Is all this work on string theory and multiple dimensions and extra universes still science? That's the question physicist Sean Carroll and writer John Horgan recently debated. Carroll, of the California Institute of Technology, also blogs regularly for Cosmic Variance, and he wrote out a detailed post explaining his position. Obviously, as a cosmologist who works full-time on these seemingly preposterous ideas, he is a bit biased. He's not the guy you'd expect to stop and say it isn't real science. But his piece on the subject does effectively explain why he and, one assumes, other theoretical physicists working on these problems think this way.