Searching for Chameleon Dark Energy with Mechanical Systems

A light scalar field framework of dark energy, sometimes referred to as quintessence, introduces a fifth force between normal matter objects. Screening mechanisms, such as the chameleon model, allow the scalar field to be almost massless on cosmological scales while simultaneously evading laboratory constraints. We explore the ability of existing mechanical systems to directly detect the fifth force associated with chameleon dark energy and apply our analysis to two mechanical systems: levitated microspheres and torsion balances, showing that the current generation of these experiments have the sensitivity to rule out a significant portion of unprobed chameleon parameter space. We also indicate regions of theoretically well-motivated chameleon parameter space to guide future experimental work.