ExtremeQuality1682 OP t1_ja4cwx1 wrote
Reply to comment by cshaiku in Eli5 Help, please my brain hurts. If there is an expanding ring of light from the big bang, what is outside it? by ExtremeQuality1682
Someone said below it's different, it's an expansion which is (distance/time)/distance. Which would make everything kinda make sense but I'm awaiting a better explanation of that cause my brain can't grasp it. Is there time outside the ring, or if that explanation is true, there is not distance but only time?
Frednotbob t1_ja4k3j0 wrote
It's more like, there is neither without the other. You can't move in space without moving in time, and vice versa.
So, my slightly-headache-inducing answer: if the universe is infinite in size, then the ring is traveling through space-time just like we are. If space is finite, then the ring just hasn't reached the 'boundary' of whatever spacetime object we're contained in (what happens when it gets there is a question I'll happily leave to philosophers and quantum physicists).
In either case, there must be space for the ring to occupy while it travels, which necessitates the existence of time outside the ring.
Junker-king t1_ja4umjz wrote
Wonderful explanation, especially the very last part! Summarized very succinctly!
Viewing a single comment thread. View all comments