Comment on Roses
gandalf_der_12te@feddit.org 1 day agoactually cosmological redshift occurs not so much because a velocity difference between source and observer, but because space is expanding while the wave is in it, or so i was told. so the wave continuously gets stretched out, which causes it to redshift. calculating it that way gives slightly different results from normal doppler redshift, i think. so it does matter.
Draconic_NEO@mander.xyz 23 hours ago
They say relative velocity because from our relative perspective they do appear to be moving away from us. It also works when the object is stationary and you are moving towards it or away from it because from your relative position it’s the thing moving away from or towards you.
gandalf_der_12te@feddit.org 23 hours ago
hmm there might be two effects at work here at the same time.