Inferring the existence of gravitons from the gravitational wave spectrum
If gravitational waves exist, we might observe them with LIGO sometime in the next decade. Just as the existence of quantized energy (photons) was inferred by the distribution of the blackbody spectrum, the existence of gravitons can be inferred from the spectrum of gravitational waves. It is therefore worth calculating to what precision and from what sources would we need to detect gravitational waves to confidently say that gravitons exist.