"Professor Max Tegmark of MIT has incorporated the river model in his
General relativity teaching MIT Course 8.033, Schwarzschild metric &
black holes

A natural interpretation of equation (2) (Hamilton 2004) is that space
is flowing radially inward [...] and that particles can travel through
this moving space according to the laws of special relativity [...]
This is analogous to the FRW coordinates, where the "river" of space
was expanding rather than flowing."

http://en.wikipedia.org/wiki/User_ta...fcva/archive_2

Double-A