More of the "serious" authors are writing SF set in Einstein's universe, for example, without cheats like warp drive and such. Oh, I'll pretty soon write another Uplift Universe novel, with twenty ways to get around old Albert. Great fun! But our most carefully crafted thought experiments — the stuff we write for grownups — these tales try to test reality the way we see it, playing with the hand that nature dealt us.
Lately, a lot of SF has peered at the so-called "Singularity"... the issue of whether exponential increases in computing power might transform us into gods... or unleash AI to leave us in the dust. That's certainly a topic in Existence.