Field Theory in Branching Spaces
P. I. Fomin, Yuri Shtanov · arXiv (Cornell University) · 2000
We consider a spacetime formed by several pieces having common timelike boundary. We establish boundary conditions for fields of various spin and derive the resulting laws of wave propagation through the common boundary, which turn out to be quite similar for fields of all spins. As an application, we consider the case of branching four-dimensional spacetime that may arise in the context of the theory of quantum creation of a closed universe on the background of a big mother universe. The theory developed can also be applied to brane-world models and to the superstring theory.