- #1
supernova88
- 13
- 1
I'm trying to reconcile the fact that regions of the universe are expanding faster than light, and that as a consequence the observable universe is far more than 13.7 billion light years across. I trust these are the facts, but I'm stuck figuring out how we know these to be true. I feel like, going off Hubble's Law of roughly 70 km/s/Mpc, we can figure out how fast distant regions of space are expanding as long as we know just how distant they are. However, to find how distant some galaxy at the edge of the known universe is wouldn't we need to know how fast it is receding in the first place. In that way it comes off to me like a chicken-egg scenario, where we need to know velocity to find distance but we need to know distance to find velocity. I'm just hoping someone could smooth this out for me because I'd really like to know how some of these amazing conclusions resulted in the first place. (Also please note I am more of a conceptual physics enthusiast, my math skills are not necessarily astrophysicist-grade, so if you throw a bunch of equations at me, or if you don't explain them thoroughly, I'm probably not going to get it. Thanks.)