> Maybe there is even some theoretical equivalent to a sonic boom where instead of sound, a type of radiation that gets emitted via gravity when a FTL craft goe

> Maybe there is even some theoretical equivalent to a sonic boom where instead of sound, a type of radiation that gets emitted via gravity when a FTL craft goes super-photonic (super-luminal? super-temporal?) that could also be detectable in bursts over the background noise. There's Cherenkov radiation, but that has bigger implications. Alcubierre drives were supposed to have an issue with something like blueshifting particles along their paths, but I think that requires them to be heading for us.