From Diracs to Nobels

UPDATE: With today's Nobel in Physics announcement, the number of Dirac Medallists who have gone on to earn Nobels has climbed to 8! See our news article about John Hopfield, one of the 2024 Physics Nobel laureates.
 

It is not difficult to imagine that an ICTP Dirac Medallist could become a future Nobel laureate. After all, ICTP's top physics prize rewards some of the world's most eminent physicists for their groundbreaking work. The Dirac Medal, first awarded in 1985, is given in honour of Paul Dirac, one of the greatest physicists of the 20th century and a staunch friend of ICTP. It is awarded annually on Dirac's birthday, 8 August, to scientists who have made significant contributions to theoretical physics.

Seven of those physicists have gone on to Nobel glory (or, in the case of Dirac Medallist Edward Witten, Fields Medal glory). Who are they and what are their contributions to physics? Will 2024 be the year that one more Dirac Medallist(s) is added to the list?

Yoichiro Nambu

The Dirac Medal was only one year old when Yoichiro Nambu shared the 1986 prize with Alexander Polyakov; the two had been preceded by inaugural winners Edward Witten (who went on to receive the 1990 Fields Medal for his work in superstring theory) and Yakov Zeldovich.

Nambu's prize citation was for being one of the first physicists to formulate the idea of spontaneous symmetry breaking and in particular, chiral symmetry breaking in relativistic particle physics. His contributions to the quark model in the sixties and, later, his geometrical formulation of the dual resonance models as the dynamics of a relativistic string are of fundamental importance.

In 2008, Nambu was awarded 1/2 of the Nobel Prize in Physics “for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics”.

David Gross

David Gross was one of two recipients of the 1988 Dirac Medal (Efim Fradkin also received the Medal that year) for his fundamental contributions to the understanding of nuclear forces at short distances and to the theory of superstrings. Together with Wilczek and, independently, Politzer and 't Hooft, he discovered the mechanism of asymptotic freedom in non-Abelian gauge theories. This discovery was central to the development of quantum chromodynamics as a viable model for the nuclear force. His invention, together with Harvey, Martinec and Rohm, of the heterotic superstring opened the way for a new understanding of the nature of spacetime and the unification of elementary forces.

That early work with Wilczek (also a Dirac Medallist; see below) led to the two sharing the 2004 Nobel prize (with H. David Politzer) “for the discovery of asymptotic freedom in the theory of the strong interaction”.

Frank Wilczek

One of only five Dirac Medallists awarded singularly for their work (the others being Michael Berry, Giorgio Parisi, John J. Hopfield, and Peter Zoller), Frank Wilczek earned the 1994 Medal for his co-discovery of the phenomenon of "asymptotic freedom" in non-Abelian gauge theories. This fundamental observation - that the effective interaction at short distances becomes weak, even in strongly interacting systems - led to the development of a realistic model for hadron physics. In particular, it provided an explanation of scaling and its logarithmic corrections in hadron physics at high energies. Asymptotic freedom has become a cornerstone of the Standard Model of elementary particles and of the theoretical extensions of this model that aim to unify the fundamental forces. Wilczek also coined the name "anyons" made important contributions to the study of particle-like excitations in 2-dimensional systems that obey "fractional statistics". These particles, for which he are now recognized to have a role in phenomena such as the fractional quantum Hall effect.

For the Nobel citation, see that for David Gross above.

Martinus Veltman 

Two years after Wilczek received his Dirac Medal, Martinus Veltman was awarded the 1996 medal for his pioneering investigations on the renormalisability of gauge theories and consequently, his analysis of the sensitivity of radiative corrections to both the mass differences in fermion doublets and the Higgs particle mass. These calculations provided the basic prediction in the search for the Top quark mass. Towards this goal, Veltman was one of the first to use the computer in Feynman diagram calculations. His software package for manipulations of algebraic symbols has been a privileged tool for a full generation of physicists.

Veltman has the distinction of becoming the first ICTP Dirac Medallist to receive a Nobel Prize: his came in 1999, shared with Gerardus 't Hooft, "for elucidating the quantum structure of electroweak interactions in physics".

Giorgio Parisi

Giorgio Parisi was the sole winner of ICTP's 1999 Dirac Medal for his original and deep contributions to many areas of physics ranging from the study of scaling violations in deep inelastic processes (Altarelli-Parisi equations), the proposal of the superconductor's flux confinement model as a mechanism for quark confinement, the use of supersymmetry in statistical classical systems, the introduction of multifractals in turbulence, the stochastic differential equation for growth models for random aggregation (the Kardar-Parisi-Zhang model) and his groundbreaking analysis of the replica method that has permitted an important breakthrough in our understanding of glassy systems and has proved to be instrumental in the whole subject of Disordered Systems.

His ground-breaking work earned him 1/2 of the 2021 Nobel Prize in Physics “for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales”.

Duncan Haldane

In 2012, condensed matter physicist Duncan Haldane shared that year's Dirac Medal with Charles Kane and Shoucheng Zhang for their independent work on two and three dimensional topological insulators, a substance that acts as an insulator with the bulk of its material but also conducts electricity along its surface as if the edge itself were a lower-dimensional metal attached to the material. This odd conductive property was first discovered in a strong magnetic field in what's called the Quantum Hall Effect. In 1980, scientists considered the Quantum Hall Effect bizarre because electrons in two dimensions are normally "localized" -- completely unable to conduct. This effect was later observed in some physical materials as well. Scientists were surprised that a perfect conductance should arise despite rampant imperfections in the material. The key was that edge states had to exist for "topological" reasons, which protected them against the material's imperfections. Haldane set the foundations for that concept with his 1980s research on electron and spin systems in one-dimension.

Haldane's 1/4 share of the 2016 Nobel Prize in Physics cited his "theoretical discoveries of topological phase transitions and topological phases of matter".

James Peebles

ICTP's 2013 Dirac Medal pivoted to fundamental physics, cosmology and astrophysics when it awarded that year's prize to James Peebles (together with Thomas Kibble and Martin Rees) whose combined work has deepened our understanding of the early universe, galaxy formation and black holes. Peebles was one of the first scientists to predict the existence of the cosmic microwave background (a background of microwaves permeating the whole universe that originated from the Big Bang) and to study its implications for the development and evolution of the universe. He has also made major contributions to all areas of cosmology, including nucleosynthesis, dark matter, dark energy and structure formation.

Six years later, Peebles became the seventh Dirac Medallist to win a Nobel Prize in Physics. His half of the 2019 prize cited his "theoretical discoveries in physical cosmology”.

Who will be the next Dirac-Nobel?

Who will be the next Dirac Medallists to win a Nobel? As of this writing (7 October 2024), two are considered in pole position (according to Chemistry World) for the Chemistry Nobel, an indication of the importance of  cross-disciplinarity in physics.  The two are Roberto Car and Michele Parrinello, who shared the 2009 Dirac Medal for their the joint contributions in developing the ab initio simulation method in which they combined, elegantly and imaginatively, the quantum mechanical density functional method for the calculation of the electronic properties of matter with molecular dynamics methods for the Newtonian simulation of atomic motions.