Understanding the “how” of existence is reasonably difficult, but science has made considerable progress toward an answer. First published in 1915, Albert Einstein’s theory of general relativity has long provided an incredible framework for understanding the complex machinations of the universe. And for things that cannot be fully explained by Einstein’s ideas, quantum mechanics goes to the finish line.
There’s just one problem: the two theories are fundamentally incompatible.
This led to two important “scaled” theories of general relativity—string theory and loop quantum gravity—attempting to bridge these two worlds. But a new theory from University College London (UCL) physicist Jonathan Oppenheim takes another approach. Oppenheim claims that spacetime is not quantum, but classical. The only difference is that spacetime “jumps” randomly rather than being uniform.
The theory is officially called the “post-classical quantum theory of gravity” and scientists have been testing it for five years. On Monday this week, UCL scientists published two papers simultaneously in the journal Physical examination X Y Natural communication.
“Quantum theory and Einstein’s theory of general relativity are mathematically incompatible with each other, so it is important to understand how this contradiction is resolved,” Oppenheim said. Press release. “Should spacetime be scaled, should quantum theory be modified, or is it something completely different?”
To test the theory, researcher Zach Weller-Davies created an experiment to disprove it. If Oppenheim’s approach is correct, a routine measurement of the same mass over time should show minute fluctuations. However, if the fluctuations are not sufficient to explain the quantum anomalies, it would prove the theory wrong.
“If spacetime does not have a quantum nature, we have shown that there must be random fluctuations in the curvature of spacetime that have a specific signature that can be verified experimentally,” Weller-Davies said in a press release. “If quantum particles like atoms can bend classical spacetime there must be a subtle connection.”
The new theory has many detractors: this “jump” represents, as Oppenheim puts it, a breakdown in predictability. Guardian, “many physicists don’t like it.” Theoretical physicist Carlo Rovelli, an expert on loop quantum gravity, has some. Friendly odds are 5,000:1 Spacetime is described by quantum theory and not by classical theory. But even if “quantum theory post-classical gravity” seems like a distant possibility, science is all about exploring the possibility.
“Most of the speculation turned out to be wrong,” Rovelli said Guardian. “Even if it’s not very plausible, I think Oppenheim would do well to explore this possibility.”
Darren lives in Portland, has a cat, and writes/edits about science fiction and how our world works. If you look hard enough you can find his previous stuff on Gizmodo and Paste.
