Wikipedia:Reference desk/Archives/Science/2017 April 22

= April 22 =

Making big chicken breasts
How do people make big chicken breasts? I don't get why a whole chicken's breasts look small while packaged chicken breasts look huge, and they are boneless and skinless! How do people make such big boneless chicken breasts? 50.4.236.254 (talk) 00:42, 22 April 2017 (UTC)
 * How much reading do you want to do?
 * Here's Small Poultry Flocks from Texas A&M, including discussion of raising, feeding, slaughtering, and packing chicken in low volume.
 * Many years ago, I toured a chicken slaughterhouse - ISO 22000-compliant - and the answer to almost all of your chicken slaughter and packaging questions, in a modern developed industrial nation, will generally be "robots." Robots slaughter the birds, clean, scald, and defeather the birds, cut the major parts of the birds, brine the birds, (which causes the meat to swell up and look nice and juicy before they put it in plastic wrap at a store) ... I was astonished how very rarely a human was required to touch the live animal, the carcass, or the meat.  Of course, in some places, there's still a lot of manual labor in meat processing.  The great read, A Nickel's Worth of Skim Milk contains descriptions of home-raised, home-slaughtered chicken in the central United States during the Great Depression, when a lot of people grew their chickens in their own back yard because the economics worked out to be more cost-efficient.
 * The process of food-processing - in small scale or in industrial scale - is a fascinating topic. When I was a younger student, I used to hang around at the Poultry Science Department and read books in their library.  You can find volumes on the care and feeding and preparation of chickens, if that sort of thing interests you.  You can get advanced graduate degrees in chemical, biological, and agricultural sciences.  You can make a souped-up, plump, healthy, safe, and delicious bio-chemico-chicken, and you do the same using "organic-" methods (whatever that even means!)  Have you reached out to your local state university's agriculture outreach cooperative extension?  Here's Agriculture and Natural Resources from The Ohio State University, and they surely publish a lot of locally-relevant information about the way chickens are raised, prepared, and retailed in your state.
 * Nimur (talk) 01:14, 22 April 2017 (UTC)
 * Poultry science department? There is a science department just for bird meat? 50.4.236.254 (talk) 01:24, 22 April 2017 (UTC)
 * Indeed, I went to school at North Carolina State University, and we had a Department of Poultry Science. There is probably one such department in your local university, too.  The broiler industry is a multi-billion dollar business employing large numbers of laborers, business-people, scientists, engineers, financial investors, and  so on.  Just in North Carolina, there are something like one billion agriculturally-raised birds, bringing in something like four billion dollars of revenue and generating many billions of more dollars in peripheral agricultural economic impact.
 * Through education, food production has become so well-refined as an art and science and business that you didn't have to catch and kill a chicken in your backyard this afternoon. Have you ever asked your elders if they have any stories about that?
 * And, bonus question - for fun and profit - if one billion birds yields four billion dollars of revenue - then, since you're surely great at math - can you figure out a way to raise an entire chicken, over its entire adult life, bring it to slaughter weight, and sell it for four United States dollars, and make money doing it? Suddenly, the problem doesn't seem so easy, huh?
 * Nimur (talk) 01:29, 22 April 2017 (UTC)


 * This means a profit of $4 per bird over the cost of raising and selling them, not a total sale price of $4/bird. μηδείς (talk) 02:11, 22 April 2017 (UTC)
 * Oh, is that so? Nimur (talk) 02:41, 22 April 2017 (UTC)
 * Our article on revenue is pretty clear that it is not equal to profit. Revenue is sales; profit is sales minus costs. Matt Deres (talk) 12:50, 22 April 2017 (UTC)
 * Never mind, for some reason I was thinking of turkeys. I can easily see a $4 revenue on a chicken.  But they only take a few months to mature. μηδείς (talk) 17:38, 22 April 2017 (UTC)
 * They actually reach slaughter weight at 5 to 6 WEEKS. DrChrissy (talk) 17:44, 22 April 2017 (UTC)
 * NC State University has a College of Agriculture and Life Sciences, so it stands to reason they would have departments on various types of agricultural plants and animals. According to this, NC State is one of six universities in America that happens to have a poultry science department. ←Baseball Bugs What's up, Doc? carrots→ 01:42, 22 April 2017 (UTC)
 * Here is a list of the departments in NC State's ag school. ←Baseball Bugs What's up, Doc? carrots→ 01:46, 22 April 2017 (UTC)
 * I expect that about every state that has at least one Morrill Land Grant university has a corresponding agriculture extension program. That would be ... every state in the Union, and Puerto Rico.  Some might not break the departments up in the same way, but if you eat chicken in your area... your state probably sponsors education on poultry science.  Nimur (talk) 01:52, 22 April 2017 (UTC)
 * The University of Illinois has a strong ag program as well. You may find it interesting reading. ←Baseball Bugs What's up, Doc? carrots→ 01:50, 22 April 2017 (UTC)
 * Turkeys are no slouches either: "Companies involved in the production and processing of turkey provide 374,600 jobs that pay $21.4 billion in wages to families throughout the country, generate about $97.5 billion in annual economic impact, and about $7.5 billion in taxes." Bus stop (talk) 01:57, 22 April 2017 (UTC)
 * By golly! (Gobbley?) Those turkeys create more jobs and pay more taxes than that turkey in the White House!  Nimur (talk) 15:18, 22 April 2017 (UTC)
 * Several of these poultry science departments and their equivalents around the world look at fundamental issues such as the the welfare concerns that are raised by creating these large breasts. See Broiler. DrChrissy (talk) 16:49, 22 April 2017 (UTC)


 * Are you sure the breeds of chicken you're seeing alive and whole are the same breeds you're seeing in shrink-wrap in the supermarket?
 * Here's a research paper about the type of chicken you'll find in the supermarket. Check out the illustration on page four.
 * That 1978 breed looks very similar to every live chicken I've ever seen up close. ... But look at that 2005 breed! It's huge! No wonder you can get such large chicken breasts in the store. ApLundell (talk) 08:44, 23 April 2017 (UTC)
 * And don't forget that photo was taken in 2005 so we have had a further 12 years of artificial selection since then. It may be of interest to some that the broiler industry follows a selection principle of "one day per year".  This means they are selecting and breeding for birds that reach their slaughter weight one day earlier each year.  It's hardly surprising they look nothing like layer hens which are the same species. DrChrissy (talk) 17:15, 23 April 2017 (UTC)

Would sleep deprivation, weed or drunkness change an eyeglass prescription?
Assuming ability to tell 1 or 2 is better is still there. Not that I plan to get glasses while sleepy, drunk and stoned. Sagittarian Milky Way (talk) 13:31, 22 April 2017 (UTC)


 * I am very short-sighted. I am aware that when very tired the eye muscles seem weaker, and focusing properly becomes much more difficult. That could have an effect during an eye test - if very tired you might end up with lenses which are slightly too strong for normal use. I cannot comment on drugs or alcohol - I don't use either. Wymspen (talk) 14:30, 22 April 2017 (UTC)


 * Marijuana definitely has a temporary effect on focus, which I can tell you from repeated direct experience. The reason it is prescribed for glaucoma is its effect on the pressure of the eye. μηδείς (talk) 17:30, 22 April 2017 (UTC)

Time travel paradoxes
Has it already been proposed that there would be no butterfly effect in time travel paradoxes because the present already occurred once and still exists with everyone else, independently of the traveller, while he is in the past? Particularly, in the grandfather paradox, all his offspring would continue to live in the present, without magically dying at the moment when he is killed in the past. This would also imply that if Hitler is killed in the past, the present where everyone, except the traveller, is living would also remain unchanged, because it's already a post-Hitler present. If, however, the time traveller decides to stay and live in the past, this entails some sort of parallel universe or spacetime where he would face a different outcome. Brandmeistertalk  14:24, 22 April 2017 (UTC)


 * Scientific arguments against fantasy seem so very pointless. Its already a contradiction to reality. Why should one try to argue further about contradictions inside such madeup fakelogic? Even the commonly cited parallel universe is a “a bunch of malarkey” realy. --Kharon (talk) 16:24, 22 April 2017 (UTC)


 * The notion of backwards time travel is strictly fictional, so you can make up any hypotheses you want to. ←Baseball Bugs What's up, Doc? carrots→ 16:25, 22 April 2017 (UTC)


 * See Time_travel. No one yet confirmed it's "strictly fictional". But that's offtopic. Brandmeistertalk  16:31, 22 April 2017 (UTC)


 * I believe the grandfather paradox proves that changing your own past is impossible. However, there's nothing in that to prevent going to another timeline identical to your own, and changing that.  The many worlds hypothesis suggests that all possible universes should exist, including those just like ours but in the past by some period, but actually getting there is the part we have no clue about. StuRat (talk) 17:56, 22 April 2017 (UTC)


 * It is certainly good evidence that time travel is impossible. However a lot of things have been thought to be impossible and yet are true, physics seems somehow to be able to get through cracks in our logic. See for example the strange case of Quantum pseudo-telepathy. What they do is just simply impossible in classical physics. Dmcq (talk) 19:23, 22 April 2017 (UTC)


 * The need to cook up ways to get around the paradoxes is a good indication of why backwards time travel cannot work. One of my old math teachers liked to say, "If you start with incorrect assumptions, you're liable to get 'interesting' results." Starting with the assumption that backwards time travel is possible leads to absurdities. ←Baseball Bugs What's up, Doc? carrots→ 20:58, 22 April 2017 (UTC)


 * Well there already is a version that does work in Quantum mechanics and is a bit like the grandfather paradox, see Delayed choice quantum eraser. Dmcq (talk) 23:05, 22 April 2017 (UTC)


 * It's simpler to take the view that time doesn't exist in the sense that we tend to think about it in our daily lives, see e.g. here. You existing now, yesterday and tomorrow are just separate realities that exist in their own worlds. It's not that one world "evolves" into another world. It's just that given the information that describes the local state near some point in one world, we can compress that information in terms of information present locally in another world, and in turn information in that other world can be compressed further in terms of information present in yet another world etc. etc. We can do this in a continuous way, which yields the illusion of a time evolution. Count Iblis (talk) 19:28, 22 April 2017 (UTC)


 * Well it's nice to be so sure but I don't think the Measurement problem and how that relates to our reality has been at all satisfactorily solved yet. And information is conserved in Quantum mechanics, you can't compress it. Dmcq (talk) 22:54, 22 April 2017 (UTC)
 * Iblis thinks Slaughter-House Five is a documentary. --Trovatore (talk) 23:04, 22 April 2017 (UTC)
 * Information is conserved in unitary QM, so you need to keep track of all sectors of the wavefunction here. Whether you believe in collapse interpretations or subscribe to the MWI doesn't matter here. So, if you prepare a spin polarized in the x-direction and I measure the z-component, then my measurement outcomes do not contain any more information than was in the original state, but here you consider information present in the probability distribution over all possible outcomes. But if we focus on a particular branch of the wavefunction where I find a definite outcome, then I need to specify one bit of information more to specify my measurement outcome. Both in the MWI and in collapse interpretation this is true, in the former case this is to specify which of the two copies I happen to be, in the collapse interpretations this is to specify which way the wavefunction has collapsed (you then assume that the other branch doesn't exist).


 * Now, all the sectors together are the same as the original state up to a unitary transform, and that unitary transform can be re-interpreted as a change of basis in Hilbert space. Therefore what we experience as time evolution which inevitably has to involve gaining information (if I feel that a second has passed then that feeling can only exist due to information that wasn't there a second ago), which must be identified with us getting located in a narrower sector of Hilbert space. So, it's then not the unitary time evolution that is involved here, rather that our time evolved versions exist in sectors that can be found by expanding in a new basis and then finding the components in that new basis. Count Iblis (talk) 00:17, 23 April 2017 (UTC)


 * There's only one answer for what happens at a given point in spacetime. Those who have suffered precognition have reason to appreciate that there is only one future, and while it may happen "because" it was seen, it won't be changed. Wnt (talk) 01:55, 23 April 2017 (UTC)


 * A lot of people here are dodging the question and instead making pretty absolute, unreferenced statements on topics that the greatest minds of several generations have failed to find a consensus on.
 * The answer to the question asker's question is : Yes. This interpretation has been proposed, and is discussed in our article on Time Travel here : Time_travel
 * This idea shows up sometimes in fiction, too. Although it's also conflated with other interpretations. (Marty McFly still has memory of his original universe, but photographs he's carrying change.) ApLundell (talk) 08:29, 23 April 2017 (UTC)
 * Thanks. Brandmeistertalk  18:51, 23 April 2017 (UTC)
 * Suppose you're driving toward town intending some minor business, and abruptly you remember that you're about to see an auto accident. Now, if this is not the first time... or the last... that prec episodes have led to just that, you take it seriously, and say screw the theory, you're going to foul this one up, and promptly divert toward a gameland where you like to walk.  In just a few minutes you're out of the car, and a bit more than an hour later you come back, hoping that the immediacy of the memory is lost.  As you approach, you hear the rustic sound of a snorting deer ... followed not long afterward by a thump out on the road.  You get in your car and drive past the crowd of folks trying to do something about the dying deer who seem to want you to help them, faster than what is polite, perhaps out of some primordial fear that they might suss out what happened and apply some fair but altogether unpleasant traditional punishment for witches.  I mean, it is impossible to sum up such things scientifically, but how many incidents do you take before you say this goes beyond a science fiction hypothesis? Wnt (talk) 21:52, 26 April 2017 (UTC)

Feynman lectures authorship and copyright
Feynman lectures' copyright does not belong to him. I want to know what share of the text was written by someone else? Are there any Feynman lectures in audio or video that match the books? — Preceding unsigned comment added by Justpierrepit (talk • contribs) 15:30, 22 April 2017 (UTC)
 * Yes, the co-authors are Robert B. Leighton and Matthew Sands . This says that Sands encouraged Feynman to prepare and deliver the lectures, and to tape-record them. Then Sands and Leighton participated in preparing them for publication. Brandmeistertalk  15:51, 22 April 2017 (UTC)

Yes but how far is the"official" text from Feynman's words? Were the other contributors just correcting errors? Or would they write whole new sections? — Preceding unsigned comment added by Justpierrepit (talk • contribs) 16:00, 22 April 2017 (UTC)
 * Wikipedia has an article on that: The Feynman Lectures on Physics (I haven't read it, tho) 2606:A000:4C0C:E200:984A:CA94:A2BD:E53B (talk) 20:11, 22 April 2017 (UTC)


 * There are multiple versions of the work.
 * Have you read the preface to your print version?
 * Have you read the preface to the version hosted by Caltech?
 * That'll explain what you want to know. Here are detailed comparisons among editions.
 * By the numbers, between 2005 and the most recent edition, the work had more than a thousand point of errata, frequently of a typographical nature, but occasionally including errors of a scientific nature.
 * Comparing versions of difficult science and math books is exceedingly difficult. I have, for example, two or three different editions of Gray and Meyer.  It's hard to read one edition, let alone to painstakingly compare my two copies side-by-side; I have occasionally tried this for a few books in my collection, and it never works well.  Imagine if we scientists followed the philosophical lead of our scholarly religious forebears: we might gather all the different personal paper copies that we have all collected among each individual version of all of our Great and Important Books.  We might gather these scrolls together in a monastery, where we might conduct Exegesis on all the great Texts, and we might form cabals and Communions and Ecumenical Councils to decide which textual passages are gospel - of the Original Truth - and which passages and phrases are canonical additions that fall outside of Feynman's core seventy-some chapters, but contain material that we believe to be factual truth and whose actual words and letters were originally inspired by The Author... and then we might even find some non-canonical chapters that we consider so wrong that we label them heresy and blasphemy...
 * This style of literate scholarly research is perhaps academically interesting, but it is is not how science works. We only began to make progress after we evolved away from that type of scholastic mindset.  Today, we value empiricism over textual analysis.  This is the scientific method.
 * Yet, you want us to apply monkish textual analysis to the works of Feynman on Physics? Blasphemer!
 * So: stop caring who wrote the book, forget about version-controlling the errata, and start judging its content by its core merit: is it readable? Does it teach?  Is it factually correct?  Is it current and well-written?  Is the presentation understandable?  Does it follow a reasonable syllabus?  When you read the book, is it good?  Equally importantly: is it better than the other books you could be reading?
 * When you critique the book by those questions, it is actually a really poor text on modern physics, and this is why nearly no actual physicist or physics educator really uses it. This is a statement that I have made, and cited on many occasions on this reference desk.
 * When in doubt about a claim made by Feynman or anyone else, why not conduct an experiment?
 * Overall levels of student performance on standardized tests of achievement may be relatively insensitive to variation in the content of classroom instruction resulting from differences in how teachers use textbooks. The unpleasant reality, repeatedly shown by many different experimental methods, is that you either understand physics, and you are good at it - or you don't understand physics, and you are bad at it, and we can't change this reality by giving you better resources and books.  Physics and math in particular are subjects for which student performance is among the least sensitive to variations in presentation of content.
 * Nimur (talk) 16:48, 24 April 2017 (UTC)

Virtual urge to urinate after drinking water
Shortly after I drink a glass of water, I sometimes feel a little sensation towards the need to urinate then the sensation subsides after a while, even without urinating. I feel like the bladder gets filled in and then empties without urinating. What causes this and does anybody else experience this? Planet Star  20:07, 22 April 2017 (UTC)


 * It can also be triggered by the sound of that water flowing into the sink. This is part of a the mechanism allowing us to postpone to urinate even when the bladder is full, allowing us to urinate at the right place and time. Such mechanisms have evolved in our early ancestors who had primitive brains, the signal to urinate can then involve simple triggers that we may not find so convenient anymore. Count Iblis (talk) 20:13, 22 April 2017 (UTC)


 * It could also be an example of individual psychological conditioning. I myself usually feel an urge to urinate when returning home and approaching my front door, even if I don't really need to: this has probably been conditioned in me by the frequent occasions on which I've returned home after drinking (beer) and did need to urinate – fortunately, I can usually suppress the urge (long enough) by particular mental imagery. {The poster formerly known as 87.81.230.915} 90.217.249.244 (talk) 02:06, 23 April 2017 (UTC)

And what about the urge that begins 10–15 minutes after drinking water then subsiding around 30 minutes later. How is this possible? Planet Star  05:52, 23 April 2017 (UTC)


 * I'm struggling to find a proper source, but I'm certain that while researching "breaking the seal" at some point, I read that there are two triggers to the sensation of having to pee: a full bladder and the sensation of the bladder filling. The first is a one-way drive: it just builds up until the pressure seems unbearable and you urinate. The second is not; if the bladder is not full, that sensation can pass as you get distracted by other things. I'll keep looking. Matt Deres (talk) 18:11, 23 April 2017 (UTC)


 * So you're saying that the secondary urge to urinate is the sensation of filling up the bladder but it subsides once it stops filling as long as if the amount of urine in the bladder is still within the comfortable level. What do you mean 'get distracted by other things'? The hyperlink to breaking the seal only talks about alcohol's effect on the urge to urinate. I don't drink alcohol, I drink mostly water. Planet  Star  02:23, 24 April 2017 (UTC)


 * I usually find I develop an urge to urinate when I feel like I need to pee. μηδείς (talk) 17:11, 24 April 2017 (UTC)

Is the longitude linear in time when I throw a ball in an angle?
Suppose I throw a ball on a large sphere in vacuum. Then the height of the ball is parabolic as a function of time, and I want to say that the longitude of the ball is linear in time. Is that correct? If not, how good is this approximation when I throw the ball not very far? (Say, tens of kilometers on earth). --46.117.104.173 (talk) 22:02, 22 April 2017 (UTC)
 * Suppose you're standing 10 meters from the North Pole, and you throw the ball very close to the Pole. As it passes by, the rate of change of longitude with respect to time will be very high.  In fact, you can get it arbitrarily high by throwing the ball arbitrarily close to the Pole.  Whereas it will not be so high at the moment it leaves your hand.
 * So in principle, no, it is not linear. But at ordinary latitudes and for reasonable distances, it's going to be pretty close, because although the ball's vertical component of velocity slows as it approaches its apex, the horizontal component remains constant. Well, almost constant.  See elaboration below. --Trovatore (talk) 22:07, 22 April 2017 (UTC)
 * And what if we throw the ball such that the trajectory stays at a constant latitude? Will the longitude be exactly linear as long as we don't pass the point of discontinuity?--46.117.104.173 (talk) 22:20, 22 April 2017 (UTC)
 * You can't actually do that, except at the equator. The ball will remain in a single plane containing the center of the Earth, which means that its ground track will follow a great circle route, not a path of constant latitude. --Trovatore (talk) 22:22, 22 April 2017 (UTC)
 * I wonder if what you're really asking is, does the point on the ground directly below the ball move at constant speed? The answer to that is "almost".  The ball's orbit looks like a parabola to us, but that's because we're only seeing a tiny bit of it near the vertex.  It's actually an ellipse.  If I recall correctly (orbital mechanics will probably give more precise information), the ball's orbital angular momentum with respect to the center of the sphere remains constant.  That's almost-but-not-quite the same as saying its transverse component of velocity remains constant, because as it's going up, it gets slightly farther from the center, so you don't need quite as much transverse velocity for the same angular momentum.  However, to keep the same speed projected to the surface, you would need more transverse velocity.
 * So bottom line, the point projected to the ground slows down slightly as the ball ascends, and speeds up slightly as it comes back down. But very very very slightly. --Trovatore (talk) 23:19, 22 April 2017 (UTC)
 * Oh, also: This is for a non-rotating sphere.  If you want to do things in the coordinate system of a rotating sphere, you also have the Coriolis effect to worry about. --Trovatore (talk) 04:05, 23 April 2017 (UTC)
 * Oh, also: This is for a non-rotating sphere.  If you want to do things in the coordinate system of a rotating sphere, you also have the Coriolis effect to worry about. --Trovatore (talk) 04:05, 23 April 2017 (UTC)