Einstein's general theory of relativity describes gravity in terms of the curvature of space and time. This theory has been very successful in describing a wide range of gravitational phenomena. Surprisingly, it has recently been shown that general relativity can describe other areas of physics as well, including aspects of particle physics and condensed matter physics. This is a result of the gauge/gravity duality that has emerged from string theory. I will explain this remarkable development and show how general relativity reproduces properties of QCD and superconductivity.