What would happen if the area a galaxy occupied spanned the influence of gravity and the Hubble flow?
This reference to the "cosmic Hubble rate" in my last post isn't quite accurate. The cosmic Hubble rate is the AVERAGE expansion rate, so it would be measured as such only in regions which are exactly at average matter density. The expansion rate obviously would be faster than this average inside large voids. Chernin calculates that a theoretically empty void (no void is every fully empty) currently would experience an additional 16 km/s per Mpc of expansion, compared to the cosmic Hubble rate.Hi Wolram,
In my opinion, the best way to think of this subject is that space is intrinsically experiencing an underlying expansion force EVERYWHERE at the cosmic Hubble rate. However, in regions of matter overdensity, the local gravitational force is stronger than the Hubble expansion force and dominates it. In effect, the Hubble expansion force is mathematically subtracted from the gravitational force.