Wikipedia:Reference desk/Archives/Science/2016 February 7

= February 7 =

Man with no brain
I've seen a photo of a man with no brain yet he functions normally. Does this give evidence for existence of the soul, or consciousness is beyond the brain? — Preceding unsigned comment added by Money is tight (talk • contribs) 00:07, 7 February 2016 (UTC)
 * Can you link us to this photo? The complete absence of a brain, or anencephaly, is lethal at or just after birth. It is true that people can have remarkably large brain defects and function reasonably well in daily life, but this is not 'no brain'. As for your other questions, the soul does not exist, and there is no evidence for conciousness 'beyond the brain'. Fgf10 (talk) 00:13, 7 February 2016 (UTC)
 * Whether there are souls is a theological question outside the scope of this Reference Desk. Wikipedia does discuss the beliefs of various religions and other belief systems about the soul.  Robert McClenon (talk) 00:22, 7 February 2016 (UTC)
 * No, it's a scientific question on the Science refdesk. There is no evidence for souls in science. Whatever various works of fiction claim is of no consequence. Fgf10 (talk) 01:08, 7 February 2016 (UTC)
 * The existence of souls, or not, is a matter of opinion, not of science. ←Baseball Bugs What's up, Doc? carrots→ 08:25, 7 February 2016 (UTC)
 * At the science desk? Don't be ridiculous. The soul, as described in various works of fiction, is incompatible with the laws of physics as we understand them, so unless we've got it very wrong, according to science it doesn't exist. End of. Fgf10 (talk) 12:49, 7 February 2016 (UTC)
 * The so-called "laws of physics" are a human interpretation. "...as we understand them..." is the key point. They are their own kind of religion. ←Baseball Bugs What's up, Doc? carrots→ 12:57, 7 February 2016 (UTC)


 * I've gone far afield with this recently, so I won't again, but I should note that science has not disproved the existence of the soul, nor has it provided a satisfactory explanation of qualia. That said, I have not heard of anyone able to use skeletal muscles in a controlled manner who does not have some apparent central nervous system to control them.  This is biology, so there is no law of nature that would prevent the autonomic nervous system, enteric nervous system etc. from growing efferents and somehow learning to control muscles without a brain present; or even preventing cells of the skin, muscles etc. from expressing proteins that lets them spread action potentials and think; but there's no evidence they have the capability and by this point such things would seem extraordinarily, extraordinarily unlikely, as would most other brain-free processes of control. Wnt (talk) 00:29, 7 February 2016 (UTC)
 * Science also hasn't disproved the existence of the Flying Spaghetti Monster. So what? Fgf10 (talk) 01:08, 7 February 2016 (UTC)
 * Then it could exist. ←Baseball Bugs What's up, Doc? carrots→ 12:57, 7 February 2016 (UTC)

There are various photos of men who are missing most of their brains and still function normally. This sometimes the result of extreme hydrocephaly or physical trauma to the brain. But rest assured, these people still have some brain left. If you find anyone claiming a human can function with literally no brain, you are being lied to without a doubt. Someguy1221 (talk) 02:49, 7 February 2016 (UTC)


 * Just realized this is an election year. You'll likely be seeing lots of men with no brains walking around and even talking. Someguy1221 (talk) 10:39, 7 February 2016 (UTC)
 * Well, let's go with malfunctioning brains - for the sake of science! SteveBaker (talk) 15:22, 7 February 2016 (UTC)
 * Or perhaps they just never figured out how to use them... Double sharp (talk) 04:37, 8 February 2016 (UTC)
 * So you're advocating that they figure out how to use their brains using...um...their brains? What could possibly go wrong?! :-) SteveBaker (talk) 17:57, 8 February 2016 (UTC)

https://www.google.com.au/?gfe_rd=cr&ei=kK-2VufIBcbN8geWxYHYBg#q=half+head+man — Preceding unsigned comment added by Money is tight (talk • contribs) 02:45, 7 February 2016 (UTC)
 * Some of those photos are real - but a lot of them are very bad photoshopped images. We do know that people can and do survive with very little brain tissue remaining...there have been cases reported where a person survived with just a 1" thick layer of brain surrounding a fluid-filled void.  But with no brain at all - that's utterly impossible.  The brain handles a bunch of functions such as the control of breathing - that you simply can't do without.
 * As for the soul - no, science has not disproved the concept - but it also hasn't disproved the concept of green aardvarks playing pianos on the far side of the moon...that doesn't mean that we have to assume that they exist. The default hypothesis in this case is that souls don't exist (and neither do those aardvarks) and since you're asking this question on the science reference desk - the scientific answer is that since we have no evidence for the existence of a soul, it is meaningless to ask whether a man without a brain (who couldn't be alive anyway) would or would not have one.  SteveBaker (talk) 15:35, 7 February 2016 (UTC)
 * Are you telling us that The Clangers did not exist? I am gutted!;-) DrChrissy (talk) 15:47, 7 February 2016 (UTC)
 * The clangers were (a) not green and (b) evidently played slide whistles rather than pianos...but aside from that, of course they existed! SteveBaker (talk) 05:28, 8 February 2016 (UTC)
 * Like in arguments about Wikipedia consensus, arguing about default hypotheses involves a lot of gaming about what is "default". "Flying spaghetti monster" is usually applied as an argument for the non-existence of God, but it's one thing to assume the burden of proof is against a very specific made-up religion, and something else (say) to conclude confidently that the universe was not designed, has no plan or purpose, that the answer to why people really feel things and really see beauty in it is that actually they don't, and that everything about the universe, including the laws of mathematics, is purely random.  ("But where did random come from?  Isn't that just begging the question?")  Perhaps the better approach here is to ask -- what, specifically, scientifically, do you mean when you say the soul doesn't exist?  Because maybe that's not part of the definition... Wnt (talk) 18:14, 7 February 2016 (UTC)
 * The default is to presume that what we can measure is "real" and what we can't measure has to be demonstrated indirectly. No such demonstration of a "soul" has ever been made - and, to the contrary, when we stick someone's head into a brain scanner, we see it light up in an appropriate and consistent manner when the person thinks about different things and in different ways.  There is sufficient complexity in the brain for "emergent behavior" to appear - so there is no reason to assume that there is "something else".  That's not to say that there isn't a "soul" - but merely that this shouldn't be the default hypothesis.
 * There is no evidence that whatever religion you're considering was not "made up" too - in fact, because there are so many religions in the world - many of which are sharply contradictory - the evidence is that even if one of them turns out to be correct, at least 99% of religions must be nonsense. Wondering what the odds of 99% of religions being incorrect rather than 100% of them provides additional reason to eliminate them from the default hypothesis.
 * As for "beauty" - you make the absolutely classic (and exceedingly naive) mistake of presuming that atheists see no beauty in the universe - and nothing could be further from the truth. The beauty is in all of the amazing mechanisms that emerge from the simplest of representations.  That the key laws of physics can be written on the front of a T-shirt (I have one) - and that is enough to understand very nearly all of it.  That, to most scientific thinkers, is beauty.  That the leaves of a tree are the result of random evolutionary processes that result in the near perfect optimisation for capturing sunlight - is incredible.  That flowers have beautiful markings on there petals that humans can't see because they are in the UV spectrum - and that the plant evolved to put them there to help bees to figure out how to orient themselves as they land to do pollination.  Please - don't tell me that you need religion to see beauty - that's complete and utter bullshit.  If all I had to believe is that a magician waved his magic wand and it all popped into existence - the world would seem to be an arbitrary, ridiculous, foolish place - and much of the beauty would evaporate.
 * The laws of mathematics are not "random" - they may all be deduced from the most simple axioms imaginable - you're entirely mistaken if you believe that.
 * The randomness of the universe comes about from quantum randomness and the randomness that comes about in some systems that are susceptible to sensitive-dependence-on-initial-conditions...Chaos theory. So we're very well aware of what those sources are.
 * What is meant by "the soul does not exist" is not a question I really need to answer. I have not been provided with a definition for this term - it's a vague piece of description that's conveniently never pinned down.  Without a definition, it's nothing more than a word.  So we have not discovered any evidence for a thing that's vaguely described in the first place.
 * The argument that a lot of people believe in something, so it must be true has been disproven more times than I can count. An enormous number of people believe that vaccination causes autism - does that make it true?  Actually - no.  It's been tested beyond reasonable need - and it's not true.  Despite that, only 52% of Americans believe that vaccines don't cause autism.  68% believe in god (in some form or another).  Does that make them right?
 * SteveBaker (talk) 05:28, 8 February 2016 (UTC)


 * I'll leave this article, about a neighbour of mine when I lived in Barnsley, here. --TammyMoet (talk) 16:00, 7 February 2016 (UTC)


 * Yes, I suspect the OP may be thinking about something like the case Tammy mentions. As for "the soul doesn't exist" I don't believe we can say that either. The definition of a soul is "the spiritual or immaterial part of a human being or animal, regarded as immortal" and all we can say is that there is no scientific evidence for that to be the case. However, we still don't have a complete theory of everything and so it is just possible that there are things or mechanisms that exist that we don't yet know about. And just to make my position clear, personally, I am 99% sure there is no God as visualised by religious people and no afterlife. I'm quite happy with that as, if I'm right, when I die my consciousness will come to an end and I won't have to worry about it. However, like everything else in life, I always entertain the possibility that I may just be wrong (a very remote possibility in this case), and if I am, it will be interesting to find out what comes next. There is the (also very unlikely) possibility that the universe was created by some intelligent entity but, if it was, then I am sure they don't really care less whether we worship and pray to them or ignore them completely. Oh, and if it does all turn out to be an experiment run by the white mice then I'm in deep shit - but that's anther story.  Richerman    (talk) 12:43, 8 February 2016 (UTC)
 * The desire to believe that your life won't just suddenly just "end" is quite powerful. You don't have to resort to religion and the concept of a "soul" to get past that though.  There is always the (MUCH more worrying) Quantum suicide and immortality hypothesis - I'm kinda hoping that's one hypothesis which turns out not to be true because it might just imply eternal (albeit religion-free) damnation!  Even without the many-worlds hypothesis, you can get pretty much the same result if the universe turns out to be infinite and the weak anthropic principle is acceptable to you.  Another one that I like is the concept of reincarnation - in which at the moment of your death, you are reborn as another human being - although you'd have absolutely no memory of your earlier life.  Many people find that to be a much more comfortable situation than just "fade to black...nothingness" - although to all measurable tests, the outcome would be identical.  So if you're OK with "no-memory-transfer" reincarnation, you have an unfalsifiable hypothesis that's every bit as good as any religious view.  Then we have the Simulation hypothesis (another theory that I'm quite fond of) - and so maybe the universe will get a blue-screen and wind up being rebooted? SteveBaker (talk) 18:12, 8 February 2016 (UTC)
 * The simulation hypothesis is something that seems quite likely to me (relatively speaking, as likely as a big bang or a multiverse) possibly because I read about the Evil demon philosophical idea when I was young. The article on quantum suicide is an interesting read, I've wondered about that idea with regards to all possible outcomes resulting in infinite universes - it's a very scary idea so I'm glad "I'm" still in this universe right now! Mike Dhu (talk) 09:24, 9 February 2016 (UTC)
 * I've been trying not to give into the temptation to infinite digression, but it's actually relevant to the original question to note that the Ancient Egyptian concept of the soul comprised multiple components, some of which we have no controversy about the existence of, and others of which are perhaps more palatable when considered separately. In particular, I should note the possibility that the ka, the non unique component of the soul, is the same in all people and is what actually feels qualia (thus the moral basis of religion to be drawn from this is that evil done to others is suffered by oneself, even if there is no memory of that).  However, the ba is more typically the portion focused on in Judeo-Christian tradition.  In religions from the Egyptian onward, the preservation of worthy ba (or portions thereof, I would think) from one universe to the next offers a possibility for worthy personal actions to have a more enduring and fundamental significance. Wnt (talk) 08:31, 11 February 2016 (UTC)

What is the meaning of the word "lead" in context of ECG?
I understand that is one of 12 electrodes, but I'm asking about the meaning of the word. I opened dictionary and I saw many meanings, but I'm not sure which one is the right.93.126.95.68 (talk) 00:08, 7 February 2016 (UTC)
 * Lead is essentially used interchangeably with electrode, not any specific one. Fgf10 (talk) 00:15, 7 February 2016 (UTC)
 * Thank you, but I'm not sure if you're right because I know that a typical ECG machine has 9 electrodes while it result give 12 leads. (aVL+aVR+aVF are augmented leads without their own electrode, so actually you can not call them electrodes, then the word lead can not be used interchangeably with electrode.)93.126.95.68 (talk) 00:41, 7 February 2016 (UTC)
 * In some versions of English, 'lead' is a synonym for 'wire' or 'cable', as in 'extension lead'. Not sure whether that helps though. Akld guy (talk) 01:02, 7 February 2016 (UTC)
 * That is exactly the relevant meaning here yes. As per a quick read, the electrodes mentioned actually physically use the same electrodes as some of the main 9, but are referenced differently, so are essentially 'virtual' electrodes. REF Fgf10 (talk) 01:14, 7 February 2016 (UTC)
 * See our Electrocardiography article. The leads run from the machine and have detachable electrodes  which are stuck on to the patient's skin with a conductive gel.  Richerman    (talk) 13:03, 8 February 2016 (UTC)

Do all the muscles of the body have origin and insertion?
Do all the muscles of the body have origin and insertion? and if they do have, doed the heart (as considered as muscle) also have origin and insertion? 93.126.95.68 (talk) 00:31, 7 February 2016 (UTC)


 * Hmmm, also External sphincter muscle of male urethra, external anal sphincter, iris sphincter muscle (sort of, though you can argue that starts as smooth muscle which we know is different). In the case of the anal sphincter there actually *is* an insertion, for one layer - might be worth looking deeper into the embryology to see if the circular layer is a late specialization in development? Wnt (talk) 00:49, 7 February 2016 (UTC)
 * I believe the tongue does not. DrChrissy (talk) 00:51, 7 February 2016 (UTC)
 * From our article:
 * "The eight muscles of the human tongue are classified as either intrinsic or extrinsic. The four intrinsic muscles act to change the shape of the tongue, and are not attached to any bone. The four extrinsic muscles act to change the position of the tongue, and are anchored to bone."
 * It goes on to describe which bones the four extrinsic muscles are anchored to. So for the tongue as a whole, half yes and half no. {The poster formerly known as 87.81.230.195} 185.74.232.130 (talk) 15:04, 8 February 2016 (UTC)

In genetics, sex can be dominant?
In genetics, sex can be dominant? I mean to male or female, does one of them can be dominant just because of his sex? 93.126.95.68 (talk) 00:56, 7 February 2016 (UTC)
 * If you mean dominant in the Mendelian sense, then one could argue that the answer is yes when sex determination is chromosomal. In placental mammals, one could say that male is dominant in the Mendelian sense because a single Y chromosome determines male sex.  In birds, one could likewise argue that female is dominant in the Mendelian sense.  If you mean something other than the Mendelian sense, please clarify. — Preceding unsigned comment added by Robert McClenon (talk • contribs)
 * Yes, User:Robert McClenon's comment is basically correct for mammals, insofar as the presence of the Y causes male characteristics, whatever the number of the X chromosomes. See XXY.  That doesn't apply for certain birds and insects, e.g., though. μηδείς (talk) 02:20, 7 February 2016 (UTC)
 * To be nitpicky, it's specifically the gene SRY that causes development of male phenotype in mammals when expressed. SRY is normally located on the Y chromosome, but it is possible for mammals to have a Y chromosome and still be phenotypically female, to varying degrees, like if the SRY gene is broken, or if there are other conditions like androgen insensitivity. --71.119.131.184 (talk) 07:14, 7 February 2016 (UTC)
 * How rare is this? Are they any more likely to have male traits than XX women? What happens if both the mother and the father give a Y chromosome each? Sagittarian Milky Way (talk) 07:59, 7 February 2016 (UTC)
 * You might like to read this if you haven't already done so.   D b f i r s   10:04, 7 February 2016 (UTC)
 * Are there any XY females who are actually capable of getting pregnant in the first place? Certainly it wouldn't be the ones with complete androgen insensitivity syndrome, because they don't have ovaries or a uterus.  But I don't know for sure that it isn't possible in some other way. --Trovatore (talk) 23:18, 7 February 2016 (UTC)
 * I don't think people with 100% XY have gotten pregnant, but there are rare cases like this that come pretty close. - Lindert (talk) 23:34, 7 February 2016 (UTC)
 * Very interesting. The abstract says that the daughter got a Y from the father, but doesn't say, as far as I saw, whether the mother had any viable Y-bearing ova.  Is it known whether that's possible?  --Trovatore (talk) 23:47, 7 February 2016 (UTC)
 * Any mammalian embryo with no X chromosome is nonviable, as the X chromosome contains many essential genes. Embryos with abnormal chromosomes inevitably get created as a result of errors in meiosis. Down syndrome is a well-known example, but most chromosomal abnormalities are lethal and cause the pregnancy to spontaneously abort. The Y chromosome is not essential, which is obvious as half of mammals don't have one. Because of this, evolutionary pressure inevitably reduces the Y chromosome over time (see the article for details). --71.119.131.184 (talk) 10:58, 8 February 2016 (UTC)
 * Hmmm, I suppose you could say that maleness is a recessive lethal with some phenotypic effects in the heterozygote. (That link should go to lethal allele, but that article was written by someone who defines that term altogether differently than what I'm familiar with!!!) Wnt (talk) 18:20, 7 February 2016 (UTC)


 * You might like reading about the evolution of sex and anisogamy. SemanticMantis (talk) 15:45, 8 February 2016 (UTC)

Date of official information on the name of element 113
I could have asked the question any time I wanted to, but I chose now because we've reached the first time in a week when doing a Google News search on "ununtrium" doesn't reveal anything less than a week old. Can anyone predict the date I'll get official info?? Georgia guy (talk) 01:18, 7 February 2016 (UTC)
 * Only the people at RIKEN and IUPAC will be able to answer that one. Fgf10 (talk) 01:23, 7 February 2016 (UTC)

Odors emitted by the Feces and Urine of Mammals and Birds
Where can I find material on the intensity of odors emitted by the feces and by the urine of various mammals and birds? Thank you.Simonschaim (talk) 10:49, 7 February 2016 (UTC)


 * We don't have an article specifically on this topic (although Category:Feces might prove useful). It should be covered in any general work on woodcraft, and a web search on animal-specific terms ("bear scat", "fox scat", etc) will usually come up with the appropriate details. Tevildo (talk) 12:03, 7 February 2016 (UTC)


 * Bile contributes to the smell of feces. StuRat (talk) 18:13, 7 February 2016 (UTC)


 * This is a tough one. I mean... we all know from experience how much it can vary based on diet.  Beyond that, intestinal microflora.  If you take some lab animals and do a poo sniff-off, mostly you've learned what the lab techs are feeding the animals.  I'd be wary of general statements. Wnt (talk) 18:23, 7 February 2016 (UTC)
 * It might be difficult to find information on the intensity per se, but articles the OP might want to look at include Pheromone, Vomeronasal organ and Flehmen. DrChrissy (talk) 18:31, 7 February 2016 (UTC)


 * As a long-time pet owner, I would point out that the intensity and nature of the smell of animal pee depends on its age and storage condition. Cat urine on cat litter which is less than a day old is different from cat urine deposited on a plastic bag or piece of fabric on the floor behind a couch which is not discovered for a week. The question seems like a readily quantifiable one.It would be surprising if no date had been collected and published. Subjects could give subjective ratings of odor strength for standardized samples under well defined experimental conditions, and we could learn the relative intensity of either a constant volume of parakeet/lizard/hamster/cat/rattlesnake/dog/human/deer/lion/bear/dolphin/horse/hippopotamus/elephant/whale urine or feces, or the relative subjective odor strength of a normal deposit of said substances. Edison (talk) 21:19, 7 February 2016 (UTC)


 * Skatole is responsible for much fecal odor, and the term may help you find more quantitative assessments. SemanticMantis (talk) 15:44, 8 February 2016 (UTC)

Thank you to all those who supplied me with answers. Simonschaim (talk) 11:44, 10 February 2016 (UTC)

Oil drilling -- env. impact
What substances/materials (if any) which are involved in oil drilling (particularly in offshore oil drilling) are classified as highly toxic? In particular, which are toxic not only by ingestion, but also by skin contact and/or inhalation of vapors? 2601:646:8E01:9089:F88D:DE34:7772:8E5B (talk) 12:01, 7 February 2016 (UTC)


 * Here's a list of the types of chemicals likely to be used during the drilling of offshore wells - not much there on toxicity though. The oil itself may be the most toxic chemical that people may come into contact with. Mikenorton (talk) 12:11, 7 February 2016 (UTC)


 * And that last material is only moderately toxic. 2601:646:8E01:9089:F88D:DE34:7772:8E5B (talk) 12:16, 7 February 2016 (UTC)


 * Found some data for benzalkonium chloride (used in oil drilling as a corrosion inhibitor) -- it's pretty toxic, rather more so than crude oil. Benzalkonium_chloride 2601:646:8E01:9089:F88D:DE34:7772:8E5B (talk) 12:39, 7 February 2016 (UTC)

Oil drilling, part 2
If there's an oil spill at sea and it catches on fire by itself, is it ever put out or is it universal practice to let it burn? (I know, for example, that oil spills are sometimes deliberately set on fire as a last-ditch cleanup measure.) In what circumstances, if any, should it be put out? Is it a conceivable scenario where a burning oil slick is first extinguished and later deliberately ignited again as part of the disaster response? 2601:646:8E01:9089:F88D:DE34:7772:8E5B (talk) 12:21, 7 February 2016 (UTC)


 * NOAA page on in-situ burning. Mikenorton (talk) 12:26, 7 February 2016 (UTC)
 * Crude oil does not inflame itself. Setting it on fire deliberately is most likely motivated by "saving" near coastlines, which else have to be cleaned up later. In contrast to coasts our oceans and atmosphere have always been treated as a dump for toxic wastes anyway. --Kharon (talk) 12:46, 7 February 2016 (UTC)
 * I did not mean spontaneous combustion, I meant accidental ignition from a stray source. 2601:646:8E01:9089:14B5:216D:30B1:F92 (talk) 07:34, 8 February 2016 (UTC)

Near earth approach of 2013 TX68 in March 2016
Asteroid 2013 TX68 is due to make a near Earth approach next month. Per the article and news stories, it was only observed for 3 days in its previous approach in 2013, and is too dim to be seen when distant from the earth. Stories say it could come as far as 9.2 million miles or as close as 11,000 miles,(and equivalent 2 digit precision in metric units) but that it can't possibly hit the earth. Christian Science Monitor says "There is no possibility that this object could impact Earth" in 2016, per a NASA press release. Its nearest approach time is uncertain ("sometime between March 3–8, 2016",per the Wikipedia article) and we can't see it until it is within a couple of days of closest approach. So if the largest number is "9.2 million miles," apparently to two digits of precision, how can NASA be so certain that 11,000 miles is the closest possible approach? Is this just false confidence to avoid public alarm? I've seen a lot of confidence intervals, and "11,000 to 9,000,000" as stated in some news articles is an odd one. It's like saying "4505500 miles plus or minus 4494500 miles" if we take the average as the midpoint. Then they give odds on its closest approach on future occasions, but an approach to tens of thousands of miles would cause a huge deflection in its direction, with the deflection dependent on the closeness of approach. How does the certainty that the closest approach is 11.000 rather than zero square with the a large magnitude of the farthest approach?, Given apparent uncertainty about the nearness of this approach. how can there be much certainty about the next approach? Edison (talk) 14:29, 7 February 2016 (UTC)
 * JPL has a graphic that shows possible points of closest approach given the orbital uncertainties. It seems that these points are restricted to a plane that appears to be well constrained and does not contain Earth. The closest point of that plane to our dear planet is 11,000 miles away and thus gives the minimum possible approach distance. --Wrongfilter (talk) 14:56, 7 February 2016 (UTC)
 * In other places (HERE for example) you can see the calculations are being done to higher precision than the Christian Science Monitor quoted...in a news item, journalists rarely want to write hugely precise numbers because they are hard to read and assimilate.
 * But I agree with User:Edison - we know the plane in which the rock orbits with great precision - and we know that this plane only comes within 11,000 miles of Earth - but we have much greater uncertainty about where 2013TX68 will be within that plane at the point of closest approach.


 * Perhaps an analogy would be useful: It's kinda like worrying about cars on a fast stretch of a flat, straight road going right past your house.  You have no idea whether they'll be driving at 30mph or speeding way over the speed limit at 90mph - so your error margin in their speed is huge.  But you do know - with great precision and high confidence - that they'll stay within that narrow corridor prescribed by the edges of the road.  So if you're walking home along the sidewalk and you see a car that's 5 miles away on the horizon coming towards you.  You don't have any good idea at all of how close it'll be when you reach the safety of your home...but you're confident that it's not going to hit your house with almost complete certainty.  If asked how close the car might get to you as you open your front door, the larger number would be "a couple of miles...maybe?" and the smaller number would be the distance from your house to the edge of the road (18 feet 7 inches).


 * Your error margin on the larger number is enormous - but you still know with near certainty that your house is safe.


 * SteveBaker (talk) 15:16, 7 February 2016 (UTC)


 * Thanks. Confidence of it being in a plane 11,000 miles from earth is a fine explanation for the amazing figures cited.It makes perfect sense. But wouldn't a possible pass 11,000 miles from earth deflect, it putting it in a different orbit/plane? It sounds like they are forecasting approaches years in the future based on a scant 3 days of observation 3 years ago. Te graphic from JPL is odd, since it basically shows two rows of dots, and nothing between them. Is there an explanation for that? Edison (talk)
 * That depends on how exactly that figure was created. I assume it was some sort of Monte Carlo simulation - randomly pick a possible value of starting parameters out of the possible range in 2013, calculate the orbit, plot the position of closest approach in 2016. Now, if they picked the extremes for the starting parameters (values around, say, the 1σ contour) rather than the best-fit values, those would map to something like an ellipse in the output parameters, i.e. this graphic. So the lack of dots inside these two rows would be due to them not bothering making the computation for those values. But this is just me guessing, I can't back this up with a publication or so. The deflection during this approach will certainly affect the prediction for the next one, and it will depend on how close this approach will actually be. --Wrongfilter (talk) 21:45, 7 February 2016 (UTC)


 * Hmmm - I wonder if one row of dots comes from the sunward-leg of the orbit and the other as it returns from the sun, heading out towards deep space? That would explain two neat sets of numbers like that.  That's a guess though. SteveBaker (talk) 05:02, 8 February 2016 (UTC)


 * The orbit of the asteroid is known to an accuracy of a few thousand kilometres. The accuracy isn't the same at every point of the orbit or in every direction, but that's the order of magnitude. The uncertainty in the semi-major axis translates into an uncertainty in the orbital period, and in the 2.5 years since it was last observed this accumulated into a quite large uncertainty in the phase of the asteroid's orbit of about 14 million kilometres. In other words, we know quite well where the orbit is and that Earth will pass at 17000 km away from the orbit, but we don't know where the asteroid will be at that moment. I assume the figure published by JPL indeed results from a Monte Carlo simulation. One row of dots comes from the asteroid passing Earth's orbit ahead of Earth, the other row comes from the asteroid passing Earth's orbit behind Earth. PiusImpavidus (talk) 11:11, 8 February 2016 (UTC)

sources of oxidants in natural shale gas reservoirs
A few years ago I came across a lot of industrial presentations on natural gas reservoirs, especially shale gas, and something that was mentioned is that shale gas reservoirs can become "overmature" where the hydrocarbons become CO2. This was puzzling to me because I couldn't figure out what could be oxidizing the gas only after the organic material has been sitting there for around 200 million years, when it appears to be fine from the 50 million year period onwards.

Two questions: 1) What are the source of reducing agents that reduces longer-chain fatty acids and carboxylic acids to methane? Why can't we exploit these reducing agents directly? 2) What are the source of oxidizing agents that oxidise methane to CO2 deep in the ground, underneath the bedrock?

Yanping Nora Soong (talk) 17:18, 7 February 2016 (UTC)


 * I'm not familiar with this, but the first few sources I found    give me the impression that there is an "oil window" and a "gas window" in which kerogen (of which there are apparently four types) is cracked under heat and pressure.  I see different estimates for the window, doubtless because some specifics of how they are measured are different, but they say roughly 50-100 celsius at 2-4 km depth produces oil, maybe 100 to 150? 200? more? celsius at 3-6 km depth produces gas.  Very hot gas undergoes "secondary cracking" that the first source says can first produce wet gas, and
 * "Metagenesis marks the final stage, in which additional heat and chemical changes convert much of the kerogen into methane and a carbon residue. As the source rock moves farther into the gas window, late methane, or dry gas, is evolved, along with nonhydrocarbon gases such as carbon dioxide [CO2], nitrogen [N2] and hydrogen sulfide [H2S]. These changes take place at temperatures ranging from about 150°C to 200°C [302°F to 392°F]. These stages have a direct bearing on source rock maturity."  (This appears to be cited to  Peters KE, Walters CC and Moldowan JM: The Biomarker Guide, 2nd edition. Cambridge, England: Cambridge University Press, 2005) Wnt (talk) 18:01, 7 February 2016 (UTC)
 * I'll pass the ball to someone else at this point. Wnt (talk) 18:01, 7 February 2016 (UTC)


 * To build a bit on Wnt's excellent information. Initially organic matter is trapped in fine clays and silts.  As the organic rich clay is buried under millions of years of sediment accumulation, the clay turns into shale and the organic material transforms into kerogen.  As it is buried deeper and deeper, the heat and pressure transform (or mature) the kerogen into oils and eventually gas (by combining hydrogen with carbon to form long chain {ex. octane} and eventually short chain hydrocarbons {ex. methane}).  Once all the hydrogen in the organic matter has combined with carbon to form hydrocarbons, increasing heat and pressure will never create any additional hydrocarbons and the reservoir is overmature.


 * Obviously we can't apply 150-200 C or the pressure at 3-6km depth (about 5,000-10,000 psi) to convert organic matter into CO2 on the surface, or at least not economically.Tobyc75 (talk) 21:59, 8 February 2016 (UTC)
 * I'm talking about redox balance. What reduces the hydrocarbons to form methane? There must be a reducing agent. Similarly, what is oxidising the methane (and other hydrocarbons) to CO2? There must be an oxidising agent. Reduction and oxidation always pair together. I'm aware there is some disproportionation involved, such that medium-oxidised organics (aldehydes, alcohols, alkenes, etc.) oxidise/reduce each other, forming longer and shorter chains respectively, but you can't just oxidise all the hydrocarbons to CO2 without the electrons going *somewhere*. Are metal oxides in the ground being reduced? Yanping Nora Soong (talk) 09:37, 9 February 2016 (UTC)


 * Methane is just the last product of thermal cracking of the original long-chain hydrocarbons. As to the CO2, it is formed early in the generation process as the original kerogen breaks down (it does contain some oxygen). It doesn't migrate in the same way as the hydrocarbons as it is quite soluble in water and may remain in the shale layer after the hydrocarbons have moved off. CO2 also moves upwards from deeper levels, derived from thermal breakdown of carbonates. I don't think that there is any oxidation going on to produce the CO2. Mikenorton (talk) 09:53, 9 February 2016 (UTC)

Are all stars main sequence stars at some point in their life-cycle?
Do all stars belong either to the main sequence stars, have once been main sequence or will inevitably become main sequence stars?
 * See stellar evolution. It appears from that article that all protostars that are large enough to fuse hydrogen (and thus become stars rather than brown dwarves) will enter the main sequence for some period of time.  Robert McClenon (talk) 20:28, 7 February 2016 (UTC)

are there compounds which are poorly soluble in aliphatic hydrocarbons (e.g. cyclohexane) but dissolve well in aromatic ones (like benzene or toluene)?
I note that neutral (zwitterionic) L-DOPA is weakly soluble in water but even less soluble in diethyl ether or chloroform. However, would it be more soluble in aromatic solvents? Yanping Nora Soong (talk) 21:25, 7 February 2016 (UTC)
 * Buckminsterfullerene is substantially more soluble in aromatics than in aliphatics. DMacks (talk) 21:33, 7 February 2016 (UTC)

Really how important is fruit?
I've gone months of having a bowl of fruit nearly every morning and months of having no fruit at all yet feel no different during that time. 2.103.13.244 (talk) 22:29, 7 February 2016 (UTC)


 * We cannot give actual medical advice here, but you might be interested in the underlying reasons for medical and public-health organizations publishing various food pyramids and promoting balanced diet. See whether it's strictly about the types of foods or the types of nutrients or the trade-offs in a real economy or other cultural/political environment. DMacks (talk) 22:33, 7 February 2016 (UTC)


 * Nutritional advice is not medical advice (or everyone who publishes a diet book would be arrested for practicing medicine without a license), so we are free to reply. Fruit does have some good stuff, like vitamin C in citrus, antioxidants/phytochemicals in berries, lycopene in tomatoes (technically a fruit), and healthy fats in avocados, but you can also get those from other things.  So, in that sense they aren't essential.  On the other hand, if eating fruit for dessert stops you from eating something far worse, that's a real plus.  StuRat (talk) 22:39, 7 February 2016 (UTC)


 * Fruit also has soluble and insoluble fiber. On the downside, it does have a lot of sugar (at least if you're talking about the fruits most people think of as fruit, meaning not tomatoes, not green beans, etc).  A lot of people track "added" sugar, but I think this is one of the tradeoffs DMacks is talking about &mdash; your body can't (or I expect it can't) tell whether the sugar is "added".  But the experts don't want to discourage people from eating fruit, so they don't emphasize tracking total sugar. --Trovatore (talk) 22:46, 7 February 2016 (UTC)


 * Sugar isn't too bad in whole fruits, where it gets to be a problem is with juices, where all the fiber has been removed and the sugar concentrated, or where you actually add sugar, like sugar on grapefruit, whipped cream on berries, or even more sugar added to "juice". StuRat (talk) 23:09, 7 February 2016 (UTC)


 * Sugar is sugar. Well, certainly there are different kinds of sugar, but the dominant one in fruit is fructose, which is the same thing people get upset about in high-fructose corn syrup.
 * I don't think your body can tell whether you ate the sugar as part of a whole fruit or not. But the fruit has other benefits, which is why the experts don't want to discourage you from eating it. --Trovatore (talk) 23:36, 7 February 2016 (UTC)


 * Reducing the amount of sugar (by eating one orange versus the juice of 10), and increasing the amount of fiber in order to slow digestion, both reduce the sugar spike, which is what leads to most of the health problems associated with sugar. Also, it takes more energy to digest whole fruit, and some of the sugar can be burned in that way. StuRat (talk) 17:49, 8 February 2016 (UTC)


 * Avoiding sugar in "too sweet" fruits is a recommendation in the low-carbohydrate diet community. Also, not all sugars are equal. Glucose is more likely than fructose to reach cells throughout the body rather than get metabolized in the liver. Yanping Nora Soong (talk) 01:04, 8 February 2016 (UTC)

Thanks for the replies but I'm wondering why I feel exactly the same whether or not I eat fruit. Is the effect of eating fruit everyday to extend your life by a few years or are there present-day benefits? 2.103.13.244 (talk) 02:44, 8 February 2016 (UTC)


 * That's hard to answer unless we know what you're eating instead of fruit (or conversely, what fruit is replacing when you eat it). If you're eating good, nutritious stuff instead of fruit you're doing fine. If you're eating cheeseburgers and Twinkies and such instead of fruit, it will probably catch up to you over the long term, though not necessarily in a few days or even weeks. Shock Brigade Harvester Boris (talk) 04:34, 8 February 2016 (UTC)


 * Below, our OP also indicates an aversion to vegetables too...so I think that it's unlikely that there is good stuff being eaten in place of fruit. SteveBaker (talk) 17:43, 8 February 2016 (UTC)


 * Most of the damaging effects of unhealthy food have no immediate and obvious symptoms. For example, plaque forming in your arteries may not be apparent until a heart attack. StuRat (talk) 17:53, 8 February 2016 (UTC)


 * Not medical advice, again, but an anecdote: I'm a long-time diabetic who was placed on a low-carbohydrate, high-fiber diet recently (within the past two months). In this diet, green leafy vegetables and fresh fruits like apples and oranges may be relatively freely eaten, while "empty carbohydrates" like bread, refined sugar and grits (ground parched white corn boiled as a porridge) are off the diet. Meat and other protein foods are permissible in reasonable amounts. Regular daily exercise is part of the regimen, as well.


 * I've lost thirty pounds in less than two months, and my control over my blood sugar has increased to the point that it's at the upper normal levels with only dapaglifozin ("Farxiga") as glycemic control medication. Prior to this, my blood sugar wasn't well-controlled at all, despite daily therapy with sitagliptin ("Januvia").  I use less pain medication for my cancer pain, and the issues I'd begun to have with swelling of the feet and ankles have disappeared.  Fresh fruit isn't entirely responsible for this improvement in my condition, but it replaces much less healthy food in my diet, and the fiber it contains is almost certainly good for my health.loupgarous (talk) 05:51, 11 February 2016 (UTC)