9309834 Laguna Gravitational Physics is one of the areas in which supercomputer technology has imprinted its most dramatic effects. One and two dimensional numerical simulations of strongly gravitating systems and inhomogeneous spacetimes can be performed with an extremely high degree of resolution, and modeling of three dimensional systems is finally within reach. Three dimensional studies of general relativistic systems require, even with existing supercomputers, codes capable of efficiently utilizing computer memory and speed. The challenge is then an intensive pursuit of computational optimality as a function of physical information obtained. Two principal areas will be investigated: 1. ` ` Numerical Relativity and Black Hole Collisions: Work will be conducted to obtain initial data using York's original conformal method. The three dimensional cosmological code developed by Kurki Suonio, Laguna and Matzner is being adapted to compute black hole evolution. This code will serve as an arena to investigate implementations of boundary conditions, gauge conditions and evolution schemes. Numerical evolution of an inhomogeneous, planar, vacuum cosmology using Ashtekar's new variables will be studied. !` 2. ` ` Inhomogeneous Cosmologies and Inflation: The Kurki Suonio/Laguna/Matzner cosmological code will be used to investigate the onset of inflation under inhomogeneous matter sources. The COBE satellite has provided observations of cosmic background radiation anisotropies. Collisionless matter and eventually hydrodynamical sources will be implemented into the Kurki Suonio/Laguna/Matzner code to inves tigate anisotropic effects in the cosmic background radiation from the propagation of microwave photons through evolving density inhomogeneities (Rees Sciama effect). !` ***
