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Angular momentum conservation for uniformly expanding flows
Angular momentum has recently been defined as a surface integral involving an
axial vector and a twist 1-form, which measures the twisting around of
space-time due to a rotating mass. The axial vector is chosen to be a
transverse, divergence-free, coordinate vector, which is compatible with any
initial choice of axis and integral curves. Then a conservation equation
expresses rate of change of angular momentum along a uniformly expanding flow
as a surface integral of angular momentum densities, with the same form as the
standard equation for an axial Killing vector, apart from the inclusion of an
effective energy tensor for gravitational radiation.Comment: 5 revtex4 pages, 3 eps figure
How much negative energy does a wormhole need?
It is known that traversible wormholes require negative energy density. We
here argue how much negative energy is needed for wormholes, using a local
analysis which does not assume any symmetry. and in particular allows dynamic
(non-stationary) but non-degenerate wormholes. We find that wormholes require
two constraints on the energy density, given by two independent components of
the Einstein equation.Comment: 6 pages, no figure
Disgorgement of Defendant\u27s Gains from Opportunistic Breach of Contract: Its Fit in Rhode Island
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