Zbigniew Haba

Is the quantum Universe Euclidean?

I review various ways to make field theory Euclidean: as a technical tool or as a dynamical outcome. Then, the problem with the Big Bang in quantum field theory will be discussed. Gibbons-Hartle-Hawking suggestion of a passage at the Big Bang from the Lorentzian signature to the Euclidean one will be explained. A simple model how this can happen will be presented. The theoretical virtues of an Euclidean origin of the universe will be advocated.