I will review the cyclic model of the Universe, a model motivated both by M theory and by observations of cosmic acceleration in today's universe. The model is an alternative to cosmic inflation, providing a more economical explanation of the origin of large scale structure. The model also suggests a natural explanation of why today's cosmological constant is small and positive. I will review future observational probes which can in principle discriminate between the inflationary, and cyclic scenarios. The critical assumption behind the cyclic model is that a big crunch/big bang transition is possible. I will review a series of indications that this is indeed the case, when it is the M theory dimension which collapses and re-expands.