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.