[superposeur]

Most sci fi just pretends relativity doesn’t exist.

Yes, the point is that any way to send a signal between space like separated events A and B (in sr or gr) would also allow a return signal to be sent back from B to event C in the past of A. So any means of ftl signaling (wormhole, warp drive or whatever) is tantamount to building a time m achine. No amount of techno optimism or can-do cleverness will ever be sufficient to surmount this obstacle in real life.

Incidentally the Gödel metric runs into causality violation in a different way: closed timelike curves. No need for ftl , it’s even less realistic as Einstein is quoted pointing out in the article.

[chatmasta]

I enjoyed this lecture [0] from Scott Aaronson about closed timelike curves and the impact they would have on computational complexity theory. Basically, they would give you the ability to spend an eternity computing some subcalculation, and then return to where you started with the result in hand.

[0] https://youtube.com/watch?v=Ha4eG8gLSK4

[superposeur]

Yes it’s really interesting how the quantum information folks have managed to recast known features of classical physics (second law of thermodynamics, no closed timelike curves) as “implausible computational tasks”.