Showing papers by "Roger Penrose published in 1973"

A space‐time calculus based on pairs of null directions

Abstract: A formalism is presented for the treatment of space‐times, which is intermediate between a fully covariant approach and the spin‐coefficient method of Newman and Penrose. With the present formalism, a pair of null directions only, rather than an entire null tetrad, is singled out at each point. The concept of a spin‐ and boost‐weighted quantity is defined, the formalism operating entirely with such quantities. This entails the introduction of modified differentiation operators, one of which represents a natural extension of the definition of the operator ð which had been introduced earlier by Newman and Penrose. For suitable problems, the present formalism should lead to considerable simplifications over that achieved by the standard spin‐coefficient method.

Internal instability in a Reissner-Nordström black hole

Abstract: The question of the effect of asynumetries in gravitational collapse is investigated by considerations of test electromagnetic fields in an extended Reissner-Nordstrom background. It is found, with ths aid of computer calculations, that instabilities in the test field arise at the inner (Cauchy or anti-event) horizon, though not at the ouier (event) horizon. Thus it is reasonable to infer that in the full coupled Einstein-Maxwell theory the inner horizon will not survive as a non-singular bypersurface when asymmetric perturbations are present, but will instead become a space-time curvature singularity.