
 Scale factor (Universe)  Wikipedia, the free encyclopedia 
  The scale factor, parameter of FriedmannLemaĆ®treRobertsonWalker model, is a function of time which represents the relative expansion of the universe. 
  The evolution of the scale factor is a dynamical question, determined by the equations of general relativity, which are presented in the case of a locally isotropic, locally homogeneous universe by the Friedmann equations. 
  The scale factor could, in principle, have units of length or be dimensionless. 
 en.wikipedia.org /wiki/Scale_factor_(Universe) (192 words) 
