Talk:Pauli exclusion principle
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Conceptually, it is simple to understand the correspondence between fermions/matter and bosons/[fields; energy; ??]. It's an important point for this article too, I think - it's one of the most important consequences of the Pauli principle. What's the best way to describe it?
On one hand, describing bosons as "fields" is a little misleading, because fermions are also described as fields in QFT. The reason light is classically thought of as a "field" instead of a particle has as much to do with the fact that the photon is massless (hence long-range, hence classically detectable as a field) as the fact that it is a boson. So the distinction isn't too clear.
On the other hand, describing bosons as "energy" is also misleading, because obviously fermions carry energy just as well as bosons.
Thoughts? CYD
I changed "fields" to "non-matter".
There's a hint in Quantum Physics by S. Gasiorowicz that fermions do not require a totally antisymmetric wavefunction if there is sufficient separation. From memory, it said something like: "the reader might expect that if we have one electron on earth and one on the moon, they won't require antisymmetrization... Indeed, even at lattice spacing distances of 5-6 angstroms, antisymmetrization is usually unnecessary".
Unfortunately, the only mathematics presented to support this was a calculation of the amount of overlap in probability densities between distant electrons.
That's as much as I know - I couldn't write an authoritative summary on the matter. If true, it would impact on not only this article, but also identical particles and fermions, and perhaps others.
-- Tim Starling 11 Oct. 2002
I believe he's saying that, under certain circumstances, you can make an approximation of ignoring antisymmetrization. -- CYD
Maybe... I have the book here now, and I can quote the most suggestive statement:
"The question arises whether we really have to worry about this when we consider a hydrogen atom on earth and another one on the moon. If they are both in the ground state, do they necessarily have to have opposite spin states? What then happens when we consider a third hydrogen atom in its ground state?"
I'll try to find some more authoritative information on this. -- Tim
Okay, CYD is right. Sorry everyone. -- Tim
Is the Pauli exclusion principle a complicated way of saying that two things can't be in the same place at the same time?
Pauli exclusion principle seems to be an ADDITIONAL assumption to the quantummechanical principles, since it seems (to me) that there is no proof WHY spin-half particles have anti-symmetric wavefunction and integer spin are symmetric. If this is indeed true, can someone edit the text in this respect? The exclusion principle is explained a thousand times on the web, but (almost) no one mentions this aspect. -- John
One of the results of quantum mechanics is that spin is quantized - the spin of a particle is either an integer or a half-integer times hbar. There is a theorem in relativistic quantum mechanics, called the spin-statistics theorem, which says that particles with integer spin obey Bose-Einstein statistics, whereas particles with half-integer spin ovey Fermi-Dirac statistics, and therefore obey the Pauli exclusion principle. In non-relativistic quantum mechanics, however, the Pauli principle must be postulated (and there is certainly enough experimental evidence to call it an empirical fact.) See identical particles for a little discussion of this. -- CYD