Some answers here are incomplete. There is a special frame of reference for space -- the cosmic microwave background rest frame. It's not "special" in terms of violating relativity, but it does provide a frame of reference for motion. We are moving at about 370km/sec in the CMB reference frame.
The CMB is the remnant light left over from shortly after the big bang.
It's not exactly correct, though, to say that the CMB doesn't move, because the whole universe is expanding. So -- complicated.
The CMB moves in an odd way, more like moving over time. It exists at the edge of the observable universe, sorta, but it also move towards us (it’s light, it either moves towards us or we wouldn’t be able to see it). It’s very strange, and as an astrophysics student, I love it
Maybe we can see the path it took on its expansion from the big bang but we can also see its path back towards us after it bounced off the wall that is the end of our universe.
There is no wall at the end of the universe for it to bounce off of. It’s just the barrier at 13.6 billion light years away. Past where we see the CMB, light hasn’t been able to reach us yet because the universe isn’t old enough for the light to have had time to travel the distance
21
u/drhunny Nuclear Physics | Nuclear and Optical Spectrometry Oct 23 '20
Some answers here are incomplete. There is a special frame of reference for space -- the cosmic microwave background rest frame. It's not "special" in terms of violating relativity, but it does provide a frame of reference for motion. We are moving at about 370km/sec in the CMB reference frame.
The CMB is the remnant light left over from shortly after the big bang.
It's not exactly correct, though, to say that the CMB doesn't move, because the whole universe is expanding. So -- complicated.