  We consider the gravitational collapse of a spherically symmetric ball of
dust in the general relativistic weak gravity regime. The velocity of the
matter as viewed by external observers is compared to the velocity gauged by
local observers. While the comparison in the case of very strong gravity is
seen to follow the pattern familiar from studies of test particles falling
towards a concentrated mass, the case of weak gravity is very different. The
velocity of the dust that is witnessed by external observers is derived for the
critically open case and is seen to differ markedly from the expectations based
upon Newtonian gravity theory. Viewed as an idealized model for a cluster of
galaxies, we find that with the general relativistic velocity expression, the
higher-than-expected constituent velocities observed can be readily correlated
with the solely baryonic measure of the mass, obviating the need to introduce
extraneous dark matter. Hitherto unexplained and subject-to-reinterpretation
astrophysical phenomena could also be considered within this context. It is
suggested that an attempt be made to formulate an experimental design at
smaller scales simulating or realizing a collapse with the aim of implementing
a new test of general relativity.
