I'm a theoretical physicist at Caltech in sunny California. Most of my career has been spent doing research on cosmology, field theory, and gravitation, looking at topics such as dark matter and dark energy, modified gravity, topological defects, extra dimensions, and violations of fundamental symmetries. These days my focus has shifted to more foundational questions, both in quantum mechanics (origin of probability, emergence of space and time) and statistical mechanics (entropy and the arrow of time, emergence and causation, dynamics of complexity), bringing a more philosophical dimension to my work. See my research page or annotated publications for more details. I also wrote a personal narrative as part of applying for a Guggenheim fellowship.

I've written a few books, both popular-level and textbook-level. My most recent is Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime. I've also done a few lecture courses for The Great Courses, and there is various video and audio evidence online of me talking about one thing or another, including a series on The Biggest Ideas in the Universe. I'm relatively active on Twitter. My podcast, Mindscape, features me conversing with smart people about interesting ideas in science, philosophy, culture, and the arts.