  We consider Unruh effect as an origin for Schwarzschild black hole entropy
thus implying unitarian evolution of gravity. We simulate the black hole by set
of Unruh horizons and estimate total entropy of the system. Dependence on mass
and spin of the emitted particles is taken into account. The obtained results
may be easily extended to any other intrinsic degrees of freedom of the
particles. Unruh effect contribution to Schwarzschild black hole entropy is
presented in exact analytical form.
