Space-time symmetries are a crucial ingredient of any theoretical model in physics. Unlike internal symmetries, which may or may not be gauged and/or spontaneously broken, space-time symmetries do not admit any ambiguity: they are gauged by gravity, and any conceivable physical system (other than the vacuum) is bound to break at least some of them. Motivated by this observation, I will discuss how to couple gravity with the Goldstone fields (that non-linearly realize spontaneously broken space-time symmetries) by weakly gauging the Poincare symmetry group. As an illustrative example of the power of these techniques I will build an effective action that describes spinning objects coupled to gravity. Furthermore, I will discuss how this relates to effective field theories pertinent to cosmology such as “the effective field theory of inflation” and “solid inflation.”
