Celestial Holography

The quest for a complete theory of quantum gravity that describes the real world remains a fundamental open problem in modern physics. Holography -- the proposal that quantum theories of gravity have equivalent formulations in terms of ordinary non-gravitational theories in fewer spacetime dimensions -- has emerged at the forefront of solutions to the problem of quantum gravity. Despite impressive insight gained from concrete calculations in AdS/CFT, the nature of quantum gravity in asymptotically flat and de Sitter spacetimes has generally remained murky when viewed through the lens of holography. In this talk, I will present celestial holography: a novel application of the holographic principle to asymptotically flat spacetimes. The talk will review the current status of the subject and highlight the insight gained to date into the prospects of holography beyond AdS/CFT as well as into general features of real world gravity.