http://en.wikipedia.org/wiki/Gravitational_constant
"The accuracy of the measured value of {G} \ has increased only modestly since the original experiment of Cavendish. {G} \ is quite difficult to measure, as gravity is much weaker than other fundamental forces, and an experimental apparatus cannot be separated from the gravitational influence of other bodies. Furthermore, gravity has no established relation to other fundamental forces, so it does not appear possible to measure it indirectly. A recent review (Gillies, 1997) shows that published values of {G} \ have varied rather broadly,
and some recent measurements of high precision are, in fact, mutually exclusive."
Ah ha! The gravitational
constant might not be a constant after all.
I bet it has a generally increasing trend. Though another thing that would be interesting ... what if we were inside a black hole that evaporated instead? Would we appear as energy in a different universe?