The $3 Million Breakthrough Prize in Fundamental Physics was shared between theorists Sergio Ferrara (CERN), Daniel Z. Freedman (Massachusetts Institute of Technology and Stanford University), and Peter van Nieuwenhuizen (Stony Brook University). The three are being honored for “the invention of supergravity, in which quantum variables are part of the description of the geometry of spacetime.”

## Supergravity

Ferrara, Freedman and van Nieuwenhuizen are the architects of supergravity, a highly influential 1976 theory that successfully integrated the force of gravity into a particular kind of quantum field theory (a theory that describes the fundamental particles and forces of nature in terms of fields embodying the laws of quantum mechanics).

The 1960s and early ’70s saw the construction of the Standard Model, a quantum field theory that still remains the most precisely verified theory in physics, and whose achievements include the prediction of the Higgs boson. However, it was clear that the Standard Model was not complete. In particular, it described only three of the forces of nature: it left out gravity, which was the domain of Einstein’s theory of general relativity. It also retained some major puzzles, including masses of particles that were many orders of magnitude below their expected values, and the lack of any particle that could explain dark matter, the invisible substance that pervades the Universe.

Then in 1973, physicists developed a principle, “supersymmetry,” which extended the Standard Model to include a new family of particles. Supersymmetry postulated that each of the known particles had an unseen “partner:” the fermions (such as electrons and quarks, which make up matter) had bosons (force-carrying particles) as partners; while the bosons (such as photons of light) had corresponding fermions. Though the existence of these “super-bosons” and “super-fermions” is yet to be confirmed experimentally, supersymmetry is an attractive idea because of its explanatory power. It relates the characteristics of fermions and bosons as manifestations of an underlying symmetry – much as different shapes might represent a single object reflected in a mirror. And it offers solutions to some of those perplexing puzzles in the Standard Model, including a mechanism explaining the tiny particle masses, and a natural candidate for dark matter, which – like the hypothesized super-bosons – is massive but invisible.

But for supersymmetry to describe the phenomena we do see around us – like apples falling to Earth – it would have to be extended to include gravity. This was the task that Ferrara, Freedman and van Nieuwenhuizen set their minds to. Beginning with discussions between Ferrara and Freedman at the École Normale Supérieure in Paris in 1975, continuing via collaboration with van Nieuwenhuizen at Stony Brook University, and culminating in a laborious series of calculations on a state-of-the-art computer, they succeeded in constructing a supersymmetric theory that included “gravitinos” – a super-fermion partner to the graviton, the gravity-carrying boson. This theory, supergravity, was not an alternative theory of gravity to general relativity, but a supersymmetric version of it: the algebra they used in the theory included variables representing part of the geometry of spacetime – geometry which in Einstein’s theory constitutes gravity.

## A Deeply Influential Theory

In the four decades since its development, supergravity has had a powerful influence on theoretical physics. It showed that supersymmetry was capable of accounting for all the phenomena we see in the real world, including gravity. It represented a completion of the current understanding of particle physics – a rigorous mathematical answer to the question, “What theories of nature are compatible with the principles of both quantum mechanics and special relativity?” And it provided a foundation for the attempt – still ongoing – to build a full theory of quantum gravity that describes space and time at a fundamental level

## Special Breakthrough Prize in Fundamental Physics

A Special Breakthrough Prize in Fundamental Physics can be awarded by the Selection Committee at any time, and in addition to the regular Breakthrough Prize awarded through the ordinary annual nomination process. Unlike the annual Breakthrough Prize in Fundamental Physics, the Special Prize is not limited to recent discoveries.

This is the fifth Special Prize awarded: previous winners are Stephen Hawking, seven CERN scientists whose leadership led to the discovery of the Higgs boson, the entire LIGO collaboration that detected gravitational waves, and, last year, Jocelyn Bell Burnell for her discovery of pulsars.