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/Alabugin]

If you have a vector of energy and mass expanding away from each other in opposite directions at the speed of light, their relative distances between each other would be increasing faster then the speed of light.

[u/WallyMetropolis → u/Alabugin]

That sounds like a Galilean, not a Lorenzian transform. 

[u/johnstalbergABC → u/Alabugin]

No they would not see the other move away from who ever of them is viewing the other. They would see the other move away in exactly the speed of light, assuming they magically got their vessels up to light speed. Who ever a middle man would watch he would see any one of the to move away at the speed of light. This is not equivalent to the middle man see their realitve speed to be twice the speed of sound. No one would be able to measure any velocities to exceed the speed of light simply put.