[stanfordkid]

Is it really true that nothing would change if the Sun's mass was suddenly compacted by several orders of magnitude (into a point mass or black hole)?

This seems unintuitive to me. The sun is a million miles in diameter, so surely shrinking that to zero would lower the amount of gravitational force infinitesimally since the gravity is 1/distance^2 not linear. I would think the planets would sort of drift ever so slightly farther.

[voidmain]

For Newtonian gravity at least, the gravitational force everywhere outside a sphere or spherical shell is exactly the same as if it was a point mass (and everywhere inside a spherical shell it is zero). Not sure if it holds exactly for general relativity.