A collaboration of physicists from India and the UK has designed an experiment to examine if gravity exhibits quantum behaviour. The experiment is spearheaded by Professor Sougato Bose from University College London (UCL) and also involves Dr Debarshi Das. With this new experiment,  the team aims to explore whether gravitational interactions follow the peculiar rules of quantum mechanics, similar to other fundamental forces such as electromagnetism. The experiment will measure gravitational effects between two minuscule diamond crystals, with results potentially reshaping our understanding of gravity.

A New Approach to Test Gravity’s Quantum Properties

This novel experiment, outlined in Physical Review Letters, will utilise tiny diamond crystals as tools to detect potential quantum disturbances. By placing one crystal as a detector and another as the gravitational source, the researchers intend to observe whether the act of measuring gravity induces a disturbance in the system. In classical physics, observations don’t influence the system under study, but quantum mechanics suggests otherwise. According to Professor Bose, “Once experimental errors are eliminated, any disturbance observed would signify gravity’s adherence to quantum principles.”

A Solution to a Persistent Mystery in Physics

Physicists have long sought to reconcile gravity with quantum mechanics, the established framework for understanding the other three fundamental forces: electromagnetism, the weak nuclear force, and the strong nuclear force. The quantum behaviour of these forces is well-documented, but gravity has consistently eluded similar classification. Despite attempts by large research groups, including experiments with neutrinos in Antarctica, no conclusive evidence of quantum gravitational effects has yet been found.

A Long-Term Vision for Testing Quantum Gravity

The proposed table-top setup offers an efficient and compact way to test for quantum gravity, but the experiment hinges on advanced technology that can manipulate and measure the gravitational pull of extremely lightweight nanodiamonds. Dr Das noted that it may take a decade or more to perfect the technique, adding that “a table-top experiment is far more practical than alternatives, such as constructing a particle accelerator on a cosmic scale.”

The Path to Unified Physics

Team members like Dr Dipankar Home from the Bose Institute in Kolkata see the experiment as an opportunity to test quantum mechanics’ predictions uniquely for gravity. While theories like string theory attempt to bridge the gap between quantum mechanics and gravity, no direct experimental evidence exists.