Does the speed of universal expansion lead to time going backwards?

Question

After reading that time stops at the speed of light and at event horizons I wondered if when the speed of light is exceeded does time loop backwards ...

The thought struck me too that the term space-expansion might also imply the space between subatomic particles ...

It seems you're assuming that if time goes slow enough it goes backwards, but I don't see how it follows — Kyle Kanos, Nov 10 '19 at 23:43
To reopen this post (v5) consider for starters to only ask 1 subquestion per post. — Qmechanic, Nov 13 '19 at 19:13

score 4 · Accepted Answer · answered Nov 10 '19 at 23:55

4

The question you ask isn't well-posed (whose time is "flowing backwards?") but there's still a clear answer: no.

This is because the expansion of space is unconstrained by the speed of light. No physical thing can travel faster than light, but the universe can still expand faster than light because it's not physical. Since the expansion of the universe isn't physical, we can also say that the usual special relativity effects such as time dilation don't apply.

answered Nov 10 '19 at 23:55

Allure

20,501

@Wookie not saying the expansion isn't physical, but rather that it isn't a physical object that's expanding. Space itself is expanding; there's nothing made of atoms that's expanding. – Allure Nov 12 '19 at 10:37
@Wookie The cosmological models that predict expansion apply on large scales only. They assume a uniform distribution of mass & energy everywhere and do not consider local objects like atoms, or even planets & galaxies. Small-scale objects may not be participating in the expansion, due to local effects. – D. Halsey Nov 13 '19 at 19:06

Does the speed of universal expansion lead to time going backwards?

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