Mindscape with Sean Carroll

349 | Daniel Harlow on What Quantum Gravity Teaches Us About Quantum Mechanics

In this episode Sean Carroll talks with MIT physicist Daniel Harlow about the current landscape of quantum gravity research and how it forces us to rethink the foundations of quantum mechanics. Harlow explains why gravity’s universal coupling makes it a uniquely promising arena for progress, contrasting the relatively tractable black‑hole setting with the observer‑dependent challenges of cosmology. He argues that the standard Copenhagen view—quantum systems measured by an external classical observer—breaks down when the universe itself is the system, prompting his team to propose a new framework that treats observers as part of the quantum description. Throughout, Harlow emphasizes humility, the incremental nature of advances, and the interplay between modern quantum‑information tools and classic ideas like the path integral.