The Special Breakthrough Prize in Fundamental Physics has been awarded to Sergio Ferrara, Daniel Z. Freedman, and Peter van Nieuwenhuizen for their discovery, back in 1976, of the minimal version of supergravity.
Supergravity is a theory that tries to bridge the gap between general relativity and quantum mechanics, bringing the four fundamental forces of the universe together in a single theory. These two theories are extremely successful in their own fields but when put together, they don’t really see eye to eye anymore.
This limitation hints at physics beyond what we have currently proven and supergravity, in one form or another, could be the theory we need. In the four decades since its discovery, it has played an influential role in fundamental physics, and “popularized” the concept of higher dimensions in the universe beyond the four we can experience. Its discovery has shaped important ideas such as string theory.
“In my opinion, the most important consequence of the discovery was that it was realized that supergravity in five dimensions can describe the fundamental forces in a supersymmetric model in four dimensions. So it gives us the link between a higher-dimensional gravitational theory and lower dimensional non-gravitational theories,” laureate Dr van Nieuwenhuizen, Distinguished Professor of Physics at Stony Brook University, told IFLScience.
The theory is strongly linked to another theory called supersymmetry that has been proposed to solve problems in the Standard Model of particle physics, currently our best description of fundamental physics. In the supersymmetry scenario, all particles have partners. Discovering their existence will allow us to overcome the limitations of the Standard Model.
In this theory, the particle that carries gravity, the graviton, also has a supersymmetric partner called the gravitino. And discovering this particle could give us a way to find evidence in favor of supergravity.
“One possible source of evidence for [supergravity] has to do with cosmology and the possibility that the gravitino is dark matter. The gravitino is the only particle that naturally doesn’t carry any quantum number of the known forces,” laureate Dr Ferrara, from CERN, told IFLScience. “Another possibility is, of course, particle physics. We know that the Standard Model... is not going to be the full story of particle interactions because of certain problems, such as the hierarchy problem. Many of the particle accelerator experiments are looking at the existence of supersymmetric particles to solve these problems.”
Supergravity might not have been proven to be the correct description of the universe yet, but it can be employed to solve real physical problems. In 1981, the theory was used to prove an extremely complex problem of general relativity in a very simple way.
The person responsible for this solution is Edward Witten, who is the chair of the Selection Committee for the Special Breakthrough Prize in Fundamental Physics. A prize that the three academics weren’t really expecting.
“I never thought that we would win such a prize, so for us it was a big surprise,” Dr Ferrara told us.
“I am overwhelmed! It is very meaningful to have been chosen by the group of previous winners who I have always admired as the leaders of our profession,” Dr Freedman, who is a visiting professor at Stanford University explained.
Dr van Nieuwenhuizen too was taken aback when he was told about the prize. Although, in his own words, his experience was a bit of a comedy of errors.
“I was sitting at my kitchen table having just come back from Europe. I saw on my computer screen a message from Edward Witten asking me what my phone number was. I got a bit worried because he's a very, very smart physicist and I thought he wanted to ask me a very difficult question that I didn't know the answer to. I took a deep breath and gave him my phone number, but no phone call came.
“I got an email back and turns out I had accidentally given him the number of someone in Massachusetts. I gave him the correct number. He called me and told me we won the prize. I was absolutely speechless. I told him that. And then he said ‘you don't have to say more. Please don't tell anybody.’ And that was it. The shortest and the most contentful phone call of my life.”
The three physicists will share a prize of $3 million and will be at the 2020 Breakthrough Prize ceremony on Sunday, November 3, 2019, where the winners of the Breakthrough Prizes in Life Sciences and Mathematics will be honored as well.