General relativity encodes gravity in the very geometry of space-time. Its most spectacular predictions such as the big bang and black holes can be traced back to this encoding. But general relativity is incomplete because it ignores quantum physics. I will describe loop quantum gravity, a leading approach to unify the the two theories, where the interplay between gravity and geometry is elevated to the quantum level. Here, quantum geometry displays a fundamental discreteness. The familiar space-time continuum arises as a coarse grained approximation. Under normal conditions quantum effects of geometry are negligible but they dominate physics near the Big Bang and inside black holes. The talk will be addressed to non-experts and its goal is to provide a few glimpses of this world in which gravity, geometry and the quantum merge.

ANL Physics Division Colloquium Schedule