What is the acceleration scale?
a0 = 1.2 x 10-10 m s-2, i.e., about one Angstrom per second per second. This is one part in 1011 of what we feel on the surface of the earth. The precise value depends on the distance scale to galaxies, so perhaps it would be better to say a0 = 1.2 x 10-10 m s-2 h752, where h = H0/75 is the Hubble Constant (the expansion rate of the universe) in units of H0 = 75 km s-1 Mpc-1. (Currently, most measurements report values in the neighborhood of H0 = 72 km s-1 Mpc-1.
