Max Tegmark, born in Sweden as Max Shapiro, is a cosmologist formerly at the University of Pennsylvania but now at the Massachusetts Institute of Technology as an Associate Professor.

He is one of the proponents of the quantum suicide thought-experiment, and has come up with a nice mathematical argument for the multiverse. The computational expression of a single random number between one and zero (with all its infinite decimals) is longer than the computational expression of the whole set of numbers that exist between 1 and 0, so it may be more informationally economical for reality to consist of infinite parallel universes instead of just one. The computer code for such a computation is only two lines long.

He has also been a strong critic of those who would infer a theory of consciousness from quantum effects, such as Roger Penrose and Stuart Hameroff.