Theorists Sergio Ferrara (CERN), Dan Freedman (MIT/Stanford) and Peter van Nieuwenhuizen (Stony Brook) have been awarded a Special Breakthrough Prize in Fundamental Physics for their 1976 invention of supergravity. Supergravity marries general relativity with supersymmetry and, after more than 40 years, continues to carve out new directions in the search for a unified theory of the basic interactions.
“This award comes as a complete surprise,” says Ferrara. “Supergravity is an amazing thing because it extends general relativity to a higher symmetry – the dream of Einstein – but none of us expected this.”
Supergravity followed shortly after the invention of supersymmetry. This new symmetry of space–time, which enables fermions to be “rotated” into bosons and vice versa, implies that each elementary particle has a heavier supersymmetric partner and its arrival came at a pivotal moment for the field. The Standard Model (SM) of electroweak and strong interactions had just come into being, yet it was clear from the start that it was not a complete: it is not truly unified because the gluons of the strong force and the photons of electromagnetism do not emerge from a common symmetry, and it leaves out gravity, which is described by general relativity. Supersymmetry promised a way to tackle these and other problems with the SM.
It was clear that the next step was to extend supersymmetry to include gravity, says Ferrara, but it was not obvious how this could be done. During a short period lasting from autumn 1975 to spring the following year, Ferrara, Freedman and van Nieuwenhuizen succeeded – with the help of state-of-the-art computers – in producing a supersymmetric theory that included the gravitino as the supersymmetric partner of the graviton. The trio published their paper in June 1976. Chair of the prize selection committee, Edward Witten, says of the achievement:
“The discovery of supergravity was the beginning of including quantum variables in describing the dynamics of space–time. It is quite striking that Einstein’s equations admit the generalisation that we know as supergravity.”
It is quite striking that Einstein’s equations admit the generalisation that we know as supergravity
Despite numerous searches at ever higher energies during the past decades, no supersymmetric particles have ever been observed. But the importance of supergravity and its influence on physics is already considerable – especially on string theory, of which supergravity is a low-energy manifestation. Supergravity was a crucial ingredient in the 1984 proof by Michael Green and John Schwarz that string theory is mathematically consistent, and it was also instrumental in the M-theory string unification by Edward Witten in 1995. It played a role in Andrew Strominger and Cumrun Vafa’s 1996 derivation of the Bekenstein–Hawking entropy for quantum black holes, and is also important in the holographic AdS/CFT duality discovered by Juan Maldacena in 1997.
“Supergravity led to great improvements in mathematical physics, especially supergroups and supermoduli, and in the growing field of string phenomenology, which attempts to include particle physics in superstring theory,” adds Ferrara.
Ferrara, Freedman and van Nieuwenhuizen have received several awards for the invention of supergravity, including the 1993 ICTP Dirac Medal and the 2006 Dannie Heinemann Prize for Mathematical Physics. The Breakthrough Prize, founded in 2012 by former theoretical particle physicist and founder of DST Global, Yuri Milner, rewards achievements in fundamental physics, life sciences and mathematics. The $3m Special Breakthrough Prize can be awarded at any time “in recognition of an extraordinary scientific achievement”, and is not limited to recent discoveries. Previous winners of the Special Breakthrough Prize in Fundamental Physics are: Stephen Hawking; seven physicists whose leadership led to the discovery of the Higgs boson at CERN; the LIGO and Virgo collaborations for the detection of gravitational waves; and Jocelyn Bell Burnell for the discovery of pulsars.
The new laureates, along with the winners of the Breakthrough Prize in Life Sciences and Mathematics, will receive their awards at a ceremony at NASA’s “Hangar 1” on 3 November.