Dynamical Backreaction in Robertson-Walker Spacetime

Understand

The treatment of a quantized field in a curved spacetime requires the study of backreaction of the field on the spacetime via the semiclassical Einstein equation.

• We consider a free scalar field in spatially flat Robertson-Walker space time.
• We require the state of the field to allow for a renormalized semiclassical stress tensor.
• We calculate the sigularities of the stress tensor restricted to equal times in agreement with the usual renormalization prescription for Hadamard states to perform an explicit renormalization.