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How Big Was the Source of the Cosmic Microwave Background Radiation 13.7 Billion Years in the Past?

-- Richard | March 31, 2021

Question:

There currently could be a earth like planet with intelligent life 25 billion light years from us. They would detect the CMB from all directions 13.7 billion years in the past also.
How big was the source of the CMB 13.7 billion years in the past?

-- Richard

Answer:

I believe that this question has been answered on the Physics Stack Exchange. 13.7 years in the past the distance to the source of the CMB emission was about 42 million light years, or about 13 mega parsecs.

-- Jeff Mangum

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