Modern physics faces a philosophical dilemma: its main pillars, quantum theory and the theory of gravity, are based on assumptions about nature that are mutually exclusive. If quantum physics is correct, we must rethink our ideas about space and time. If Einstein's theory of gravity is correct, the role of quantum physics must be revised. Both theories cannot be universally valid at the same time.

This is an experimental problem. So far, we have no evidence that gravity requires a quantum description—our experiments currently only observe phenomena that can be explained by a classical theory of gravity.

Starting from this premise, Markus Aspelmeyer discusses the question of how to build a gravitational experiment that can no longer be described by Einstein's general theory of relativity. To do this, a quantum system must be made so heavy that it generates a measurable gravitational field. Then it would be possible to test directly whether gravity, and thus spacetime itself, follows the laws of quantum physics – or not.

In celebration of the twentieth anniversary of the Einstein Lectures Dahlem, Freie Universität Berlin and the Max Planck Society are offering guided tours and a film screening in addition to the lecture itself: Einstein Lectures.

About Einstein Lectures Dahlem

The Einstein Lectures Dahlem, hosted by Freie Universität Berlin since 2005 in partnership with several external institutions, are dedicated to the epochal work of Albert Einstein. Einstein was the director of the Kaiser Wilhelm Institute of Physics for almost two decades.

Since 2017, this first-rate-interdisciplinary colloquium is hosted in cooperation with the Max Planck Society, the successor of the Kaiser Wilhelm Society.

The lectures are held in Dahlem, a district in Berlin known for its tradition as a center of scientific research. They address a broad academic audience and cover various scientific disciplines influenced by Einstein’s thinking.

Einstein Lectures Dahlem