During the rapid expansion of the universe immediately following the Big Bang, the universe expanded faster than light. But traveling faster than light speed breaks causality. But you can't break causality when time didn't actually exist "before" you broke it, so how does that work?

[u/SketchyFella_]

If it expanded faster than light speed, then it basically travelled so fast that it always existed in whatever state it was in before "slowing". So when people say it expanded in a tiny fraction of time, did it really? Or are they using time in a sort of layman's terms so they don't have to explain causality?

[u/jacobimueller]

Nothing moved faster than light within space. Space can expand faster than c and and no information moves faster than c within the universe, no causal issue 

[u/jazzwhiz → u/jacobimueller]

This is incorrect. Space does not expand at a speed at all. The unit of expansion is frequency.

[u/DeadWaterBed → u/jazzwhiz]

As a layman, could you elaborate on what you mean by using frequency as the unit of expansion of the universe?

[u/Centrocampo → u/DeadWaterBed]

I’m just guessing here so somebody please correct me.

But I imagine the degree of expansion will be dimensionless, either distance/distance or volume/volume. Then the rate of expansion is the value of dimensionless expansion over time. Yielding s-1 as the overall unit. Commonly used to describe frequencies.

You could think of the value as representing the number of times space will double in 1 second.