Solving for the dynamics of the universe

A new method of solving the Einstein-Friedmann dynamical equations of a spatially homogeneous and isotropic universe is presented. The method is applicable when the equation of state of the material content assumes the form P = (gamma-1)rho, gamma = constant. The solution for the expansion factor is commonly given only for gamma = 0, 1, and 4/3 when the curvature index is K = +/-1. The proposed procedure is valid for general gamma and K and it allows for ease of derivation of the solutions. This alternative method is useful pedagogically to introduce basic cosmology. (C) 1999 American Association of Physics Teachers.