Atom-interferometry Limits on Dark Energy

Dark energy drives the expansion of the universe, but its nature remains mysterious. Some proposed theories can soon be confirmed or falsified by searching for tiny forces on individual atoms. As a first step, an atom interferometer has already ruled out a range of models.

In this lecture, Dr. Holger Müller will explain recent experimental searches for certain models of dark energy. How can it be that dark energy, which is supposedly ubiquitous in the cosmos, has never been observed in experiments? Called chameleon theories of f(R) gravity, some theories postulate long-ranged fields in empty space that become extremely short-ranged near massive objects and, thus, hard to observe. But advanced technologies from atomic physics can be used to sense them anyway. They already place stringent bounds on chameleons and could one day be used to find or definitely rule out a broad class of dark-energy candidates.