6 research outputs found
The energy-momentum tensor,the trace identity and the Casimir effect
The trace identity associated with the scale transformation x^\mu\tox'{}^\mu
= e^{-\rho}x^\mu on the Lagrangian density for the noninteracting
electromagnetic field in the covariant gauge is shown to be violated on a
single plate on which the Dirichlet boundary condition is imposed.It is however respected in free space,i.e. in the absence of
the plate; these results reinforce our assertions in an earlier paper where the
same exercise was carried out using the Lagrangian density for the
free,massive,real scalar field in 2 + 1 dimensions.Comment: 22 page
Quantum time machine
The continuation of Misner space into the Euclidean region is seen to imply
the topological restriction that the period of the closed spatial direction
becomes time-dependent. This restriction results in a modified Lorentzian
Misner space in which the renormalized stress-energy tensor for quantized
complex massless scalar fields becomes regular everywhere, even on the
chronology horizon. A quantum-mechanically stable time machine with just the
sub-microscopic size may then be constructed out of the modified Misner space,
for which the semiclassical Hawking's chronology protection conjecture is no
longer an obstruction.Comment: 6 pages, RevTe