Propagation of jump discontinuities in relativistic cosmology

Henk van Elst, George F. R. Ellis, Bernd G. Schmidt
2000 Physical Review D, Particles and fields  
A recent dynamical formulation at derivative level ^3g for fluid spacetime geometries ( M, g, u), that employs the concept of evolution systems in first-order symmetric hyperbolic format, implies the existence in the Weyl curvature branch of a set of timelike characteristic 3-surfaces associated with propagation speed |v| = 12 relative to fluid-comoving observers. We show it is the physical role of the constraint equations to prevent realisation of jump discontinuities in the derivatives of the
more » ... derivatives of the related initial data so that Weyl curvature modes propagating along these 3-surfaces cannot be activated. In addition we introduce a new, illustrative first-order symmetric hyperbolic evolution system at derivative level ^2g for baryotropic perfect fluid cosmological models that are invariant under the transformations of an Abelian G_2 isometry group.
doi:10.1103/physrevd.62.104023 fatcat:5pn6cbr3tzgijpbrcltuc2qgge