This made me wonder how far we are from being able to create and detect gravitons.  The Wikipedia page on gravitons [0] addresses this question:<p><i>Unambiguous detection of individual gravitons, though not prohibited by any fundamental law, is impossible with any physically reasonable detector. The reason is the extremely low cross section for the interaction of gravitons with matter. For example, a detector with the mass of Jupiter and 100% efficiency, placed in close orbit around a neutron star, would only be expected to observe one graviton every 10 years, even under the most favorable conditions. [...]<p>However, experiments to detect gravitational waves, which may be viewed as coherent states of many gravitons, are underway (such as LIGO and VIRGO). Although these experiments cannot detect individual gravitons, they might provide information about certain properties of the graviton. For example, if gravitational waves were observed to propagate slower than c (the speed of light in a vacuum), that would imply that the graviton has mass [...].</i><p>Fascinating!  I take it that the question of whether the graviton could have mass is now considered to be well answered in the negative.<p>[0] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Graviton" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Graviton</a>