Originally posted by @moonbus
As I understand it, we have not measured particles in motion, but rather wave-like distortions. The structure of space has rippled, like someone shaking a blanket. No particles involved. There may be quanta of energy, of course, but that is still not a particle.
But we know those waves travel damn close to c. Theory says anything with zero mass can go exactly at c and that seems to be the case with these waves. BTW, when the first set of detections happened, they calculated a full sun's worth of energy, that is to say, all the energy available say in fusion reactions or matter-antimatter reactions, was put into making the gravity waves so it started out as a very powerful event and what we got is just the echo of it spreading through space and time.