Quantum Electrodynamics in Curved Spacetime

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Discussion Overview

The discussion revolves around the formulation of Quantum Electrodynamics (QED) in curved spacetime, exploring theoretical frameworks, references, and the challenges associated with quantizing fields in non-flat geometries. Participants inquire about existing literature and methods for addressing these complex interactions within the context of quantum field theory (QFT) on curved manifolds.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the existence of a formulation of QED in curved spacetime and request references to relevant papers.
  • One participant references a specific paper that discusses corrections to QED due to non-flat background metrics.
  • There is a question regarding attempts to formulate QED from the beginning using the formalism of QFT on curved spacetime.
  • Another participant clarifies their understanding of the formalism of QFT on curved spacetime, citing works by Wald and Birrel & Davies, and discusses the quantization of scalar fields on curved manifolds.
  • Some participants express skepticism about treating interacting fields like QED in the same manner as free fields, noting the complexities involved in perturbative approaches in curved backgrounds.
  • One participant suggests that while QED cannot be treated as free fields, perturbation theory can still be applied in curved spacetime, similar to flat spacetime, and provides a reference for further reading.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of formulating QED in curved spacetime, with some suggesting that perturbative methods can be applied while others emphasize the challenges posed by interactions in this context. No consensus is reached regarding the treatment of realistic interacting fields.

Contextual Notes

Participants highlight limitations in the current understanding of QED in curved spacetime, including the ambiguity in the division of solutions to the Klein-Gordon equation and the implications for Hilbert spaces. The discussion remains open-ended regarding the application of these methods to interacting fields.

paweld
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Does anyone know if there exist a formulation of QED in curved spacetime.
If yes could you give me some references to papers in which solution
to these problem is described?
 
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paweld said:
Does anyone know if there exist a formulation of QED in curved spacetime.
If yes could you give me some references to papers in which solution
to these problem is described?

see, e.g., http://arxiv.org/pdf/0906.3837
 
Thanks. This paper show how to compute some correction to QED which arises
as a result of nonflat background metric. Are there any any attempts to formulate
QED on a classically described curved background from the beginig using the formalism
of QFT on curved spacetime.
 
paweld said:
Thanks. This paper show how to compute some correction to QED which arises
as a result of nonflat background metric. Are there any any attempts to formulate
QED on a classically described curved background from the beginig using the formalism
of QFT on curved spacetime.
I can answer your question, but first I must ask what you mean by "the formalism
of QFT on curved spacetime". The answer will depend on this.
 
By the formalism of QFT on curved spacetime I mean theory which is presented in book
"QFT on curved spacetime and black hole thermodynamic" by Wald or "QFT
in curved spacetime" by Birrel, Davies. They state procedure how to quantize scalar
noninteracting Klein-Gordon field on curved manifold (in breif: one can find a
"complete" set of solution of Klein-Gordon eq which in general are not plane waves
and write the field as a combination of these solution; coefficients which appear
in this decomposition are creation and anihilation; the division on positive and
negative solution of KG eq. is not unambiguous; different divisins often lead to
Hilbert spaces which are not unitarly equivalent; Wald describes also algebraic
approach to QFT in CS which is more mathematically rigorous). I know that
it is possible to quantize in this manner free Dirac and electromagnetic field.
I wonder if anybody tried to treat realistic interacting fileds in this approach.
 
paweld said:
By the formalism of QFT on curved spacetime I mean theory which is presented in book
"QFT on curved spacetime and black hole thermodynamic" by Wald or "QFT
in curved spacetime" by Birrel, Davies...
No, QED cannot be treated that way since it is interacting.

However since those methods give rise to a good construction of free fields they allow you to perform perturbation theory in curved spacetime, just as easily as you could perform it in flat spacetime. In fact a renormalizable theory in flat spacetime can be shown to be renormalizable in curved spacetime.

So one can treat perturbative QED on curved backgrounds. For an introduction to what is involved, but simplified for the scalar case try:
http://arxiv.org/abs/math-ph/9903028"

Perturbative QFT is much more difficult in curved backgrounds.
 
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