Cosmology
posted by qwerty .
The equation describing the geometry and massenergy distribution of a homogeneous and isotropic universe is known as:
 The Einstein Equation
 The Friedmann Equation
 The RobertsonWalker Equation
 The Hubble Equation

None of the above. Four have gotten into the act.
http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric 
The Friedmann Equation