Gravitational spectral shift caused by Casimir stresses
  The linearized Einstein field equations with the renormalized stress tensor of a massless quantum scalar field as source are solved in the 4-dimensional spacetime near an infinite plane boundary. The motion of particles and light is investigated disclosing a variety of effects. For instance, it is shown that light rays initially parallel to the boundary do not bend. On the other hand, under the same initial conditions, particles will be affected by the presence of the quantum field, being accelerated toward the plane boundary or departing from it depending on the value of the curvature coupling parameter {\xi}. It is suggested that {\xi} can be set by measuring the spectral deviation of a light ray travelling perpendicularly to the boundary. 
V. A. De Lorenci, L. G. Gomes, and E. S. Moreira Jr
hep-th gr-qc