PHENOMENOLOGY OF THE GOWDY UNIVERSE ON T-3XR

Numerical studies of the plane symmetric, vacuum Gowdy universe on T(3 )xR yield strong support for the conjectured asymptotically velocity t erm dominated (AVTD) behavior of its evolution toward the singularity except, perhaps, at isolated spatial points. A generic solution is cha racterized by spiky features and apparent ''discontinuities'' in the w ave amplitudes. It is shown that the nonlinear terms in the wave equat ions drive the system generically to the ''small velocity'' AVTD regim e and that the spiky features are caused by the absence of these terms at isolated spatial points.