Do Gedanken experiments compel quantization of gravity?

Erik Rydving, Erik Aurell, Igor Pikovski

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Whether gravity is quantized remains an open question. To shed light on this problem, various Gedanken experiments have been proposed. One popular example is an interference experiment with a massive system that interacts gravitationally with another distant system, where an apparent paradox arises: Even for spacelike separation the outcome of the interference experiment depends on actions on the distant system, leading to a violation of either complementarity or no-signaling. A recent resolution shows that the paradox is avoided when quantizing gravitational radiation and including quantum fluctuations of the gravitational field. Here we show that the paradox in question can also be resolved without considering gravitational radiation, relying only on the Planck length as a limit on spatial resolution. Therefore, in contrast to conclusions previously drawn, we find that the necessity for a quantum field theory of gravity does not follow from so far considered Gedanken experiments of this type. In addition, we point out that in the common realization of the setup the effects are governed by the mass octopole rather than the quadrupole. Our results highlight that no Gedanken experiment to date compels a quantum field theory of gravity, in contrast to the electromagnetic case.

Original languageEnglish
Article numberA44
JournalPhysical Review D
Volume104
Issue number8
DOIs
StatePublished - 15 Oct 2021

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