In terms of QFT in curved spacetime (qftics), are there any known tests that confirm/void it to be a correct prescription for a first order approximation quantum theory of gravity? Obviously the extension makes some sense but how is it confirmed?

I know there are a lot of tests including Lorentz violation in qft, ultimately a possible search route to test qftics, but if there are more specific cases this would be extremely useful to know about.


1 Answer 1

  1. By its very definition, QFT in curved spacetime assumes the background spacetime to be fixed and is a framework to treat quantum fields on the fixed spacetime. Hence the question "are there any known tests that confirm/void it to be a correct prescription for a quantum theory of gravity?" is ill-posed; as the mentioned formalism tells us the first-order corrections due to quantum fields only; as opposed to a full understanding of quantum gravity which would also involve taking into account how the geometry changes due to the dynamics of the fields. The key idea is that QFT in curved spacetime is the $O(1)$ correction in a full theory of quantum gravity.

  2. With regards to the question whether there have been any experimental tests of QFT in curved spacetime, there have been some proposals. You might want to have a look at this and this.

  • $\begingroup$ I think I found my answer here physics.stackexchange.com/questions/156709/… $\endgroup$
    – MKF
    Aug 20, 2018 at 12:23
  • $\begingroup$ @MKF The linked answer tells you that it is difficult to measure such effects. The papers I have linked in the second part of my answer tells you why it is so, and contain some clever proposals which can be used in future to observe such effects. Have a look at them. $\endgroup$
    – Bruce Lee
    Aug 20, 2018 at 12:57

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