James hartle gravity pdf

Hawking state, named after James Hartle and Stephen Hawking, is a proposal concerning the james hartle gravity pdf of the universe prior to the Planck epoch. Hartle and Hawking suggest that if we could travel backward in time toward the beginning of the universe, we would note that quite near what might have otherwise been the beginning, time gives way to space such that at first there is only space and no time.

Big Bang, the concept of a beginning of the universe is meaningless. Hawking proposal, the universe has no origin as we would understand it: the universe was a singularity in both space and time, pre-Big Bang.

Hawking state is the wave function of the Universe—a notion meant to figure out how the Universe started—that is calculated from Feynman’s path integral. More precisely, it is a hypothetical vector in the Hilbert space of a theory of quantum gravity that describes this wave function. Universe, where D is the spacetime dimension. Hawking state is the path integral over all D-dimensional geometries that have the required induced metric on their boundary.