Wednesday, December 23, 2015

Hubble-collapse

can you show that the density inside a sphere which contracts according to a Hubble-law $\upsilon(r)\propto -r$ remains homogeneous? what's the relation between density $\rho$ and time $t$?

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1 comment:

1. I'll leave the answer as an exercise for the readers, but offer the following related comment: The Robertson-Walker metric contains no physics. A homogeneous and isotropic universe must have this metric, which is completely independent of any physics.