Exploring quantum gravity with a simple pendulum experiment

Despite its potential importance, progress in developing a theory of quantum gravity has been slow. A significant obstacle is the lack of technology capable of creating the extreme conditions necessary to observe quantum effects in gravity. For example, studying quantum effects in a laboratory would require particle accelerators with energies 15 orders of magnitude greater than those currently available.

A team of physicists have proposed a simpler experiment to study quantum gravity, one that might be easier to carry out than previous methods. Published in Physical Review X, the team’s idea involves examining gravitational interactions between harmonic oscillators–systems that oscillate at a constant frequency, such as pendulums.

“We designed and investigated a class of experiments involving a system of massive ‘harmonic oscillators’ — for example, torsion pendulum, essentially like the one that Cavendish used in his famous 1797 experiment to measure the strength of the gravitational force,” Ludovico Lami, theoretical physicist at the University of Amsterdam and QuSoft, and one of the authors of the study, explained in a press release. “We establish mathematically rigorous bounds on certain experimental signals for quantumness that [the] classical gravity should not be able to overcome.”