Gravity is a fundamental theory of physics, but so weak, that we still know very little about it. A new exciting development is that the Laser Interferometer Gravitational-Wave Observatory (LIGO) can now measure the effects when massive black holes collide in the Universe. This has stimulated many new and interesting studies of gravitational interactions. I will in this talk discuss recent computational advances and discuss how to derive results for observables in general relativity from amplitudes.