The big bang and quantum cosmology.

The notion of the origin of the universe in a big bang is based on the mathematical models constructed from Einstein's field equations of general relativity. however, these equations are classical in nature and they break down when the characteristic radius of curvature of the universe is smaller than ~10 −33 cm; the behaviour of the universe can then be described by quantum physics. the question of the big bang origin of the universe belongs therefore to quantum gravity. This article describes an approach to quantum gravity that throws light on this important question.