  We present a novel approach for setting initial conditions on the mode
functions of the Mukhanov Sazaki equation. These conditions are motivated by
minimisation of the renormalised stress-energy tensor, and are valid for
setting a vacuum state even in a context where the spacetime is changing
rapidly. Moreover, these alternative conditions are potentially observationally
distinguishable. We apply this to the kinetically dominated universe, and
compare with the more traditional approach.

General Relativity and Quantum Cosmology;Cosmology and Nongalactic Astrophysics