In this film Stephen Hawking, James Hartle and Thomas Hertog explain their model of the early universe: The No Boundary Proposal. In the 1960's and 70's Hawking and Penrose showed that according to classical general relativity, given some minimal assumptions the origin of an expanding universe is a singularity: a point of infinite density and spacetime curvature. But this and other singularity theorems do not take into account the strange world of quantum mechanics. So in the 1980's Hawking and collaborators started to build a model of the big bang that included quantum effects.The result is the No Boundary Proposal, a model that may be able to explain some of the deepest mysteries of the cosmos such as, is there a multiverse? how is there an arrow of time and what really happened a the big bang? This is the fifth in a series of films exploring competing models of the early universe.—Skydivephil

In my doctoral thesis I showed that, according to Einstein's theory of relativity, the universe must have had a beginning. But the theory of relativity did not say how the universe had begun. Since then, a key focus of my research has been to better understand the origin of the universe. I am pleased to present a new film which explains the model I developed over the years, initially with James Hartle and then later with Thomas Hertog and others. In "Before the Big Bang 5: The No Boundary Proposal", Jim, Thomas and I guide you through our No Boundary Proposal for the quantum origin of the universe and reveal how it can explain some of the universe's deepest mysteries. The film is free to view and part of a series developed by Youtuber skydivephil to explore competing models of the early universe. We hope you share and enjoy.—Stephen Hawking