# Does the universe expand at the same rate everywhere in the universe?

Specifically, I am wondering if some areas of the universe expand faster than other areas and whether the faster expanding areas diffuse the expansion through the slower expanding areas or does the expansion occur at a uniform rate throughout the entire universe.

What's outside the observable Universe, we can't say anything about, but averaged over large enough scales ($\gtrsim$ a billion lightyears), it does indeed seem to be expanding uniformly.
• @mick: The value of the Hubble parameter $H_0$ is an average of all of the Universe, since it's calculated on the basis of several observables in all directions, and at various distances. $H_0$ does not describe the expansion rate in different regions of the Universe, it describes the overall expansion rate. Locally, galaxies may recede from each other faster or slower than 68 km/s/Mpc, but the term $H_0$ describes the average expansion rate at distances so large that peculiar velocities can be neglected (i.e. velocities due to local kinematics like two galaxies orbiting each other). – pela Sep 5 '15 at 19:53
• For instance, within the Milky Way space doesn't expand. But we wouldn't say that $H_0=0$ in the Milky Way. – pela Sep 5 '15 at 19:53