[krapp]

If the Alcubierre drive were possible, some civilization would have already discovered it, and we would see evidence of its use. This is certain to be the case with any kind of FTL travel, if such a thing is even possible.

But when we observe the universe we see nothing. Therefore either no advanced life exists in the universe besides ourselves, which seems unlikely, or none have spread to space in any significant degree and FTL is either impossible or so difficult no one bothers. There doesn't seem to be a secret third thing that both satisfies our observations and obeys known physics.

[oneshtein]

Geminga?

[krapp]

Everything I read tells me it's a gamma ray pulsar.

[oneshtein]

Something like Alcubierre drive must move fast (0.1% of c at least), be very heavy and dense (to create protected environment inside), and emit lot of high energy gamma rays because a spacetime with negative energy will accelerate light a lot.