With the announcement of the detection of gravitational waves, questions about the implications proliferate. Some relate to the possible existence of gravitons. The analogous relationship between gravitons/gravitational waves and photons/electromagnetic waves is frequently mentioned.
The detection of individual photons required experiments of very low intensity light, yet their existence was inferred (prior to their actual detection) by Planck and Einstein (among others) using the properties of experimental black body radiation and the photo-electric effect.
If the prospects for detection of gravitons requires similar study of very low intensity gravitational waves, then those prospects are very dim indeed. My question: are there similar indirect "experimental" methods for inferring the existence of gravitons?
Answer
The short answer is no.
As far as I know the first person to address this issue was Freeman Dyson - at least his is the name you see associated with the question. Googling finds only this article from 2004 that is behind a paywall, though I'm sure I encountered Dyson's ideas some time before 2004.
Anyhow there is a thorough discussion of the problem in Can Gravitons Be Detected? by Tony Rothman, Stephen Boughn. They confirm that the answer is no in practice though they suggest that in principle gravitons could be detected.
The problem is that gravitons interact extraordinarily weakly with matter, and there simply isn't any physically realistic equipment with the sensitivity to detect a single graviton. Incidentally the same problem means it's extremely unlikely we'll ever be able to observe a graviton being produced in a collider.
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