This week we interview the internationally renowned cosmologist Thomas Hertog, who for many years was a close collaborator and mentee of the late Stephen Hawking. His book, On the Origin of Time: Stephen Hawking’s Final Theory, was published by Bantam in April 2023. Hertog currently serves as professor of theoretical physics at Belgium’s University of Leuven, where he studies the quantum nature of the big bang. Thomas Hertog was interviewed by fellow biographer and BIO member John “Jack” Farrell.