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July 10

Why can't I run an electric heater in reverse to cool a room?

Headphones convert electricity into sound. Plug headphones into a mic jack, and they can be run in reverse, that is, convert sound to electricity, and work as a crude microphone.

An electric heater converts electricity to heat. So why can't it be run in reverse, converting heat to electricity and cooling the room?

Is there any way to lower the temperature in a closed room (i.e. without venting heat to the outside)? (Assuming there is electrical power available in the room, raising the temperature is easy: electric heater.) --Lph (talk) 00:40, 10 July 2013 (UTC)

Because heat is a statistical representation of kinetic energy; and if you make something hotter than its surroundings, the probabilities are higher that energy will transfer out of the object: in other words, heat flows from high-temperature objects into lower-temperature objects. This is a direct requirement of statistics that define the probability of one air-molecule bouncing in to another one.

We quantify the average behavior using Newton's law of cooling, or the Stefan-Boltzmann law, or the Maxwell distribution; but they are all derivable using similar mathematical analysis. Nimur (talk) 00:57, 10 July 2013 (UTC)

No, there's no way to lower the temperature of a closed system, such as a sealed room, see the laws of thermodynamics. Intuitively, try to imagine unburning something to see why this won't work. μηδείς (talk) 01:15, 10 July 2013 (UTC)

No, you can sometimes lower the temperature, just not the entropy. We have a very brief stub on the instant cold pack. --Trovatore (talk) 01:42, 10 July 2013 (UTC)

Now that I think about it, I'm not sure, but Medeis did specify a closed system. Does an endothermic reaction in an idealized "box universe" lower the temperature of the whole system, or just transfer some kinetic energy from one part (cold pack) to another (surrounding air in the box)? SemanticMantis (talk) 02:28, 10 July 2013 (UTC)

It lowers the temperature of the whole system. --Trovatore (talk) 22:12, 10 July 2013 (UTC)

Right, and if you drop a rock from a few meters, it releases energy as heat (sound and vibrations) -- yet adding that heat to a rock on the ground will not cause it to jump a few meters in the air. The OP may also be interested in reading about the arrow of time, which some scientists and philosophers have interpreted in terms of entropy. SemanticMantis (talk) 01:23, 10 July 2013 (UTC)

Also an electric heater does not form a closed system with the room. If you check behind the device that converts electricity into heat you will usually find a wire that then connects through a series of transformers to a device that converts heat into electricity. Hcobb (talk) 02:33, 10 July 2013 (UTC)

Along the same line of reasoning: supposing we have a very warm room; and we connect it to the (colder) outside world using a copper wire. The thermoelectric effect is a real thing - a voltage could be produced, and the hot air in the room that impinges on the copper inside the room can excite some valence electrons, creating a voltage relative to the copper wire outside the room. Current could flow.

However - we know this doesn't happen in practice. Why? It's statistics, again. Hot air impinging on a copper wire is more likely to transfer its energy as a phonon than to thermoelectrically-excite a valence electron - in other words, the heat transfer is more likely to occur through thermal conduction - so the copper wire will be a heat pipe conducting heat energy out of the room through thermal conduction. For every electron that gets knocked into a conduction band by a thermal process, millions of thermal phonons (ordinary thermal vibrations within the atomic lattice) are created. The magnitude of this effect dwarfs any thermoelectric effect, which is so far below the noise-floor as to be un-measurable.

A few very special materials do exhibit the thermoelectric effect in a way that is measurable, (but copper is not one of those materials). In principle, if you had a huge chunk of thermoelectric material, and you had a very warm room, and a very cold outside, you could hook up a wire and generate a non-negligible amount of electric current. The current would carry energy out of the room. The key point is, there is a cold reservoir - the outside world - where the heat-energy is getting dumped out. Through the thermoelectric effect, electricity is just a mechanism by which that energy is getting transferred from hot to cold. And this method would be very inefficient, compared to using a conductive material, or allowing regular air convection to run its course and transfer the heat by more conventional means. Nimur (talk) 02:59, 10 July 2013 (UTC)

The OP specified: "in a closed room (i.e. without venting heat to the outside)". μηδείς (talk) 03:05, 10 July 2013 (UTC)

Exactly. Thermoelectric conversion involves moving heat from a hot junction to a cold junction in order to generate electricity (the Seebeck Effect) and the cold junction would have to be outside the room.

Yes, as noted above, it is possible to lower the temperature of a room without dumping heat outside: just use a cold pack. The endothermic chemical reaction doesn't actually change the internal energy of the room--it just arranges the atoms so that some of the energy that used to be heat is now trapped as potential energy in the structure of the cold pack's molecules. If this seems surprising, it shouldn't be. Consider that you can turn the room into a 1000-degree inferno just by lighting a fire, and that definitely doesn't absorb heat from the outside!

These kinds of chemical reactions are irreversible, so once the cold pack is used, it can't return to its original state without releasing heat (and dumping it into the room). If you want a purely physical process, that would involve taking thermal energy out of the room, and that energy has to go somewhere. You could maintain a temperature differential, where a tiny portion of the room is extremely hot and everywhere else is cold, but that differential requires additional energy to maintain--and the whole room will eventually heat up. You could cheat by dumping the energy outside in a different form--for example, using a laser beam to shoot it into outer space, where it doesn't heat up the Earth. You could convert the energy to another form of potential energy, for example by using it to lift up a heavy object.

EDIT: here's a very specific example of a physical process that cools a room. Suppose you have a giant cylinder with an airtight, and initially immobile, partition in the middle. On one side of the partition is a vacuum, and a spring that attaches the partition to the top of the cylinder. On the other side is a highly pressurized gas. Now, you release the latch holding the partition in place. The pressurized gas pushes on the spring and compresses it. The gas cools due to adiabatic expansion, and some of the gas's thermal energy turns into the potential energy of the spring. When the room reaches thermal equilibrium with the cylinder, it will be cooler than before. --Bowlhover (talk) 06:24, 10 July 2013 (UTC)

Certainly there are on-off things (such as instant-cool ice packs) that will convert heat into chemical bonds and thereby cool the room. However, they are one-off things. Once the ice pack has done it's thing, the room returns to an equilibrium temperature - and no further cooling is possible without buying more of them. With an electric fire, you can make the room hotter only by bringing in energy from the outside and keeping it there. Air-conditioners aren't like reverse-electric-fires. They don't suck heat out of the room and produce electricity as a by-product (which would be VERY handy here in Texas right now!) - instead, they consume electricity, suck heat from one place and generate even more heat in another place...a typical household A/C unit dumps the excess heat outdoors - and the heat it produces out in my back yard is considerably more than the heat it removed from the room, which explains my soaring electricity bill!

A reverse-electric fire (ie a device that turns heat into electricity) would be a violation of the second law of thermodynamics. There are devices that can turn a heat-gradient into electricity (a "peltier-effect" device, for example) - but in order to pass muster with the second law, they have to heat up something else in the process. Using a peltier device to cool a room will only work if it's colder outside than inside...and you can achieve that effect just by opening a window!

In the end, we're running into the problem of entropy. The tendency of the universe to move from a more ordered state into a more disorderly one. Electrical flow is very organized - heat is pretty much the ultimate in disorder (at the molecular level)...so the universe lets us convert electricity into heat (order-to-disorder) - but not the other way around. Thermoelectric devices like peltier-effect gizmos work by increasing the orderlyness of one place at the price of increasing the disorder in some other place to an even greater degree. The total amount of disorder in the universe is thereby increased and the laws of physics are happy!

SteveBaker (talk) 14:06, 10 July 2013 (UTC)

The OP could sit for a while with the heater blowing in his face. When he turns it off, it should feel cooler in the room. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:25, 10 July 2013 (UTC)

Of course if you were using an air source heat pump to heat your room, rather than an electric heater, you could run it in reverse as an air conditioning unit. Mikenorton (talk) 18:10, 10 July 2013 (UTC)

Thanks, everyone, for the very interesting and informative replies! --Lph (talk) 22:43, 10 July 2013 (UTC)

Angular momentum II

This is a continuation of the discussion I initiated a few days ago and which is still posted on this page. Although a few interesting ideas transpired the overall result left me dissatisfied. The most interesting comment was that by SteveBaker that two non rotating balls after collision may acquire angular momenta. That's fine but I don't think this can be applied to the early Universe. There were no balls there of any size. There was plasma there until 370,000 years of age, that's it. Was there any verticity? I cannot answer this question but I wish someone could.

I have two hypotheses, one is sort of crazy. At the very earlier stage, really before the inflation, the system was subject to quantum fluctuations which later generated sound waves and clumps of matter. One of those "fluctuations" could have been a lateral jolt that gave the system a rotation, but one can ask: a rotation in respect to what? Still another difficulty arises: how this rotation of the whole Universe translated into verticity of the local matter? The fact that we cannot detect this universal rotation now may be one of the results of inflation although I have hard time visualizing how this could happen. If I am not mistaken rotation of superfluid like liquid helium can generate local vertexes although I may be wrong on that.

My second hypothesis assumes that up to the age of about 100 million years or so there were no rotating parts in the whole Universe. At that time massive stars were formed (which had no angular momenta) and after about 1 million years of burning collapsed into supernovas or neutron stars. What are the stars made from? Plasma. Plasma supports sound waves. There were sound waves on the surfaces of earlier stars. So, when the stars exploded they threw much of their mass into the surrounding space but those jets were not symmetrical, they were once-sided perhaps or more complex. They must have given the remnants of the stars an angular momentum because of the reactive force. Perhaps strong magnetic fields also contributed to this irregularity. I hope I use correct terminology.

Once the star begins to rotate, the surrounding medium must rotate in the opposite direction.

How does it sound? Are there non-rotating stars in the sky?

Thanks, - Alex174.52.14.15 (talk) 03:30, 10 July 2013 (UTC)

I think you mean to say vortex and vorticity; a vertex is something else altogether.

Symmetry breaking in the very early universe is a complicated topic. I found a nice website, on the topic, part of an elementary course on Cosmology from the University of Oregon. All 26 lectures are available at no cost. I skimmed several of them, and read a couple in more depth - they meet with my approval, for what that's worth).

Before you jump to hypothesizing, it's not a bad idea to educate yourself about all the things that are factually known. Nimur (talk) 03:45, 10 July 2013 (UTC)

It actually should be verticity. Vorticity is a measure, verticity is a quality. Thanks for the references.

Thanks, - Alex174.52.14.15 (talk) 02:01, 11 July 2013 (UTC)

You imply that the acquisition of rotation was not possible because "there were no balls" - but rotation can be induced in any volume of tiny objects if there is some kind of force binding them together - gravitation, for example. To create a rotation, you only need a "couple". Any object of non-zero size can be started in rotation if there are two or more non-parallel forces being applied to it...so in a system of three bodies, each with mass and non-zero size, any two of them are exerting gravitational forces on the third - and unless they are in a perfectly straight line, you'll have a couple - resulting in rotation. SteveBaker (talk) 18:56, 10 July 2013 (UTC)

To clarify, two non-rotating balls have a net angular momentum before an off-center collision. To see this, imagine they just barely miss each other, but catch each other by a little hook - now they don't move on in either direction, but their entire energy remains as the two twirling madly around their common center of gravity. The result is that if you have n particles moving through space, any two of them have some angular momentum around a given axis as determined by the lever arm of their torque, and only if all the net angular momenta happen to add to zero do you have a system with zero angular momentum.

There is, admittedly, something that seems haphazard about all this; just as it seems strange that angular momentum is quantized while the position in space seems not to be. I feel as if, somehow, we are viewing the universe in a fictional mental framework very different from its physical reality. Wnt (talk) 21:33, 10 July 2013 (UTC)

Thanks to everyone who contributed but I am still dissatisfied. For one thing the "references" although cute are too elementary and too familiar to me in topics to be of any help. It was nice to read some of the pages just to enjoy the technical language. SteveBaker continues to argue that the colliding masses do not have to be solid to generate momentum. This might well be true but I cannot visualize it. It simply isn't very intuitive. Let's say a mass of plasma flies through space and meets another cloud of same. The particles should just mix, that's it, if they are electrically neutral. Now, if they are not and also if strong magnetic fields are involved, then a cloud of plasma can act as a solid object, this is true. Perhaps this is the correct path to understanding how galaxies get rotated.

Thanks, - Alex174.52.14.15 (talk) 02:01, 11 July 2013 (UTC)

Taking your two masses of plasma colliding. You seem to agree that if they are charged or magnetic - then rotation can be induced by the electromagnetic force. In fact, the only way those two clouds could pass through each other without any interaction whatever is if there are no forces whatever between the particles that make them up. But why only consider the electromagnetic force? Any pair of forces acting on an object with non-zero size will suffice to make a "couple" - and that includes the strong and weak nuclear forces and gravitation. Since all objects that have mass produce gravitational forces - then rotation of some kind is more or less guaranteed to emerge from any interaction - even at a distance. In the case of two clouds of plasma, the amount of gravitation and other forces may be very tiny indeed - and the resulting rotation will also be tiny - but over an uncountably large number of interactions happening in the universe, sizeable rotations will eventually emerge. SteveBaker (talk) 14:05, 11 July 2013 (UTC)

Thank you but now I clearly see that you are mistaken. Week and strong nuclear forces act on subatomic distances only and I don't think they are applicable here. Imagine a ball at a certain height falling on the surface of earth under the condition that no lateral wind force is applied. Do you expect the ball to start rotating BEFORE it hit the earth? I don't think so. So, gravitation alone cannot do it.

Thanks, - Alex174.52.14.15 (talk) 17:11, 11 July 2013 (UTC)

Tidal Force allows bodies to exchange angular momentum through gravitation. 209.131.76.183 (talk) 17:29, 11 July 2013 (UTC)

Alex - when you ask a question here, you might take the time to actually read what's written rather than triumphantly telling us that you now understand it all and we're wrong. Gravitation can cause rotation in the case when there are THREE or more bodies involved AND when the gravitational vectors are not parallel. When you drop a ball, it pretty much falls DIRECTLY towards the center of the earth - and indeed, if the ball and the earth are the only bodies in consideration, your common experience of gravitation is correct. But when there are multiple sources of gravity (the earth, moon and sun, for example) and the motion of the ball isn't conveniently directly towards or away from any of them - then induced rotation of all of those bodies is inevitable. Your common intuition defeats you here. Similarly, the nuclear forces do indeed operate at very small distances - but if they are inducing rotation in very tiny objects, and if there is enough time for their tiny influences to add up - then that's enough to break that "symmetry" and cause the onset of rotations. But no matter, gravity is plenty powerful enough. SteveBaker (talk) 01:32, 12 July 2013 (UTC)

Well, it might be true (actually it is certainly true) but we are talking about the primordial angular momentum when right after the inflation there was no angular momentum anywhere. At that time there was nothing to exchange. This is the enigma. How did it all start? - Alex174.52.14.15 (talk) 18:15, 11 July 2013 (UTC)

You're simply not understanding what we're telling you - you can get rotation from simple translation in the presence of forces such as gravity. I've shown you that in two previous responses. Admittedly, a clockwise rotation induced in one object will be precisely equalled by anticlockwise rotation in the other - so the NET rotation of the universe is still zero - but multiple swirls and eddies will start to build even in an initially rotation-free universe. SteveBaker (talk) 01:32, 12 July 2013 (UTC)

The structure formation in the early universe happened in a turbulent environment where vortexes easily formed. Do a google scholar search for 'universe "structure formation" vortex' to get a some papers on the topic. here is an interesting example. Dauto (talk) 13:38, 12 July 2013 (UTC)

Asking for how things changed from the state "just after inflation" seems particularly frustrating. I'm not an expert, but so far, I don't see what advantage the inflation model has over saying "well, God must have made it that way". I mean, cosmic inflation is a whole quiver of models, meant to explain how the universe happens to be flat without very specific starting conditions by requiring even more specific starting conditions and some kind of gee-whiz inflaton physics based on no actual particle or force that seems to be nameable. What the universe looked like afterward? Who knows! It seems to be defined by "it must have undergone some process of inflation to work out so that it looks like it does now". Wnt (talk) 20:52, 12 July 2013 (UTC)

Go fuck yourself

The phrase "go fuck yourself" is often censored as "instructed to perform an anatomically impossible act". Some time ago I encountered what appeared to be a photograph of a man with the tip of his penis inserted in his anus. Was this a photoshop job, or was he actually managing to have anal sex with himself? --67.160.38.148 (talk) 04:53, 10 July 2013 (UTC)

It is probably technically feasible given the ranges of sizes of various body parts. That is, a man with a particularly long penis could probably make it reach. The Wikipedia article titled Human penis size may lead you to the necessary measurements to determine this on your own. --Jayron32 04:57, 10 July 2013 (UTC)

I can make mine reach and could have probably put the tip in, but didn't want to. Of course, if I really wanted to fuck myself, I'd need an erection, and I am absolutely certain it doesn't bend that way. Mine, anyway. If the guy in your picture looked hard, I'd assume it's fake, but who knows? It could have just been terribly damaged. InedibleHulk (talk) 05:31, 10 July 2013 (UTC)

I've seen pics and videos of such things but, as you say, they were not erect and hence there was no "fucking" going on. -- Jack of Oz ^[Talk] 12:05, 10 July 2013 (UTC)

There are some misguided people who oppose Wikipedia's coverage of autofellatio, but you'll find some folks have kindly donated more proof at Commons:Category:Autofellatio. (I'd look up the other thing but ... I haven't thought of what to call it!) Wnt (talk) 21:23, 10 July 2013 (UTC)

I've seen it called "self-sodomy" (a Google search on that term - NOT AT WORK - will confirm this), but that doesn't meet WP:RS. "Autosodomy" (ditto) is also used. Tevildo (talk) 21:57, 10 July 2013 (UTC)

I thought autosodomy was when you really, really like your Duesenberg. Clarityfiend (talk) 23:33, 10 July 2013 (UTC)

Not a problem as long as you don't stick anything in the tailpipe. DMacks (talk) 01:38, 11 July 2013 (UTC)

You can check your progress on the sodometer. -- Jack of Oz ^[Talk] 07:25, 11 July 2013 (UTC)

No, no, no. You use a sodometer to find the exact amount pf sodness between steering wheel and driver's seat. - ¡Ouch! (^{hurt me} / _{more pain}) 07:01, 12 July 2013 (UTC)

Raw Pork

So how come Mett doesn't cause illness or parasitical infestation, when raw pork is considered unsafe for consumption almost everywhere? Rojomoke (talk) 12:50, 10 July 2013 (UTC)

A quick look finds a WiseGeek article on the safety of Mett [1][2], which states that it is intended to be eaten the same day the pig is killed, which should reduce the risks of a bacterial build-up. As with most foods though, cultural factors are often significant when it comes to issues of what is considered safe, and objective data on safety may be hard to locate. AndyTheGrump (talk) 13:03, 10 July 2013 (UTC)

The main risk of raw pork is trichinosis. At least in Germany (where Mett is popular), this risk has been basically eliminated by strict inspection codes for meat, especially pork, and by particularly strict production codes for all minced meat products. --Stephan Schulz (talk) 13:41, 10 July 2013 (UTC)

You might want to read this[3] before you jump to conclusions about pork safety. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:18, 11 July 2013 (UTC)

I really don't quite see how the sale (or not) of a US pork producer (which will likely export to China) affects the effectiveness of food inspections in Germany. --Stephan Schulz (talk) 11:26, 11 July 2013 (UTC)

Maybe you should change the section header to make it clear this is only about German hogs. ←Baseball Bugs ^{What's up, Doc?} carrots→ 11:36, 11 July 2013 (UTC)

There may be some confusion here. In my original comment (the one you, at least according to our standard indentation patterns) replied to, I pointed out that in Germany, where Mett is popular, proper production codes and food inspections mean than pork is quite safe. If you did not intend to reply to my comment, sorry, but then please make it clear what you reply to. I really don't see a strong connection of your comment to any of the preceding posts. Indeed, now I'm not even sure if you warn us that pork may not be safe (because it might be imported from China?), or that pork can indeed be safe (as "several senators" seem to imply for meat meeting American safety standards). --Stephan Schulz (talk) 11:59, 11 July 2013 (UTC)

It's not that it doesn't cause infection. You can be sure that well cooked pork is safe against trichinosis and other bacterial infection. Raw pork can be safe or not, depending on the handling and inspections. In doubt, then, cook it. OsmanRF34 (talk) 16:39, 10 July 2013 (UTC)

In addition to trichinosis being rare in many countries, it's killed by freezing the pork before preparation. --Sean 20:06, 10 July 2013 (UTC)

The genetics of the royals

Have the European royal families been an object of scientific research? It's clear that having children with your relatives is a bad idea, but how bad is it? How many more cases of mental retardation, disabilities, speech disturbances and so on are there? OsmanRF34 (talk) 16:35, 10 July 2013 (UTC)

See Haemophilia in European royalty for one possible issue. AndyTheGrump (talk) 16:37, 10 July 2013 (UTC)

Inbreeding increases the chances of a phenotypic abnormality with autosomal recessive genes, but doesn't really have anything to do with hemophilia, which is inherited as a sex-linked recessive gene. Hemophilia B spread through the royal families after a single mutation, and was inherited in the usual straightforward way, without any couples who *both* bore the mutation. - Nunh-huh 13:17, 11 July 2013 (UTC)

See Prognathism, and this article in Discover magazine [4]. Note that it is a bit simplistic to think "inbreeding causes bad things". In fact, most race horses, prize dogs, etc are highly inbred. But, when it's done intentionally to keep "good" alelles, it's usually called line breeding (unfortunate redlink, just google it). Cleopatra is sometimes mentioned as a human who may have benefited from such a collapsed family tree. Finally, all of the above can be considered as aspects of founder effects. SemanticMantis (talk) 18:03, 10 July 2013 (UTC)

But pedigree dogs are very frequently afflicted with genetic diseases. Surf to almost any of our articles about famous dog breeds and you'll see a list of genetic problems brought about by inbreeding. I looked up Poodle (at random) and found that the breed suffers from: "Addison's disease, gastric dilatation volvulus, thyroid issues (hyperthyroid and hypothyroid), tracheal collapse, epilepsy, sebaceous adenitis, juvenile renal disease, hip dysplasia, and cancer". But pick another breed and you'll get a different list - so these diseases can only have become more prevalent because of the specializations the "poodle-ness" implies - and that's due to inbreeding. In recent years breeders have started to work hard to eliminate these problems - but that degree of gene-pool management would be a brutal thing to impose on humans!

One or two generations of in-breeding may not do too much harm - but when you do it for dozens of generations (as european royalty did) - you effectively cut off these people from the rest of the species and (in effect) you have a new sub-species with a gene-pool of maybe 100 individuals. A gene pool that small is just too small to avoid genetic problems from accumulating. There does seem to have been research on the effects of all this. Type "inbreeding european monarchy" into Google scholar and you find a TON of papers that have been written on the topic.

SteveBaker (talk) 18:48, 10 July 2013 (UTC)

I take your point, certain dog breeds are plagued with genetic disorders. But I wasn't referring to just any poodle. I mean the show winners, who may have several generations pedigree of ancestors that did not have e.g. juvenile renal disease. Very bad things have happened to breeds when they were obsessively bred to meet bizarre standards, and in those breeds, a pedigree with documentation of lack of a disease is a very valuable thing indeed. The fact that people in the past didn't breed their poodles with genetic disease in mind doesn't mean that selective line breeding can't be used to improve individual traits and performance, or that such practice must necessarily bring deformity and disease. For instance, this breeding project is very focused on dog health and longevity (and dire wolves) [5]. Here's another example that illustrates a "positive" founder effect: all modern Thoroughbred racehorses are thought to descend from a single, very large-hearted 17th century mare! [6]. Finally, I must confess I find all this artificial selection a bit creepy. I don't mean to defend inbreeding in general, but I do think "inbreeding=bad" is an overly simplistic message. Clearly, the sad state of poodles and Hapsburgs tells us that it can cause problems when taken to extremes, but cousin marriage doesn't really have many risks. You seem to understand the subtleties here, so I'm mainly pointing out to others that there are also potential benefits to inbreeding. SemanticMantis (talk) 19:25, 10 July 2013 (UTC)

"doesn't really have many risks" is not how I would interpret statistic that show a 50% to 500% increase in risk. Some drugs are sold with far less effects. Rmhermen (talk) 20:06, 10 July 2013 (UTC)

500% increase in risk of what? I'm no expert, I was basing my claim on my reading of our article, which says "The children of first-cousin marriages have an increased risk of genetic disorders, though the incremental risk enhancement is relatively small, according to many researchers." Cousin_marriage#Genetics says, with citation: "In April 2002, the Journal of Genetic Counseling released a report which estimated the average risk of birth defects in a child born of first cousins at 1.7–2.8% over an average base risk for non-cousin couples of 3%, or about the same as that of any woman over age 40" -- so my understanding of our article is that cousin procreation poses a low-level risk to offspring, which is not very different from other "risky" procreation. SemanticMantis (talk) 21:47, 10 July 2013 (UTC)

2.8+3=5.8 or almost 6 which is nearly 100% increase. Later in the article you will even higher increase in spontaneous abortion rate and infant mortality in various arrangements of cousin, second cousin and double cousin marriages. Rmhermen (talk) 21:19, 11 July 2013 (UTC)

There is a fairly detailed exposition on the subject of inbreeding in Robert Heinlein's Time enough for love, where Lazarus Long tries to figure out if it would be okay for twins to make babies together (the subject is relevant in other portions on the book, but lets pass on the details dreamed up by Heinlein's perverted mind), and the conclusion was that it was basically okay. I also remember reading something about an island where a goat couple was introduced, and then the island was pretty much left alone for a long time, and then when humans came back there was a large population of goats with a pretty good genetic diversity - and if I'm not mistaken, the explanation was that the island actually had predators for the goats which culled the (probably numerous early on) genetically defective individuals. The problem with the Rois faineants is that they were probably not under considerable evolutionary pressure, letting shortcomings accumulate (most people in the middle ages probably had a much lower of chance of surviving hemophilia than the average king). I'd love to provide references but my internet access is limited at work. I think the island in question may have been Arapawa Island? 64.201.173.145 (talk) 20:42, 10 July 2013 (UTC)

Yes, Arapawa mentions the relevant solution: culling. If you are willing to have a large number of children or animals die, so long as you have enough to carry on the line, inbreeding's problems can be tolerated. But as the quoted Discover article mentions, part of that culling is also effective sterility. (Sterility in this case being culling at the level of gametes or early embryos. The same with the goats, obviously. As long as they produce enough kids fast enough they will survive. Sexual reproduction also weeds out the harmful mutants. Imagine two carriers of a gene that's lethal when homozygous have four offspring. One will be homozygous and die, two will be heterozygous and live, one will be mutation free. That is a change from 1/2 to 1/3 rate of the gene in one generation. As for a %500 increase in risk, if the original risk is 1/10,000, a 500% increase means a risk of 1/2,000. Again, tolerable. μηδείς (talk) 01:34, 11 July 2013 (UTC)

For most of human history in most societies, marriage of cousins (not always necessarily first cousins) has been the norm (since nearly everyone within walking distance was related). We've survived, though often at the cost of high infant mortality in the past. Dbfirs 06:10, 11 July 2013 (UTC)

...but with very much of that infant mortality not being the result of genetic defects, but of bad nutrition and infectious diseases. Marriage between close relatives is primarily a problem in the case of recessive gene defects, it does not magically create monsters. --Stephan Schulz (talk) 07:12, 11 July 2013 (UTC)

(Anecdotal evidence:) No, cousin marriage certainly is not an instant recipe for mutants. I am the product of many generations of cousin marriages (including an avunculate marriage or two), and none of my close relatives on any side are monsters—or particularly unhealthy in any way. הסרפד (call me Hasirpad) 23:05, 11 July 2013 (UTC)

I have found the relevant passage from Time enough for love on Google Books: [7] - however, some parts are missing and the page numbers are not indicated. Searching for "Unfavorable gene reinforcement" should lead to the proper page if you can find a complete electronic edition. 64.201.173.145 (talk) 12:54, 11 July 2013 (UTC)

It's one of Heinlein's best books if not best. One should read the whole work. μηδείς (talk) 18:03, 11 July 2013 (UTC)

Royal intermarriage has a (rather disappointingly) short section on inbreeding.

For those interested in inbreeding in general ;-), we have an article on Patrick Stübing who had four children with his sister, one of them healthy, one with a heart condition and two with severe disabilities (could be case specific, maybe neither of them should have children, period.) Ssscienccce (talk) 13:56, 12 July 2013 (UTC)

Aren't "nonpaternity events" a cure for inbreeding of royals? They can be pretty sure that the mother is the mother, but without simple DNA testing, they can't be sure who the father is. Would a DNA result which showed the father was not really the mother's husband make a baby ineligible to become the monarch, or would they fall back on the usual practice of pretending the mother's husband is the father? Edison (talk) 19:04, 12 July 2013 (UTC)

The "Runaway Train" Lever

According to [8], "Local firefighters were later called to put out a fire on the train. While tackling that blaze, they shut down a locomotive that an engineer had left running to keep the brakes engaged." -- and the train went off and killed 60 people!

The article Lac-Mégantic derailment gives a similar opinion, though saying there were supplemental brakes that should have been set.

In forum discussions [9] some people say what I would have expected, namely that the brakes are like on trucks where a failure of air pressure makes them engage. Meanwhile, others say that there is an emergency lever somewhere on the outside of the train that can shut off the engine automatically!

Does this mean that someone can go wherever local news reports have quoted residents complaining about idling trains, find one, pull the lever, and (with some probability, depending on if hand brakes were set) sit back and watch the fireworks? Wnt (talk) 17:09, 10 July 2013 (UTC)

I hope you realize Barack Obama now knows you said that. μηδείς (talk) 17:45, 10 July 2013 (UTC)

Well, if I'd seriously been planning to derail trains I'd have kept it to myself! Thing is, maybe the spooks ought to notice this because lots of people must have thought of this after reading today's news. Wnt (talk) 17:58, 10 July 2013 (UTC)

It's evidently not a simple matter. There are two completely separate braking systems - the air brakes require positive air pressure to engage the brake, but there is a separate hand-brake system - which has to be applied separately to each car. Evidently the hand brakes are activated by external levers - but in this case, they didn't set the hand brakes on all of the cars...certainly there were insufficient to stop the train from running downhill without help from the air brakes. Our article Railway air brake explains the rather complex system which prevents the air brakes from failing when the locomotive ceases to supply air or if either of two redundant sets of hoses breaks. As far as I can tell, that "fail-safe" system works by filling up a pressurized reservoir on each car which holds the brakes on in case of problems. In this case, the air supply from the locomotive ceased - the brakes on the cars duly engaged - which is why it didn't immediately run away when the engine was stopped. But the brakes would only stay engaged as long as their air reservoirs held out. When that air finally ran out, the cars would start to un-brake, and eventually there were eventually insufficient cars with either reservoir air remaining or hand-brakes applied to keep the whole thing from running away.

I think it's a bit simplistic to take the view that the entire system is ridiculously flawed and that a trivial modification would make it all safe. The engineers who design these things aren't stupid - and there is enough history of runaway trains for them to know the importance of getting this right. But it's clear that despite multiple backup systems, a sufficiently complicated set of human procedural screwups and mechanical failures can still result in a runaway train.

SteveBaker (talk) 18:30, 10 July 2013 (UTC)

See Chester General Rail Crash for a virtually identical accident (with less serious consequences) in the UK. The train involved in that accident wasn't fully-fitted, but did have sufficient continuous brakes to prevent the runaway - _if_ they'd been connected correctly. Not that we should speculate about Saturday's accident beyond the officially-published investigations. Tevildo (talk) 19:57, 10 July 2013 (UTC)

And this incident report from 2007 contains a detailed description of the failure mechanism that Steve describes. Tevildo (talk) 20:00, 10 July 2013 (UTC)

Hmmm, the Chester General Rail Crash article talks about vacuum brakes not being connected properly to work while in motion. Seems about as different as it could be - is that the wrong link? And to make an off-topic editorial response -- what's "ridiculously flawed", that's not the engineering but the design. Leaving trains idling unattended is, first and foremost, a serious noise nuisance to the local community - the biological instinct that finds it to be a nuisance is dead-on, namely that large heavy objects moving continually lead, eventually, to disasters; that's the instinctive dread that low-frequency noise makes people feel. The design of the train should have taken deliberate and accidental terrorism into account, so that if a well meaning fireman pulls a lever it isn't going to cause a catastrophe. Whatever engineering it takes to implement such common-sense priorities simply needs to be done, rather than not done; the quality of the engineering is not really at issue. Wnt (talk) 21:16, 10 July 2013 (UTC)

What is ridiculously flawed is not the engineering or the design, but the railroad's operations procedures! Had they followed proper safety procedures by parking the train on the siding (rather than the mainline like they did), and then not just screwing down the handbrakes but also blocking the wheels and/or applying the derail, the whole disaster wouldn't have happened even if all the air brakes failed! No amount of safety engineering can prevent disasters if people ignore the safety procedures, as they did here! (I believe the technical word for blocking the wheels is "scotching", and the blocks used for this are known as "sprags" -- or is that only in British English?) 24.23.196.85 (talk) 02:27, 11 July 2013 (UTC)

Scotch says you're right about scotching (and notes chock as a similar concept...that's the more general term I've heard in the US for many different types of wheeled vehicles). Sprag sounds like a different approach. DMacks (talk) 04:25, 11 July 2013 (UTC)

Given that they were actually blaming the fire company, are these established as universal safety procedures? And from a counterterror perspective, how much extra protection does setting handbrakes and/or chocks actually provide? I'd feel a lot more comfortable if they followed the rules of the rest of the world and parked their train (true, in a proper parking space, not the middle of the road) with the ignition off, the brake set in some permanent way, and preferably, with the turn of a key required before it can be started moving again. Why are they so insistent on having their engines idling uselessly and bothering the neighbors? Wnt (talk) 05:01, 11 July 2013 (UTC)

Note that on most sidings, both the switch and the derail (if equipped) are secured in position with padlocks to deter tampering. As for leaving the engine running, the reason why they do that is because starting a diesel locomotive is not as easy as starting your car -- the procedure for doing this is more involved (more like starting a plane engine), and can take several minutes. Plus, after starting, the engine must warm up for 10 minutes or more before the train can safely be moved. 24.23.196.85 (talk) 01:43, 12 July 2013 (UTC)

The parallel plane and train disasters of this past weekend, both potentially due to (whose?) negligence, remind me of Sean Connery's comment in Rising Sun: "In Japan, they fix the problem. In America, they fix the blame." ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:11, 11 July 2013 (UTC)

Coke didn't freeze

I forgot a bottle of coke in the freezer but it didn't freeze. When I opened it the coke started to, so I quickly closed it again and now it's a viscous liquid. What is the physical explanation to that? Thanks, 84.109.248.221 (talk) 19:01, 10 July 2013 (UTC)

See Supercooling. 209.131.76.183 (talk) 19:07, 10 July 2013 (UTC)

I don't think that's what is happening here -- or at least not all that is happening. The CO2 coming out of solution plays an important role, I believe. Looie496 (talk) 21:33, 10 July 2013 (UTC)

Adiabatic cooling? Dismas|^(talk) 23:34, 10 July 2013 (UTC)

I konw this works much better when the coke is shaken up before putting it in the freezer, though not sure why this lowers the freezing point/ removes nucleation sites (I think the lack of nucleation sites is what is stopping it from freezing.). When you open it the CO2 is released and bubbles provide nucleation sites for ice to form. The viscous fluid you have is just a slush of ice and coke. 80.254.147.164 (talk) 12:31, 11 July 2013 (UTC)

Unsourced speculation - is it possible that the freezing point is just below the freezer temperature when under pressure? Looking at our graph of the melting point of water vs pressure, I doubt that the pressure of the carbonation (<1 MPa, I think) would lower the point enough to make it work reliably, but if the freezer (or the part of the freezer the bottle is in) is only slightly below freezing, it could be what does it. 209.131.76.183 (talk) 19:44, 11 July 2013 (UTC)

One possible confound is that regular Coke has a lot of sugar in solution in addition to the carbon dioxide in the liquid. The presence/absence of the carbon dioxide in solution should make less of a difference for regular Coke than for Diet Coke, which has less material in solution than regular Coke, and which freezes at a noticeably higher temperature, or more quickly in the same freezing compartment. Edison (talk) 18:56, 12 July 2013 (UTC)

I used to do that with beer. Changes in pressure and amount of dissolved co2 have little to do with it, it's mostly supercooling.

• the amount of CO₂ that escaped was minimal, and considering that for an ideal solution the amount of freezing-point depression is only a function of the solute concentration (i.e. the molality) which won't change much when a bit of gas escapes. (on the other hand, when the water starts freezing, the co2 concentration in the remaining liquid will rise.)
• freezing is an exothermic process that releases a lot of heat (for water: heat of fusion is 80 cal/g, while raising the temperature one degree (C or K) requires only 1 cal/g), so a slight rise of the freezing point because of changes in solute concentration or in pressure would only require a small amount of the liquid freezing to be compensated. In other words, if your beverage is only 1° undercooled, it can't produce much ice.
• Pressure: the pressure has little effect on the freezing point, for example: 50 psi lowers it with just 0.03°F (http://www.nytimes.com/2006/02/21/science/21ice.html?pagewanted=all&_r=0)
• supercooling: just like supersaturated mixtures can remain quasi-stable for a long time (sugar solutions take ages to start crystallizing), so can supercooled liquids and mixtures. Supercooled water can reach temperatures as low as -40° Heating_pad#Chemical with sodium acetate solutions are based on this, they are supersaturated but stay in solution until you trigger freezing by creating nucleation sites. Something similar happens when you open the bottle, you create bubbles that form nucleation sites.
• There's also a phenomenon called Melting-point depression, but that's for nano-particles. Ssscienccce (talk) 07:03, 14 July 2013 (UTC)

July 11

Post-operative fever : another Five Ws  ?

Hello Learned Ones ! I was inopportunately dozing at the end of Grey's Anatomy (of which I am a late-coming fan) , season I, episode 3, & did'nt catch clearly the five causes for post-op. fever as enumerated by Meredith : "wind (splint, ...), water, etc...". Could some of you recall them to me ? , this mnemotechnic line seems quite interesting. As for the term "splint", I infer it means that patient must learn to gently hold his abdomen while coughing ? Thanks beforehand for your answers , t.y. Arapaima (talk) 17:39, 11 July 2013 (UTC)

Look at our article on postoperative fever -- hey, presto!, it's right there. Looie496 (talk) 17:50, 11 July 2013 (UTC)

Aw, I'm so ashamed : it was just there (& even with the ref. to "Grey's Anatomy" ! ) , & I didn't find it !. I swear I looked for it, but I typed "post-operative" , continental way, & it gave me a useless page ([ http://en.wikipedia.org/w/index.php?title=Special%3ASearch&search=post-operative+fever&fulltext=1]

. Thanks Looie for you time & kindness, have a good summer day. T.y. PS : I thought WP could correct a (slight) mispelling in a search statement ? ... And how come Five Ws didn't mention it ? Arapaima (talk) 07:08, 12 July 2013 (UTC)

User:Arapaima, you make some good points here! Wikipedia only gets better when people like you notice these things, and take a bit of time to fix them. You can add a "see-also" to the bottom of Five Ws that points to the postoperative fever article. You can also make a "redirect" of post-operative fever and post operative fever to postoperative fever, and that will change the redlinks to blue! If you need help on how to do this, you can ask at the Village Pump or Help desk. SemanticMantis (talk) 14:59, 12 July 2013 (UTC)

Actually I found our article by Google-searching. It's better at handling variations than the Wikipedia search facility. Looie496 (talk) 21:32, 12 July 2013 (UTC)

Cricket Revometer

In their coverage of the The Ashes, Sky are showing off a new gadget called the "revometer". It measures the number of revolutions per minute that spin bowlers put onto the cricket ball, which is an indication of the amount of drift and turn they should extract. There's no gadget inside the ball and I don't think the data comes as part of the Hawk-Eye system, although I suspect a specialist (presumably high-speed) camera is involved. Does anyone know how it works? ManyQuestionsFewAnswers (talk) 18:09, 11 July 2013 (UTC)

The cricket ball doesn't have a uniform surface. I suspect what it's doing is using computer vision to identify the portion of a ball-tracking camera's image that contains the ball, then checking for a periodic variation in brightness. The length of that period is determined by the speed the ball is spinning. --Carnildo (talk) 22:48, 11 July 2013 (UTC)

That would be kinda tricky because the balls' axis of rotation isn't necessarily perpendicular to the camera - if it were spinning end-on, then there wouldn't be any overall flicker at all. So I suspect it's grabbing two very high resolution photographs close enough together in time and tracking where the seam is moving...that's not *so* difficult and would result in a reasonably accurate spin rate measurement regardless of the axis of spin...providing that the camera has a sufficiently large image of the ball at two consecutive moments in time and a sufficiently short capture time (ie shutter speed) to end up with a reasonably sharp image. SteveBaker (talk) 01:09, 12 July 2013 (UTC)

Ashton Agar in particular has been bowling with some atypical axes of rotation for a spinner - with unusual amounts of topspin or with a scrambled seam. I'm not sure what difference that makes technically. ManyQuestionsFewAnswers (talk) 12:05, 12 July 2013 (UTC)

The axis doesn't need to be perpendicular, it just needs to be non-parallel. The closer it is to perpendicular, the stronger the signal is and the better the measurement is, of course. --Carnildo (talk) 01:14, 13 July 2013 (UTC)

I would expect doppler effect (radar or sonar) to be the easiest method, techniques are well-known, maybe two or three detectors to get all the angles. No problem with filtering out other objects, the ball will be the only object in the volume being scanned. If we can measure the rotation of Venus using radar on earth (Venus#Ground-based_research), measuring a ball should be child's play. Ssscienccce (talk) 07:34, 14 July 2013 (UTC)

Could you elaborate on the "well-known" technique somewhat? I didn't realise the the doppler effect could be used to measure rates of rotation! ManyQuestionsFewAnswers (talk) 23:30, 15 July 2013 (UTC)

Gastritis

The gastritis article claims that sometimes it can occur after infections but surely this should say during infection? Doesn't the bacterial infection cause the inflammation or gastritis in the first place and after the infection is gone, the inflammation will also go, unless there's another cause? Clover345 (talk) 21:45, 11 July 2013 (UTC)

Boiling water with vending machines... in SECONDS! A miracle!

How do vending machines boil water so quickly to make instant coffee cups or instant noodle cups? I suspect they have some sort of high pressure thingy inside there. Sneazy (talk) 22:17, 11 July 2013 (UTC)

Maybe they have a Instant hot water dispenser inside? Vespine (talk) 22:42, 11 July 2013 (UTC)

(ec) There are two approaches that can be used, depending on the required flow rate and available electric supply. Some machines maintain a small well-insulated hot water reservoir at close-to-boiling temperatures; this hot water can be dispensed on demand for hot beverages and instant noodle cups. Having a hot reservoir means that the manufacturer can get by with a smaller heating element, since the heating cycle can last a lot longer than the few seconds that the cup is being filled. Here's a surprisingly detailed schematic of a hot band cold instant beverage vending machine, featuring a six-liter holding tank with a 900-watt heating element: [10].

It's also possible to heat water on demand, however the electricity requirements are steeper. To heat 1 mL of water from room temperature to boiling takes about 300 joules; to heat a cup (eight ounces or about 250 mL) of water from room temperature requires 75 kJ. If dispensed over twenty seconds, that's just shy of 4 kilowatts of on-demand heating. (That is a fairly hefty load, but not impossible to supply if the vending machine location is designed with this type of use in mind; it's comparable to the power drawn by an electric clothes dryer.) TenOfAllTrades(talk) 23:10, 11 July 2013 (UTC)

Is that energy source green? Is there a particular company or set of companies that sells these types of products? Do they use greener energy, or do they just don't care about where the energy source come from? Sneazy (talk) 00:52, 12 July 2013 (UTC)

I doubt it's anything other than whatever wall socket is handy nearby...so no more or less green than the lights in the area where the machines is situated - or other vending machines at that location. What is "green" is minimising the amount of water that has to be kept hot. The instant heaters - while they use a lot of power, only do so for a short amount of time. The total energy they use is less than the type that keep a small tank of hot water because no matter how well insulated that tank is, it's going to be losing some energy over time. SteveBaker (talk) 01:01, 12 July 2013 (UTC)

As Steve says, the source is the wall plug of course, so it entirely depends where you are. If you are in Canada or in Sweden, it is likely to be mostly from hydroelectric powerplants. If you are in France, it is 77% nuclear power. If you are in Dubai, it is most likely from burning some sort of fossile fuel like gas. --Lgriot (talk) 08:58, 12 July 2013 (UTC)

Well to make this instant heater work anywhere, why they don't just put like a supercapacitor to store the electrical energy so it can distribute the load over a longer time? Modern SMPS have 80+ efficiency so... everyone is happy 140.0.229.26 (talk) 13:51, 12 July 2013 (UTC)

A 75kJ supercapacitor isn't cheap, and the existing technology works well and service people are familiar with it. Keeping water warm in a well-insulated tank won't waste that much power, and the machine can be scheduled to shut off at hours it won't be used. Also, many machines are operated by vending services, and they aren't concerned about the amount of power being used unless the owner of the site starts complaining. 209.131.76.183 (talk) 14:53, 12 July 2013 (UTC)

Vending machines tend not to be in service very long. So if the OP saw this in the last few years it was probably using a 'flash boiler' with no hot-tank reserve. Yet that can depend on were you live. For instance in North America, most power outlets appear to be split-phase 120 volt sockets. That, (as tenofalltrades points out) would require an aprox 20 sec fill time of your pot noodle with the socket delivering its max current. If you look behind the machine and its pluged in to a full phase (240volt) socket, it can achieve a fill time of about half that time. There should be a plate on the back (use a mirror if space is tight) that states both its max amperage and working voltage. If it uses around 3½ to 4 KVA then it likely uses a modern flash boiler. --Aspro (talk) 19:14, 12 July 2013 (UTC)

Well if they use a reverse cycle heat pump, they could get more heat for their input power, But due to extra cost, and time delay to heat, this is probably in the same boat as the super capacitor! Graeme Bartlett (talk) 21:16, 12 July 2013 (UTC)

July 12

Heads of State who were also Medical Doctors?

Hi, does anyone know of any Heads of State (current or former) who were medical doctors? The only one I've been able to find is Ram Baran Yadav, President of Nepal. Thank you for your help. LastPolarBear (talk) 11:24, 12 July 2013 (UTC)

François Duvalier -- Finlay McWalterჷTalk 11:37, 12 July 2013 (UTC)

Mohammad Najibullah (he article says he graduated as a doctor; it doesn't say whether or not he practised as one). -- Finlay McWalterჷTalk 11:49, 12 July 2013 (UTC)

Sun Yat-sen. {The poster formerly known as 87.81.230.195}212.95.237.92 (talk) 12:57, 12 July 2013 (UTC)

Bashar Hafez al-Assad. OsmanRF34 (talk) 17:09, 12 July 2013 (UTC)

Not technically a head of state or "real doctor", but Grigori Rasputin's healing powers put him in a place of influence among (or over, some say) the ruling family of Russia. Depending on why you ask, he might count. InedibleHulk (talk) 03:12, July 13, 2013 (UTC)

Gro Harlem Brundtland. --NorwegianBlue ^talk 22:17, 14 July 2013 (UTC)

More info at List_of_physicians#Physicians_famous_as_politicians, which features among others Salvador Allende and Papa Doc (the latter already mentioned by Finlay McWalter). --NorwegianBlue ^talk 00:37, 15 July 2013 (UTC)

Added Radovan Karadžić to the list (as politician, he was already on the Physicians famous as criminals list). --NorwegianBlue ^talk 08:24, 15 July 2013 (UTC)

I've added Sir Earle Page to the list. He wasn't a head of state, but a head of government (Prime Minister) for a short time. -- Jack of Oz ^[Talk] 08:36, 15 July 2013 (UTC)

How soon til the island of stability?

I am curious if there is anything similar to Moore's Law in regard to the creation of heavier elements? Thanks μηδείς (talk) 22:11, 12 July 2013 (UTC)

Are you really curious? Haven't you been paying attention to physics for the last three decades? The Superconducting Supercollider was canceled. The funding at Lawrence Berkeley National Laboratory has been diverted to "bio-research." The National Ignition Facility is the last large program at Lawrence Livermore Laboratory. Stanford Linear Accelerator is dissociated from its parent institution and they turned the beam tube into an X-ray laser for biological research applications. Fermilab shut down the Tevatron. Brookhaven National Laboratory is shutting down their synchrotron. The Spallation Neutron Source is sputtering along at Oak Ridge. The program at Los Alamos has been shifted to theoretical work, "arsenal maintenance," and treaty compliance. No, there is not an accelerating trend in the current state-of-the-art in nuclear, heavy ion, and high energy physics. This field is very rapidly dying, especially in the United States. Nimur (talk) 23:02, 12 July 2013 (UTC)

I didn't realize one needed high-end supercolliders to do that work, does one? I thought, from reading our article, the problem was the lack of precursor. My only knowledge of the subject is from the even more decrepit Scientific American, or Guccione's sci-porn. μηδείς (talk) 23:21, 12 July 2013 (UTC)

SLAC is being used for physics as well, just not particle physics. IRWolfie- (talk) 23:48, 12 July 2013 (UTC)

Let me specify I am still confused by the above comments. I have only had enough physics to fullfil an undergrad requirement for the biology major. μηδείς (talk) 00:24, 13 July 2013 (UTC)

Moore's law describes a rapidly accelerating pace of technological development, fueled by massive investment and acceleration of technology. Basic science rapidly pushes the frontier; new technology is immediately adopted by industry and put to practical use. Moore's law describes a particular state of affairs that characterized the computer and electronics industry over the last three or four decades; it has taken many forms, from the vague description of a technology "acceleration," to specific claims about technology parameters and durations. If you contrast that to the sorts of theoretical physics and basic science that are related to nuclear research, or to the industrial applications therein, you find no such acceleration or rapid progress. Technological and scientific development is slowing down in the areas of basic science related exotic nuclear physics research. Without a cold war between nuclear-armed states, there is little incentive to pour resources into the field. There is still progress on the edges of the current state-of-the-art, but it is nothing like the electronics industry. Nuclear technology is not "accelerating," and it is certainly not doubling its capabilities every two years.

At best, we can say that there's been a tiny break in the ice - after nearly forty years with no new plants, Shearon Harris Nuclear Power Plant was approved for a second reactor, four or five years ago; many more nuclear facilities shuttered operations during that timeframe. Existing technology is stagnant; new technology and basic science research are rapidly declining.

This state of affairs for nuclear technology is nothing like Moore's Law. The cutting-edge of nuclear technology is barely funded; existing technology is deployed at new facilities slower than a pitch drop experiment. Contrast this with Moore's Law - corporations and governments pour money and time and manpower to invent new technology; performance doubles every two or three years; existing infrastructure is totally overhauled and replaced every six or ten years. Nimur (talk) 01:07, 13 July 2013 (UTC)

Thanks, that's an interesting and quite clear response. μηδείς (talk) 01:15, 13 July 2013 (UTC)

Nimur is certainly knowledgeable and seems quite cogent here, yet... I wonder. To begin with, I wonder how much is being kept back from us - even as described in the island of stability article - because it has to do with making nuclear initiators. This isn't my field, but my crude understanding is that a nuke works in a way analogous to regular explosives, with a sort of "blasting cap" in the middle to set it off; this cap is made up of these exotic high-numbered isotopes. (As I recall, in the news item that ran in Nature right after India's first nuclear test, the scientists responsible were photographed holding up 2, 5, and 1 fingers respectively... which is right around the top of the public list of stable isotopes, I think) Next, there is the question of whether more and more giant accelerators are really the answer, or if there are other ways - how about "surfatrons" (plasma acceleration), tabletop neutron sources, etc.?) Is there a way to avoid the accelerator, and if not, then do the people who say that the world is better with one giant project than five national ones have a point? And of course, does scientific research really require nuclear power plants be built for routine electric power? Wnt (talk) 04:00, 13 July 2013 (UTC)

Here are some nice educational web pages produced on behalf of the Nobel Foundation: on the history of the integrated circuit - the evolution of which is described by Moore's Law; and on making energy from matter - nuclear fusion, the process by which lighter elements are combined into heavier elements. You can decide for yourselves whether these technologies and the basic science that underpins them are trending in the same way. Nimur (talk) 05:41, 13 July 2013 (UTC)

I'm not sure what to make of that. But it seems like new elements are being confirmed at a fairly steady pace - Timeline of chemical elements discoveries seems to indicate this, if I'm correct in assuming that most of the "unconfirmed" discoveries will eventually count as discoveries at the times indicated. This is all the more remarkable considering that most of these things are incredibly not worth discovering in any isotope that has yet been observed, and it is possible that there is simply nothing more worth finding, though I doubt that. Wnt (talk) 06:13, 13 July 2013 (UTC)

So, how much did L Ron Hubbard actually get right...

...in terms of his theories on the human mind and mental illness? Are there any good online resources that discuss this in layman's terms? I'm looking more for things written by people who understand the subject matter they're discussing - not random haters who're all like 'bleh, the guy was an asshole... and fat - and his followers suck', etc. --87.114.56.70 (talk) 23:37, 12 July 2013 (UTC)

Perhaps it would make sense if you looked at the current state of the art with regards to the human mind and mental illness become familiar with it, and then look at his claims? IRWolfie- (talk) 23:56, 12 July 2013 (UTC)

And it should be stated, with regard to anything he may have gotten right, "even a blind dog hits the tree once in a while". --Jayron32 00:05, 13 July 2013 (UTC)

• It might be hard to find a better online source than our article on Dianetics, in particular Dianetics#Scientific evaluation and criticisms. Looie496 (talk) 00:11, 13 July 2013 (UTC)

Note that much of the "engrams" bit is, according to many sources, based on Freud's idea of repressed trauma. Bear in mind that Dianetics was initially an offshoot of psychology, but as the professional racket got organized Hubbard wasn't invited, so in order to remain legal he had to brand his practice as a "religion". Wnt (talk) 06:16, 13 July 2013 (UTC)

There are many conflicting stories about how Hubbard got into the religion business. One that I heard from another science fiction writer was that he initially did it to win a bet with some other writers that he could start up his own religion. If that's true then clearly things got a bit out of hand! But there are *many* "origins" stories for Dianetics. SteveBaker (talk) 14:23, 15 July 2013 (UTC)

Natural human lifespan in the wild, without modern medicine

Gorillas live up to 37 years in the wild (I think). How long is the lifespan of a human in the wild? If someone has a minor heart attack, they just go to the hospital to get treated. But if we didn't have hospitals or any other form of modern medicine, we would no longer be artificially prolonging our lives. So how long would a human's lifespan be, then? Rebel Yeh (talk) 23:55, 12 July 2013 (UTC)

The Wikipedia article titled Life expectancy answers your question and many more. --Jayron32 00:15, 13 July 2013 (UTC)

Likely worth pointing out, though, that looking at life expectancy at birth seriously exaggerates the contribution of medicine to how long you can expect to live, because the largest contribution is in the reduction of infant mortality. Still, sure, we have a better chance of reaching any given age than we would have without it, but significant numbers of people live to advanced ages with no medicine, as we think of it, at all. --Trovatore (talk) 00:27, 13 July 2013 (UTC)

Are we talking about humans with no health knowledge of their own? Modern humans, whether in the big cities or in the bush, still know about bacteria, and using clean water, and how to manage certain diseases, even without drugs. HiLo48 (talk) 00:58, 13 July 2013 (UTC)

(edit conflict) Reply to Trovatore: That's broadly true. I remember studies that have shown that, for males who reach adulthood and avoid warfare, the average expected life expectancy hasn't been significantly longer today than in the past. It has never been unheard-of for such people to reach 100 years old, and lots made it into their 70s. The biggest advances have been in reducing infant mortality, childhood diseases, and women dying in childbirth. Other medical advances have only made marginal increases to lifespan for the average person. I know it isn't "humans in the wild", but there's an interesting study done in John Putnam Demos's work A Little Commonwealth on life in Plymouth Colony, and there was essentially no medicine at all to speak of, which shows broadly that adult males did not live unusually short lives. Children tended to die of things we vaccinate for today, and women died in childbirth a lot but otherwise, people who avoided those things regularly lived into their 60s and 70s. Given that the state of "medicine" in the 1600s was not significantly better than, in say, 5000 BC, I suspect that human's "natural" lifespan is roughly in the 70-100 year old range. Medicine; even modern medicine, has done little to combat the effects of senescence, which is what gets you if something else doesn't first. And human senescence, it seems, has followed roughly the same pattern for all of human history. --Jayron32 01:00, 13 July 2013 (UTC)

• Nicholas Wade's Before the Dawn is an excellent book that covers this sort of comparison with the great apes. The usually quoted number is 35 years. μηδείς (talk) 01:17, 13 July 2013 (UTC)

Life expectancy would be much lower without modern science. In the middle ages, the life expectancy was low due to the Black Death, that reduced the life expectancy in Europe to the same level of some African countries of today. These, in turn, are presently heavily affected by the AIDS epidemic. And Europe and North America would be at the same level as those, if they didn't have an effective public health system to deal with it. The restraining of the spread of AIDS in the USA and Europe is a proof of a successful public health intervention (which includes everything ranging from sex education, public campaigns, and availability of condoms).

Add to that, that modern science could fight other epidemics, like bubonic plague, the flu pandemic, syphilis, Malaria, TBC and many others. Indeed, I can't say that Trovatore above is right. Reducing death of child and mother at birth is certainly a great thing accomplished with minor means, but we can't know what would be life expectancy if science hadn't being there and a lot of epidemics were still present. Possibly we wouldn't be here to tell. OsmanRF34 (talk) 01:46, 13 July 2013 (UTC)

You've made several comments about AIDS, OsmanRF34, that I am not sure there's a factual basis for. There's a suggestion that HIV has become less virulent. And the prevalence of bareback sex has shown the failure of health campaigns. As far as I am aware, access to modern medicine, i.e., drugs, and not propaganda, is the reason for a higher life-expectancy in the developed West. μηδείς (talk) 02:26, 13 July 2013 (UTC)

I do not know if the virus per se is different in any way. I claim that the epidemic is not growing in all countries, but it is just under control in most countries. There is some reason why people in some African countries are infected up to 26.10% of the population according to List of countries by HIV/AIDS adult prevalence rate and there is a reason why the top countries by percentage of affected people are in Africa. Modern medicine shapes public health. If someone distributes syringes among drug addicts in Canada, it helps against the spread of AIDS in North America. No matter what you do with your sexual partners, there is a lower chance that you meet an infected partner due to that. And if someone in Africa even denies the existence of HIV, then your chances are pretty low of developing an effective public health policy down there.

I do not claim that propaganda alone has a positive effect on life expectancy in the West, but I agree that legal medicine do have a positive outcome, combined with the whole range of public health tools. OsmanRF34 (talk) 23:32, 13 July 2013 (UTC)

If you read our article Black Death, you'll notice that it killed between 75 to 200 million. If you read our article 1918 flu pandemic, you'll notice that it killed 50 to 100 million people. However, if you look at the time scale, the flu pandemic was far more deadly over a unit of time. I've read a good bit about the "science" views of the plague that were held during the time, way way more primitive than in 1918. If I had to wager, I'd bet that while science can help, to a degree, the major determining factor of how lethal a virus is is the virus. Depending on what exactly plague was and how exactly it spread, we might not be much better off today. While I don't have any sources of my own to contribute, I'd agree with Trovatore; although, it does depend on exactly how much of sanitation and food safety is considered medicine (I would say they aren't, maybe others disagree).Phoenixia1177 (talk) 03:59, 13 July 2013 (UTC)

I think Trovatore has the best approach here, which is to point out that average life expectancy statistics give a really warped view of how pre-agriculture humans lived (say 10,000 years ago). Infant mortality and childbirth are huge killers, dying beyond those two events is much closer to what we'd find almost normal. That's not to undermine modern medicine's contribution either, but some of the really big chunks of that advantage go to a few discrete things: vaccines, basic antibiotics, and improvements in obstetrics. Shadowjams (talk) 06:49, 13 July 2013 (UTC)

I still maintain that no one can know what would have happen to our life expectancy in the West if we didn't had modern science (including medicine, of course, but specially including public health). Would the bubonic plague, flu pandemic, syphilis, Malaria, TBC, AIDS everywhere and others spread beyond measure? Nobody knows. No one can claim he can predict an alternative history with bubonic plague, flu pandemic, syphilis, Malaria, TBC, AIDS everywhere and others but without modern medicine. Humans in the past couldn't understand epidemics well, but they knew something about them. For example, they knew that could get contaminated if they got in contact with sick people. Knowing helped us to avoid epidemics, it was not like a meteorite striking us.

Bottom line: humans in primitive societies without any health issues have live up to many years, sometimes even over 90. But all the rest, even with a minor issue like a broken leg and without medicine would have lived much shorter lives. Epidemics have a negative effect, both in terms of size of human population and in terms of individual life expectancy, but it's not possible to calculate exactly for how much smaller would the population be or how many years less. OsmanRF34 (talk) 23:32, 13 July 2013 (UTC)

I am not quite sure what prediction is required, we know from the 20th century that the average lifespan in stone-age societies is about 35, and it was only about 45 in the West at the turn of the 1900's. The fact that some people live to their 90's in primitive societies speaks to maximum life span, not life expectancy, which is a statistical value for populations, not individuals. μηδείς (talk) 01:14, 14 July 2013 (UTC)

That was my whole point above in bringing up senescence, because that's what gets you when nothing else does. While people in the past died of disease, infection, warfare, getting eaten by lions, etc. at a far higher rate in the past than they do today, the act of "getting really old and dying of just being really old" has not changed all that much over the past 10,000 years or so. That is, when one looks at a humans "natural" lifespan, if you mean "how long can a human expect to live if nothing except being old gets them" the answer is that it's probably been roughly the same for all of recorded history and then some. Of course the average life expectancy, averaged across humanity, is significantly higher today, but only because we've eliminated the risks from all the stuff that gets you before old age does. The actual age when people just die from being old, as opposed to plague or lions or whatnot, hasn't budged much. --Jayron32 03:48, 14 July 2013 (UTC)

My poorly expressed point above follows these line. Life span with modern medicine equals life span without it. Life expectancy from birth is much higher with modern medicine. Life expectancy from 5 years on: somehow higher with modern medicine. Trying to guess what life expectancy we would have (from any age) under a hypothetical case we didn't have modern medicine is alternative history/speculation/a passtime. OsmanRF34 (talk) 08:37, 14 July 2013 (UTC)

Humans' lifespan ranges anywhere from 32 to 84 years in the wild (http://animaldiversity.ummz.umich.edu/accounts/Homo_sapiens/). So a human's minimum lifespan is 32 years in the wild, and a human's maximum lifespan is 84 years in the wild. Keep in mind that this age range is huge. If you need a specific age, then the median age would have to be the "normal" lifespan of a human (in the wild), because a minimum age like 32 could be considered too short and a maximum age like 84 could be considered too long. Therefore, it would make sense to pick an age that's between the range of 32 and 84; the very middle number in that range (this would be the "average age"). That number would be 58. Thus, the lifespan of a human is 58 years in the wild, with a range of 32-84 years. Mattdillon87 (talk) 03:10, 16 July 2013 (UTC)

Ok, so it's 58 years, but can be anywhere between 32 and 84. So I guess this question is resolved then? Rebel Yeh (talk) 04:10, 16 July 2013 (UTC)

Resolved

July 13

equal pressure gas airlocks

What is the current state of the art on airlocks between gases of roughly equal pressure? Is there a reliable way to isolate each gas while allowing people and objects to pass between without using an intervening vacuum? How does it work?

I will explain the scenario in a little more detail.

A person needs to work in a hazardous gas environment, though the gasses are at roughly normal atmospheric pressure. He suits up in a sealed suit and brings his own air supply. When he's done, he needs to back to the normal air environment, but bring no gas with him. Is there an airlock like technology that does this? If you just try to pump one kind of gas out and another in, don't you either have a fatal vacuum in the middle, or just get mixed air? Is there a trick to avoid that, another system entirely, or does it just work and I'm not thinking about it properly?

Thanks for your help. (sorry, this was me. Editing in my signature) gnfnrf (talk) 01:41, 13 July 2013 (UTC)

Normally, when working in hazardous gas atmospheres, the hazardous gas would be kept at a slight negative pressure compared to the outside air -- this way, when people need to enter or exit the hazardous atmosphere (or in the case of an accidental breach), outside air will flow in but the hazardous gas won't flow out. 24.23.196.85 (talk) 05:30, 13 July 2013 (UTC)

I can imagine a horizontal interface might be fairly stable if the gasses are different weights, and especially if the lower one is also cooler - for example, an airlock between an upper inhabitable area and lower maintenance facilities in a floating base on Venus. Wnt (talk) 06:04, 13 July 2013 (UTC)

Do you have a specific gas or situation in mind? Most straightforward would be air purging in the airlock. There's a rule of thumb requiring six air exchanges to provide a 3-log reduction in airborne contamination. So it's simply blowing air through the chamber until it's diluted enough. The air goes to a scrubber or is dumped. An alternative would be a Suitport, but that seems a bit expensive. An air shower (room) is used for cleanrooms, together with an airlock.

Found a US Air force document CONTAMINATION CONTROL AREA – AIRLOCK –TOXIC FREE AREA PROCESS ANALYSIS (BRIEFING CHARTS), but that's more about "unplanned" decontamination it seems. Ssscienccce (talk) 00:19, 15 July 2013 (UTC)

No specific scenario. I started by thinking about humans on another planet with a dense but non oxygen-nitrogen atmosphere, but then I got to wondering about industrial processes, and was just generally curious. To clarify, though, you are saying that if you pump 6x the volume of the room out (to be filtered or rejected) and in as clean air, simultaneously, you will be left with 999 parts per 1000 of air, and 1 part per 1000 of the non-air gas left over?

That link looks very interesting and completely full of confusing acronyms and terminology. It'll take me a while to unpack it. Thanks. gnfnrf (talk) 20:26, 15 July 2013 (UTC)

Glycaemic Indices of Gluten-free flours.

A wide variety of gluten-free flours are now commonly advocated for consumption by persons with coeliac disease. These flours may also be advantageous for persons with diabetes or high post-prandial blood glucose levels, depending mainly on the the percentage of amylopectin in their starch, as reflected in a low glycaemic index (GI: rate of rise of blood glucose after a standard carbohydrate meal ). A low dietary amylopectin burden typically correlates with a beneficial low GI, leading to a reduced development of advanced glycation end-products (ACE), which are the cause of a variety of age-related diseases. Therefore a compilation of the GIs of a range of flours currently available and recommended for controlling coeliac disease would be helpful to persons wanting to manage their blood glucose levels in addition to any gluten sensitivity. Flour is used for baking breads around the world.

--19Grumpah42 (talk) 04:06, 13 July 2013 (UTC)

Do you have a question, or a desire for references? SemanticMantis (talk) 05:08, 13 July 2013 (UTC)

I think the OP is suggesting a new article, in which case they should ask at WP:Requested Articles. Rojomoke (talk) 07:26, 13 July 2013 (UTC)

I don't think that's at all a suitable topic for an encyclopedia article. The information may well belong somewhere on the web, but not here. Looie496 (talk) 15:00, 13 July 2013 (UTC)

But it could make a good list say: List of glycaemic indexes or perhaps spelled List of glycemic indexes or indeces. Graeme Bartlett (talk) 21:21, 14 July 2013 (UTC)

Looking for an Approachable In to Quantum Field Theory and Particle Physics (As in books)

I have a decent mathematics background (though analysis is not my strongest area) and know a decent bit of basic Quantum Theory (I've worked through a few texts), what I'd like to find is a specific type of book on the subjects mentioned. Most of the QFT and PP books I have are of three flavours: for physicists that are well acquainted with the experiments, motivations, and ideas being generalized; for mathematicians, meaning that the book becomes a book on applications of functional analysis and lie theory; or books full of toy models with vague shallow explanations tossed around. What I'd like is a book that is written as if it were physicists, but assumes the background of a mathematician (meaning that it explains the physics ideas and it isn't presented as theorems/proofs followed by a few lines about how particles are representations, then back to the general case.) It doesn't even need to cover the depths of these subjects, just enough that I could pick up a second more traditional book and follow it (with work, obviously). Sorry for the long question, I've spent a lot of time looking, but this is one of the few subjects I just can't find an in into. Thank you for any suggestions:-) Sorry for any poverty of clarity. Phoenixia1177 (talk) 10:13, 13 July 2013 (UTC)

CERN's education page provides several dozen free full textbooks; presentations, review papers, and websites. But let's be frank and honest. One does not "learn quantum field theory" by reading a textbook, any more than one learns to fly airplanes from the Airplane Flying Handbook. Like any advanced physics specialization, there are some prerequisites - time, money, and intellectual capacity. You will probably need one-on-one instruction, and interaction with others who are learning and using this type of physics, which means intensive study among experts in the field.

First, study and earn an undergraduate degree in physics, or mathematics with a strong concentration in physics, from an accredited university. This proves that you're capable of investing the time and money to tackle the field, and that you have the intellectual capacity for it. Next, enter into a program of graduate study in theoretical physics. After a year or two, apply for a special program, like one of the institutional exchanges or particle physics summer schools.

If you aren't able to follow that track, for any reason, then advanced particle physics probably isn't for you; if you still have interest in the topic, you might enjoy some of the material on the website I linked. Nimur (talk) 15:40, 13 July 2013 (UTC)

For an introduction to particle physics at a first-year undergraduate level I suggest The Ideas of Particle Physics by Coughlan, Dodd and Gripaios. Another good introduction that includes more cosmology is Quarks, Leptons and the Big Bang by Jonathan Allday. For an introduction to quantum field theory try Fundamental Forces of Nature - The Story of Gauge Fields by Kerson Huang. Gandalf61 (talk) 16:04, 13 July 2013 (UTC)

Thank you:-) I picked up the book by Huang this afternoon; I've read a decent bit of it, it's quite readable:-) I know I have a copy of From Operators to Path Integrals (same author) somewhere in my library (in quite a state of disarray at the moment...); looking at the excerpt on Amazon, it looks fairly readable, is this true of the rest? Do you know of anything along the lines of Quantum Field Theory: A Tourist Guide for Mathematicians, by Folland, that is slightly more elementary? That book is on the very edges of what I can follow, which makes it really hard to extract the physics out of it. I know I'm being weebly-woobly, and vague, here with my requests; for some reason this subject is a pain to navigate on my own (everything is too much physics or too little). I'm going to check out some of the links at the Cern site tonight, I haven't had a chance yet (it's easier to read on my Kindle at work).Phoenixia1177 (talk) 21:55, 13 July 2013 (UTC)

I'm not sure I understand what you are and aren't looking for, but I have a somewhat similar background and I remember enjoying Quantum Field Theory in a Nutshell by Anthony Zee (ISBN 978-0691140346, first chapter as a PDF), Diagrammatica by Martinus Veltman (ISBN 978-0521456920) and Introduction to Elementary Particles by David Griffiths (ISBN 978-0471603863). These are all undergraduate/graduate textbooks that emphasize concepts but also cover the mathematics in detail. -- BenRG (talk) 00:52, 16 July 2013 (UTC)

Thanks for the suggestions:-) I've read Griffiths, I've read several of his books, I like him as an author. Zee I, actually, have a copy of, but my books are in such disarray! I'll have to dig it up, though. I've never heard of Diagrammatica, but will definitely grab a copy this week. As for what I'm looking for, it's unusually hard to put in words. Essentially, the mathematics part isn't a problem (most of what I read is logic/set theory; but Lie theory and path integrals aren't at all terrifying). My difficulty is that most of the books for "mathematicians" are way to abstract, which is fine mathematically, but leaves me confused about where the physics comes in. On the other hand, the books for physicists are way too much "for physicists", if that makes sense. What I'd like to find is a book that isn't shy about the mathematics, but is very gentle in linking it up to actual physics. For example, most of the math I've seen relating to QCD makes sense to me, but everything I've read about it seems like it either spends its time doing math and never gets to the physical why; or it seems like a confusing rush of physics terms and conventions, which all seem impenetrably alien. Sorry if that's long, or unhelpful, but this is the only subject (Besides cutting edge Algebraic Geometry!) that just seems horribly impossible to learn. Thank you for the help:-)Phoenixia1177 (talk) 04:10, 16 July 2013 (UTC)

I recommend An Introduction To Quantum Field Theory by Michael E. Peskin and Dan V. Schroeder. Dauto (talk) 16:05, 16 July 2013 (UTC)

Lac-Mégantic derailment

In this article, Lac-Mégantic derailment, it states: "It is possible that some of the missing people were vapourized by the explosions." What would this mean exactly? Thanks. Joseph A. Spadaro (talk) 12:42, 13 July 2013 (UTC)

It would mean that it was so hot, they were basically incinerated, with no remains left. I doubt they were turned entirely into actual vapour, but certainly they could have mean cremated. Mingmingla (talk) 15:37, 13 July 2013 (UTC)

Probably a poor translation from French. It can be the French equivalent of "going up in smoke" / "leaving/being gone without trace", which is usually not literal either. - ¡Ouch! (^{hurt me} / _{more pain}) 16:49, 13 July 2013 (UTC)

Oops, wikt doesn't list that old meaning either. :( — Preceding unsigned comment added by One.Ouch.Zero (talk • contribs) 16:55, 13 July 2013 (UTC)

I suspect it might have simply been a word chosen for maximum emotional impact. "Vapourize" is more powerful than "burnt up". Incinerate might be too clinical or insensitive. Mingmingla (talk) 21:14, 13 July 2013 (UTC)

Do Canadians spell the word "vapourize"as in the article, presumably following British usage, or "vaporize" like folks in the US? The article should probably follow Canadian spelling conventions. Edison (talk) 02:16, 14 July 2013 (UTC)

Yes, Canadian spelling uses -our, e.g. colour, vapour, flavour, etc. as in British spelling. הסרפד (call me Hasirpad) 02:37, 14 July 2013 (UTC)

The usual British spelling is 'vaporise' or 'vaporize'. The dropping of the U also occurs in glamour -> glamorise. AndrewWTaylor (talk) 08:01, 14 July 2013 (UTC)

According to the Language Portal of Canada, vapourize is correct. So it's unlike either British or US English. Heron (talk) 10:46, 14 July 2013 (UTC)

I'm a Canadian, and have never even thought about spelling "vaporize" with a u. No more than "colourant" (which is apparently also our proper spelling, I see). Whatever the books say, it looks weird to me. "Vapour" and "colour" are cool, though.

Regardless of what the spelling conventions say, Wikipedia policy states that BOTH British (and, by extension, Canadian) English AND American English are equally appropriate in articles, and furthermore that edit warring over the use of British vs. American English is prohibited. So let's stick with whatever the article's creator decided, OK? 24.23.196.85 (talk) 01:05, 15 July 2013 (UTC)

Yeah, proper's fine. No edit war (or even edit) intended. I just, personally, wouldn't use the U. For what it's worth, a Google News search shows only the Toronto Star uses the U. Montreal, Ottawa, Vancouver and others just the O. InedibleHulk (talk) 02:33, July 16, 2013 (UTC)

As to the question, every solid that burns is vaporized, after being liquefied. Much of smoke is vapour (though the colour we see is from small solid soot). If it's hot enough, that vapour turns to plasma, which we call flames. And yes, it is also a more powerful word than burnt, implying no solids or liquids are left (which isn't true, there will virtually always be some ash). InedibleHulk (talk) 11:12, July 14, 2013 (UTC)

And I expect crispy critters is right out. The article Cremation indicates temperatures in the 1600-1800 Fahrenheit range. That "vaporizes" the flesh and leaves just the bone. So that could be compared with whatever the temperature estimates are for this railroad disaster. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:20, 14 July 2013 (UTC)

Probably somewhere around there. Some fires burned much longer here than they do in a crematorium, though. If there was a body in one of those fires, it could be more burnt than those you find in urns. Which is about as useful as pure vapour, so far as identifying it goes. InedibleHulk (talk) 14:30, July 14, 2013 (UTC)

Natives

Are Native Americans and Hawaiian and other indigenous people who have gone through mass epidemics due to weak immunities in historical times still seeing the effects of a weaker immune system or are modern high numbers in disease and death just the result of poverty in these groups? — Preceding unsigned comment added by KAVEBEAR (talk • contribs)

It's not that they had weak immune systems as such, but that (1) they had never been exposed to endemic diseases of the Europeans, so what the latter consider "childhood diseases" struck the entire population at once, and (2) they did not have the inherited resistance to some diseases conferred by genes that made the latter resistant to the plague and hence also partially to HIV. μηδείς (talk) 16:57, 13 July 2013 (UTC)

You might want to read "The Arrow of Disease", a Discover magazine article. Basically, it states that Europe had a high enough population density that some diseases became endemic, causing people to gradually become more resistant to them. The diseases evolved, forcing human defenses to counter - a sort of arms race. America, Hawaii and other places mostly didn't have enough inhabitants sufficiently packed together to go through this process, so the more evolved European maladies struck them down in droves. That also explains why few New World illnesses troubled the Old. If a disease was deadly enough, it essentially killed itself off by wiping out the isolated tribe or group it first infected. At least, that's the way I understand it. I'm no expert. Clarityfiend (talk) 19:53, 13 July 2013 (UTC)

Yes, that's accurate. And Afro-Eurasia is the biggest island (and most highly populated) on the planet. μηδείς (talk) 20:07, 13 July 2013 (UTC)

But by that same token, the entirety of the Americas is not small and, if you believe the current thinking on the subject, they were chock-a-block with people. If Tenochtitlan had a pre-contact population of between 500,000 and a million people [11] then what exactly is your definition of "high enough population density"? That's a lot of people living in hot, wet, crowded, living conditions. A more likely difference is the lack of domesticated and farmed animals. Many old-world plagues are zoonotic (carried by animals) and this typically requires humans and animals to be living in close living conditions - something that happened all the time in Eurasia and not very frequently at all in the Americas. That differential behaviour caused the Eurasians to be exposed to many more diseases historically, altering their immune system's defenses. Matt Deres (talk) 23:22, 13 July 2013 (UTC)

To continue on from a similar angle, Eurasians and Americans practiced very different kinds of agriculture. In Eurasia, ploughing was widely used in a variety of different forms. Tilling the earth in that way also digs up soil dwelling bacteria and fungi, which may also bring contact with new diseases (example). Native Americans usually didn't go in much for ploughing and felling of trees since they lacked metal tools to do the work (try hacking down a hardwood tree or cut through thick soil with a stone implement and you'll see why they turned to slash-and-burn style agriculture). Burning stuff down rather than tilling it under greatly reduces the contact between people and soil bacteria. See hygiene hypothesis for some recent work that has shown the benefits of contact with, well, filth at an early age to build up the immune system. Matt Deres (talk) 00:14, 14 July 2013 (UTC)

The Americas weren't empty, but they were a very small portion of world population, with France outpeopling all of North America, see map. While it is widely speculated syphillis came from the New World, the majority of transmission of diseases wnt from the wider pool in which they were established to the smaller. μηδείς (talk) 01:07, 14 July 2013 (UTC)

I think it's fair to say that the Old World contained far more people than the Americas, even using the highest pre-Columbian population estimates for the latter. That said, I find your map highly dubious. I don't know how it calculated Native American populations, but these calculations are notoriously difficult given the scanty data available. Virtually every society was decimated by disease before seeing the first European. In the few regions that Europeans managed to visit early enough, nobody had the means or the interest to do a census until well after the region got depopulated. Working backwards from European records to pre-Columbian populations is difficult because you have to assume a fatality rate due to disease. If you change your assumption a tiny bit--from 93% to 96%, for example--your pre-Columbian estimate changes by a lot. Due to these difficulties different scholars arrive at wildly different estimates. See Population history of indigenous peoples of the Americas#Population overview for just a few. --Bowlhover (talk) 02:15, 14 July 2013 (UTC)

The highest population estimate I have ever heard for the entire Americas is 40 million, and that is far less than half of China or India, at most three or four times estimates for France. I am not quite sure what you find dubious, but I have no necessary problem with other maps if they are provided. The point is, the New World was a colonized area with very small founding populations moving through an arctic territory that would have been unlikely to bring many endemic diseases, and other than the dog, who had no domesticated animals with them to serve as disease reservoirs. The OP asked about weakened immune systems in Native Americans, and I have never heard of such a model. μηδείς (talk) 02:37, 14 July 2013 (UTC)

Population estimates run as high as 100 million for the Americas. Having read a bit about it (and heard the politicking behind the use of small numbers), I'm inclined to believe the 100 million estimate much more than the 10 million one. I've heard the immune system theory before; it's also discussed in the 1491 book here. The short version is that the crossing of Beringia created a population bottleneck and associated founder effect. One of those long term effects was a decrease in the number of HLAs. There's some advanced biochemistry involved there that's beyond me, but the numbers suggest that pre-Columbian New World populations even today are some ten times more likely to be susceptible to a given disease than an Old World population. Matt Deres (talk) 13:47, 14 July 2013 (UTC)

I am unfortunately quite familiar with people who believe the Americas were inhabited by sparse primitive tribes without civilization, but the political point is not relevant here. The total population numbers don't really matter for the immunity of the Americans, only the fact that the diseases the Europeans brought were not already endemic there because the Beringian founder populations didn't bring those diseases with them. Regardless of their size, had the Americas been founded but multiple waves out of the tropics/subtropics then Europeans moving there would have been at much higher risk of infection than the natives, compare what happened to British colonists who went to Africa or India. μηδείς (talk) 18:23, 14 July 2013 (UTC)

You're talking in circles. You say you're "unfortunately quite familiar" with that picture of the American populations, yet you happily cited that claptrap when you thought it suited. Fewer people than in all of France - preposterous! But then you throw both arguments away in exchange for... I'm not even sure what to call your last sentence, but it's no answer to anything the OP brought up, nor anyone else. The Americas had the people and the population densities to support all kinds of diseases (as evidenced post-1492), but they had few endemic ones for the reasons I've outlined above, centering mostly on different agricultural and animal domestication strategies. Matt Deres (talk) 21:00, 14 July 2013 (UTC)

You have a strange notion I think the difference between 40 and 100 million would matter. It has nothing to do with the small, relatively disease-free founding populations from Arctic Asia. How about I stipulate 250 million Native Americans at the time of Columbus? Would that cure the accusation of clap-trap? μηδείς (talk) 00:44, 15 July 2013 (UTC)

Actually, France had a population of 15 million around the time of Columbus. North America probably had fewer people, even according to most High Counters. The article I linked says "while it is difficult to determine exactly how many Natives lived in North America before Columbus,[5] estimates range from a low of 2.1 million (Ubelaker 1976) to 7 million people (Russell Thornton) to a high of 18 million (Dobyns 1983)." Thus, even the highest non-fringe population estimate of North America is comparable to the population of contemporary France. Most state societies in the Americas, and consequently most of the population, was in Mesoamerica, Peru, and possibly the Amazon shore. --Bowlhover (talk) 01:13, 15 July 2013 (UTC)

Aside from mere population density, proximity to livestock has as much to do with this kind of immunity. The big killers were essentially agriculture-related diseases: smallpox, the plague (rats associated with grain/close quarters), measles, all the gastrointestinal water-borne illnesses, etc. This is a central point in Guns Germs and Steel. Shadowjams (talk) 06:38, 15 July 2013 (UTC)

It's worth considering that, as syphilis alone still causes 500,000 stillbirths and miscarriages a year,^[12] among other things, and was once a very major cause of death for all ages, the death from New World diseases in the Old World may well have equalled the deaths caused by Old World diseases in the New after all. (It's a bit like gravity, where the tiny effect of a falling ball on the Earth is actually equal to its effect on the ball... it just doesn't seem so visible) Wnt (talk) 15:50, 15 July 2013 (UTC)

Does the human body only use glucose and ketone bodies as fuel?

I'm not entirely sure how to word my question, but the basic idea is this: does all the food we eat eventually just get converted into glucose one way or another so the body can use it as fuel? Like the proteins in a steak, are they eventually converted into glucose? ScienceApe (talk) 16:54, 13 July 2013 (UTC)

The simple answer is no (i.e. not all of the digestible nutrients in food, including protein, can be converted completely to glucose). That said, metabolism and specifically digestion is a really complex topic, with influences from degree of starvation and many other factors. Regarding protein digestion: after protein catabolism, amino acids are often re-used to make protein; however, under some conditions the process of amino acid catabolism can convert portions of many (not all) amino acids to things like acetyl-CoA that can be used on gluconeogenesis to generate glucose (under certain conditions). Similarly, fat digestion can convert fatty acids almost completely to acetyl-CoA. Your question about ketone bodies can be answered by reading about ketosis, but a short answer is that these compounds, which are part of starvation metabolism, are not usually used for energy by most healthy tissues. -- Scray (talk) 18:06, 13 July 2013 (UTC)

So is this the reason why if you just eat nothing but meat, you'll eventually lose weight? Because your body isn't producing much glucose and the amount of fat consumed and turned into adipose tissue doesn't outweigh the amount your body burns to produce more glucose? Also if your body only needs glucose for fuel, is it possible to have a diet consisting of only carbs and vitamin supplements? ScienceApe (talk) 18:24, 14 July 2013 (UTC)

This is a huge topic, so please understand we're simplifying things here greatly. Eating nothing but meat generally results in a high-protein, high-fat (low-carb) diet. I don't think there's a consensus on the principal mechanisms at work in ketogenic diet (i.e. extremely low-carb nutrition), but one component is probably the appetite-suppressant effects of ketosis (whether these diets are safe and effective, and for whom, is still unclear). Glucose is not adequate nutrition due to needs for essential fatty acids, minerals, vitamins, amino acids, etc - so carbs and vitamins won't do the job. -- Scray (talk) 23:01, 14 July 2013 (UTC)

How amino acids enter the citric acid cycle.

(ec)No. Aside from a small amount of energy generated by glycolysis, most of the energy generated in mammalian cells comes from the citric acid cycle. Compounds can enter the cycle through a number of different pathways. While glucose goes through glycolysis and enters the cycle as pyruvate, and fats are broken apart to acetyl-CoA directly, amino acids (what proteins are made of) enter the cycle at different points depending on their identity. They don't have to go through glucose first. That said, the body can convert amino acids to glucose through the process of gluconeogenesis, though that consumes energy rather than produces it, so is only used if the body needs glucose for non-energy reasons. -- 67.40.215.195 (talk) 18:12, 13 July 2013 (UTC)

We actually have an article glucogenic amino acid that lists them. Note that glucose levels are kept up because it is absolutely required for energy, especially in the brain - even brief episodes of hypoglycemia can be lethal. (The brain also can use ketone bodies for a substantial fraction of its energy according to our article... have to admit, I didn't know that) Wnt (talk) 15:57, 15 July 2013 (UTC)

Peculiar cell nuclei

What cells of the human body contain unusual numbers of nuclei? I know that muscle cells merge and pool their nuclei. I think I knew once of neurone cells that have multiple nuclei - is that right? Why do granulocytes have peculiar-shaped nuclei? --217.16.212.250 (talk) 21:36, 13 July 2013 (UTC)

Take a look here for some information about neutrophil granulocytes, under the section "Normal cells with abnormal nuclei." Lord Arador (talk) 23:43, 13 July 2013 (UTC)

• We have an article, Multinucleate, that would be helpful if it were in better shape. It may be helpful to consider that multinucleate cells can form through fusion (a syncytium) or failure of the cell to divide after nuclear division (a coenocyte). In answer to your question, in humans multinucleate giant cells can be found in at sites of inflammation, especially activated macrophages in granulomatous inflammation, giant-cell arteritis, and multinucleate hepatocytes in some forms of (especially neonatal) hepatitis. -- Scray (talk) 01:22, 14 July 2013 (UTC)

Is that the same as neonatal jaundice? μηδείς (talk) 03:28, 15 July 2013 (UTC)

No, the usual cause of neonatal jaundice is breakdown of fetal red blood cells at a rate that exceeds the newborn liver's capacity to conjugate bilirubin. That's generally temporary, as our article explains. Neonatal hepatitis (that article needs work!) is rarely the cause of neonatal jaundice. -- Scray (talk) 04:23, 15 July 2013 (UTC)

July 14

Need help identifying a catapillar

Unknown catapillar

Spotted this little guy as I was working in my garden in Southern Norway, and am at a complete loss for what he is. He was munching away on a young aspen, and is roughly 4-5 cm long. Does anyone know what species he belongs to? WegianWarrior (talk) 13:58, 14 July 2013 (UTC)

Looks a lot like this one,[13] which I found by googling [yellow caterpillar], and which is called a Canadian Yellow Caterpillar. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:08, 14 July 2013 (UTC)

It's had a long swim from Canada to Norway! Agree it looks the same, but caterpillars are generally known by the name of the butterfly or moth that they pupate into. Alansplodge (talk) 14:38, 14 July 2013 (UTC)

Gotcha! It's an Elm sawfly, Cimbex americana. I found it through this forum which reports sightings in southern England, despite it being a native of North America (apologies to Bugs). It is "also know to feed on willow and some other plants" aspen being a member of related to the Willow family. Alansplodge (talk) 15:09, 14 July 2013 (UTC)

Here's a picture of an adult elm sawfly. Alansplodge (talk) 15:19, 14 July 2013 (UTC)

Any idea what the adult stage of the Canadian yellow is? ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:17, 14 July 2013 (UTC)

Bugs, please follow my link to the topix.com forum in my post above and read the thread - this is also the source of your photo. Alansplodge (talk) 19:25, 14 July 2013 (UTC)

If I'm reading that correctly, it's not a "Canadian yellow caterpillar", but actually just another photo of the larva of an elm sawfly. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:15, 14 July 2013 (UTC)

Correct. Alansplodge (talk) 07:27, 15 July 2013 (UTC)

Thank you all for helping out - and it certainly explains why I found no references in my Norwegian bug-books. WegianWarrior (talk) 17:31, 14 July 2013 (UTC)

Note that this is not a caterpillar - just looks like one. It's a member of the order Hymenoptera, and as the pictures linked above show, the adult is more like a wasp than a moth. -- Scray (talk) 17:51, 14 July 2013 (UTC)

Right, technically caterpillar is restricted to the lepidoptera, though informally, caterpillar sometimes means "crawly guy with legs" It is definitely a larva, but most people wouldn't call this sawfly larva a grub... so probably just larva is the best term. SemanticMantis (talk) 19:16, 14 July 2013 (UTC)

(Edit conflict) Yes, this blog says "True caterpillars have no more than five (5) pairs of prolegs, the “false legs” along the length of the abdomen that look like suction cups. Sawfly larvae have seven (7) pairs of prolegs." Alansplodge (talk) 19:20, 14 July 2013 (UTC)

As a side point of interest, sawfly larvae are often studied as a way of seeing into Evolution_of_eusociality, because the larvae exhibit some presocial behavior, while the adults are solitary. SemanticMantis (talk) 19:21, 14 July 2013 (UTC)

WegianWarrior, if you could update the details on your image, I can add it to our Sawfly article (there's a space waiting to be filled and it's a great photo). Alansplodge (talk) 09:10, 15 July 2013 (UTC)

Thank you - I just updated the description and requested a rename to a more suitable filename (ie "File:Elm sawfly larva (Cimbex americana).jpg"). WegianWarrior (talk) 11:22, 15 July 2013 (UTC)

It now adorns our article. Alansplodge (talk) 17:09, 15 July 2013 (UTC)

It looks so much like a new variation of Peep, I want to nibble on it. :-) StuRat (talk) 18:40, 15 July 2013 (UTC)

Heavy legs

A friend said her legs felt heavy, so I was wondering how to measure their mass. I was modelling a leg as a rod with a variable mass distribution joined by a hinge to another rod representing the body also with an unknown mass distribution along it. Assume the axle between has zero mass,, you can have a second equal leg but it doesn't make any difference that I can see. It certainly can't be done by just measuring where the centre of gravity is with the leg in various positions and I don't see that measuring the moment of inertia is any help either.

Anyone like to suggest a way I could measure the mass of a leg in situ or do I have to tell her that unfortunately I really will need to cut off her leg to measure it? ;-) 21:08, 14 July 2013 (UTC)

A simple and approximate way would be to sit relaxed in a chair or lying down with the leg horizontal and rest the heel or calf on a bathroom scale. By relaxing, the leg muscles should neither push down on or lift the leg, and the hip joint should act as a simple hinge. An inaccuracy is that part of the weight is supported at the hip.and the hip and the scale would provide equal support only if the leg were of constant unit mass per unit length, which is not the case. .Edison (talk) 21:37, 14 July 2013 (UTC)

Unfortunately even if all the mass in each rod is concentrated at one point that doesn't work. If one keeps mr constant for each rod where r is the distance from the pivot and keeps the sum of the two weights constant one can vary the masses and not distinguish by those type measurements. One can move a mass over from one rod to the other without making any difference, for example split one in two and move half twice as far away and the other to the pivot. Then amalgamate that mass at the pivot into the massa in the other rod moving both to their common centre of gravity. There's no way to distinguish these two cases by these type measurements. Dmcq (talk) 23:11, 14 July 2013 (UTC)

Alternatively, you could measure the volume of the leg using a bath, and find the density using a CAT scanner, and multiply the two values.--Gilderien Chat|List of good deeds 21:51, 14 July 2013 (UTC)

That does sound like a possibility, not exactly a pure science method but probably very effective. I had a look at body fat percentage and I remember reading a while back about how they measured the volume of the lungs by the percentage of gas in exhaled air but I can't find there, anyway they seemed to do quite complicated things just to do that. I wonder if anyone just uses a scanner for that sort of thing nowadays. Dmcq (talk) 23:30, 14 July 2013 (UTC)

We have an article on Heavy legs, incidentally. Tevildo (talk) 23:01, 14 July 2013 (UTC)

Gosh Wikipedia does have an article on everything. Thanks very much. I'll tell her she's suffering from hypercondria ;-) 23:16, 14 July 2013 (UTC)

No, don't do that. It will serve no purpose and will be seen as a negative comment. Guide her towards the article and let her draw her own conclusion. and its hypochondria. Richard Avery (talk) 06:50, 15 July 2013 (UTC)

Place a large garbage can in a broader, shallower pan that will hold the overflow. Have her slowly get in the garbage can without sloshing. Measure the overflow, and assume she weighs the same as the displaced water. Also, a feeling of heaviness in the legs can be the sign of a severe medical condition. Have her call her doctor. μηδείς (talk) 00:40, 15 July 2013 (UTC)

Here's a reference> An article in a journal which discusses "heavy legs." Edison (talk) 01:49, 15 July 2013 (UTC)

There are even worse medical reasons than edema that can cause such symptoms, so, again, if it is a symptom and not just "do these pants make me look fat" she should contact a doctor immediately. μηδείς (talk) 03:25, 15 July 2013 (UTC)

She's quite healthy no worries - she was dancing and it had been a hot day. It's just me taking what's said literally and wondering about it. Anyway I rather like the one about the large garbage can, I think I'll suggest that one thanks ;-) Dmcq (talk) 07:20, 15 July 2013 (UTC)

A leg could be "heavier" because the volume was constant and the density increased, or because the volume increased at constant density, or some combination. One measurement would be to measure the circumference of ankle and calf when the legs are "heavy" and when they are not, to see if the volume varies. Edison (talk) 18:30, 15 July 2013 (UTC)

Severed legs aren't that hard to come by, either. Accidents, aggravated assault, etc. Those who sever serve in the military run a nonnegligible risk of losing a leg in a war, etc.

Maybe not exactly "not hard" but not extremely rare either. There should be some data on severed legs and their weight. Not sure how "available" , but anonymized data should exist quite abundantly. - ¡Ouch! (^{hurt me} / _{more pain}) 13:21, 16 July 2013 (UTC)

Quite hard to search for. I searched for "severed leg" + weigh, and excepting the three words "RuneScape" (which was the first return), "washed", and "ashore" (we need fresh legs). Still, the returns are usually about the victim's weight, or about items on sale (practical jokes (I hope, had to kill SafeSearch!)) - ¡Ouch! (^{hurt me} / _{more pain}) —Preceding undated comment added 13:30, 16 July 2013 (UTC)

July 15

"Hearing the wind"

When you crack a whip, you know how you "hear the wind"? If you threw a fastball and "heard the wind", how fast would an estimate be of that pitch? Albacore (talk) 02:45, 15 July 2013 (UTC)

...If you're gonna find the answer anywhere, it'll be at the Physics of Baseball webpage. In fact, you can even apply for a (competitive) fully-funded summer internship to elaborate on these studies! (Here's the summer 2004 final report).

The sound we hear when air rushes past our ears actually has very little to do with the net velocity of the air (or of any object that's moving through the air). Sound is the vibration of air - its volume is determined by the amplitude of the oscillation; and the timbre of the sound is determined by the waveform shape of the oscillation. A "whoosh" is pretty much white noise. Air speed doesn't really enter into things, at least not as a direct first-order term. So, bulk velocity of the air is a secondary concern; and thus velocity of the acoustic transducer (the ball, or the whip) is even further removed from the intensity, volume, and sound we actually hear - it influences the sound in an indirect and subtle way. In practice, you might be able to empirically measure and then deduce a relation between the velocity of a ball and the amplitude of the "whoosh," but that relationship will be a little bit tenuous, because you're essentially trying to be quantitative about a very noisy signal.

In a little bit plainer English: you can make a loud "whoosh" using a slow moving object or a fast moving object. You can also make a quiet "whoosh" using a slow moving object or a fast moving object. The speed of the object is not the main factor in the "whoosh." Nimur (talk) 05:55, 15 July 2013 (UTC)

There are two situations I can think of (which doesn't mean there are only two...) - a reed (instrument) which vibrates due to its own characteristics, creating a sound that depends (among many things) on the speed of the wind, and whipcracking where the object moves at the speed of sound and all that sound emitted piles up into a little sonic boom. Wnt (talk) 15:33, 15 July 2013 (UTC)

I agree that some non-aerodynamic objects make a lot of noise in little wind by creating turbulence and perhaps snapping in the wind like a flag, while other objects create very little noise even in high winds, since they only create laminar flow. However, this Q was about a baseball, so, since we've eliminated the variable of the object type, the relative wind velocity should correspond quite well with the sound level. The only other remaining significant variables should be it's spin, and the air pressure, temperature, and humidity. StuRat (talk) 18:36, 15 July 2013 (UTC)

Why do you assert these speculations as if they are facts? We don't get to arbitrarily decide what should happen in aerodynamics. Just because you think velocity should affect audible noise doesn't mean it does. Turbulent airflow is probably one of the least intuitive, most difficult-to-speculate about, impossible-to-describe-using-simple-first-principles-of-physics subjects known to humans. As an example: one of the papers on the website I linked shows experimental data indicating that the asymmetric flow separation due to the rotation of the ball contributes to turbulent airflow. And sometimes in totally the opposite direction from that which is predicted by ordinary flow separation theory. A small scratch on the ball's surface may have more impact than the net bulk translational or rotational velocity of the ball. In another experiment, the presence of a very tiny "raised wire" on an experimental sphere changed laminar flow into turbulent flow with R=30,000. StuRat, when you assert that velocity is the chief factor - yet you have neither experimental data or theoretical explanation why you believe that should be true, you are conducting pseudoscience. This is worse than being wrong - if your fact was only wrong, we could correct it and move on with our lives. But instead, you are asserting a claim without any evidence. Your methodology is profoundly unscientific. Nimur (talk) 22:34, 15 July 2013 (UTC)

Descriptions of turbulence like this are always so fascinating. If small scratches and extensions have such an impact, why can't we use it? I mean, why can't we fly a few kites per acre on one side of a hurricane at sea to turn it, or have a computer-controlled mesh of thin wires up- or down-wind of a windmill to increase its output by a significant factor? Wnt (talk) 01:43, 16 July 2013 (UTC)

So what's happening with a Bullroarer that produces the sound? HiLo48 (talk) 09:13, 16 July 2013 (UTC)

Bullroarers produce a predominantly humming sound due to the rapid rotation about the long axis as you whirl it round on the end of the string/cord, somewhat like a fan or propellor makes a humming sound. This rapid rotation moves air in pulsations - first towards any point and then away. Bull roarers also produce a bit of shot noise (white noise or "hiss") as does any surface moviing through air, due to the random impact of air molecules on the moving surface. 1.122.182.232 (talk) 13:18, 16 July 2013 (UTC)

(ec) Lots of things are happening, and I can't pretend to list all of them: but here are some interactions that I would pay attention to. Air is rushing over the surface of the object; the object's motion is constrained by a semi-taut vibrating string whose tension varies with the speed of rotation; vibrations of the object and the air couple to the string. When tension changes, the resonant frequency and the acoustic damping change. If you modify the toy, replacing the shaped peg with something else of equal weight, the tension in the string should be identical; if you whirl it at the same speed, you may observe a change in the tone, timbre, and intensity of the sound. If you change the type of string to some other material - say, from an ordinary string to a guitar string, the sound will be totally different! If you spin an object that resonates at a particular frequency, including a tube-shaped peg, you can produce an almost clean, tonal sound - like a whistle or a flute. If you throw the whirling contraption - even if the peg reaches the same airspeed - does it produce the same "roaring" or whistling sound? Does that sound only happen when the string is taut and the object is rotating? How about if you start by whirling and then release the string, allowing the object to fly at the same speed, under its own inertia? How quickly does it stop "roaring"? How would it sound if you got a friend to drive you down the freeway, and you (safely) held the peg out the window at 65 mph?

This apparatus would be a good candidate for some fun experimental acoustics (to be conducted outdoors). The aspiring scientist could even set up a microphone to record the results. How does the sound frequency and volume change when you whirl at different speeds, or throw the object? Does the rotation rate modulate the tone? (It should, that's the basis of vibrato in the old-fashioned Leslie speaker). Just watch out if you're recording with a "smart"-device to analyze the sound - many smart devices now use digital post-processing to "denoise" and normalize the recording to a constant volume. Experimental physicists need to know everything about their measurement-apparatus, to prevent themselves from drawing erroneous conclusions about their data. Nimur (talk) 13:29, 16 July 2013 (UTC)

I have no idea what Nimur is talking about with his shapped pegs, and I suspect Nimur doesn't know either. But I do know about bullroarers. They were once a common toy here and I have played with them. They are essentially a flat plate much longer than they are wide, and are swung roung on a string or cord. When swung, they rotate about their long axis due to mass and aerodynamic unbalance, and it is that rotation that drives the production of the characteristic humming sound. The string is not used in any elastic or resonant mode - it just supplies a fixed point about which the rotation occurs. The hum frequency is twice the rate of rotation, as there are two edges on each side of the axis. If it rotates at (say) 1200 RPM, you get a frequency of 2400 cycles per minute ie 40 Hz. If you let go of the string, rotation and sound will immediately stop. If you drag it by the string from a moving car it will rotate for the same areodynamic unbalance reasons and make the same sound. As the rotation is what causes the humming sound, rotation cannot cause any vibrato. However, swinging it around oneself causes a slight "whoom-whoom" vibrato effect (doppler) for distant listeners (but not the person swinging it). Traditional use is to add rythmic loudness variation by varying how had you swing it round. The humm frequency is substantially independent of string tension. As aerodymamic force is roughly a third power of velocity and the kinetic energy in a rotating mass rises with the square of the speed, how hard you swing it (or tow it) has not much effect on the frequency. To alter the frequency to taste, alter the width or the plate, curve it to greater or lesser degree or otherwise upset the shape away form a simple falt plate, offset the string attachment point, or change its' mass. 1.122.215.76 (talk) 14:44, 16 July 2013 (UTC)

Noisy ladybirds (ladybugs)

I've just read a technical document which described a component making a noise like a ladybird... I just want to make sure that this is as rediculous as I think it is, since I've never heard them make any noise at all. MChesterMC (talk) 14:32, 15 July 2013 (UTC)

Pretty sure I've heard them [in the UK] make a fluttering sort of buzzing noise when they fly, especially to get off the ground. --Dweller (talk) 14:34, 15 July 2013 (UTC)

Yep, at liftoff, or if they happen to fly right by your ear, you'll hear a whirring buzzing sound. I'd imagine a loose fan or something could make a similar, if much louder, noise. SemanticMantis (talk) 14:52, 15 July 2013 (UTC)

This was a suggestion for an indicator noise, and the other examples given were the chirp of a grasshopper or a cricket, so I'm pretty sure the writer was just not thinking about what they were writing. MChesterMC (talk) 15:59, 15 July 2013 (UTC)

River swelling

What's the physics behind this video: http://www.youtube.com/watch?v=8sEdgHH9F10&feature=youtu.be ? What causes the river to empty and swell like that? 65.92.5.24 (talk) 15:41, 15 July 2013 (UTC)

It's hard to see quite what's going on without a better understanding of the geography, but when a ship moves in a narrow channel it can produce a soliton wave (a solitary wave of compression and then rarefaction which can retain its identity for a remarkable distance). Although solitons occur in all kinds of circumstances, they were first scientifically described when generated by canal boats. -- Finlay McWalterჷTalk 15:48, 15 July 2013 (UTC)

Perhaps Bernoulli effect is helpful? (not sure about that) Wnt (talk) 16:02, 15 July 2013 (UTC)

It's a small tsunami. That article explains the physics. Looie496 (talk) 16:14, 15 July 2013 (UTC)

Similar waves are sometimes created by tidal conditions called a tidal bore; the Severn Bore in England is a great favourite with surfers and kayakers. Alansplodge (talk) 17:14, 15 July 2013 (UTC)

A ship that size displaces an enormous amount of water. I calculate that a "Panamax" sized tanker displaces around four million cubic feet of water - and that one looked much bigger than that. As the tanker moves a distance equal to it's own length, four million cubic feet of water has to move out of it's way and somehow travel around the sides and beneath the vessel to fill in the "hole" it leaves behind the stern. Water is essentially incompressible - so it can't compress and decompress around the ship. So at typical tanker speeds of around 20mph (30 feet per second) - a 950 foot long Panamax ship covers it's own length in about 30 seconds, so the water has to flow around it at about 130,000 cubic feet per second! (Imagine filling and then draining, two olympic-sized swimming pools every second!)

When the vessel is close to land and in relatively shallow water, the water flow will be forced through narrow gaps beneath and on the shoreward side - so the speed of flow will greatly increase. It's not surprising then that water will be forced into (and then sucked out of) side-channels and inlets.

I'm not sure whether the Bernoulli effect is likely to kick in to a significant degree...but imagine if the small river in the video is connected to the larger channel with the ship in it somewhere off to the right of the camera. As the ship moved towards the point where it joins the ocean, the pressure ahead of the ship would build up, causing rapid water flow into the river - and as it passes, would cause a dramatic drop in pressure, causing rapid flow out of the river. At the point in time when the direction of flow reverses, you'd expect lots of turbulance and such - which would explain all of those big waves...but I'm not sure that's what's going on because the water level doesn't go up until after the flow direction reverses.

But if the small river connected to the ocean FAR to the left of the camera - then perhaps the initial flow towards the left is just the natural flow of the river and the temporary reversal is due to the pressure wave from the arrival of the ship - but delayed by a minute or two by the time it took for that wave to travel from the mouth of the river. We might expect an abrupt lowering of the water level sometime later as the pressure drops behind the stern of the ship - but maybe we don't see it because the video ends before that would have happened.

Similar arguments are possible if the camera person is standing on an island with the "river" connected to the ocean at both ends and the water was merely reacting to a build up of pressure before and after the ship.

I think that what we see in the video is consistent with any of the three possible connections between river and ocean...but without knowing exactly how the small river connects - it's hard to know for sure.

SteveBaker (talk) 13:58, 16 July 2013 (UTC)

Carbon emission

I've had no luck at Talk:Greenhouse gas, so I'm reposting the question here: carbon emission redirects to greenhouse gas, but the article doesn't clearly explain what "carbon emissions" mean. It doesn't seem to refer to emission of elemental carbon, but does it encompass emissions of all compounds of carbon, only gaseous compounds of carbon or some other still? — Kpalion^(talk) 14:08, 16 July 2013 (UTC)

If editors agree on a definition, then the term and the definition can be added to "Glossary of environmental science".

—Wavelength (talk) 14:18, 16 July 2013 (UTC)

From my Google search of glossary environmental terms, I have checked most of the first 50 results and I have found the following.

• http://www.epa.ie/irelandsenvironment/glossary/#C

"In the context of climate change, carbon dioxide released when substances, especially oil, gas, and coal, are burned by vehicles and planes, by factories and by homes."

• http://www.bu.edu/sustainability/reference/glossary-of-terms/

"Polluting carbon substances released into atmosphere: carbon dioxide and carbon monoxide produced by motor vehicles and industrial processes and forming pollutants in the atmosphere"

—Wavelength (talk) 14:59, 16 July 2013 (UTC)

You might wish to consult Wikipedia:List of online reference desks/Science#Ecology (577).

—Wavelength (talk) 15:08, 16 July 2013 (UTC)

• In the context of greenhouse gases, it mainly means CO2 but could also include methane, which is a very potent greenhouse gas but doesn't persist in the atmosphere for very long. Looie496 (talk) 15:11, 16 July 2013 (UTC)

Yes, "carbon emissions" is a little vague. You'll see it in press releases and such, but not usually in serious science writing (or if it is used, the scope is defined in the same article). I don't have time to check right now, but the authoritative/reliable bodies who might have a standard definition would be the IPCC and/or NOAA, who releases several freely-available white papers and technical documents that one could look into. When I'm at conferences that discuss this sort of thing, they usually present e.g. methane and CO2 (and others) in terms of Carbon_dioxide_equivalents. Basically, "tons of carbon" is not always meaningful, because different compounds have very different global warming potentials, even for the same amount of carbon per molecule. To my knowledge, solid carbon, (i.e. soot) is not ever considered an "emission" for the purposes of climate change studies. Soot particles will actually cool the atmosphere when in aerosol form, and when they settle, they become part of soil carbon (and hence are not emitted to the atmosphere). SemanticMantis (talk) 15:33, 16 July 2013 (UTC)

Totally off-topic, but I didn't find where to ask!

Some perpetual-motion believer(s) keep reverting Magnetic motor to represent it as aglorious future solution for humanity. What can be done, and how? Zarnivop (talk) 15:49, 16 July 2013 (UTC)

I have posted the article to the Fringe theories noticeboard, hopefully some editors will take a look at it to make it more neutral. You could also be bold and edit the article yourself! Mildly Mad^T_C 17:36, 16 July 2013 (UTC)

When on H. sapiens' evolutionary timeline did the equivalent of the hallux ("thumb" on lower limbs) stop being opposable?

20.137.2.50 (talk) 16:43, 16 July 2013 (UTC)