Mark_Eichenlaub comments on Frugality and working from finite data - Less Wrong
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I think that was the point, but since the expansion is accelerating this was not always the case.
A and B are retreating faster than light now (in our reference frame), so the light they are emitting now will not reach each other.
However, the A and B are far apart, say 5 billion light years. 5 billion years ago A and B were receding more slowly - perhaps half the speed of light, so the light emitted 5 billion years ago from A is now reaching B. Hence, B currently sees light from A.
Five billion years in the future this will not be the case. Sometime in the next 5 billion years B will observe A to redshift all the way to zero and wink out.
Agreed. Thanks.