i don't know what you consider plausible so i can't answer that.
Well, something that I can't take a look at and say "nope, that's not possible". For example, FTL travel is possible, but just accelerating to lightspeed and beyond is not
, and nor does light (or gravity) travel infinitely fast (for example, if you blow up a star 10 light years away, people won't see it blow up for 10 years, and you cannot ever
dodge a laser other than by knowing where it will hit before
it is fired).
Basically, exotic physics is fine, but physics that is just plain wrong isn't
. There are plenty
of films that claim to be sci-fi and just plain get the science wrong (The Core and The Day After Tomorrow just to name two), and stuff like that I wouldn't consciously allow.