Wikipedia:Reference desk/Archives/Science/2013 February 1

= February 1 =

what's the issue with horsemeat?
I don't get what the issue is with horsemeat being found in burgers. I used to be a strict vegan, but have had massive health problems that I started focusing on, and I basically eat a lot of meat now. I don't see how a horse is any worse than the modern factory farm meat in burgers - in fact if the source is like stables, aren't the horses a lot better take care of? I mean, culturally I would understand if it were dog or cat or rat or racoon/skunk or whatever, but there's no unpleasant cultural associations with horses nor are they dirty or anything...

so, what's the big deal about horse meat being found in burgers? is it dangerous or unsavory or anything else? 178.48.114.143 (talk) 04:30, 1 February 2013 (UTC)
 * Horses are cute and useful. -- Jayron  32  04:35, 1 February 2013 (UTC)
 * Here is a link to an editorial that discusses it. It has plenty of further links within. It is cultural, though. Horsemeat is available in plenty of places. I myself once ate Horse Sashimi in a local restaurant in Vancouver. Bland, I must confess. Maybe if it wasn't raw...
 * As for Jayron's reply, from what I gather from my link above and the links in it, he about sums it up. Mingmingla (talk) 04:39, 1 February 2013 (UTC)
 * (ecx2) I think the general objection to the consumption of horses is similar to that usually raised against eating cats, dogs, and other animals commonly thought of as household pets (in the US, anyway). While there isn't necessarily a meaningful objective difference that makes cows any more deserving of slaughter than any other mammal, there is a difference in the way people perceive the animals. To put it simply, people tend to bond with horses more often and more deeply than they do with cows. That's not to say that there isn't the occasional person who has an emotional bond with a cow, but it is certainly rarer than the horse/rider relationship. Just about every young girl in the Anglosphere has at one point wanted to own a pony. The same cannot be said about cows.
 * Beyond that, and extending outside the sphere of people who have ever been within fifty paces of a horse, is the cultural issue. Essentially globally, every person grows up with the idea that certain animals are eaten, while others are work animals or merely exist in the wild. Domesticated horses are almost always worth more as work animals or transportation than they are as food; it just isn't cost-effective, generally speaking, to raise horses for food when they could be plowing a field of performing other farm work for a significantly longer duration. While this isn't much of an issue in the industrialized world, it was for a long time, and the cultural idea of horses as "animals we don't eat" likely grew out of this distinction. Now we just have to wait for someone to pony up some references. (I'm sorry...) Evanh2008 (talk&#124;contribs) 04:43, 1 February 2013 (UTC)


 * (COI declaration - I'm vegetarian.) There is also the issue that the horsemeat in question was from an unknown source, and as such quite probably never passed as fit for human consumption. AndyTheGrump (talk) 04:46, 1 February 2013 (UTC)
 * That's a factor, and correlating with earlier comments, horses are considered useful, so when they get old and no longer useful, they might be sent to the glue factory or whatever, with their meat typically directed towards the pet-food makers. So, to humans, their meat might be considered unsavory for various reasons. I'm not sure I'd be keen on eating meat from a steer that was close to dying from old age, either. ←Baseball Bugs What's up, Doc? carrots→ 05:12, 1 February 2013 (UTC)
 * Rabbit. I think in the USA rabbits are considered cute pets and nobody eats them? But they are so tasty, and their meat is so healthy because it's fat free. European doctors recommend eating rabbit meat. --Enric Naval (talk) 05:39, 1 February 2013 (UTC)
 * In the U.S., rabbits aren't usually "supermarket" meat sources, but they are certainly not unknown as meat sources. I've eaten rabbit in the U.S., I had hasenpfeffer in a Chicago restaurant once, and I know of butchers here in Raleigh, NC that carry rabbit.  So, it certainly exists, unlike horsemeat, which I have never seen sold commercially in the U.S.  I'm sure you could get it somewhere, but I've never seen it.  -- Jayron  32  05:58, 1 February 2013 (UTC)
 * Try in specialized food fairs. Here in Spain I find several small artisan shops that sell hams and paté made of deer and wild boar (boars are typical of the zone, both meats are considered a rarity and capricious), and there is always one selling horse ham. If horse slaughtering is forbidden in the US, then all horse meat will have to be imported. No local small shops will be able to manufacture it locally, and it will be more difficult to find it. --Enric Naval (talk) 09:25, 1 February 2013 (UTC)
 * Neither venison nor boar is particularly rare in the U.S. They're both very common game meats; anyone who has ANY friends at all that hunt have been subject to about 1000 different venison dishes.  Deer are hunted in just about any part of the U.S., boar where they are plentiful including Florida and Texas.  -- Jayron  32  14:01, 1 February 2013 (UTC)
 * About that editorial: It's possible that the "purists" think steak tartare should be made from horse meat, and it's true that steak tartare is called filet americain in Belgium, but I can assure readers that "filet americain" does not contain horse meat. Ssscienccce (talk) 12:24, 1 February 2013 (UTC)
 * My brother encountered filet americain in a village on the French-Belgian border about 20 years ago. We'd never heard of it, and expected it to be a beefburger. He couldn't finish it. Years later, I was in Sweden, eating some smorgås with friends, and I remarked 'this beef's very sweet', only to be told 'that's not beef, it's horse'. It was delicious (unlike the filet americain) but I was still a little shocked, as Brits really don't eat horse. I'm now a vegetarian, and my brother nearly so. I'm not sure quite why people are more averse, in general, to eating horses than eating cows, as city-dwellers who almost never see either animal alive. There's a folk-theory about the sacredness of horses to the ancient Celts, but I'm not sure it's well-founded. AlexTiefling (talk) 13:11, 1 February 2013 (UTC)
 * The main issue is actually that the label at the front and the ingredients at the back are supposed to be accurate. It doesn't matter if it is healthy or not, you must only put in the food what is written in the ingredients. This only enables people to choose what they want to eat. If supermarkets start to break this rule, then how can you trust the halal sausages? How can you trust that the vegetarian burger is really vegetarian? How can you trust that their nut-free or gluten-free products really as they say? It is a wider question of trust in your provider. --Lgriot (talk) 10:17, 1 February 2013 (UTC)
 * The news talks about "very small trace levels" of horse DNA; Anyone more details about the exact amount? I'm wondering how many different DNA samples (how many cows) would be present in a typical burger. Ssscienccce (talk) 13:27, 1 February 2013 (UTC)
 * Actually the biggest problem probably was that one of them was estimated to have 29% horse. (From what I heard, for most of the others there was only trace amounts that could arise from processing with the same equipment.) Nil Einne (talk) 13:39, 1 February 2013 (UTC)


 * The right to know what you're eating is one factor, as others have discussed above. A second is, as AndyTheGrump says, whether the horseflesh is fit for human consumption; it's fair to say if a meat supplier can't accurately tell you what species his meat is (and some of the affected burgers were also contaminated with pork) it's reasonable to have doubts about his control and knowledge of his supply chain from a food safety perspective. BBC Radio 4 had a programme last week (it may have been File on Four) about the world horse meat trade. It said that much of the consumption was in Belgium, France, Italy, and to a lesser extent Germany. There are a lot of horses produced in the US and Canada, for sporting purposes, but these countries have a very low consumption of horse meat. So when sport horses are retired, many are exported (by means of a series of intermediaries) to Europe (with slaughter and freezing done in Mexico).  The concern is that racehorses are often treated with drugs like the anti-inflamatory phenylbutazone; doing this renders the horse's meat unfit for human consumption (phenylbutazone causes aplastic anaemia, and may be carcinogenic, in humans). So a racehorse treated with phenylbutazone ("bute") should never be introduced into the human food system, and instead should only be sold for dog and cat food. But as horsemeat for human consumption is much more valuable than for petfood, there's a risk that one of those middlemen will alter the paperwork and declare the horse wasn't treated with bute. This AP report says none of the burgers detected in Ireland showed evidence of bute, but given that the contamination may have been going on for a year or more, the suppliers really can't honestly say they're confident where their horsemeat came from or what's in it. -- Finlay McWalterჷTalk 13:53, 1 February 2013 (UTC)


 * I find myself skeptical of this explanation. Phenylbutazone's article says that there is insufficient evidence of carcinogenicity at effective doses in humans, let alone as a minor food contaminant, and I would expect the same of the anemia (after all, it was used for some time as a human drug).  There is just a tremendous pseudo-religious intolerance toward all sorts of alternate food sources in the U.S., as surely as there is to the clothing of other cultures. Wnt (talk) 15:18, 3 February 2013 (UTC)

Gravity waves caused by a relativistic object
Let's say you have an object like an asteroid that is the size of Texas. But let's say this asteroid is moving at a relativistic velocity (very close to the speed of light). If it passes by earth, would the gravity waves be larger than if the asteroid were moving at a "normal" speed? If this is correct, then the gravity of the asteroid should be a factor of its rest mass plus its relative velocity? But if you were standing on the asteroid, the gravity should only be a factor of its rest mass, since relative velocity is zero. So doesn't this suggest that gravity also has a relative factor? ScienceApe (talk) 06:28, 1 February 2013 (UTC)


 * The gravitational field about any object is dependent not only on its mass, but also on its linear and angular velocity. However, it is not as simple as applying a gamma factor, as the field about a moving object is not uniform. I am not competent in general relativity, so that's all I can give you. Someguy1221 (talk) 06:34, 1 February 2013 (UTC)


 * I think it's similar to the electromagnetic field of a moving charge. The electric (resp. gravitational) field lines look like a Lorentz-contracted version of the usual field lines, so the field is stronger perpendicular to the motion by a factor of gamma. The magnetic (resp. gravitomagnetic) field looks like the magnetic field of a current-carrying wire except that it falls off in front of and behind the charge. Like the electric field it doesn't lag the charge, contrary to what you might expect. -- BenRG (talk) 19:02, 1 February 2013 (UTC)
 * I'm not very sure about what I wrote above. There may be an extra factor of gamma in the GR case. -- BenRG (talk) 19:34, 1 February 2013 (UTC)


 * Also, an asteroid moving at constant speed doesn't produce gravitational waves. They must be accelerated in order to produce them. Note that gravity waves are an entirely different thing. Dauto (talk) 19:19, 1 February 2013 (UTC)

Coffee and smell
I've heard on various occasions down the years that coffee grounds/granules absorb [bad] smells. The effect is supposedly more than just a nice smell overlaying any bad smells. Is this just an old wives' tale? --Dweller (talk) 09:34, 1 February 2013 (UTC)
 * The idea seems plausible, ground coffee can be used to make activated carbon, but even without activation ground coffee has a large surface area that could adsorb chemicals. Surface area is still several orders of magnitude smaller, but activated carbon used in industrial processes has to adsorb much larger quantities of gas. Ssscienccce (talk) 12:56, 1 February 2013 (UTC)


 * Here is a discussion of this on the Straight Dope discussion board.
 * Here is Heloise's advice.
 * Here are some actual tests done by real scientists. Alas, they did some extra processing (Add zinc chloride, baked it at 800 degree Celsius / 1,472 degrees Fahrenheit) which sounds a lot like making charcoal.
 * --Guy Macon (talk) 13:18, 1 February 2013 (UTC)

Armour and Antiarmour IV
I′m sorry because I′m writing my contributes seperated from each other because I don′t know how to edit a page but relating to what we were talking about from yesterday I conclude that tanks are necessary for offensive operations, antitank weapons are -mainly- defensive weapons , tanks armour is still being upgraded , tanks will remian the main weapon for ground forces. — Preceding unsigned comment added by Tank Designer (talk • contribs) 13:47, 1 February 2013 (UTC)


 * To edit a previous question, find it on the page and click the "[edit]" link to the right of the header. I would suggest the following revisions to your conclusions:
 * For the first, tanks remain a useful option for offensive operations. They are not necessary, as can be easily demonstrated via any modern offensive that didn't use them. Depending on the operation, they may even be a hindrance.
 * For the second, only if you mean strictly man-portable anti-tank weapons. Vehicular (tanks) and airborne (attack helicopters) anti-tank weapons absolutely have offensive capabilities to match their defensive ones. I'd still question "mainly" in the infantry case -- mostly for a discussion of "mainly intended for" vs "mainly used for".
 * For the third, yes. Note also that a major area of research is active anti-missile defense (i.e. shooting down the anti-tank missile before it reaches the tank). Does that really constitute "armor"? I don't know, but it certainly plays into the discussion of whether tanks remain viable on the battlefield into the future.
 * For the last, tanks probably aren't vanishing in the near future, but that doesn't guarantee that they will be "the main weapon". As noted in prior discussions, tanks haven't played a primary role in Afghanistan over the past 10 years. &mdash; Lomn 16:12, 1 February 2013 (UTC)

Weight of motor
what is the weight of a Starboard crane hydraulic motor — Preceding unsigned comment added by Chibuikeone (talk • contribs) 14:04, 1 February 2013 (UTC)


 * ( I've given this question its own section and title ) SemanticMantis (talk) 15:44, 1 February 2013 (UTC)


 * Can you tell us the make or model of the crane? The type or class of boat? Otherwise, I don't think we have enough information to give you an answer. SemanticMantis (talk) 15:49, 1 February 2013 (UTC)

Sound, density and bulk modulus in the upper atmosphere
Hi. This problem has intrigued me since a recent physics lecture. I have always assumed that sound travels faster in the lower atmosphere, slower in the upper atmosphere, faster in water, and faster still in solid objects. However, as I recently learned, a medium's volume density is inversely proportional to the speed of sound in the medium, while the Bulk modulus, which is higher for incompressible fluids, is positively correlational to the sound speed. This confused me: what would happen if the pressure was so low that the molecules were too far spaced apart for sound to transmit quickly? I was told that the theory and the model breaks down. What happens when it rains? And now, I just have one more question:

At what milibar height in the atmosphere does sound transmit the fastest, if it is not at the surface, prior to the molecules being spaced too far apart to transmit sound effectively? My first guess would probably be somewhere near the mesosphere or tropopause. Thanks. ~ AH1 (discuss!) 17:19, 1 February 2013 (UTC)
 * At very low particle density in gasses, you start to run into the issue of low signal to noise ratio and the best explanations of the limits of sound are best understood from the point of view of information theory more than anything else. Essentially, the medium doesn't have enough information carriers (particles) to effectively preserve the signal (sound) over that of the background noise (random motions of the particles).  As the mean free path of particles goes up, the number of collisions goes down, and thus the ability to transmit sound reliably also goes down.  This is something kinda-sorta like shot noise as it applies to light transmission, except that particle models of sound energy only work well in condensed matter (like solids and liquids, see phonon).  Gases, because of their very different organization, need to be understood differently.  -- Jayron  32  17:26, 1 February 2013 (UTC)
 * If I understand that correctly, though, it means that there is no actual limit. To get any desired arbitary signal to noise ration, one merely has to employ a sound emitter or micrphone diaphram of sufficient area.  That is, the harder the vacuum, the bigger the transducer area required.  It is analogous to the use of radio vacuum tubes in low noise amplification - one can achieve any desired signal to noise ratio (which is set by electron shot noise) by using a low enough source resistance and a tube with a big enough electron emission area (neglecting certain other practical circuit factors).  Wickwack 60.230.221.94 (talk) 03:35, 2 February 2013 (UTC)
 * True, but all you're doing is using a bigger signal: that's how you conquer the signal-to-noise ratio problem in almost any application. Using a giant transducer gives you a bigger signal cross section, which counteracts the lower particle density.  Of course, the relationship quickly becomes impractical, as there comes a point when the size of the transducer becomes a real physical limitation.  A speaker coil the size of the earth is kinda hard to drag around.  -- Jayron  32  04:48, 2 February 2013 (UTC)
 * This might help. It's quite near the stratopause. Dncsky (talk) 18:52, 1 February 2013 (UTC)

SETI
Suppose there is an advanced non-human civilization somewhere in the Milky Way. They have technologies similar to ours and they have the same power of the radio emissions. Like a copy of the present-day Earth with TV-Stations etc, but far far away.

How far away can they be to be still detectable from Earth? (we use only present-day instruments to detect transmissions; they don't use active SETI) --Blacknight87 (talk) 18:22, 1 February 2013 (UTC)


 * For an earlier discussion which did focus on active SETI, see WP:Reference desk/Archives/Science/2011 December 30. -- ToE 20:35, 1 February 2013 (UTC)


 * One thing you need to be careful of in such questions is "when is now" ? If this other civilization has our technology now, then, when our signal gets there, it will be years, decades, centuries, or millennia later, so their technology will have advanced.  Do you mean to ask about a civilization which has our level of technology, when the signal arrives ?  (Or, in the reverse case, a civilization which had our level of technology, when they sent a signal arriving on Earth today.) StuRat (talk) 18:28, 1 February 2013 (UTC)
 * Like they had our level of technology X years ago and they are exactly X light years from us --Blacknight87 (talk) 18:31, 1 February 2013 (UTC)
 * From the Fermi paradox article: It should be noted however that even much more sensitive radio telescopes than those currently available on Earth would not be able to detect non-directional radio signals even at a fraction of a light year, so it is questionable whether any such signals could be detected by an extraterrestrial civilization. Don't know if this is true for all signals. Ssscienccce (talk) 19:13, 1 February 2013 (UTC)
 * Active SETI has used radio telescopes to send directed messages. These will be much stronger, but I can't find details about the strength of the signal. Those radio telescopes have been used as radar to track planets, asteroids and other objects; those radar signals could also be detected, but again, I don't know how far. Ssscienccce (talk) 19:27, 1 February 2013 (UTC)


 * From, the Square Kilometre Array being presently developed (operational circa 2025), will be capable of detecting signals equivalent to airport radar at a distance of 50 light years. Aside from Active SETI, and other directional deep space transmissions, radar systems emit some of the strongest radio signals on Earth, and hence are a much better candidate for a detectable signal than something like a TV broadcast.  So, in the not-too-distant future it would appear that we will be capable of detecting a civilization like ours out to 50 light years.  Dragons flight (talk) 19:40, 1 February 2013 (UTC)


 * Related: http://wiki.answers.com/Q/How_many_stars_within_50_light_years_from_earth --Guy Macon (talk) 20:55, 1 February 2013 (UTC)


 * I think I read that Arecibo Observatory would be able to detect a similar transmitter about 100 light years away. Bubba73 You talkin' to me? 03:09, 2 February 2013 (UTC)


 * We need to find some references - I read (admittedly several years ago) that our most sensitive radio telescope would be unable to detect our most powerful radio transmitter at a distance of 4 lightyears (ie at the nearest star system to ours)...which would mean that the answer to our OP's question would be a definite "No". However, I don't recall where I read that...so I'll defer to your suggestion if you can recall where you read it! SteveBaker (talk) 03:16, 2 February 2013 (UTC)


 * We should be able to calculate it for Arecibo by how strong of a signal it camn transmit and how weak of a signal it can receive. Bubba73 You talkin' to me? 04:31, 2 February 2013 (UTC)


 * The range for a hypothetical Arecibo-to-Arecibo communication has been calculated. The most oft-quoted number comes from Frank Drake (widely known as the creator of the eponymous Drake equation) and comes in at about half the width of our galaxy.  I can't readily find an online copy of Drake's calculation, but this page uses a similar approach and shows how the number changes with different assumptions.  The pessimistic number is closer to 10,000 light years; the optimistic number (which incorporates some relatively minor and readily-available upgrades to Arecibo's equipment) is good for detection across the full width of the galaxy: roughly 100,000 light years.
 * That said, those numbers are for detection and not for communication. One could confirm the presence of a signal, but not transmit much data; the integration times used in the above calculations fall between 2 and 6 hours, so you're looking at a few bits per day, at best.  (The ability to detect a signal improves with the square root of integration time; with a one-second integration time rather than a two-hour (7200-second) integration, the range is reduced by a factor of about 85, and we're down to exchanging data with our neighbors within a hundred or so light years.)  TenOfAllTrades(talk) 16:55, 2 February 2013 (UTC)


 * Thank you, those are interesting details. Bubba73 You talkin' to me? 17:28, 2 February 2013 (UTC)


 * Yes, but those numbers are for a highly directional transmitter and a highly directional receiver. I think the statement I heard was in the context of an omnidirectional transmitter and a directional receiver, or vice-versa which is a more likely case for SETI. SteveBaker (talk) 14:02, 4 February 2013 (UTC)