Talk:Quantum field theory in curved spacetime

From Wikipedia, the free encyclopedia

WikiProject Physics This article is within the scope of WikiProject Physics, which collaborates on articles related to physics.
Stub This article has been rated as Stub-Class on the assessment scale.
??? This article has not yet received an importance rating within physics.

Help with this template This article has been rated but has no comments. If appropriate, please review the article and leave comments here to identify the strengths and weaknesses of the article and what work it will need.
This article has been automatically assessed as Stub-Class by WikiProject Physics because it uses a stub template.
  • If you agree with the assessment, please remove {{Physics}}'s auto=yes parameter from this talk page.
  • If you disagree with the assessment, please change it by editing the class parameter of the {{Physics}} template, removing {{Physics}}'s auto=yes parameter from this talk page, and removing the stub template from the article.

[edit] Particles Depend on Observer

This is said a lot, and it is misleading. The definition of "particle" here is the occupation number for a global field mode, an asymptotic definition. There is a second definition of particle which is local, where the particle is what you get when you apply a local field operator to the vacuum.

Then the excitations of the quantum field theory are represented as a sum over these local particle paths. The local particles are not different in different frames. The new particles in Unruh's and Hawking's calculation can, in the local particle picture, be traced back to the horizon, and they get to the detector by meandering around in the usual way.

The source of the confusion is the fact that the local-particle interpretation was confined to Feynman and a few others until the seventies. Everybody else followed Wigner and defined a particle as a global excitation which serves as an in or out state. This changed when quarks became particles, which was a catalyst for a linguistic transformation that caused people to redefine particles as local constructions in Feynman diagrams or in path integrals which follow particle trajectories, not as asymptotic excitations of global field modes.

I tried to make the distinction clear.Likebox (talk) 23:07, 8 January 2008 (UTC)