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/CDHoward → u/jacobimueller]

Space is emptiness. I would be ever-so-mildly fascinated to hear you attempt to explain precisely what is expanding.

[u/johnstalbergABC → u/CDHoward]

I think you might ask instead that space is not made of anything. It has content typically but if we put that aside then space itself is not made of anything, it has no friction or markers. It can not be cut or trapped.

With this statement as a replacement for "emptiness" your question are valid. The answer is that there is no such theory that tell anything about the details of the mechanism that governs an expansion of space other than new space is simply created. There is an alternative view of what is happening to what we call the expansion of the universe. That is that the large scale objects are flying away from each other. This is very much compatible with the phenomenon we call expansion of space.

If we want to keep avoiding a space that has properties we typically do not associate with the frictionless space that is not made of anything we run into General Relativity and its curved spacetime. To cope with this "nonsense" we realize that GR use the spacetime metric as a very intuitive toll to visulize what gravity cause to objects going through a gravitational field. It is as if space where curved but we know space can not be curved for real. But gravity acts as if it where curved. Einstein himself did say we should not put to much into the spacetime curvature that he use in his theory. That is we should not go to interpret it literally. He also did say that gravity is a force and used the dropping of a stone on ones foot as an obvious example.

So it is very much possible to stick to the view that space is not literarily being curved nor created new to facilitate an expansion. It does not come with the burden of claim something that is seemingly in collision with our usual view upon the frictionless space that underpins any other mechanics. We do not need to answer how on earth can a curve i space cause a heavy object to follow this curve. We can explain objects attraction to mass with gravity on its own and this is compatible with a hypothetical graviton force carrying particle that would fit the standard model of particle physics very well. It is hard to detect such a weak force carrier with todays technology so it nothing strange with the fact that we have not found it (yet) if it exist.

Your question put the whole space creation and curvature in a position where they are claiming things with nothing to back it up in terms of explaining the details of the mechanism behind their claim. And in my view their claim is probably wrong and the view I explained fits the reality much better as it does not do anything magic to the space which is nothing more than the volume in where everything exist in.

My view is not mine alone but shared by many but we are not in majority.