  The subject of this study is Quantum and Statistical Mechanics of the Early
Universe. In it a new approach to investigation of these two theories - density
matrix deformation - is proposed. The distinguishing feature of the proposed
approach as compared to the previous ones is the fact that here the density
matrix is subjected to deformation, rather than commutators or (that is the
same) Heisenberg's Algebra. The deformation is understood as an extension of a
particular theory by inclusion of one or several additional parameters in such
a way that the initial theory appears in the limiting transition. Some
consequences of this approach for unitarity problem in Early Universe,black
hole entropy, information paradox problem,for symmetry restoration in the
associated deformed field model with scalar field are proposed.
