22 research outputs found
The constraint algebra of quantum gravity in the loop representation
We study the algebra of constraints of quantum gravity in the loop
representation based on Ashtekar's new variables. We show by direct computation
that the quantum commutator algebra reproduces the classical Poisson bracket
one, in the limit in which regulators are removed. The calculation illustrates
the use of several computational techniques for the loop representation.Comment: 18 pages, Revtex, no figures, CGPG-94/4-
Tetrads in Geometrodynamics
A new tetrad is introduced within the framework of geometrodynamics for
non-null electromagnetic fields. This tetrad diagonalizes the electromagnetic
stress-energy tensor and allows for maximum simplification of the expression of
the electromagnetic field. The Einstein-Maxwell equations will also be
simplified
Nonexistence of conformally flat slices of the Kerr spacetime
Initial data for black hole collisions are commonly generated using the
Bowen-York approach based on conformally flat 3-geometries. The standard
(constant Boyer-Lindquist time) spatial slices of the Kerr spacetime are not
conformally flat, so that use of the Bowen-York approach is limited in dealing
with rotating holes. We investigate here whether there exist foliations of the
Kerr spacetime that are conformally flat. We limit our considerations to
foliations that are axisymmetric and that smoothly reduce in the Schwarzschild
limit to slices of constant Schwarzschild time. With these restrictions, we
show that no conformally flat slices can exist.Comment: 5 LaTeX pages; no figures; to be submitted to Phys. Rev.