A Smooth Horizon without a Smooth Horizon

The nature of the black hole horizon and whether spacetime ends there has been a puzzling question ever since the discovery of the first black hole solutions of Einstein's general relativity. Principle of equivalence suggests that the horizon should be smoothly traversible. Smoothness of the horizon is also directly responsible for the thermal properties of black holes discovered by Hawking. But a smooth horizon, at very long time scales, leads to the breakdown of quantum mechanics, our most experimentally successful theory. We will discuss some of these questions from the vantage point of recent puzzles about the black hole information paradox in quantum gravity. There is evidence from very recent results that suggest that the black hole interior is an emergent feature that arises in the weak-gravity limit, in a manner similar to how magnetism arises from spins in the large-volume limit of metals. This will mean that just as magnetism is not to be found in the metal atoms, smoothness is not to be found in the full ``UV-complete" description of quantum gravity, but only only in its effective description in terms of general relativity and quantum field theory at low energies.