On 11 October 2002 the American physicist Frank Wilczek (1951), who is attached to the Massachusetts Institute of Technology (MIT), will receive the Lorentz Medal from the Royal Netherlands Academy of Arts and Sciences (KNAW).

He is being awarded the prize for his pioneering work in particle physics

Professor Wilczek is one of the most influential theoretical physicists of his generation. He was an instrumental figure in the discovery of the phenomenon known as 'asymptotic freedom'. This is a phenomenon whereby the building blocks which make up the nucleus of an atom - 'quarks' - behave as free particles when they are close together, but become more strongly attracted to each other as the distance between them increases. This theory forms the key to the interpretation of almost all experimental studies involving modern particle accelerators. In the view of the Academy, Wilczek's work is characterised by both its breadth and its depth. For example, his research on particles which can only move in a two-dimensional plane was of great importance in the understanding of two-dimensional electron gases in semiconductors.

Professor Wilczek studied at the universities of Chicago and Princeton, where he obtained his doctorate in 1974. He later became professor of physics at Princeton and at the University of California, Santa Barbara. Since 2000 he has held the Herman Feshbach chair at MIT. He is a member of the American National Academy of Sciences, and has received the Dirac Medal (1994) and the Michelson-Morley Prize (2002). In recent years Professor Wilczek has developed a close association with physics in the Netherlands, and in 1998 he was the Lorentz Professor at Leiden University. He recently became an international member of KNAW. Frank Wilczek regularly speaks and writes on theoretical physics for a wide audience.

The Academy instituted the Lorentz Medal in 1925 to mark the fiftieth anniversary of the awarding of a doctorate to Hendrik Antoon Lorentz (1853-1928). The Medal has been awarded every four years since 1927 to researchers who have attained outstanding achievements in the field of physics. Lorentz was a member of the Academy, where he held various administrative posts. In 1902 Lorentz and Pieter Zeeman were awarded the Nobel Prize for Physics for their research on electrons. Many winners of the Lorentz Medal have later gone on to win the Nobel Prize; examples include Max Planck, Wolfgang Pauli and Petrus Debije. More recently the Medal has been awarded to Carl E. Wieman and Eric A. Cornell (1998), Alexander M. Polyakov (1994), Pierre-Gilles de Gennes (1990) and Gerard 't Hooft (1986).

The Lorentz Medal will be presented by the president of KNAW, Professor Willem J.M. Levelt, at 15.30 hours on Friday, 11 October 2002 during a symposium entitled 'Zeeman, Lorentz and the electron'. The symposium is being organised jointly by the universities of Leiden and Amsterdam to mark the centenary of the awarding of the Nobel Prize to Zeeman and Lorentz.

The chairman of the jury awarding the Lorentz Medal, Professor Ad Lagendijk, will deliver a laudation, following which Professor Wilczek will give a lecture entitled 'Evolution of the concept of particle and the origin of mass'.

The symposium will take place in the Gorlaeus Laboratory, Einsteinweg 55, Leiden, and will start at 10.00 hours. The programme also includes lectures by Serge Haroche (Paris), Anne J. Kox (UvA) and Martinus J.G. Veltman (UvA). The symposium will be open to all, though advance registration is required. More information and registration details can be found at http://zeeman.lorentz.leidenuniv.nl.