I'm understanding that the Path Integral formulation of quantum mechanics includes every possibility - every possible trajectory of a particle in QM, and every possible field configuration in QFT. So I'm wondering, if we consider the Path Integrals in both QM and QFT, either separately or in combination somehow, then do the possibilities in the path integrals include "paths" that branch off into many-particle configurations that interact with each other... where some possibilities form structures like atoms, planets and people? If so, I'm thinking that only one wavefunction is needed to describe the universe, and it may be arbitrary where the start and end points/states are in calculations. I wonder how close these ideas are to the idea of the universal wavefunction and the many worlds interpretation. Thanks.