Abstract
Although quantum gravity is often described as empirically inaccessible, in fact astrophysics and cosmology teem with situations in which both gravitational and quantum-mechanical effects are relevant, and so we have abundant observational constraints on quantum gravity at energy levels low compared to the Planck scale. That evidence supports (to a variable degree) the description of quantum gravity as an effective field theory version of general relativity, breaking down at Planckian energies. I briefly present this theory, review its empirical support and its problems (including the cosmological constant problem) and consider the prospects for gaining empirical evidence for quantum gravity beyond the low-energy regime.
