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June 27

Specifying a reference for US City in Infobox Settlement

I'm trying to update the Template:Infobox settlement#Geographic information for a US city article, and can't find where exactly to specify the information for the water, land, and total area for the page. The closest I can come is the rounded off number of 7 from US Census quick facts. The article for Cleveland, Ohio specifies this info using the American Fact Finder, but I'm not seeing that information on any of the pages there. Also, I've already got the elevation and co-ordinates from GNIS but that isn't showing area. Is there any specific reference I should be using to so I can get the area information (with the 7.6 number)? -Optigan13 (talk) 00:26, 27 June 2009 (UTC)[reply]

Nevermind, found it at [1]. -Optigan13 (talk) 00:58, 27 June 2009 (UTC)[reply]

Question about social group dynamics

So I was watching some people at a mixer today, and I was intrigued by the regularity of the group structures they form and how those structures evolve over time, and how people enter and leave groups, and the type of cues and conventions they use. What I wonder is, is there a branch of science that studies this type of interaction? The closest thing I could find was microsociology. Thanks! Dcoetzee 01:50, 27 June 2009 (UTC)[reply]

I think you're looking for social psychology, and the works of Michael Argyle (psychologist) in particular. --TammyMoet (talk) 09:29, 27 June 2009 (UTC)[reply]

Bamboo Growth

I have some fernleaf bamboo (Bambusa multiplex Fernleaf) that, for whatever reason, no longer looks like fernleaf bamboo. Typically, the plant has many small leaves clustered at the tips of the canes, hence the variety name. However, once I planted the bamboo, the fernleaf quality disappeared, and now it grows more like a wild type specimen of the same species. Can anyone explain the reversion to the normal leaf pattern and suggest a way to restore the fernleaf growth pattern? I'm guessing the condition is related to water stress and/or having compacted roots, but I don't know.Calamus Fortis 02:50, 27 June 2009 (UTC)[reply]

Bamboo generally needs a rich soil, and dappled to full sunlight. They need a lot of water on the growing season, but can be left to dry out until drooping leaves signal a need for water. If they become root-bound in a pot or a root barrier in open ground) they can become sickly, with fewer and yellowish leaves. If the net result of the changes is a lot more leaf surface, it suggests a need for more transpiration and more sun ( = too wet and too dark).It may also be the wrong climate for your plant, which is suited to about Florida and Texas. But I couldn't say if this would cause the leaf shapes to change. I do know tight-curled asparagus ferns will always get the odd stem that has reverted to the more common appearance.- KoolerStill (talk) 17:56, 27 June 2009 (UTC)[reply]

Not an expert on Bamboo, or any horticulture for that matter, but are exotic bamboos grafted onto more common rootstock, like with many other ornamental plants? If that is the case, then perhaps its the rootstock you are seeing, and not the grafted ornamental? --Jayron32.talk.contribs 02:42, 28 June 2009 (UTC)[reply]

Broken Blood Vessel in the back of the Eye

Is a broken or burst blood vessel in the back of the eye (that causes complete or almost complete blindness) reversible or treatable in any way? Digger3000 (talk) 03:58, 27 June 2009 (UTC)[reply]

Is this a request for medical advice? We cannot give any medical advice, but we sometimes answer factual questions about medical issues which do not relate to the treatment, diagnosis or prognosis of a particular individual. Edison (talk) 04:18, 27 June 2009 (UTC)[reply]

Nope not medical advice, just a general question about whether or not the type of condition I described can be treated. Digger3000 (talk) 04:33, 27 June 2009 (UTC)[reply]

Floater see Floater#Treatment and Vitrectomy, Terson syndrome. Cuddlyable3 (talk) 09:07, 27 June 2009 (UTC)[reply]

While not directly asking advice, the question unfortunately lacks the detail to be answered properly. What does the OP mean by "back of the eye"? Cuddlyable3 assumed this to refer to the vitreous but it could as easily refer to the retina, choroid, or optic nerve. The effect on vision also depends on whether the fovea is affected. The retinal haemorrhage article is pretty skimpy but could be a place to start. Another thing to consider is the underlying cause of the hemorrhage, such as diabetic retinopathy for example. The likelihood of blindness either 1) occurring in the first place, or 2) being reversible or treatable, is therefore dependent on the circumstances: the anatomic site, size of vessel, amount of bleeding, duration of bleeding, affected areas, timing of the intervention, etc. In other words, the only answer to the question as posed above is "It depends. Go see an ophthalmologist". --- Medical geneticist (talk) 10:31, 27 June 2009 (UTC)[reply]

Literature, cellular suicide, and spaceflight

I've tried to google this but I can't come up with good keywords... A while ago I read a book. Q1: name that book! Something about things that defy science, ten things we can't explain yet, ...? One of the mysteries is death. The book tells how our cells have a built-in counter that limits how many times they will divide before refusing to produce new generations. Q2: what is this phenomenon called and where's the Wikipedia article on it? The book also tells the story of a woman who had cancer, and her doctor was amazed to discover her mutated cells had forgotten the ability to count and would live forever. Though sadly she died, her cells live to this day in laboratories, and have flown in space in experiments. Q3: who was she and where's the Wikipedia article on her cell cultures? 85.77.250.219 (talk) 10:47, 27 June 2009 (UTC)[reply]

A1: No idea, the book doesn't sound like a WP:RS for anything.

A2: The article is Programmed cell death.

A3: ~~No such article exists.~~ Cuddlyable3 (talk) 10:57, 27 June 2009 (UTC)[reply]

Question 3 refers to HeLa cells (WP:WHAAOE), derived from a cervical cancer sample from Henrietta Lacks. Mind you, there are large numbers of cell lines that came originally from a variety of cancer tissues, it's just that HeLa cells are widely used in lab research and somewhat famous for a variety of reasons. --- Medical geneticist (talk) 11:13, 27 June 2009 (UTC)[reply]

A1: No Idea.

A2: Read Telomere for more information.

A3: Henrietta Lacks and the resulting cell line is known as HeLa Unomi (talk) 11:21, 27 June 2009 (UTC)[reply]

Could Question 1 refer to "Ten Questions Science Can't Answer (Yet!): A Guide to Science's Greatest Mysteries" by Michael Hanlon (Macmillon, 2007)? I found a copy at Amazon but seemingly no Wikipedia article. --- Medical geneticist (talk) 11:28, 27 June 2009 (UTC)[reply]

Thank you all! That's a lot of good reading to do, and on something so trivial as, oh, well, you know, why we get old, and why we die, and stuff. The identity of the book isn't that important of course, though the above mentioned one looks very interesting, I'll need to check it out; if someone guesses the book it's going to be one of those slap-your-forehead-of-course moments, very well known and surely WP:WHAAOE. 85.77.250.219 (talk) 12:16, 27 June 2009 (UTC)[reply]

The Most Baffling Scientific Mysteries of Our Time (Michael Brooks) ?? - KoolerStill (talk) 15:04, 27 June 2009 (UTC)[reply]

~~Oh, you got the author right!~~....and not only the author; that's the subtitle of the book. 13 Things That Don’t Make Sense^{very much recommended btw} by Michael Brooks (science writer) was what I was trying to recall. Though I hate to give up the answer as the guesses were more valuable; those things go on the top of my reading list. 85.77.250.219 (talk) 17:09, 27 June 2009 (UTC)[reply]

For A2, the number you describe is the Hayflick limit. - Draeco (talk) 02:10, 3 July 2009 (UTC)[reply]

fajan's rule

What is the statement of Fajan's rule which determined the percentage of covalent character in a bond.Rikichowdhury (talk) 11:04, 27 June 2009 (UTC)[reply]

We have an article, Fajans' rules. Please try to read the relevant articles before posting questions on the Reference Desks. Rkr1991 (talk) 11:20, 27 June 2009 (UTC)[reply]

Impact of science

What impact has science had on the life of man from the first to fifth generation:41.210.21.227 (talk) 15:48, 27 June 2009 (UTC)[reply]

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. Tempshill (talk) 16:18, 27 June 2009 (UTC)[reply]

I must admit though to being intrigued what 'the life of man from the first to fifth generation' refers to. My first guess is it has some religious significance like anthropologists are always ascribing to ancient artifacts they don't understand. Dmcq (talk) 16:39, 27 June 2009 (UTC)[reply]

Purpose of the Human Beard

Every organ or part of a living thing has a purpose. Occasionally the purpose becomes obsolete and the organ no longer has a useful function (e.g., the human appendix). What is the purpose of the beard in human males? If it has become obsolete, what was its former purpose? Some members of oriental races have only a wispy beard. Black males have no beard at all unless they have some White ancestry. Why is there a racial difference in this? - GlowWorm. —Preceding unsigned comment added by 174.130.255.30 (talk) 17:01, 27 June 2009 (UTC)[reply]

"Every organ or part of a living thing has a purpose".^[Dubious] Nothing in evolution says all parts of an organism must have a purpose. As long as they are not maladaptive, they could arise by mutation and permeate through a population. And even maladaptive traits exist in all species as part of natural variation.Yob Mod 17:08, 27 June 2009 (UTC)[reply]

YobMod is correct. I call ^dubious on black males having no beard. Tempshill (talk) 17:23, 27 June 2009 (UTC)[reply]

It's true that some ethnic groups are naturally beardless; and some of these are "black", but likely not what the OP has in mind. —Tamfang (talk) 17:42, 27 June 2009 (UTC)[reply]

Do you have an example? Or source? This is all news to me. I know there is a lot of variation in speed and thickness of facial hair growth, but I've never heard of entire ethnic groups being completely beardless. --Tango (talk) 18:52, 27 June 2009 (UTC)[reply]

Native americans are well known to be beardless. See this book for instance. SpinningSpark 19:17, 27 June 2009 (UTC)[reply]

That book says it is likely to be partially genetic and partially cultural, which suggests they do have some facial hair but shave it off. --Tango (talk) 19:29, 27 June 2009 (UTC)[reply]

Mainly I'm remembering a picture in National Geographic in the Seventies, showing a Melanesian(?) rubbing cheeks with a bearded foreigner, and the caption saying that beards are rare to unknown in that (lo-tech) tribe. —Tamfang (talk) 16:38, 22 July 2009 (UTC)[reply]

Women who don't shave can also grow beards. See bearded lady. ~A H 1^(TCU) 18:26, 27 June 2009 (UTC)[reply]

I always thought that the purpose of a beard was to serve as the only visual means, other than getting a tattoo or an interesting scar, of showing the world that you're a *real man*... ;) --Kurt Shaped Box (talk) 18:37, 27 June 2009 (UTC)[reply]

Yeah, probably serves the same purpose as the lion's mane or the peacock's tail. Completely pointless except for displaying to females. SpinningSpark 19:20, 27 June 2009 (UTC)[reply]

Isn't there some 'old Chinese proverb' that goes something like "Man without beard is like peacock without tail"? --Kurt Shaped Box (talk) 20:14, 27 June 2009 (UTC)[reply]

Actually, a huge mane is a turn-off to the average lioness. </trivia> Vimescarrot (talk) 18:13, 28 June 2009 (UTC)[reply]

I think that the really interesting question is why do some men shave? If asked why I bothered to grow a beard, I always say that I didn't grow one, I just didn't shave. Returning to the question, I have always assumed the beard to be just another secondary sexual characteristic as suggested above. Mikenorton (talk) 19:26, 27 June 2009 (UTC)[reply]

Our beard article does have a couple of interesting stories about the history of shaving in the ancient and classical world. Tempshill (talk) 22:09, 27 June 2009 (UTC)[reply]

It is chest hair that is supposed to show a "real man" - at least in some of the societies that have occasional members capable of such hirsute growth. As far as I know, only a minority of Whites have chest hair (except perhaps for male Australian aborigines?). – GlowWorm. —Preceding unsigned comment added by 174.130.255.30 (talk) 21:47, 27 June 2009 (UTC)[reply]

There is a lot of variety in chest hair, it's not a "yes/no" thing. Chest hair can also develop quite a bit later than other secondary sexual characteristics, making simple statistics on the subject pretty much impossible. --Tango (talk) 21:50, 27 June 2009 (UTC)[reply]

GlowWorm, are you trolling? I mean, the Australian aborigine thing went a bit too far. I give you 6/10, though. Tempshill (talk) 22:09, 27 June 2009 (UTC)[reply]

I seem to remember seeing photos of Auistralian aborigenes with chest hair, though I am not sure I remember correctly. - GlowWorm.

And you haven't seen photos of Caucasians with chest hair? --Tango (talk) 01:33, 28 June 2009 (UTC)[reply]

The immediate evolutionary predecessors of humans doubtless had relatively heavy and densely packed hair over almost the entire body, as do all other anthropoids to this day. (The human body still has fine hairs scattered at intervals over areas that do not have relatively heavy, densely packed hair, at least in Whites). As evolution proceeded, the predecessors of humans lost most of their heavy, densely packed hair. (An advantage in not having hair is that hair can harbor vermin, even though it retains body warmth. Perhaps the use of fire had something to do with the disappearance of hair.) In humans, hair may have been retained in places where it served a purpose. The hair on the head protects from the sun. Pubic hair is a sign of sexual maturity; so is under-arm hair. The beard, as another poster suggested may be a gender indicator, as also may be a mustache and chest hair. But why don't all human races have facial hair? (A peacock's tail has the serious disadvantage of hindering flight. So it can survive in nature only where that can be tolerated.) - GlowWorm.

Here is another suggestion about beards. Large wild animals that use teeth as a weapon may lunge for the throat of an opponent. If a stone-age man has a beard, it will sometimes protect him from that form of attack. Women were not hunters, so rarely needed that protection. Men were the hunters, women were the gatherers. – GlowWorm.

I am now more convinced you're trolling, but see Hair for theories about the evolution of hair distribution on humans. Tempshill (talk) 00:20, 28 June 2009 (UTC)[reply]

I have an unproven hypothesis that a beard's primary function is to expel unwanted materials from the body. Eat a lot of mercury-laden tuna and it comes out your follicles, for instance. Vranak (talk) 19:07, 30 June 2009 (UTC)[reply]

Osteopathic Medicine vs Allopathic Medicine

--Jessica A Bruno 22:14, 28 June 2009 (UTC) Oops forgot to say this is indeed an science question, yobmod. Anyway, this question to my previous question on here (homeopathic medicine vs allopathic medicine). Since I have some experience with this as well.

Had good and bad experiences with both DO (Doctor of Osteopathy) and MD (Doctor of Medicine). Which I'm not really getting into on here.

Do you have a science question? This is a reference desk, not a discusion forum.Yob Mod 17:12, 27 June 2009 (UTC)[reply]

Osteopaths are basically "real doctors" and often share practices with MDs. They are in no way comparable to homeopaths. Edison (talk) 19:54, 27 June 2009 (UTC)[reply]

It should be emphasised that that is US terminology. In the UK, an osteopath is not a doctor (but it is a regulated profession and usually restricts itself to stuff where osteopathy has actually been demonstrated to work) and does not receive training in general medical stuff. (Someone with a DO from the US can register as a doctor here, though - it is recognised as a medical degree.) --Tango (talk) 20:47, 27 June 2009 (UTC)[reply]

--Jessica A Bruno 22:14, 28 June 2009 (UTC)Thanx for your answer to my question. Its interesting as well. —Preceding unsigned comment added by Jessicaabruno (talk • contribs) 21:05, 27 June 2009

What is the mass of the Earth's crust?

Crust (geology) states that it's "less than 1% of the volume" of the Earth and gives densities for upper and lower crust ( "2.69 g/cm3 and 2.74 g/cm3 and for lower crust between 3.0 g/cm3 and 3.25 g/cm3" ), but that's it. Plugging in 1% of Earth's volume and say 3 g/cm^3, gives about:

1.0832073 × ((10^12) (km^3)) * 0.01 * (3 (g / (cm^3))) = 3.2496219 × 1022 kilograms

Does that look right? Anybody have a better calculation? Thanks. --Rajah (talk) 20:39, 27 June 2009 (UTC)[reply]

This book [2] by Robert D. Hatcher gives the following statistics for the crust "5.25 x 10⁹ km³, 1.44 x 10²⁵g", not too dissimilar to your calculated values although it appears that 'less than 1% of the volume' is actually about half a percent. Mikenorton (talk) 22:02, 27 June 2009 (UTC)[reply]

Thanks for the source, although Hatcher says "the continental crust( 5.25 x 10⁹ km³, 1.44 x 10²⁵g", so , it sounds like the oceanic crust is omitted there. (And as one might imagine with a book title 4-D Framework of Continental Crust . Thanks again for the source --Rajah (talk) 17:51, 29 June 2009 (UTC)[reply]

Car trunk

So the other day I was leaving my driveway when I noticed that I had left my trunk open. But instead of getting out of the car, I backed up the car and hit the breaks. As expected, the trunk closed, but I still can't figure out where the torque that caused the trunk to start rotating comes from. Is there even a torque (from the perspective of someone outside the car)? If not, how is angular momentum conserved? And if the car was initially going at a speed v and stopped quickly, would the angular velocity be v*L (L=length of trunk)? —Preceding unsigned comment added by 74.15.138.134 (talk) 22:12, 27 June 2009 (UTC)[reply]

Doesn't need any torque. Think of it like this -- you can close a door by pushing on the door parallel to the doorway. Takes more force than doing it the sensible way, but it works. --jpgordon^{::==( o )} 22:27, 27 June 2009 (UTC)[reply]

When the trunk is open, its center of mass is well above the hinges, so when you hit the brakes, the forward horizontal force acting on the trunk is not aligned with that center of mass. That misalignment translates to the torque that causes the trunk to rotate toward its closed position. -- Tcncv (talk) 22:57, 27 June 2009 (UTC)[reply]

But isn't that "force" just the ficticious force arrising when we consider the situation from the pov of the car? If we're in an inertial reference frame, shouldn't there be no force on the centre of mass, just inertia? —Preceding unsigned comment added by 74.15.138.134 (talk) 23:13, 27 June 2009 (UTC)[reply]

The trunk cover has an inertia like anything else. WHen you stop short, the trunk tries to continue to move forward, and will do so until it hits as far as the hinges will allow. Since the trunk lid still has momentum, that momentum is conserved as the lid then bounces back at roughly the same speed as it was going forward. Since it is only anchored at one end, that momentum is an angular momentum, but the difference is moot here. The lid keeps moving until it hits something with enough resiliency to stop it; in this case when the latch engages, it lacks enough momentum to break the latch, or move the whole car, so it stops. But if the latch were broken, or failed to engage, the lid would bounce open and closed until friction slowed it to a stop... --Jayron32.talk.contribs 23:56, 27 June 2009 (UTC)[reply]

The OP reports the car was reversing when the brakes were applied. That makes it unlikely the lid bounced against an upper stop, unless it is a rear-engine car. However only a minority of cars are rear-engined and it is hard to imagine a driver not seeing immediately that their front lid is open. In the event that the front lid was only slightly open i.e. resting on but not engaged with its latch, braking could not be expected to close it because of the relatively high instantaneous force needed with no added assistance from gravity. Cuddlyable3 (talk) 13:44, 28 June 2009 (UTC) [reply]

I think the key thing you are missing is that the car is not a rigid body. A rigid body in its own inertial reference frame has no forces acting on it (by definition), but that's not the case for the car since it isn't rigid - the trunk (why you have an elephant's nose attached to your car is beyond me...) can move relative to the rest of the car, so you have internal forces. Anyway, you're not in an inertial reference frame, you're braking, that's an acceleration. --Tango (talk) 00:54, 28 June 2009 (UTC)[reply]

To create a rotation - you need a pair of unequal forces that are not in the same straight line. This is called a Couple (mechanics). In this case, the momentum of the trunk-lid is operating along it's center of mass towards the rear of the car - and the hinges are providing a force in the opposite direction when you stomp on the brakes. This creates the rotation you need to shut it. Imagine if (somehow) the hinges were mounted in the middle of the trunk lid...at it's center of mass...in that case it wouldn't rotate because these two forces would be acting in the same straight line. SteveBaker (talk) 01:04, 28 June 2009 (UTC)[reply]

Since when has momentum been a force? The torque comes from a force that isn't acting through the centre of mass, doesn't it? There is only one force acting on the trunk (unless you choose a frame of reference where there are "fictitious" forces, but I can't see why you would - I would work in the centre of mass frame of the trunk) and that is a forwards force acting on the hinges (since that's the part which is joined to the car). Since the hinges are below the centre of mass and the force is horizontal, that causes a torque. I think some people are trying to consider the trunk rotating around the hinges, which is how we usually think of it in real life (because the car is big and heavy and it makes sense to think of it being stationary), but the maths is far easier if you think of the centre of mass of the trunk being stationary and everything rotating relative to that. --Tango (talk) 01:31, 28 June 2009 (UTC)[reply]

Alright, I think I've isolated my principal trouble. If the force is acting at the hinge (axis of rotation), why is there a torgue (radius is zero)? I would have assumed that there was no torque, and to do the calculations one would have to invoke the conservation of angular momentum. And nobody addressed my last question: is the angular velocity v*L? —Preceding unsigned comment added by 74.15.138.134 (talk) 02:26, 28 June 2009 (UTC)[reply]

If you take the hinge as the axis of rotation then yes, there is no torque from the force on the hinge (there isn't even a force if you consider the hinge to be stationary and everything else moving around it, but you then have to consider the weight of the trunk and the car and both of those will produce a torque, which will partially cancel with each other and the braking force of the car needs to be factored in and you end up with a complete mess of equations), but I would take the centre of mass of the trunk as the axis, it's much easier. You then don't need to consider the car in any of this, it's big and heavy and will just sit where it is, so you can just assume it is still where you expect it to be. You can then consider the trunk with some horizontal force being applied to the hinges. You then work in the frame where the centre of mass of the trunk is stationary. The trunk will then rotate around its centre of mass due to the force on the hinge not being through that centre of mass. It will rotate until it is horizontal when it will hit the car (which has moved and rotated in this reference frame, but you don't need to worry about that, you can switch reference frames again once the trunk is moving to one that keeps the Earth as fixed and the car will be essentially fixed in that frame since it is heavy enough to be considered immobile) and stop, it is then closed and we are finished. The angular velocity (and you need to specify of what part of the trunk and relative to what axis) has no simple relationship with the velocity of the car before it brakes. --Tango (talk) 02:56, 28 June 2009 (UTC)[reply]

Whenever doing calculations about torque or angular momentum it is important to chose one axis (which does not have to be a fixed point of the object) for all the calculation. The hinge of the trunk is accelerated and therefore is not associated to any unique choice of axis. In other words, your intuition doesn't work when dealing with an accelerated reference frame. Dauto (talk) 06:03, 28 June 2009 (UTC)[reply]

Wave function collapse

Can conscious thought precipitate wave function collapse? Please think carefully before replying. —Preceding unsigned comment added by 79.75.10.205 (talk) 22:44, 27 June 2009 (UTC)[reply]

Sure, it just did. You've collapsed quite a few just typing your question, haven't you? --Dr Dima (talk) 23:07, 27 June 2009 (UTC)[reply]

I'm sorry , I don't understand your response: can you please explain/--MusicPhysician (talk) 23:14, 27 June 2009 (UTC)[reply]

Well, it's simple. Your frontal lobe is the system, and your motor cortex + hand + keyboard is the measuring device. --Dr Dima (talk) 00:17, 28 June 2009 (UTC)[reply]

Insofar as conscious thought involves the movement of electrons around your brain, lots of wavefunctions collapsed in producing that thought... --Jayron32.talk.contribs 23:50, 27 June 2009 (UTC)[reply]

The whole concept of "wave function collapse" is very wishy-washy. It's the bit the quantum mechanics lecturer mumbles about as he trails off at the end of the lecture while waving his hands around a bit. We don't really understand what happens, it's just we know something has to happen because the maths doesn't quite fit with what we see, so it's difficult to give any detailed answers on the subject. --Tango (talk) 00:16, 28 June 2009 (UTC)[reply]

It's not that the math doesn't fit with what we see; the math agrees with the experiments, at least so far. It's more like what we see (in the theory or in the experiment) doesn't fit with our "common sense", or with what we see in our everyday life. But you are right, the notion of collapse is not even a necessary part of quantum mechanics, although the notion of measurement certainly is. You can imagine that the collapse does not have to happen at all, and the system is a priori in one of its possible states (Bohm interpretation); or that there is no collapse at all, and all possibilities exist in parallel. --Dr Dima (talk) 00:36, 28 June 2009 (UTC)[reply]

The maths says its in all the states at once but our measurements show only one state - that's a disagreement. The concept of collapse is just thrown in at the last minute to resolve that. --Tango (talk) 00:49, 28 June 2009 (UTC)[reply]

Sure. Before the measurement occurs, experiments - not measurements - seem to show superpositions; or at least that's what the Copenhagen interpretation says. At any rate, experiments confirm the math so far. But measurements proper show less-superposed (e.g. position measurement) or pure (e.g. spin measurement) states, because that's what constitutes a measurement. --Dr Dima (talk) 02:22, 28 June 2009 (UTC)[reply]

The results of experiments are always measurements. The measurements are always single values (with appropriate error bars), but we can only explain those measurements if we assume there was a superposition of states before the observation was made. It's when we try to explain the measured results that superpositions come into it, the measurements themselves are perfectly simple. --Tango (talk) 03:00, 28 June 2009 (UTC)[reply]

The math in quantum mechanics does fit with what we see, it’s just that the math description is a statistical one, which is a little disconcerting. It’s very much like modeling a die tumbling through the air with a discrete random variable with a uniform probability mass function, where the random variable is which face of the die will land up. A superposition state is basically just a probability mass function or a probability density function. It’s disconcerting that it isn’t possible to go beyond a statistical model to a deterministic one in quantum mechanics, as is possible with dice (up to a point, due to chaos). And how the superposition state is calculated has some features that are counterintuitive. But a superposition state is a statistical mathematical model, that correctly predicts the outcome of measurements of systems in that state, in a statistical sense. The math fits the measurements, statistically. Red Act (talk) 04:25, 28 June 2009 (UTC)[reply]

The Bohm interpretation of the Double-slit experiment invokes a so-called hidden variable, the ψ-field, that is as convincing as any God of the gaps explanation, and fails Occam's razor where "entities should not be multiplied unnecessarily" as badly. Cuddlyable3 (talk) 13:25, 28 June 2009 (UTC)[reply]

The maths is statistical and what we see is definite. That doesn't fit. You have to add "wave function collapse" to the maths in order to make it fit. I'm not disputing that superposition happens, the evidence is pretty conclusive, I'm just saying that wave function collapse is not part of the maths but is required to make the theory fit what we see. (Well, wave function collapse or some alternative, as people have already mentioned.) --Tango (talk) 17:41, 28 June 2009 (UTC)[reply]

This difference in perspective can’t really be resolved, since it all just boils down to a matter of semantics – Does “fitting” in only a statistical sense really count as “fitting”? That depends entirely on how you define “fitting”, which doesn’t have a standard mathematical or physical definition, as far as I know.

It does seem to me like quantum mechanics (or more generally, quantum field theory) is probably an incomplete theory, and some day a replacement theory will be developed that predicts observations individually, rather than observations just “fitting” the theory only in a statistical sense. My personal hunch is that the ultimate theory will obey a principle of locality, but the notion of what a principle of locality entails will have to be modified, due to causality being less tied to time than we usually think of it as being. I view negative energy relativistic propagators as pointing in that direction of needing a new notion of causality. Of course, I’m not defining my terms well, so my last couple sentences don’t really amount to more than unfalsifiable ramblings. Red Act (talk) 19:50, 28 June 2009 (UTC)[reply]

The answer to the question, in the sense that I think the question is intended, is no. Dr. Dima points out perfectly validly that you typing a key on your keyboard is ultimately the result of a wave function collapse (actually, a bunch of them) that was precipitated by your conscious thought. However, I presume the question was asked in the spirit of how new age quantum mysticism abuses quantum mechanical concepts, and in that sense, the answer is an unequivocal “no”.

For example, someone I know, who is very heavily into new age stuff, quit her very good job a year ago, and is still unemployed, in large part because she believed (and still believes) that she will win the lottery jackpot. According to her new age beliefs, she can win the lottery by choosing to win the lottery. This is consistent with quantum mechanics, according to her new age interpretation. Her interpretation is basically the participatory anthropic principle or consciousness causes collapse interpretation, in which all collapsing of wave functions is ultimately due to a consciousness causing it. So by intending to win the lottery, she can collapse the wave functions that affect which lottery balls will be chosen, in such a way that the numbers she selected will be chosen.

The standard scientific interpretation of quantum mechanics, the Copenhagen interpretation, is considerably different from that mystical, new age interpretation. According to the Copenhagen interpretation, the collapses of wave functions are random, and cannot be predicted, much less controlled by conscious intent.

If it was possible to control wave function collapses consciously in the new age mystical sense, it would be possible to demonstrate that effect fairly easily, with a well-designed, repeatable experiment, that would involve a conscious interaction with equipment that’s vastly simpler than in the case of causing certain lottery balls to be selected. The simplest, most direct experiment I can think of would be sending a series of particles in a superposition state through a Stern–Gerlach device, such that theoretically half of the particles should be measured as being in a “spin up” state, and half of the particles should be measured as being in a “spin down” state. Then have a new age subject concentrate on trying to collapse the wave functions in such a way that an unexpectedly large number of particles wind up being measured as being in the “spin up” state. For the experiment to be well-designed, there would have to be runs in which nobody was intending to collapse the wave functions in one way or another, as a control.

Nobody has ever performed a well-designed, repeatable experiment like that, that would show that the new age, mystical interpretation of quantum mechanics was actually correct. Therefore, using Occam's razor, one must assume that there is no such interaction between conscious intent and the collapsing of wave functions in unobvious ways.

As a general rule, anthropocentrism in a theory is usually a really solid red flag, suggesting that the theory is nonsense. Three examples of that rule as I see it are the participatory anthropic principle of quantum mechanics as discussed above, the geocentric model of the universe, and any idea of an anthromorphic God. Red Act (talk) 07:02, 28 June 2009 (UTC)[reply]