
 PlanetMath: Einstein field equations 
  The Einstein Field Equations are a system of second order coupled nonlinear partial differential equations containing over one thousand terms when written out explicitly. 
  Crossreferences: ricci scalar, Ricci tensor, Einstein tensor, densities, mass, information, tensor, constant, representation, terms, partial differential equations, second order 
  This is version 2 of Einstein field equations, born on 20050216, modified 20050216. 
 planetmath.org /encyclopedia/EinsteinFieldEquations.html (106 words) 
