Averaged Null Energy Condition.
Abstract: The achronal averaged null energy condition (ANEC) is a sufficient
condition to rule out exotic spacetimes such as time machines and wormholes. We review how
achronal ANEC is used to prove such restrictions, and the status of the condition. We find
counterexamples to achronal ANEC using conformally coupled scalar test fields in a
conformally flat background. These examples involve ra... read morepid variation in the stress-energy
tensor in the vicinity of the geodesic under consideration, suggesting that averaging in
additional dimensions would yield a principle universally obeyed by quantum fields.
However, we further develop counterexamples to alternative transversely averaged energy
conditions. In order to arrive at a valid energy condition, we must then either restrict to
minimal coupling or to self consistent rather than arbitrary background metrics. We
construct a state as a candidate reference state for quantum difference inequalities, which
could then be used to prove ANEC in these conditions. The proposed recently massless vacuum
is defined for a region of spacetime which may be embedded in a manifold which for all
times prior to some recent Cauchy surface has vanishing potential energy. It is similar to
the standard in vacuum, with a modified spacetime taking the place of an asymptotically
distant massless region. This allows us to focus on the contribution of local terms to the
Thesis (Ph.D.)--Tufts University, 2013.
Submitted to the Dept. of Physics.
Advisor: Ken Olum.
Committee: Hugh Gallagher, Kryzstof Sliwa, Peggy Cebe, and Larry Ford.
Keyword: Physics.read less