I suppose that the question first posed by "Chicago Transit Authority" aside:

1) Time is only really perceived by two objects of matter (cooled-off energy) that interact. A highly energized particle (like a photon) wouldn't even (or hardly) "notice" time. Famously, it also "stands still" in a black hole.

2) Perceptions of an Einsteinian Universe are sort of giving way to multiverse theories of which the E.U. is a subset, and all bets are off?

3) Hubble Constant values, Dark Matter and Energy theories are all in a state of flux, hopefully soon reconciled. When larger particle accelerators are made (some perhaps of enormous, planetary size?) secrets of Higgs-Bosons, Neutrinos, Anti-matter may help better define time?

4) Many threads about how "time doesn't exist" (only a meaningless, perceived medium of exchange, sort of like money, existing only in our reference frame)

5) If you believe in "Many Worlds", maybe all the time paradoxes don't exist, which would perhaps imply that time doesn't exist?