That concept that time moves at different speeds relative to your position and the speed you are moving at, is the basis of Einstein's Theory of Relativity, and it's provable physics (send a clock around the world in an aircraft and it will come back showing a different time to clocks that stayed on the ground). However, I cringe at the concept being explained by a Nolans' script.
I think your point about whether good sci-fi is rooted in science-fact or in pure fiction is really interesting. My experience is that a lot of science fiction stories are based on extensions of existing scientific theory, flights of fantasy from proven ideas. The waves of stories based on computing principles or robotics came after the theories had been posited. I agree, though, that the author/ creator generally fantasises those ideas way beyond the basic theory. The it's interesting how those fantastic stories start to appear as real-life concepts. Everyone seems to have a Star Trek type communicator these days, and some people now hold their phones, more like those comm units than phones; out in front of their faces, not to their ears.