In one minute

Christopher Fewster works on worldline quantum inequalities, lower bounds on the averaged energy density of a quantum field along an observer's worldline. They matter because a quantum field's energy density at a single point has no lower bound. For a linear scalar field in any globally hyperbolic spacetime, he proves an inequality on the normal ordered energy density for any smooth timelike trajectory, any smooth compactly supported weight and any Hadamard state. This generalises an earlier result for static trajectories in static spacetimes. The argument is made rigorous with microlocal analysis and the microlocal spectral condition for Hadamard states, with a compact form given for stationary trajectories.

A general worldline quantum inequality