Charles Radin is a professor at the University of Texas at Austin. He received a Ph.D. in physics at the University of Rochester. He was previously a postdoc under physicist Arthur Wightman and mathematicians Mark Kac and Richard Kadison. His work is published in both mathematics and physics journals, and includes experiments on granular matter coauthored with Harry Swinney. Lorenzo Sadun is Marian Harris Thornberry Centennial Professor at the University of Texas at Austin. He received his Ph.D. from UC Berkeley and was previously a postdoc at Caltech and NYU (Courant). He is the author of more than 100 papers and five books on mathematical physics and related fields. His research interests include aperiodic order (tiling dynamical systems, especially topological dynamics) and random graphs.