Reasoning QM with laymen


by Gza
Tags: laymen, reasoning
Gza
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#1
Feb10-07, 12:35 AM
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There is a person I know that believes that there is a nonzero possiblity that the moon will suddenly "jump" to a different spatial location, based on the axioms of quantum mechanics. I present their argument/thought process in it's entirety as worded by the person, with the hopes of seeing how people with knowledge of the field would counter this argument, within terms that the layperson can understand (I have my own reasoning, just want to see if it's heuristically sound):

"What many of you are confusing is that there is no such thing as a system of particles in QM. There is only one wave equation for a system, not a wave equation for every particle which are then added together. The existence of other particles always shift the nature of any single particle( such as photons tend to move toward eachother, the concept that leads to the technology of lasers) and this is indeed why on large scales the random movements of quantum particles in the moon do truly cancel out to make it impossible for it to quantum jump as a massive object. This concept has been a part of science sinse prior to QM and is the basis of all thermomechanical theory and has never been questioned in respect to the random movement of molecules which still follow absolute deterministic laws( such as entorpy). Another misunderstood idea is that quantum motion is inherently different than "classical motion" as if an electron making a jump from a certain energy state to another is different than the moons orbit. In fact QM teaches us all movement everywhere is only of the quantum jump vairety and for this reason if all the particles in the moon happened to begin to select in a single direction toward the other side of the Earth it would necisarily have the effect of the moon actually beginning to collide with the Earth and the effects of inertia and gravity would force the overall average movement of the moon to remain as it has been for quite some time now. The main point to understand here is that we can not consider any particle as a single entity, this is in fact demanded by QM, instead we can only view every particle of the moon as part of a system which indeed does have 0 probability as a whole to move anywhere but along the path described by general relativity. Any single particle will have some probability to appear in many different seemingly bizarre places, but we must remember this does not mean we can ignore their nature as a whole and hypothesis an extremely minute probablity of the moon itself performing a quantum jump. "
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FunkyDwarf
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Feb10-07, 03:11 AM
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someones been reading God's Debris :P
Gza
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Feb10-07, 03:15 AM
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Quote Quote by FunkyDwarf View Post
someones been reading God's Debris :P

nope, have no idea what book that is, but if you have something constructive to contribute, by all means.......

Wiemster
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Feb10-07, 03:38 AM
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Reasoning QM with laymen


Quote Quote by Gza View Post
There is a person I know that believes that there is a nonzero possiblity that the moon will suddenly "jump" to a different spatial location, based on the axioms of quantum mechanics.
The propbability is nonzero by QM, but is so small that it would take probably many and many times the age of the universe to become a reasonable chance to make such a leap (even a mm probably).

Quote Quote by Gza View Post
Another misunderstood idea is that quantum motion is inherently different than "classical motion" as if an electron making a jump from a certain energy state to another is different than the moons orbit.
It is actually quite different, maybe not in principle but at least to many degrees of accuracy. For the many particles of which the moon consists, the quantum behaviuor can be safely neglected and we can speak of it's position and followed path and orbit.


Quote Quote by Gza View Post
The main point to understand here is that we can not consider any particle as a single entity, this is in fact demanded by QM, instead we can only view every particle of the moon as part of a system which indeed does have 0 probability as a whole to move anywhere but along the path described by general relativity.
In principle still nonzero, only unimaginably small.

If you (by followoing this persons argument) you would consider the moon as one entity with a single wavefunction (which is quite reasonable) with this wavefunction a huge mass is associated. By Heisenbergs uncertainty principle there is a very small uncertainty in the the verlocity and position of the moon. In a formula

[tex]\Delta x \Delta v < \hbar/2m [/tex]

So the product of uncertainties in velocity and position of the moon is smaller than the unimaginably small number on the right. For all purposes the unvcertainty in position (and thus the chance of the moon leaping to some different position) is negligible.


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