How can I calculate the distance of a point from Earth now vs 13 billion years ago? The excerpt below claims it is 8 times further now. Can someone provide relevant equations ?
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If the remote object is not moving other than due to the expansion of the universe (i.e. at rest in co-moving coordinates) and distance $d_0$ today then the proper distance at time t is $d(t)=a(t)d_0$ where $a(t)$ is the scale factor. If you know the redshift $z$ then the distance is $d_0/(1+z)$. – Anders Sandberg Mar 06 '20 at 13:00
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@AndersSandberg hello, I was wondering if you could look at a question I asked yesterday. “A question about supernova explosions (redshift decay curves) Thanks – Bill Alsept Mar 06 '20 at 15:55