The Fall 2012 quarter of the Modern Physics series concentrates on Einstein’s theory of gravity and geometry: the General Theory of Relativity. Beginning with the basic ideas of Riemannian and curved space, and Minkowski’s “space-time,” we learn about Einstein’s discovery of how gravity is really the curvature of space-time. We also cover the theory of black holes and their strangely paradoxical properties. The final weeks of the course develop the essential ideas of Big Bang cosmology.