Oppenheim's 'post-quantum gravity' is now testable
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- Jonathan Oppenheim at University College London developed "post-quantum gravity," which unlike competing quantum gravity theories doesn't try to quantize space-time — instead proposing gravity is continuous and fundamental, without constituent building blocks.
- Post-quantum gravity calculations predict small, random fluctuations in the flow of time — "wobbly" time occurring on scales too small for humans to notice, with tick intervals flowing unpredictably forwards.
- Oppenheim's theory suggests these time fluctuations, when folded into quantum mechanical calculations, reproduce several fundamental quantum behaviors, including the collapse rule that turns Schrödinger's cat into a definite alive-or-dead state upon observation.
- Oppenheim admits the idea is highly controversial — "I don't know anyone who thinks it's more likely to be true than not true" — but says many physicists agree the experiments are worth running.
- Giuseppe Fabiano at Lawrence Berkeley National Laboratory, who is developing testing parameters and calls himself "agnostic" on the theory, said it is "useful" as long as it makes testable predictions.
- Proposed experiments aim to measure gravity between pairs of objects, since unpredictability in time's flow would necessarily produce unpredictability in gravity — but reaching the necessary precision could take decades.
Why it matters: Most proposed quantum-gravity theories cannot be experimentally tested. Oppenheim's can — and if the experiments detect his predicted 'wobble' in time and gravity, it would mark gravity as fundamentally different from the other forces, potentially resolving the century-long conflict between general relativity and quantum mechanics while upending the orthodoxy that gravity must be quantum.
