Joe Rosen is a theoretical physicist with particular interest in symmetry considerations, high-energy physics, cosmology, space-time and the quantum, and the foundations of physics. He was for many years a member of the School of Physics and Astronomy of Tel Aviv University and also served as chair of the Department of Physics and Astronomy of the University of Central Arkansas. He has authored or edited eleven books, and many of his publications have dealt with various aspects of symmetry in physics and in science. His most recent book is Lawless Universe: Science and the Hunt for Reality. Now semi-retired from academe, Joe Rosen is involved in research, writing, and physics teaching as Adjunct Professor at The George Washington University.
As a unique phenomenon, the Universe is lawless. In order to try to make sense of the origin and properties of the Universe, physicists revoke its uniqueness by making the Universe a member of ensembles of universes. I describe five kinds (with variations) of other universes that serve that purpose: bubbles, cyclic universe, black-hole babies, other babies, and many worlds.