem unable to distinguish between the risks of each. StuRat (talk) 19:32, 1 November 2011 (UTC)


 * My understanding is that the ingestion hazard of metallic mercury is mainly that of mechanical damage: mercury is very dense, so having a few pounds of the stuff pool up in one place can cause problems. It's mercury compounds and mercury vapor that cause mercury poisoning. --Carnildo (talk) 00:42, 4 November 2011 (UTC)


 * AFAIK having "a few pounds" of mercury inside your body (as opposed to a few ounces) can actually result in enough absorption to get toxic effects. As for mercury compounds causing poisoning, this applies to all ORGANIC compounds of mercury without exception; INORGANIC mercury compounds, on the other hand, actually have a pretty low toxicity -- in fact, lower in many cases than that of metallic mercury.  FWIW 67.169.177.176 (talk) 06:05, 4 November 2011 (UTC)

Scientist who controlled a bull's brain
Who was the scientist who implanted an electric device in a bull's brain, rigged up a remote control, let the bull charge at him, and made the bull stop just before hitting him?198.228.194.215 (talk) 11:49, 31 October 2011 (UTC)


 * First result for a Google search of "science who controlled a bull's brain" for me is which says José M.R. Delgado. Come on, you could have done that. --Mr.98 (talk) 12:25, 31 October 2011 (UTC)


 * Interesting, I wonder if the operating principle of Delgado's stimoceiver is the same as that employed in the God helmet, only with wires in the case of the stimoceiver and less-invasive fields in the case of the helmet. 20.137.18.53 (talk) 12:47, 31 October 2011 (UTC)

On You Tube here, or so it seems.--Shantavira|feed me 15:44, 31 October 2011 (UTC)


 * This stuff was seriously overhyped. What Delgado actually did was to implant electrodes into a part of the brain where electrical stimulation causes an animal to turn sideways (the basal ganglia).  When the bull would charge at him, he would activate the stimulator, and the bull would veer off to the side.  It was not really very sophisticated, but it got huge press at the time as an example of "mind control". Looie496 (talk) 17:09, 31 October 2011 (UTC)


 * Sounds like it influenced the minds of journalists at least a little. :) I wonder if it (the publicity stunt) ended up loosening any funding dollars his way. 20.137.18.53 (talk) 18:14, 31 October 2011 (UTC)


 * FWIW though, "mind control" has existed for a very long time in the natural world, most notably in parasites and parasitoids, including parasites that infect mammals. Glyptapanteles, Ampulex compressa, Leucochloridium paradoxum, and Toxoplasma gondii, for example.--   Obsidi ♠ n   Soul   16:18, 2 November 2011 (UTC)


 * Not to mention the rabies virus. 67.169.177.176 (talk) 23:31, 2 November 2011 (UTC)

Identify large structures
See advert on http://content.yudu.com/Library/A1u4hi/HLPFISeptOct2011/resources/49.htm (Heavy Lift and Project Forwarding International, Sept/Oct 2011, p.47 (enter p.49-49 - Goldhofer advert) - there are two structures - the scale of which leaves me blank as to what they are? Anyone know (thanks in advance)Imgaril (talk) 16:43, 31 October 2011 (UTC)


 * They look like sections of an offshore production platform (for oil and/or natural gas). In the photo they're shown on their sides - the same photo also appears on Goldhofer's offshore applications webpage. It's modern practice to build complex offshore systems in modules, with all the equipment, wiring, pipework etc. prefabricated. -- Finlay McWalterჷTalk 20:08, 31 October 2011 (UTC)


 * Yes, so it never occurred to me they were on their sides for some reason - I'm not familiar at all with the oil industy - but I guess they must be some sort of Spar (platform) - http://www.globalsecurity.org/military/systems/ship/platform-spar.htm has a diagram deep link image for same site.
 * Still the ones I linked look really big to me - larger than Brent Spar (and until today I never realised "Brent Spar" was a "spar" - I just thought spar was some obscure geological term they'd decided to use in naming the thing.)
 * Thanks.Imgaril (talk) 21:32, 31 October 2011 (UTC)

Florida building code
why is it that in Florida the building code is so lax when it comes to insulation I read that in new construction is only required to have r-5 insulation that is just mind-boggling to me. Why is this? In most other states next to them like Georgia and South Carolina they have much stricter building code and require the homes to be well insulated and have vinyl double pained windows also other hot states like Nevada and Arizona also require good insulation — Preceding unsigned comment added by 92.48.194.151 (talk) 16:24, 31 October 2011 (UTC)


 * You're looking at how hot the states get, when you should be looking at how cold they get. Being surrounded by water, it rarely goes below freezing in Florida (except for the panhandle).  So, I'd compare with Hawaii building codes.  And, while insulation also helps with air conditioning in summer, it rarely gets more than about 20° F warmer than you'd want, in most of Florida, so insulation isn't much needed for that. StuRat (talk) 17:13, 31 October 2011 (UTC)

20° is actually a big difference it regularly gets up to 100° in South Florida and In North Florida they can actually get fairly cold in the winter. Florida's climate is only slightly different than the climate for a place like Nevada or South Carolina and they have much stricter building codes for example in Nevada the state actually recommends r-20 in walls and r-40 in attics that is a huge difference to r-five. I have some friends in South Florida and they tell me they pay 3 to 400 a month air conditioning and 200 a month for heating in the winter obviously those bills would be much lower with  proper insulation and its ridiculous in this day and age that the state would not ask for higher insulation values  — Preceding unsigned comment added by 92.48.194.181 (talk) 17:27, 31 October 2011 (UTC)


 * 20° F is a tiny difference, compared with many places where temps get down to 100° F colder than you'd want. As for Nevada, I find temperature ranges of -50° F to +125° F, versus -2° F to +109° F in Florida, or a 175° F range versus a 111° F range, at this site: .  And, of course, this includes the panhandle.  If you only look at the peninsula, then temperature ranges are even less.  For example, according to our Climate of Miami article, the temperature range in Miami is +24° F through +100° F.  So, state-wide codes don't make much sense, they need different codes for the panhandle and peninsula. StuRat (talk) 17:39, 31 October 2011 (UTC)

you have ignored the huge heating and cooling bills these people have clearly they could benefit from better insulation — Preceding unsigned comment added by 92.48.194.188 (talk) 17:52, 31 October 2011 (UTC)


 * Well, everyone could benefit from more insulation, it's just a question of whether the large upfront cost of insulation will be returned in a reasonable period. The figures you quote are meaningless without knowing the size of the home, form of heating, what temperature they keep the home, etc.  Another factor in Florida may be that many homes there are "summer homes", so not heated much in winter, when insulation would be most beneficial.  There may also be a political reason, with many Floridian voters being Republican, and Republicans wanting less government regulation. StuRat (talk) 19:49, 31 October 2011 (UTC)


 * I think that, culturally, heating in the winter in northern states is seen as a necessity, whereas cooling, even in Florida, is more of a luxury, having been introduced in fairly recent history. Philosophically, it may be seen as one thing for the state to make a building code that requires buildings to provide necessities, but another to compel the effective delivery of luxuries.  But consider moving this question to the Humanities desk; you might get a better answer. Wnt (talk) 01:25, 1 November 2011 (UTC)

yes, but in other cooling dominated climates That use a lot of air conditioning the states there require good insulation because air-conditioning is actually more expensive to run than heating because it runs off electric as opposed to gas. It just doesn't make sense that the state would wouldn't mandate along with the rest of them that they put in good insulation. It doesn't take much cost or effort to put in some r – 19 batts before they put the drywall on. However, for the homeowner to do that at a later date would be extremely expensive because they would have to rip off all the drywall. — Preceding unsigned comment added by 92.48.194.162 (talk) 08:28, 1 November 2011 (UTC)


 * Florida temps get miserably hot, but generally not hot enough to kill many people, unlike in Nevada. So, combine this with the Republican concept of having laws only when necessary to protect human life (if even then), and you have your answer.  Their argument would be that if it makes economic sense to build well insulated homes, then the market will move in that direction without the need for government interference in their business. StuRat (talk) 19:03, 1 November 2011 (UTC)

Windows of buildings: Europe vs. US
Why are they different? In Europe they are often tilt turn windows, which offer the option of being opened either tilted in vertically or pivoted horizontally, all from a single handle; and in the US they slide like a guillotine. Quest09 (talk) 16:30, 31 October 2011 (UTC)


 * I'm not sure it's such an even division. In houses in the USA, a sash window (your guillotine) is common, but in many other contexts, the casement window (your hinged window) is not at all unheard of. Our window article implies that sash windows are common in UK countries and former UK colonies, and says casements are more popular specifically on the continent, but even then I can't wonder if there's a lot of variation being concealed there. In any case, it seems like this is just differences in architectural styles and not much else. You can certainly get both types of window in your average American Home Depot. --Mr.98 (talk) 16:48, 31 October 2011 (UTC)


 * I've never seen (or at least, never noticed) a new sash window in the UK, though I've seen a lot of old ones (from Victorian era to maybe 1960s). My answer is "fashion". I guess the UK adopted continental windows at about the same time as discovering the merits of the continental quilt. Card Zero  (talk) 20:32, 31 October 2011 (UTC)


 * I have seen them, but it was on a very upmarket neo-georgian house, designed to look like a period house. -- Q Chris (talk) 13:13, 2 November 2011 (UTC)


 * As for why there is a choice, it has to do with purpose. Assume you require a screen on the outside of your window to keep things like mosquitoes out. If your window tilts or twists outward, it will hit the screen and cause a problem. Now, assume you don't need a screen, but you get a lot of rain. You want to be able to open your window in the rain without having it continuously sprinkle inside. A window that swings out, directing the water outward, is preferable to one that just slides up. So, when building a house, a good designer will consider the use of the window when picking the design of the window. Unfortunately, I suspect they just get whatever is on sale. -- k a i n a w &trade; 16:56, 31 October 2011 (UTC)


 * You simply put the screen inside the window to fix this problem. Of course, this means you can't push the window open and pull it closed manually, so some type of crank is used for that.  This does make the window more complicated, and thus more prone to failure, however.  Also note that large panes really aren't suitable for tilting, as the forces on the hinges are too high and windows which tilt up or down would also tend to sag out of the frame (the weight also makes raising vertical windows difficult, but this can be countered with springs and even electric motors).  StuRat (talk) 17:08, 31 October 2011 (UTC)


 * These days it comes down to tradition and people's expectations of what's right for their house. Going back 100 years or so, in North America screens were fitted outside the sashes in summer and storm windows in winter, in wood frames. There was no crank hardware on outward-opening casements, for the most part, just a simple retainer bar, and inside screens were highly unusual and cumbersome. Most sashes were double-hung, so the upper sash could be opened to let hot air near the ceiling out, on the same principle as the operable transoms often found over doors in the 19th and early 20th centuries. Nowadays nobody has transoms or uses the upper sash, and screens are permanent and storm windows used only on older houses, but everybody has developed an expectation that windows should look the same. The only remaining reason for single or double-hung sash windows is that they take up no extra room when open. Europe doesn't seem to use screens or storm windows as much, using shutters to a much greater degree. Tilt/turn windows open inwards, by the way, so you have to leave room for the swing of the window. Tilt/turn windows solve almost all the problems and perform all the functions of double-hung sashes, but unfortunately haven't caught on in North America.   Acroterion   (talk)   20:50, 31 October 2011 (UTC)


 * I have no sources to back this up, but my observation in Germany matches the OP's completely, at least in every single hotel I've ever stayed in there. And my reaction was always, "Why do they insist on putting these REALLY HEAVY and PRESUMABLY EXPENSIVE windows in EVERY SINGLE WINDOW of this Hotel?"  And my jump-to-the conclusion is that whoever built the hotels was not trying to save a buck, or the window contract was not competetively bid, and only lastly that nobody was interested in less expensive, lighter weight construction.
 * The discussion should thus consider cost and competetiveness as well as tradition -- I don't have an answer for that.
 * --DaHorsesMouth (talk) 01:42, 1 November 2011 (UTC)


 * Street noise is a major concern in an urban hotel, and the only way to combat that is with mass and good sealing, which leads to heavy windows. Counterbalanced sashes would not be so obviously heavy: an argument in their favor except that sash windows perform poorly  for noise control compared with positive-latching swinging or tilting windows, due to the lack of a compressible seal.   Acroterion   (talk)   13:46, 1 November 2011 (UTC)


 * Just a note on tilt windows... There is a claim above that they tilt inwards. That depends on the window. I had tilt windows when I lived in Hawaii and when I lived in the Mojave. In both cases, they swung outwards. I now have sliding windows because it would be idiotic to open a window in the sand-flea breeding grounds without a permanent and well-sealed screen outside the window. -- k a i n a w &trade; 13:49, 1 November 2011 (UTC)
 * There are a variety of ways for swinging and tilting windows to open. Top-hinged windows generally open out (awning windows), bottom hinged in (hopper windows), and side-hinged casements can open in or out. European tilt/swing windows are hinged on the bottom and sides and can either open in from the top as hoppers or in from the sides like casements .  The side hinges tilt along with the window unit in the tilt mode. The handle lets you select the mode.   Acroterion   (talk)   16:01, 1 November 2011 (UTC)


 * It might be that all the above reasons have some bearing on why sash windows are often found in the U.S. I can tell you from a lifetime of living in the Southern United States that life without window screens - easily fitted on the outside of sash windows, much less easily on other types - would quickly become unbearable, the house being filled with flies, mosquitoes, moths, wasps, etc., etc., and in some places like here in Texas, locusts in season.  Hell, sometimes we even get a plague of flies that manage to creep in through totally closed windows!  But apparently other parts of the country, to the north and west, are exempt from these concerns; a friend who attended a family wedding in Northern California a couple years ago reported that all the windows (none of them screened) in the resort they stayed at were left wide open night and day, and not a single flying critter to be seen, despite the presence of quantities of edibles.  Amazing.  Textorus (talk) 03:54, 2 November 2011 (UTC)


 * Here in Detroit, we still get flies. Even more annoying are gnats, fruit flies, etc., which pass right through the window screens and seem to enjoy flying into people's mouths, noses, and eyes.  When watching shows like International House Hunters I'm amazed to see the total lack of screens in most countries.  I'd like to think they don't have flies there, but I'm guessing they do and just let them crawl all over, like the starving Ethiopian kids you often see on TV with flies on their faces. StuRat (talk) 15:48, 2 November 2011 (UTC)


 * Once during a trip to France, I popped into a little patisserie, and asked for a sweet roll from the large trays in the glass cabinet under the cash register. While the saleslady was reaching for a little bag to put my order in, I looked more closely and saw to my horror that all the sweet goods were covered with winged insects, sort of like wasps, crawling about on top of them.  Yet nobody in the shop, customers or staff, was paying any attention to this phenomenon whatsoever.  I was too young and shy then to refuse the order, so I paid and left with my little bag, which I promptly discarded at the next corner.  I still don't understand what that was all about.  Ugh!  Textorus (talk) 11:06, 3 November 2011 (UTC)


 * I once had a similar experience at a Dunkin' Donuts, except that I refused the order and told them why. I did the same at a Subway restaurant when I saw the food preparer rub her nose with her hand between adding the peppers and olives (I asked for black olives, so didn't want them to be green with snot).  If enough customers walk out on them, they will either clean up their act or go bankrupt, solving the problem either way.  StuRat (talk) 04:19, 4 November 2011 (UTC)

Adhesive connecting painted wood and Styrofoam
I put Styrofoam sheets in windows of storage rooms, for insulation during winter, and tape up the edges. I find that the tape adheres poorly, however, particularly halfway up, where the Styrofoam wants to bow inward. The changing temperatures and condensation seem able to defeat any tape I apply. So, is there any tape or adhesive which might hold up, or do I need to screw the Styrofoam down to the window frame, making lots of ugly holes and reducing the resale value of the house ? StuRat (talk) 17:30, 31 October 2011 (UTC)


 * Why do you need to insulate your Windows? I thought 20° wasnt much of a difference? — Preceding unsigned comment added by 92.48.194.153 (talk) 18:00, 31 October 2011 (UTC)


 * I don't live in Miami, I live in Detroit, where temps range from -21° F to 105° F. StuRat (talk) 19:38, 31 October 2011 (UTC)


 * I'm sure there is some way to avoid having to use screws or nails, but if you are talking about painted wood, I don't see how a screw hole will affect the resale value since you would probably have it repainted before selling it, wouldn't you? Dauto (talk) 19:23, 31 October 2011 (UTC)


 * You'd need to fill the holes with something before repainting, and, even then, it would be difficult to hide the holes entirely. StuRat (talk) 19:43, 31 October 2011 (UTC)


 * Because it will be expanding/shrinking, you want a glue that remains flexible for a long time. You can use a caulking sealant which has good flexibility but barely acceptable stickiness. On the other extreme, rubber cement retains barely acceptable flexibility with good stickiness. No matter what you choose, there is a very high risk of pulling the paint off the wood. -- k a i n a w &trade; 19:28, 31 October 2011 (UTC)


 * I think you'll find that rubber cement contains solvents that will turn styrofoam into mush - test any adhesive you use on a scrap piece first. AndyTheGrump (talk)


 * Use wood glue (old fashioned type), latex glue, or PVA glue - according to some forums you can apply one of these glues (possibly diluted with water) - to coat the surface like a paint primer -then tape may work better too. Generally there is an issue getting stuff to stick to it. http://www.istonline.org.uk/Handbook/36-37.pdf  -there is specialise glue for it eg http://www.wonderlandmodels.com/products/uhu-por-expanded-polystyrene-glue/ - note standard UHU isn't suitable.


 * Also you can use decorator's tape (Masking tape) to stick to the painted wood -it comes off easily.94.72.193.44 (talk) 19:38, 31 October 2011 (UTC)


 * Rubber cement will dissolve the Styrofoam. A possible solution might be to wash down the paint-work with the European version of Sugar soap to clean the surface. Then fix the foam sheeting with wide Masking tape. Also, a 40 mph gust of wide exerts a pressure of approximate 1 psi. The leak-through of that will exert a force over the whole sheet. Cut a hole in it and tape a poly bag over it, so as to form a Ballonet. Yes, you'll loose a little heat but it will be  a small percentage. Final, draft-proof the room so as to ensure that the room space provides a little back pressure to the wind forces. As air is compressible, this might not add much resistance but it might help. When the sheet bows inwards or outwards the width/hight dimensions will change a little,  so allow for this too. Failing this, move to England. We have a lot of weather here too, but over the centuries we have tamed it to behave like a pussy cat.   --Aspro (talk) 20:08, 31 October 2011 (UTC)


 * I think you may be on the money with the wind issue - the low mass means (assuming the windows are drafty) the foam acts as a pretty good sail - there's no mass to absorb the momentum - it might actually help to glue some heavy chipboard or mdf to the backs of the foam boards - increasing the overall mass.


 * That said StuRat wasn't completely clear on which bit was coming unstuck ie the connection to the window, or to the foam, or both?Imgaril (talk) 21:36, 31 October 2011 (UTC)


 * I'd use Velcro tape. and if it doesn't stick well to the foam, you can sew it on. --Modocc (talk) 22:10, 31 October 2011 (UTC)


 * I would not depend on any adhesive tape to hold a piece of styrofoam over a drafty window through an entire Detroit winter. I would suggest using rope or twine bound to tacks or small nails if that is feasible. If it begins to fail you can always add more bits of twine in the problem area and/or tighten up what you've already got. Beeblebrox (talk) 22:28, 31 October 2011 (UTC)


 * The longish duration a wind-gust mean that even the mass of extra backing will move. As it is a storage room - why not block it up permanently? On a hourly basis of what one's time is worth, it would be cheaper to switch on the electric light each time you enter the storage space (summer and winter), than mess around each year fixing the foam! Moreover, it will leave you with more time to edit WP. --Aspro (talk) 22:34, 31 October 2011 (UTC)


 * Time and expenses do matter, and doing it right once can be better than messing around with it each year. I can stitch fairly quickly, and it wouldn't take that many stitches to fasten velcro straps securely at the corners of the foam board and every few feet if necessary. The tape's adhesive is better quality than masking tape and should hold to whatever part of the window is used and once completed, removal and replacement is quick and easy. You can do the same for any windows of your home and with a little imagination create and display an assortment of semi-permanent holiday decorative pieces, which should add some cheer to this winter too. --Modocc (talk) 23:31, 31 October 2011 (UTC)

The tape becomes unstuck from both sides. Wind isn't really the problem, it's the Styrofoam's tendency to sag under it's own weight (and the lack of adhesion between the tape and the surfaces). I leave it untaped at the top, figuring that will allow any drafts through and yet not allow much cold air to pour in, as it naturally will want to sink, not rise. The Velcro is an interesting idea, although how would I attach that to the window frame ? With tacks ? I don't want to block the window up permanently. Just because it's currently a storage room doesn't mean it will always be, and blocked-off windows would also hurt resale value. Neighbors would also be more likely to complain than if the windows are only blocked off during winter. I also put fans in those windows for ventilation and cooling in summer.

As for fighting the Styrofoam's tendency to sag, perhaps a thicker sheet would cure that ? (The current sheets are 1 inch thick.) StuRat (talk) 00:02, 1 November 2011 (UTC)


 * If the foam sags – then the U value is not high enough to make it worth while anyway. 4 to 6 inches will make a difference. Also, do you live in a 'home' or simply an asset. We are only on this world once.  Some old age pensioners have scrimped and saved all their miserable lives so that they can die rich and let their children squander their savings. Live in the present. Moreover: If your neighbours think like that -move. --Aspro (talk) 00:16, 1 November 2011 (UTC)


 * I think you need more support at the top so the material hangs with the tension from that, just as you would hang a cloth curtain. That will take a good amount of the weight off the tape at the edges, thus leaving the top few inches of the side untaped would work better than the entire top. There are a number of ways you can do this too. String and hooks at the top will work and hooked to a wedged rod maybe. Double-sided tape run lengthwise along the top or Velcro along the inside edge (which can be tacked, although I don't think that will be necessary because you should be able to run two or more lengths across the top as needed for larger windows and heaver foams). All these will give a more uniform support and should alleviate the sagging and tape separation problem.--Modocc (talk) 01:14, 1 November 2011 (UTC)  --Modocc (talk) 00:32, 1 November 2011 (UTC)


 * If (semi-)rigid foam sheets work for you, then keep using them. However, instead of trying to glue them to the frame in a removable fashion, may I suggest a wood cleat or two, that spans the foam and screws into the frame.  Horizontal or vertical doesn't really matter.  Done well, and with quality screws, you can reuse the cleat and the holes for multiple years, and only have to worry about patching ONE pair of holes per frame when you finally leave the place.
 * --DaHorsesMouth (talk) 01:49, 1 November 2011 (UTC)


 * Also, depending on how the windows open and close, you could wedge a sheet of construction paper or cloth at the top and glue the foam to that. --Modocc (talk) 02:07, 1 November 2011 (UTC)


 * I'd suggest a two-layer construction, with maybe 1-1/2" of Styrofoam (the thickness doesn't matter too much, as the presence of any kind of insulation at all to create a thermal break makes the biggest initial difference, extra thickness is a marginal improvement unless it's applied on a large scale) with a somewhat larger piece of foam-core mounting board (the white stuff from art shops) glued onto the room side, sized to suit the opening. The flange you create will give  better seal, and you can use double-stick foam or Velcro or toggles through the flange to hold it. You could even gasket it, and the plain white foam-core will be more attractive than the blue or pink insulation. Please note that foam insulation burns with nasty fumes and should be kept well away from ignition sources.   Acroterion   (talk)   16:12, 1 November 2011 (UTC)


 * It's not near an ignition source, but I do hate to bring flammable materials into the home when not necessary. The only less flammable material I can think of to use in place would be a chunk of dry wall.  Are there any other options ?  (Incidentally, one advantage of Styrofoam is that it does let some light in, hopefully enough to find the light switch, at least.) StuRat (talk) 18:50, 1 November 2011 (UTC)


 * Unfortunately, there are few materials with Styrofoam's advantages. Windows aren't a very likely place for fire hazards, or we'd have a lot more curtain fires, so I wouldn't sweat it too much.. Drywall would be awfully heavy. 1/8" white masonite might work over the foam, shielding it and giving a neutral finish. The best stuff for your purposes would be cellular polycarbonate (less R-value, but way more light), but it's not easily available at the big box home center and would probably cost too much.   Acroterion   (talk)   20:12, 1 November 2011 (UTC)

Thanks for the answers, everybody. StuRat (talk) 04:14, 4 November 2011 (UTC)

IFF: The German roll
Identification Friend or Foe, the system used to tell friendly aircraft from enemies, started off in WW2, with the Germans doing a roll to create a distinctive blip on a radar (source, the "Beginning of Electronic Identification" section).


 * 1) Would anyone happen to know where I might find a picture or illustration of this "distinctive blip" as opposed to a normal one?
 * 2) Would this information belong in the Identification Friend or Foe article?

Thanks in advance. (captcha: closeexact. huh.) 90.193.232.195 (talk) 20:15, 31 October 2011 (UTC)


 * The article explanation looks like an over-simplification. See Polarization. Rather than a blip proper, it was more likely a change in signal strength from hight-to-low-back-to-high of the returning echo. If a reliable source can be found for this manoeuvre, then yes it does belong in the article.--Aspro (talk) 20:47, 31 October 2011 (UTC)
 * In other words the "blip" is a temporal one - ie a pulse (not a shape) - the "dot" will get pulse brighter (or weaker) as the signal reflection is modulated by the varying reflective area as the plane rolls ??Imgaril (talk) 21:38, 31 October 2011 (UTC)


 * Think the early German radars would have only shown a increase of of amplitude of the retuning signals, so that  would not have even been and increase I brightness of a dot. Yet that amounts to the same thing that Imgaril is saying  -there would have been no 'shape' to the blip referred to that could be shown in a single image. We really need a better technical explanation of what he German  operators saw.  Maybe a German speaker could ask on the de. WP article on radar and for a link to a good reference source. --Aspro (talk) 22:12, 31 October 2011 (UTC)


 * As a person who's somewhat familiar with WW2 radar equipment, I can tell you that any talk of "blips" or "dots" is based on false assumptions about what the operators saw. First of all, WW2 radars didn't have the same kind of displays that modern radars have, with dots representing targets -- what they had was an oscilloscope with a range scale, which showed the outgoing pulse at zero range, and return pulses at their respective ranges (calculated using a basic pulse-delay system and displayed in simple analog format), plus mechanical indicators for bearing and elevation.  So when the return strength changed, the operator could clearly see the return pulse getting taller or shorter in relation to the outgoing pulse.  (Of course, the downside was that finding the bearing and altitude required stopping the antenna's rotation in order to read the pointers, and often manually adjusting the bearing/elevation of the beam, during which time the radar could not see anything in other directions -- in other words, track-while-scan was not possible with this equipment.) 67.169.177.176 (talk) 23:58, 31 October 2011 (UTC)


 * There we are then, the “the return pulse getting taller or shorter” is in other words a change in amplitude. So no 'blip'. 'Track-while-scan' radars where  fitted to some later versions of  the Lancaster.  These, however had the advantage of the higher output of the magnetron  which the Germans never had, so we could get by with a very much smaller Rx/Tx air-borne unit. It might be be possible that the German had an additional oscilloscope display with a slower time base that showed a fall and rise of the signal that was proportional to the role rate. That would actually show a neg blip (but lets not complicate things). We don't even know if this was  a full roll manoeuvre or a  choreographed rocking from side-to-side wave.  So we still need some tech import as to what the Germans method and equipment was.--Aspro (talk) 00:44, 1 November 2011 (UTC)
 * A little speculative in the absence of a source but rolling the aircraft would create a significant and distinctive change in the Radar Cross Section over a brief period. That change in RCS is known as "glint".
 * As already noted, it's quite clumsy.
 * ALR (talk) 08:56, 1 November 2011 (UTC)
 * Thanks for the information, everyone. 90.193.232.195 (talk) 19:50, 1 November 2011 (UTC)


 * Swiss roles are the best. I'm sorry, someone had to say it. Plasmic Physics (talk) 03:34, 2 November 2011 (UTC)
 * Just as long as you don't start doing barrel rolls right after eating one. ;-) 67.169.177.176 (talk) 05:24, 2 November 2011 (UTC)

Reverse Time
In a reverse time universe, perhaps similar to ours, with reverse time planets and reverse time life forms, would these life forms get to experience free will or would they almost be forced to perform tasks that they would otherwise do, almost like fate? 64.229.204.14 (talk) 21:56, 31 October 2011 (UTC)
 * Uh, reverse time? What would that be exactly? Sounds more like science fiction than science. Beeblebrox (talk) 22:09, 31 October 2011 (UTC)


 * Whilst on paper the mathematics may allow for a universe with time running backwards, I can’t get my mind round the Entropy thing where things start in chaos and end up in order. Think about other things – far more productive.--Aspro (talk) 22:21, 31 October 2011 (UTC)


 * Isn't the idea that time in the universe as we know it ambiguously runs backwards or forwards? So this is a reverse time universe, as much as it is a forward time universe. Card Zero  (talk) 22:36, 31 October 2011 (UTC)
 * Yes -on paper, or chalk marks on a blackboard at MIT!--Aspro (talk) 22:51, 31 October 2011 (UTC)


 * I've always wanted to unpop a balloon. Plasmic Physics (talk) 22:32, 31 October 2011 (UTC)


 * Yeah, wouldn't that be amazing. Your in a jungle repairing a slash in a rubber tree and a few month later, shreds of latex suddenly fly together to produce a perfectly formed condom! No, No; my head can't take it!--Aspro (talk) 22:44, 31 October 2011 (UTC)
 * No, no, you've got it ... um ... forwards. That condom unpopped a couple of months before your rubber tree mending.  How else the reverse causality? -- 110.49.227.102 (talk) 04:38, 1 November 2011 (UTC)


 * Is there more to this imaginary universe than just a meaningless re-labelling of the past as the future and the future as the past? If so, please specify what. Card Zero  (talk) 22:52, 31 October 2011 (UTC)


 * Whatever you would like the answer to be, that's what the answer is. "A reverse time universe" is not a well-defined scientific concept, so we can't use established science to answer your question.  You're the one that's defining this made-up alternate universe that works differently from the real universe, so how the universe that's purely in your imagination works is purely up to you.  If you're inventing a "reverse time universe", a good place to start might be T-symmetry, which lists a bunch of things which you may want to have work differently under a time reversal symmetry transformation in your universe than in the real universe.  Arrow of time may also be useful.  Red Act (talk) 22:59, 31 October 2011 (UTC)


 * If I'm not mistaken, that's not a list of things that would work differently: it's a list of variables which can arbitrarily have minus signs put in front of them, without anything changing (provided you negate all of them together). Card Zero  (talk) 23:07, 31 October 2011 (UTC)


 * .thgir touba smees tahT .desrever tceffe dna esuaC. Plasmic Physics (talk) 23:26, 31 October 2011 (UTC)

It's what Red Act says, a reverse time universe is the same as our universe up to CP conjugation. The arrow of time is determined by boundary conditions. If you were to impose low entropy boundary conditions on the distant future instead of the past, you would just perveive to evolve in the negative time direction. There are in fact theories on the early universe where the part of the universe that underwent a period of inflation was actually in a local minimum of the entropy at that time. So, if you go back further in time, you are actually going forward in time again. This means that you could have a copy that lives 27.4 billion years ago that evolves in the wrong time direction relative to how we define the positive time direction. Count Iblis (talk) 23:40, 31 October 2011 (UTC)


 * Just because time runs backwards doesn't mean sentient beings wouldn't still remember the "past" (lower-entropy state). The universe would seem like it was running forwards in time to these beings, despite the opposite being true. In other words, time could be travelling backwards right now, and you'd never know it! --Goodbye Galaxy (talk) 13:32, 1 November 2011 (UTC)

when the univers get backward in time or to anter dimention, the one that know , erase bad and put good up for the next world and acttuly choose good from bad , thanks water nosfim  — Preceding unsigned comment added by 84.228.231.84 (talk) 15:39, 1 November 2011 (UTC)
 * I'm sorry, but that makes no sense. Please write in your native language and we will translate it. --Tango (talk) 18:44, 1 November 2011 (UTC)
 * ממילא אני כותב הפוך בעברית water nosfim — Preceding unsigned comment added by 84.229.88.81 (talk) 17:35, 2 November 2011 (UTC)
 * the google translate lost the joke "Make any case I am writing in Hebrew "    , Water Nosfim  — Preceding unsigned comment added by 84.229.92.192 (talk) 17:44, 2 November 2011 (UTC)
 * I recall reading something about CPT universes, but unfortunately I cannot remember what it meant, other than T standing for time. → Σ  τ  c . 00:51, 3 November 2011 (UTC)
 * See CPT symmetry. Red Act (talk) 13:36, 3 November 2011 (UTC)

Junk food
Why did humans evolve to like junk food? --70.141.193.98 (talk) 23:30, 31 October 2011 (UTC)


 * Because sugar, salt, and fats were rare in nature, and are important nutrients, so we craved them to ensure that we ate all we could, on the rare occasions when they became available. The modern problem in our diets is due to them now being plentiful, but our cravings still being appropriate for when they were rare. StuRat (talk) 23:42, 31 October 2011 (UTC)


 * As Stu say's: Fats and sugars are a high energy food sources. In primitive times these where in short supply, so  our  instinctive drive (developed over many uncountable millennia of evolution) programmed (some of) us to seek this these these two characteristic out. Food companies know this and thus provide wealthy consumers with what they know what most people will buy.--Aspro (talk) 23:45, 31 October 2011 (UTC)


 * Actually, junk food evolved so as to be liked by humans :) . Count Iblis (talk) 23:46, 31 October 2011 (UTC)


 * There might be some truth to that as well. Gosh! I just want to marry that beefburger --Aspro (talk) 23:53, 31 October 2011 (UTC)


 * There is some truth to that, technically speaking. If you see human beings as part of the "natural" world (and not just "artificial") that there are species whose selfish genes are getting passed on largely because they are appealing to human beings. This is the line of reasoning more or less used in The Botany of Desire, and it applies as well to domesticated animals as it does plants. (Still doesn't make junk food good for you.) --Mr.98 (talk) 01:03, 1 November 2011 (UTC)


 * A lot of it is still linked to economics. Junk food is very cheap, per calorie.  If you had a choice between 1000 calories of pretzels (maybe $1) and 1000 calories of beef jerky (maybe $13) without having to pay, which would you want? Wnt (talk) 01:29, 1 November 2011 (UTC)


 * The economics of it is largely linked to food subsidies and things like that. Anything made with corn byproducts, for example, is artificially cheap because of government intervention. If you applied similar incentives to manufacturing non-junk food, it would be cheaper for the consumer as well. This is Michael Pollan's pitch for what we ought to do with subsidies, if we actually care about public health. --Mr.98 (talk) 11:45, 1 November 2011 (UTC)


 * Junk food does "evolve", in the same sense that memes evolve. The junk food that has most sugar/fat (and thus tastes best to most people) sells better, so "survives" in the market place, displacing the healthy but less popular food. Mitch Ames (talk) 12:17, 1 November 2011 (UTC)


 * We didn't. Junk food hasn't really existed long enough for us to have "evolved" in relation to it. What really happens is we intentionally make food that triggers our primitive instincts for sugar, salt, and fats.


 * For example, in the "wild" it'd be hard to find sweet foods. For the most part the sweetest foods we'd be able to find would be fruits and berries that contain important nutrients. Now we can manufacture food that's even sweeter than fruits and berries. So, ironically, our instincts that made us like fruit make us love candy. APL (talk) 03:20, 1 November 2011 (UTC)


 * Still economics. If you could walk into your kitchen and feast from a magic never-ending bowl of ever-fresh blueberries, would you really reach instead for the candy hearts all that often? Wnt (talk) 15:11, 1 November 2011 (UTC)


 * If you want to remove economics from our food choice equation, then you should also remove the effect on our health. That is, if you had the choice of any food, didn't need to pay for it, and it had no effect on your health, what would you eat ?  I think I'd eat things high in fat, sugar, and salt, and low in fiber. StuRat (talk) 21:24, 1 November 2011 (UTC)
 * Wnt, maybe not candy hearts, but give me an infinite bowl of chocolate or peppermint over an infinite bowl of blueberries any day. APL (talk) 23:40, 1 November 2011 (UTC)
 * Well, that's why I didn't say chocolate. ;) Wnt (talk) 02:24, 2 November 2011 (UTC)


 * The original question seems to imply that humans who do not like junk food are inferior to humans who do like it.
 * —Wavelength (talk) 06:09, 1 November 2011 (UTC)


 * Don't be ridiculous — it does not imply that at all. Just because something is or is not linked to some sort of evolved trait does not mean that people with or without it are in any way superior or inferior to others in an objective sense. Not all evolved traits are positive, and judging "superiority" with regards to them is a grade school error anyway. Don't read your own errors into the OP! --Mr.98 (talk) 11:45, 1 November 2011 (UTC)


 * I used the word seems.
 * —Wavelength (talk) 19:51, 1 November 2011 (UTC)


 * Also note that we evolved to avoid various things, like fiber, because historically we got way too much fiber, whereas now we get too little. We also developed a preference for white foods, as they show contamination or mold more easily.  Hence our preferences for white sugar and white bread. StuRat (talk) 18:43, 1 November 2011 (UTC)


 * See http://multilingualbible.com/genesis/3-6.htm and http://multilingualbible.com/romans/5-12.htm and http://multilingualbible.com/romans/7-19.htm and http://multilingualbible.com/2_corinthians/7-1.htm.
 * —Wavelength (talk) 19:51, 1 November 2011 (UTC)

Batteries
I have an odometer and a number of partly used batteries. How do I test the batteries to get a reading that is more accurate than the odometer alone will give? Presumably I need to add a load in the form of a light bulb into the circuit somehow. Kittybrewster  &#9742;  23:36, 31 October 2011 (UTC)


 * Whilst on this subject does anybody know how I can use a voltmeter to tell me how far I have traveled.--Aspro (talk) 23:49, 31 October 2011 (UTC)


 * How_to_identify_used-up_batteries_with_a_odometer --Aspro (talk) 23:59, 31 October 2011 (UTC)


 * In four easy steps: 1.Take odometer to second-hand dealer or pawnshop. 2.Trade odometer for a voltmeter. 3.Take voltmeter home. 4.Measure battery voltage. Roger (talk) 07:09, 1 November 2011 (UTC)


 * (serious answer) Yes, of course you can test without buying a multi-meter. Voltage alone is not a reliable indication, by the way.  Just connect a small torch bulb to the battery with a spare bit of wire (I've successfully used metal scissors instead).  If your bulb is 2.5v or 3v then a single cell will make it glow only dimly, but you can still tell which battery is dead and which still has some life left.  This test under load is more reliable than just using a voltmeter (even if you've already swapped your odometer for one) .  Some multi-meters have a battery test setting that measures the voltage under load, and this is slightly more accurate, but the bulb test is adequate for most purposes.    D b f i r s   07:55, 1 November 2011 (UTC)


 * Don't test with an odometer, since mileage may vary. See the earlier Ref Desk answer, where I recommended currents to use in testing batteries. Edison (talk) 05:56, 2 November 2011 (UTC)


 * Yes, if your odometer is actually a voltmeter, then connecting your battery to a load such as a torch-bulb, and measuring the voltage across the bulb, will give a better indication of battery health (in effect, measuring current, as suggested by Edison).   D b f i r s   09:39, 4 November 2011 (UTC)