PARTICLE-LIKE DESCRIPTION FOR FRW COSMOLOGIES

We show that the dynamical behavior of the scale factor in FRW cosmolo gies with equation of state p = (gamma - 1)rho is formally equivalent to a classical particle under the action of a homogeneous potential V( q) = alpha q(n), where alpha and n are constants. The relations gamma( n) and epsilon(E, n), where epsilon is the curvature parameter and E i s the total energy of the test particle, are established. It is shown that the same approach can be generalized to include a nonvanishing co smological constant as well as to describe viscous models. A compariso n is made between the Lagrangian and general relativistic possibilitie s.