There are actually five:
Greg Bernhardt, who runs a discussion website called Physics Forums, did a pretty extensive interview about my life and work.
The mathematical physicist Bruce Bartlett interviewed Urs Schreiber and I about our blog with David Corfield, called The n-Category Café.
Helen Joyce, editor of Plus Magazine, interviewed me about two number systems I like: the quaternions and octonions.
A high-school student named David Morrison had to interview someone for an assignment, so he sent me some questions, which I answered.