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Nov28-11, 11:11 AM
P: 1,101
Quote Quote by stglyde View Post
In SR. Anything FTL or superluminal can affect causality because there would be some frame where things move backward in time. Since SR is equivalent to Lorentz Ether Theory. And LET is about additional dynamics that occurs in the backdrop of newtonian absolute space and time. Then how can you model FTL and LET and things moving back in time since the background is supposed to be absolute space and time (where things moving backward is in conflict with its main postulate)? I've been googling this but can't find the information. Thanks.
What FTL scenario would break causality? I can understand that FTL would mess up measurements of time/distance for that FoR. You mean "move backward" in propertime, not coordinate time right?.

So then what does negative propertime mean? Seems meaningless.

So I think that means FTL breaks the "all physics the same in all FoR", not causality.

I don't know for sure but isn't a postulate of SR that c is the maximum whatever? Seems like this would have to be assumed for the rest of the theory to "work". Said differently SR doesn't (directly) address FTL. Is that right?

Picturing the light cone in 3D (as a sphere) was pretty enlighting, including seeing that speed of cause isn't as "important" as it preceeds effect.