Talk:Fock space

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[edit] Help!

Could somebody knowledgeable in this area take a look at the article. The sentence "WARNING: Fock space only describes noninteracting quantum fields. See Haag's theorem." is strange, but I don't know what to do about it. Thanks! Oleg Alexandrov 02:34, 9 Mar 2005 (UTC)

"(to describe many species of particles, made the tensor products of as many different Fock spaces)." I assume that "make" is meant, and not "made." Since I don't know that, I'll let someone else fix it.

[edit] Bottom two paragraphs

I can't seem to make head or tail out of the last two paragraphs, so I have moved them over here instead:

WARNING: Fock space only describes noninteracting quantum fields. See Haag's theorem. However, if the model has a mass gap, the asymptotic past and asymptotic future states can be described by a Fock space. Fock space does not describe finite temperature physics as well.

While Fock space is appropriate for free massive particles with finite energy (i.e. zero temperature) because for a collection of these particles, finite total energy and finite particle number mean the same thing, it is no longer appropriate for massless particles because an infinite number of them can still have finite energy. See soft photon

Some of the terminology seems out of place, and sounds extremely foreign in the context of quantum chemistry. Perhaps it would make more sense in quantum electrodynamics? --HappyCamper 02:02, 19 November 2005 (UTC)

The context doesn't have to be quantum chemistry. Fock spaces are used in quantum field theory in general. I dunno what the guy is talking about though. I think this is an example of people from different fields talking past each other - for instance I've seen Fock space used to derive temperature-dependent stuff, but then again I'm a condensed matter guy. These kinds of conflict are somewhat common on physics-related pages, I wonder if there's some kind of resolution mechanism. Nvj 20:57, 29 May 2006 (UTC)

Is all the notation correct within this article, why these different phi for single particle states? and one could better describe the indices, because this is where many of the things are that one needs to understand. why are the indices sometimes in the bracket, sometimes out of the bracket?