Solution

ID: past-exam-of-the-general-relativity-course-of-the-university-of-oxford/2022/4/a/solution

For the hypothetical Hubble flow, Hubble's law gives , where and is the Hubble constant. The accompanying constants sheet is not present in the supplied PDF, so retain its dependence explicitly. Taking as an illustrative input, and using one million parsecs equal to ,
A year of days contains . Therefore
Equivalently, gives . This is a counterfactual recession rate for independently comoving bodies, rather than a prediction for the actual Earth-Moon orbit.

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