INSTANTONS AND GRAVITATION IN THEORY

Some problems related to using nonperturbative quantization methods in theories oi gauge fields and gravitation are studied. The unification of interactions is considered in the context of the geometric theory of gauge fields. The notion of vacuum in the unified interaction theor y and the role of instantons in the vacuum structure are considered. T he relation between the definitions of instantons and the energy-momen tum tensor of a gauge field and also the role played by the vacuum sol utions to the Einstein equations in the definition of vacuum for gauge Fields are demonstrated. The Schwarzschild solution, as well as the e ntire class of vacuum solutions to the Einstein equations, is a gravit ational instanton even though the signature of the space-time metric i s hyperbolic. Gravitation, including the Einstein version, is consider ed a special case of an interaction described by a non-Abelian gauge f ield.