Wikipedia:Reference desk/Archives/Science/2011 June 17

= June 17 =

Average weight for Americans and Europeans
Where can I find the average weight for (adult) American men & women and European men & women? --CGPGrey (talk) 12:28, 17 June 2011 (UTC)
 * A search for 'average weight american' easily finds . My guess even before searching is trying to find an average weight for Europeans is unlikely to be easy and a search for 'average weight European'. I would suggest you compare different European countries. If you really want an average for 'European' you should at least definite the term. Do you mean all EU countries only? Nil Einne (talk) 12:43, 17 June 2011 (UTC)


 * The WHO keeps a lot of health facts for countries throughout the world here. For weight, I believe they only report the percent that are obese instead of actual weight. You can go into the data repository to get actual weight values. The result will be a bit useless. For example, I only have around 2 million patients in the data set I'm using right now and the average weight is 84+-27kg. That is a HUGE variance and it give no information about the distribution. -- k a i n a w &trade; 12:49, 17 June 2011 (UTC)
 * Obesity is usually determined by body mass index which has numerous criticisms (see the article) but is far better then weight alone. You can find average BMIs for various European countries fairly easily. E.g. . However the OP is apparently interested in weight Nil Einne (talk) 13:41, 17 June 2011 (UTC)
 * This BBC article has figures for America and Britain (wouldn't be such a bad call for Europe, depends how far east you include) that they believe are comparable. Grandiose (me, talk, contribs) 13:15, 17 June 2011 (UTC)
 * I'm not convinced the UK is a good choice to represent Europe since various sources say the UK is one of the highest in Europe  for females. Notably France is on the lower end of the scale (not sure about Germany, I guess it's in the middle since usually not mentioned.) That's for BMI not weight but still seems a bad choice if you want an average European figure. Nil Einne (talk) 13:41, 17 June 2011 (UTC) Edit:  is the study mentioned in the Daily Mail article. It has a lot of data on the BMI of different countries including for Western Europe (as they define it) although is primarily analysing the change rather then just the current figures. 14:05, 17 June 2011 (UTC)
 * (e/c, not significantly.) Well, another article suggested French women - the thinnest - were about 9st11. The BBC article says British 10st3-and-a-half. So perhaps we can refine the average figure to only a little under the British one, perhaps 10st. Depends how accurate the OP needs. That would be around 1st lighter than America (this article actually gives a somewhat higher figure than 11st, 11st10lbs. Grandiose (me, talk, contribs) 14:09, 17 June 2011 (UTC)
 * Well the Telegraph article gives 70.6kg UK women for 2008 (well the Lancet figures seem to be from then). Having said that is also gives 63.5kg for 1980 and I doubt it went from 63.5 to 65 kg in 2001/2002 (BBC article is 2004 but suggests the data is from then) then to 70.6 kg in 2008 suggesting these figures aren't from really comparable.
 * The difference in BMI from the Lancet article (in 2008 26.9 for the UK, 24.8 for France) definitely suggests a bigger difference although we don't know if the average height is the same (but the average height in the Telegraph article and the article on French women's weight is the same, although that article is from 2006). This meanwhile gives 66.7kg for UK women in 2006. I notice some sources are using a BMI of 26.2 for UK women but the Lancet gives this as the 2000 figure (for comparison the French were 24.7 in 2000).
 * BTW if the OP does want to use BMIs, the 2000 figure for US men is 27.7, 2008 is 28.5; 2000 US women is 27.5, 2008 28.3. For UK men 2000 is 26.6, 2008 is 27.4. For French men 2000 is 25.4, 2008 is 25.9. These figures are all taken from the Lancet megareview so are intended to be comparable.
 * P.S. The average weight for US is 71 kg in the BBC article (the time frame is unclear but let's take it as 2001/2002) vs 74.7 kg by the CDC (which appears to be using 2006 figures). In other words, it may be fair to compare the Size figures since they come from a comparable data source but comparing those to other figures is probably not a good idea. In terms of the UK average as a European average, since the data is fairly old it's not quite as bad (since UK women seem to be increasing faster then the French at least) although it's possible/likely? the average weight for French women would be lower then the figures from the above article if comparable SizeFrance figures were used.
 * Nil Einne (talk) 22:30, 17 June 2011 (UTC)
 * I believe this is from the same Lancet survey and fun to look at. --JGGardiner (talk) 06:11, 18 June 2011 (UTC)

Figures for the US from old data must be corrected for inflation: "Americans are not just getting fatter, they are ballooning to extremely obese proportions at an alarming rate." Count Iblis (talk) 15:00, 17 June 2011 (UTC)


 * BMI at least factors in height. It would be silly to compare the weight of tall and short people without factoring in height, and conclude a taller population was fatter just because they weighed more. Americans seem to be bimodal. I see some children and young adults who sit and eat and plump up. If their Mom tells them to "Go play," they sit in front of a video game with a supply of snacks. Others run all the time, go to health clubs, ride bicycles, participate in competitive sports like soccer or swimming, and stay quite thin and well muscled. I suppose if there were a major conventional war, the lard-butts could be drafted to remotely fly combat drones using their well-honed joystick skills. Edison (talk) 15:19, 17 June 2011 (UTC)


 * ...and the healthy ones would be drafted and sent to front line infantry positions. Hmmm, pass the Cheesy Poofs please. StuRat (talk) 18:05, 17 June 2011 (UTC)
 * You might be interested in Drop Bears.5BYv8cUJ (talk) 11:01, 18 June 2011 (UTC)
 * That's supposedly what happened to the French. I used to hear that the Napoleonic Wars shortened the height of the average Frenchman by several inches. (I guess DeGaulle's ancestors were 4-Fs). ←Baseball Bugs What's up, Doc? carrots→ 19:33, 17 June 2011 (UTC)


 * I don't think we should make any assumptions here. There is convincing evidence that adenoviruses are involved - for all we know, obesity is the outcome of some kind of Cold War battle.  There's also epigenetics to consider, which involves some truly fearsome risks that people really haven't considered at all.  If the effects of the easy life are passed on from parent to child, accumulating as methylations or chromatin changes, there's truly a chance that we get to a point in a few generations where children are metabolically prone to unlimited weight gain.  Likewise, we might find over the course of a few decades that some unknown factor added to our environment has led 90% of newborns to be autistic.  Stuff like this could happen, and if it does is almost impossible to predict it, figure out why, or stop it. Wnt (talk) 23:32, 17 June 2011 (UTC)


 * So the Soviet Union won after all? Nil Einne (talk) 01:07, 18 June 2011 (UTC)


 * I don't think that the common cold is usable as a bio-weapon -- it's just not lethal enough. 67.169.177.176 (talk) 04:07, 20 June 2011 (UTC)
 * You must be right, the USSR has made everyone lazy and sit in front of a TV or a computer all day instead of going outside for some physical activity. Or maybe it has more to do with the fact that the TV now has 500 channels instead of 5 and the computer can do more then play pong.  Googlemeister (talk) 15:18, 20 June 2011 (UTC)

Bawris
What are Bawris?Why are these being recieved due to peoples participation? — Preceding unsigned comment added by Rudraksh Parey (talk • contribs) 14:21, 17 June 2011 (UTC)
 * I take it you're not referring to Stepwell? Nil Einne (talk) 14:31, 17 June 2011 (UTC)
 * Seriously, I searched really hard, but I have no idea what you are asking, Rudraksh. Can you attempt to re-phrase your question?- Running On Brains (talk) 18:27, 18 June 2011 (UTC)

Small photography
I am interested in taking photographs of relatively small things. Not electron microscope stuff, but I would love to be able to, for example, take a clear photograph of a single poppy seed at the level so that it took up most of the frame. Can anyone give me a short explanation of the equipment I would need? and any tips? I know this is not very properly a science question, though it is somewhat in the bailiwick, and the miscellaneous desk is in read-only mode (there's a note to that effect when you try to post there). Thanks.--108.14.194.26 (talk) 15:26, 17 June 2011 (UTC)


 * The article on Macro photography might provide some guidance, but you would need a powerful lens to photograph a single poppy seed full-frame. I haven't tried this level of magnification, so await some experts to give tips.    D b f i r s   15:38, 17 June 2011 (UTC)


 * The most critical piece of equipment for macro photography is a macro lens. This is a lens with a short minimum focusing distance; it usually also has a large aperture and short focal length.  Most macro photography guides and tutorials also recommend a very large lens aperture so that you can collect a large amount of light in a short time and control your depth of field.  Many macro lenses also have a short focal length (because this helps frame close subjects and makes it easier to design a short minimum-focus-distance.  On top of this, you may want some "whisker" flash equipment for off-center illumination.  Here's an example of a full kit, the Nikon SB-R1 "Close-Up Flash" system.  If you have a large budget, a full-frame sensor can make a big difference; the optics are much more expensive, but this allows the optics to resolve a more sharp image, which makes a big difference when you are shooting a very close-up object.
 * You don't require any of this for macro-photography; in fact, modern mobile-phone cameras and point-and-shoot cameras usually have wide-angle lenses with ridiculously short close focal distances. (This is an "added bonus" due to their compact size).  But, you can control image quality, lighting, noise, and other photographic and optical parameters much more closely when you switch to a DSLR camera.
 * Personally, I do not shoot much macro-photography, but when I do, I use the (very unconventional) 70-300mm lens on my Nikon D90. My close focal point is about 2 meters away, so it does not appear to be macro-photography; but with the DX crop-factor and 300mm focal length, I actually produce a larger "magnification" (pixels per mm of subject, or "reproduction ratio") than most of the macro-lenses I have compared.  I should also say, the Nikon 60mm "Micro" produces incredibly sharp pictures at close focus; but I don't want to spend 600 dollars on what I consider a "single-purpose" piece of equipment.
 * Here's a great tutorial on macro photography equipment and technique from Ken Rockwell. And, here's an official tutorial from Nikon, Minimum focus distance.  Nimur (talk) 16:25, 17 June 2011 (UTC)


 * "Single poppy seed full frame" is somewhat out of the range of macro photography, and more in the range of microscope photography. While typical micrographs are usually thought of at the 400x/single-cell level, you can also do ~10-40x photography, e.g. with a dissecting microscope. I haven't done any photography with them, but I have used dissecting scopes to examine small object, and you can get good detail without having to do any special preparation. A decent dissecting scope with a camera mount shouldn't be all that more expensive than a decent DSLR macro lens. (P.S. The Refdesk randomly being read-only for IP users is a known issue - usually it can be resolved simply by refreshing the page in your browser.) -- 140.142.20.229 (talk) 16:50, 17 June 2011 (UTC)
 * There's a difference between "full-frame" and "full-frame." In common parlance, full frame means "takes up the entire area of the picture," which is a very useless term - because you can crop any photo so that the subject fully fills the entire crop area.  "Full frame" in photographic jargon means "projects an optical image whose size is equivalent to that projected onto 35-mm film."  This is a much more specific description - it tells you how much optical zoom you have provided; if a poppy-seed fills a full-frame camera, you can calculate the magnification ratio at any given subject distance, and therefore pick the lens focal length you need to do it.  (For example, here's a free online calculator).  And, as seen here, a poppy seed shot through a 50mm macro lense will nearly fill APS-C - no microscope required!  A longer focal length lens will fill full-frame, but you'll have to use every trick in the book to focus (and brightly illuminate) the poppy seed.  Nimur (talk) 17:51, 17 June 2011 (UTC)


 * I second the suggestion for using a microscope with a camera. One potential problem is the vibration created by hitting the shutter button, which can ruin the photo.  This could be handled with a timer that allows time enough for the vibration to settle, or with a remote trigger (wired or wireless). StuRat (talk) 17:59, 17 June 2011 (UTC)
 * Thanks for all the information, everyone. I have printed this out and will check out the external sources and links at my leisure!--108.14.194.26 (talk) 21:49, 17 June 2011 (UTC)
 * As for getting really close, as you said, there are a couple of options. This lens can shoot extremely close (but comes only for Canon mounts). You can also try a macro lens that has a relatively long focal length, such as this or this, and then using close-up filters and tele-extenders to get even closer. And then you can try to make a beast like this or this, with a reverse lens attached to a macro lens. And you can always attach a camera to microscope too. --  T H F S W  (T · C · E) 05:08, 18 June 2011 (UTC)
 * Vibration shouldn't be a big deal for objects on this scale, as long as the microscope mount is pretty stable. I take photos of objects this size all the time, using a good quality microscope at low magnification, and a camera pressed up against the microscope's eyepiece (a cheap clear filter attached to the front prevents damage to the lens). For good pictures, focus the microscope by looking through the eyepiece and keeping your eyes relaxed. Then manually focus the camera at infinity. Disable the flash, of course. Depending on the camera, you may also need to set the exposure manually. You will need a bright light source to illuminate your sample. I use a ring light designed to attach to a microscope.--Srleffler (talk) 16:59, 20 June 2011 (UTC)
 * A good photo of sesame and poppy seeds. See the article Poppy seed. Cuddlyable3 (talk) 14:25, 18 June 2011 (UTC)

Does a Encyclopedia Naziana exist?
Does a Encyclopedia Naziana exist?Smallman12q (talk) 16:02, 17 June 2011 (UTC)
 * Not according to Google. Red Act (talk) 16:36, 17 June 2011 (UTC)
 * Yes and we can be sure that there exists one where Smallman12q is editing :) Count Iblis (talk) 18:29, 17 June 2011 (UTC)
 * To provide a serious answer (as others might be reading this, you know), a four-volume condensed edition of Brockhaus, which contained a considerable amount of information on contemporary German life, was published in 1938 - see . It only merits a passing mention in our article on the encyclopaedia - why, I won't speculate. Tevildo (talk) 19:05, 17 June 2011 (UTC)

Big bang?
Is an expansion of the Universe starting from a point in the "Big Bang" the only explanation of the red shift observed by astronomers? — Preceding unsigned comment added by 84.209.86.125 (talk) 19:19, 17 June 2011 (UTC)


 * No. In particular Hoyle's Steady State theory was proposed to explain the observed red shift. But other evidence rejects the SST, in particular the cosmic microwave background radiation. BBT (or really the set of very similar "universe was once exceedingly small" theories we might collectively call the BBT) also explains the relative preponderance of elements very nicely. -- Finlay McWalter ☻ Talk 19:29, 17 June 2011 (UTC)


 * There is also the tired light theory which has also pretty much been ruled out. Dauto (talk) 20:02, 17 June 2011 (UTC)


 * Incidentally, if you're interested in this kind of thing, I can recommend Simon Singh's book Big Bang: The most important scientific discovery of all time and why you need to know about it. Despite its title, the book is mostly about the evolution of cosmological ideas and the weighing up of evidence that forced paradigm shifts (gosh that sounds boring); it's about why smart people believed wrong things and how new evidence made for better knowing (that sounds better). -- Finlay McWalter ☻ Talk 20:12, 17 June 2011 (UTC)


 * You could come up with alternate explanations, but Occum's Razor comes into play, and thus the simplest theory to explain why everything seems to be moving away from a single point is that it is. StuRat (talk) 23:13, 17 June 2011 (UTC)
 * But any theory is simpler than decompression with a bang of everything from a mathematically singular, physically impossible, MAGICAL MYSTICAL point. Some have thought that dubbing the theory after it was hypothesized "Big Bang" was meant to ridicule its unlikeliness. It is also unfalsifiable. Cuddlyable3 (talk) 12:38, 18 June 2011 (UTC)
 * It's not unfalsifiable; there are many predictions based on the Big Bang theory which can be proven true or false. The reason the theory became so prominent is due to one of these predictions: the Cosmic background radiation. Physicists predicted it should exist, and two radio technicians who didn't even know about this prediction found it. I'd say that's almost the opposite of unfalsifiable.- Running On Brains (talk) 18:31, 18 June 2011 (UTC)
 * Of course, there are many hypotheses on what started the big bang: brane theory, the big crunch of another universe or a scientific experiment by higher-dimensional beings, for example. See also non-standard cosmology. ~ AH1 (discuss!) 15:19, 18 June 2011 (UTC)


 * Big bang cosmology is about the evolution of the universe from an early hot, dense, uniform state of (as yet) unknown origin. It is not about a bang, or a singular point. -- BenRG (talk) 21:31, 18 June 2011 (UTC)

Fixing nesting box on to tree trunk
I've got a wooden nesting box, without any bracket or screw holes. What is the best way to fix it to a tree trunk of about one foot or so diameter? 92.24.136.31 (talk) 21:14, 17 June 2011 (UTC)


 * The RSPB has a page of info about nest boxes here, which says "Fixing your nestbox with nails may damage the tree. It is better to attach it either with a nylon bolt or with wire around the trunk or branch. Use a piece of hose or section of car tyre around the wire to prevent damage to the tree." It also has advice about locations for the box, which varies depending on the species of bird you're accommodating. -- Finlay McWalter ☻ Talk 21:30, 17 June 2011 (UTC)


 * Perhaps bungee cords would work, provided you can find a place to attach the hooks to the box (you may need to drill holes). The flexibility they provide would allow for tree growth.  You'd also want to put the box above where a branch leaves the trunk, so the weight of the box is supported by the branch. StuRat (talk) 23:03, 17 June 2011 (UTC)


 * And please make sure it is in shade or faces north, otherwise the chicks can roast to death on a sunny day. If you live in the northern hemisphere there is not much point in putting it up before next year.--Shantavira|feed me 10:41, 18 June 2011 (UTC)


 * We hung them in scouts using hanger wire and did it in the fall. I am sure the birdds will not mind when the boxes are hung so long as they are hung before they nest.  Bungee cord is ugly and expensive. μηδείς (talk) 02:11, 20 June 2011 (UTC)

How should I attach the wire to the boxes themselves? 92.28.240.2 (talk) 09:27, 20 June 2011 (UTC)

Detection of light at great distance
Hi. Suppose I have an automatic gun on a rotating turntable, firing ten rounds a second or something. If I stand some distance away, then (ignoring all "indirect" evidence like sound and sight) I can only detect that the gun is firing if I happen to be standing in the right place so that a bullet actually hits me. On the other hand, if someone drops a rock into the middle of a pond then I can, in principle, detect the ripples anywhere on the perimeter of the pond at any distance.

OK, so now suppose I sweep a torch across the heavens. Would anyone along that path, say in a distant galaxy, be able in principle to detect the torch, like the waves in the pond? Or would only those lucky people hit by a photon be able to detect it, like the turntable gun? If the latter, then "what happened to the light waves in the gaps"? 86.160.209.60 (talk) 22:00, 17 June 2011 (UTC)


 * I believe light behaves like a particle in this instance. That is, the distant planet would have to be lucky for one of the photons from your flashlight to reach it.  We have dim objects in space that our best telescopes can only detect as an occasional photon, but a computer (or previously long exposure film) can eventually form an image out of those individual photons.  As for why light is sometimes a particle and sometimes a wave, or how you can predict which it will be at an given moment, I'm clueless there, and I don't think I'm the only one. StuRat (talk) 22:55, 17 June 2011 (UTC)


 * It is not uncommon for a single photon to act like a circular wave, yet be detectable in only one place. See the classic double-slit experiment.  One single photon, emitted from a source, moves through two slits, interfering with itself like a wave, as evidenced by the probability of detecting it varying according to wave interference.  Yet it's just one single photon that lands in one single spot. Wnt (talk) 23:26, 17 June 2011 (UTC)


 * Can a single photon interfere with itself? I thought the interference only built up with many photons. [ignore that; I didn't properly take on board your "as evidenced by..."] But carrying on from what you say, does that mean that anywhere along the torch's sweep you have some probability of detecting a photon -- but whether you will or not at any given place can be determined only by trying to detect one, rather than it being (in principle) pre -determined from the moment the light left the torch (as is the case in the bullet analogy)? Does that question make sense? 86.160.209.60 (talk) 00:32, 18 June 2011 (UTC)


 * Well, that's where thing gets weird. On countless planets across the universe, people look up, waiting for that first photon your torch emitted.  But only one shall find it.  The photon has not decided, before it has been seen, where in the cosmos it might be.  And yet once it decides on the world of its choice, all those countless others will look up in vain.  One way to put it is that the state vector "collapses"; the detection removes the chance of it being detected anywhere else by a "spooky action at a distance".  It is faster than light transmission of information, in a sense - the catch being, no one can say in advance where it will be found, so there is no predicting the information to be transmitted - just like with entangled particles.  I am more fond of the transactional interpretation in which the detection sends a wave backward in time to match the first. Wnt (talk) 06:47, 18 June 2011 (UTC)


 * Thanks Wnt, your answers have been very ... ahem ... illuminating. 86.160.222.31 (talk) 11:19, 18 June 2011 (UTC)


 * The only reason you can detect the ripples on a pond is due to what you call "indirect evidence" (in this case, light reflecting from the ripples and reaching your eyes). Take this away (say, drop the rock into the water on a really dark night, or when blindfolded) and you'll only be able to detect them by actually dipping some part of your body into the water and feeling the ripples on your skin. Same thing with your flashlight -- the only way anyone can detect it is either if they're in the path of the beam, or by seeing light that has been scattered by the atmosphere. Also keep in mind that even in the absence of any scattering or absorption, the light will spread out and therefore decrease in intensity as the inverse-square function of the distance, so that even by the time it reaches the Moon, it will be so dim as to require advanced sensors for detection. -- An American ultranationalist 67.169.177.176 (talk) 23:30, 17 June 2011 (UTC)

NOTICE to whomever it may concern. It has come to my attention that your intra- and intergalactic electromagnetic intercourse may be impinged by radiations emanating from this planet on which I have assert right of occupancy as a partial spherical-polyhedral wedgeholder. I wish to assure you that no such radiation, coherent nor pulsed, is authorized as a communication by me nor is it emitted on my behalf. As a representative of decent humans I beg to offer apology for any inconvenience, and trust that no unpleasant misunderstanding will marr the mutual cordiality of our relations as neighbours. Klaatu barada nikto. Cuddlyable3 (talk) 14:12, 18 June 2011 (UTC)