After almost a century, the field of quantum gravity remains as difficult, frustrating, inspiring, and alluring as ever. Built on answering just one question – How can quantum mechanics be merged with gravity? – it has developed into the modern muse of theoretical physics.

Things were not always this way. Indeed, inspired by the monumental victory against the laws of Nature that was quantum electrodynamics (QED), the 1950s saw the frontiers of quantum physics push to the new and unchartered territory of gravity with a remarkable sense of optimism. After all, if nothing else, gravity is orders of magnitude weaker than the electromagnetic interaction; surely it would succumb more easily. Nature, it would seem, is not without a sense of irony. For an appreciation of how this optimism eroded over the next 30 years, there is perhaps no better account than Feynman's Lectures on Gravitation. Contemporary with his epic Feynman Lectures on Physics, these lectures document Feynman's program of quantizing gravity “like a field theorist.” In it he sets out to reverse-engineer a theory of gravity starting from the purely phenomenological observations that gravity is a long-range, static interaction that couples to the energy content of matter with universal attraction.