My current guess is the universe is infinite and the night sky is dark due to energy density, not amount of space.
I find both of those theories implausible. This is why. The universe currently expands too quickly for the big bang to be true. The expansion is too quick for a recycled big bang. Currently, it would spread into nothing and the idea that energy suddenly appeared out of nothing to create space-time is a joke. My current guess is that the density surrounding the current universe captures light creating the appearance of darkness and is also pulling it apart. I think this universe was seeded by placing energy in a spot and then putting a lot of space around that energy and will be sucked back in by the density surrounding it. Big Bang is weak and violates the conservation of energy law.
I would guess the dark backdrop will suck it all up at some point and then seed another universe. Anything sucking up light will suck up black holes. Black holes always stick to each other when they finally collide.
Einstein was playing and never got anywhere with it. We cannot exist inside a singularity. Energy density is too high for what we are. Light doesn't move. There is nothing to do because gravity locks everything down. Hawking has played with the idea some, but his border theory is the only useful stuff since it seems to explain the emissions from black holes better.
Einstein wasn't talking about time travel, he was talking about seeing the past and slowing your metabolism down to get deep into the future. You see, our perception of time is based on the speed electrons orbit our atomic nuclei. If we go really fast our electrons must orbit very slow and we don't age. It's not time travel, it's slowing down our bodies at the atomic level with high velocity. If you travel faster than light, which Einstein explained is impossible since your mass turns into light to get to light speed, then you could see past images as you would catch up to them.
I've never seen any plausible wormhole kind of thing.
Worm holes to date are nothing but fiction. Digital design has improved that pictures must be assumed fake until proven otherwise. Spin clouds are all manufactured. Space is so huge it appears to stand still despite extremely high velocities.
cpg: If the Universe is already infinite, how can it be expanding and who says it's expanding so fast it could not have been from Big Bang? Also, how does Big Bang violate conservation?
The Big Bang was itself a singularity. I read a theory that this occurs when black holes gobble so much energy and mass it "drops off" like a globulator into - NOTHING - where another Universe is created by a Big Bang.
Black Holes of course are singularities and what bothers me recently is the idea that since most galaxies have one at their center, won't each galaxy be swallowed eventually?
The other mind bender was suggested by killer is that expansion will eventually place galaxies so far away their light will never reach here and, save the Milky Way, no galaxies will be seen.
The "shortcuts" are wormholes.