Ask Ethan: Is it possible that gravity isn’t quantum?

The two greatest leaps of 20th century physics still leave physicists grappling to understand how it’s possible, at a fundamental level, that they can coexist. On the one hand, we have Einstein’s general theory of relativity (GR), which treats space as a continuous, smooth background that’s deformed, distorted, and compelled to flow and evolve by the presence of all the matter and energy within it, while simultaneously determining the motion of all matter and energy within it via the curvature of that background. On the other hand, there’s quantum physics, governed at a fundamental level by quantum field theory (QFT). All the quantum “weirdness” is encoded in that description, including ideas like quantum uncertainty, the superposition of states, and quantum indeterminism: fundamentally anti-classical notions. <a href="https://medium.com/starts-with-a-bang/ask-ethan-is-it-possible-that-gravity-isnt-quantum-8b63178904ac">Website</a>