Full Idea
The left-hand side of the general relativity equations descrbe the curvature of the universe, and the strength of gravitational forces acting on matter and radiation. The right-hand sides reflect the total density of all kinds of energy and matter.
Gist of Idea
General Relativity: the density of energy and matter determines curvature and gravity
Source
Lawrence M. Krauss (A Universe from Nothing [2012], 04)
Book Reference
Krauss,Lawrence M.: 'A Universe from Nothing' [Simon and Schuster 2012], p.57
A Reaction
I had assumed that the equations just described the geometry. In fact the matter determines the nature of the universe in which it exists. Presumably only things with mass get a vote.