Monday, December 7, 2020

Hard Predictions About Quantum Gravity

One of the challenges of distinguishing between classical and quantum theories of gravity is how to distinguish the two experimentally. A new paper make a precise generic prediction about quantum gravity theories that could do just that. 

Specifically, gravitational interactions that are present in quantum gravity, but not in classical gravity should trigger a transition from "coherent" to "decoherent" behavior in light and massive particles propagating through space at a precisely quantifiable distance that is a function of particle velocity for massive particles and a function of frequency for photons.

These are measurable properties of particles (at least statistically) and the distances involved reasonably susceptible to measurement.

The paper is as follows:

arXiv:2012.02288 [pdfother]
Wave optics of quantum gravity for light and particles
Comments: 16 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

Effects of the quantum gravity under Minkowsky space-time background are considered. It is shown that despite the absence of the full theory of quantum gravity, very concrete and definite predictions could be made for the influence of the quantum gravitational fluctuations on the propagation of the particles and light. It is shown that the operator of the gravitational potential in a vacuum has the correlator <0|Φ̂ (r)Φ̂ (r)|0>δ(rr)/M3p. As a result, nonrelativistic massive particle waves lose their coherence at a distance proportional to the fourth degree of the particle velocity. Coherent electromagnetic wave attenuates due to metric fluctuations inversely proportionally to the fifth degree of a frequency.

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