Emergent Spacetime in Quantum Theories of Gravity

Christian Wuthrich
Philosophy
UC San Diego

The nature of space and time are perennial and fruitful issues in philosophy, engaging deeply with other disciplines such as physics. Relativity was the last revolution in the physics of spacetime, the next one involves quantum theories of gravity, or quantum gravity. While approaches to quantum gravity are legion, and the field as a whole is very much in flux, one important suggestion is shared by almost all approaches: that space and time are not fundamental ingredients of the world, but somehow emerge from deeper, non-spatiotemporal physics. The idea that space or time are not real at the basic level would shatter our current conception of the universe, and hence of our place within it. This collaborative project endeavors to investigate these implications. This is the first such project by philosophers, showing how many central philosophical ideas must be rethought. Since the physics and the pertinent mathematical apparatus involved are unusually demanding, the project is divided into two main sub-projects, one focusing on string theory (headed by Nick Huggett) and the other on loop quantum gravity (led by Christian Wuthrich), thus covering the two main approaches to quantum gravity.