Can quantum mechanics be valid on large scales? (video)

Renato Renner, Professor of Theoretical Physics and head of the research group for Quantum Information Theory, Institute for Theoretical Physics, ETH Zürich

Although quantum mechanics is sometimes said to be our best tested physical theory, almost all experiments are restricted to microscopic systems. It is therefore still an open question whether quantum mechanics, without modifications, accurately describes macroscopic (e.g., human-size) objects. In this talk, I tackle this question from a theorist's perspective, i.e., with a thought experiment. Combining ideas from Wigner, Bell, and Hardy, I show that there exist scenarios where quantum mechanics yields a set of predictions that are mutually contradictory.