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- Gravity wave astronomy could confirm groundbreaking theories on massive gravity.
- The elusive graviton has been the subject of debate in theoretical physics for almost 100 years.
- One physicist has followed a groundbreaking 2011 paper with years of additional research and now, a $100,000 award.
A theoretical physicist in England has won a prestigious award for her work on the theory of massive gravity, which could explain why gravity hasn’t constrained the rapid expansion of the universe. The $100,000 award honors the work of Claudia de Rham, who has worked for 10 years on a way to turn massive gravity theory into something measurable.
Cosmologists have puzzled for decades about how to marry gravity with the speed at which the universe is expanding. Gravity as we understand it would work to hold the universe together, not let it race apart from itself into eventual oblivion. Enter the counterpart to dark matter, dark energy, which is what scientists call whatever is pulling the universe apart. Dark matter helps to explain the amount of gravity we observe in some circumstances; dark energy handles the amount of gravity we don’t observe in other circumstances.
Probing the nature of dark energy has paralleled the study and theorization of dark matter. It’s easy to posit that everything you can’t actually observe has shared properties that glue the world together, but it’s harder to pick out individual parts of the theory to prove them or even fit them into the rest of accepted wisdom in physics.
Enter the theory of massive gravity. It’s just what it says on the tin: adherents believe that gravitons, which are hypothetical particles that apply gravity, have mass themselves. The implications for this are far ranging, and trying to assert the theory in order to study it in more detail has made (gravity) waves among physicists and cosmologists. Massive gravity changes Einstein’s theory of general relativity, and it implies some truly wild stuff, like that gravity waves with mass would consequently have momentum.
de Rham is a champion of cutting-edge massive gravity theory. In 2011, she coauthored an important paper that shifted the discourse on massive gravity—and drew a ton of negative attention from established people in her field. Over the years, the most popular emerging theory of massive gravity involved a kind of placeholder called a ghost. de Rham’s paper set out to displace the ghost named for fellow physicists David Boulware and Stanley Deser and explain new ideas for massive gravity “which are ghost-free.”
So to other theorists, the new ideas were so different and radical that they were hard to swallow. “If you say ‘Well actually what you did 40 years ago wasn’t quite right’, they’re not going to say ‘Let’s talk about it’,” de Rham told The Guardian. But the Blatnavik Award people don’t shy away: “In 2011, de Rham and her collaborators made a breakthrough by constructing a more sophisticated mathematical framework for the theory of massive gravity, completely avoiding the problems of previous versions.”
Gravitational wave astronomy is about to revolutionize massive gravity theory, although the results might take decades more. In 2017, the Nobel Committee awarded the physics prize to a group that had at long last detected a gravitational wave. That technology is developing in tandem with the rush of researchers who are working to continue or elaborate on de Rham’s theory of massive gravity, offering a way we may be able to confirm her mathematical model.
“That may or may not happen,” she told The Guardian, “but what will happen is that we’ll have a much better fundamental understanding of gravity and that’s […] one of the big questions today.”
