What was expansion speed at the time of the CMB?

In summary, the expansion speed at the time of the Cosmic Microwave Background (CMB) radiation, approximately 380,000 years after the Big Bang, was significantly slower than the current rate of expansion. During this epoch, the universe was transitioning from a hot, dense state to a cooler, more transparent one, allowing photons to travel freely. The expansion rate, characterized by the Hubble parameter, was lower than today due to the dominance of radiation and matter in the early universe, leading to a different dynamic in cosmic expansion compared to present times.
  • #1
sjordannc
1
0
To be clear, I'm looking for the speed at which points in space were moving apart from one another in the universe as it existed 370000 years after the big bang, not the Hubble parameter (expansion rate) derived from our current distance within our current time.

Thanks in advance!
 
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  • #2
Why are you interested in specific 370000 year after bigbang and not current Hubble parameter ?
 
  • #3
sjordannc said:
the speed at which points in space were moving apart from one another
There is no such thing. The "speed" depends on how far apart the points are.

If you want to know the Hubble parameter at the time you give, that is a single meaningful number, but it's not a speed.
 
  • #4
sjordannc said:
I'm looking for the speed at which points in space were moving apart from one another
The problem with this is that Hubble's law says that the recession speed is proportional to distance. So we can tell you the Hubble parameter back then, or we can tell you the recession speed of points a specific distance apart, but there is no single recession velocity. Not then and not now.
 

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