Einstein in one sentence

This is a neat article by John Baez and Emory Bunn which discusses the geometrical meaning of Einstein’s equations. It includes this characterization of Einstein’s equations in one plain English sentence:

Given a small ball of freely falling test particles initially at rest with respect to each other, the rate at which it begins to shrink is proportional to its volume times: the energy density at the center of the ball, plus the pressure in the x direction at that point, plus the pressure in the y direction, plus the pressure in the z direction.