  Vacuum polarization of the quantized massive fields in Bianchi type I
spacetime is investigated from the point of view of the adiabatic approximation
and the Schwinger-DeWitt method. It is shown that both approaches give the same
results that can be used in construction of the trace of the stress-energy
tensor of the conformally coupled fields. The stress-energy tensor is
calculated in the Bianchi type I spacetime and the back reaction of the
quantized fields upon the Kasner geometry is studied. A special emphasis is put
on the problem of isotropization, studied with the aid of the directional
Hubble parameters. Similarities with the quantum corrected interior of the
Schwarzschild black hole is briefly discussed.
