The two cornerstones of modern physics are Einstein's general theory of relativity, which explains gravity through the bending of spacetime, and quantum theory, which controls the tiniest particles in the universe.

However, there is a conflict between these two hypotheses, and a solution has eluded researchers for more than a century.

The general consensus has been that Einstein's theory of gravity needs to be "quantized," or changed, to make it compatible with quantum theory.

This is the methodology of two prominent contenders for a quantum theory of gravity: loop quantum gravity and string theory.

However, a recent idea put forth in a study published in Physical Review X and created by Professor Jonathan Oppenheim of UCL Physics and Astronomy casts doubt on that consensus.

The hypothesis—dubbed a "postquantum theory of classical gravity"—modifies quantum theory and anticipates an innate breakdown in predictability mediated via spacetime,

rather than altering spacetime. If an object's apparent weight is measured accurately enough, this leads to larger-than-expected random and violent fluctuations in spacetime, which are not consistent with the predictions of quantum theory.

A second study, undertaken by former Ph.D. students of Professor Oppenheim and concurrently published in Nature Communications, examines some of the implications of the theory and suggests a test procedure that involves accurately measuring a mass to see if its weight appears to change over time.