Julius Wess, 72, Theoretical Physicist - New York Times

Julius Wess, 72, Theoretical Physicist - New York Times http://select.nytimes.com/search/restricted/article?res=F30E16FD3B5F...

August 27, 2007 Julius Wess, 72, Theoretical Physicist

By KENNETH CHANG

Julius Wess, a theoretical physicist who plumbed the universe for unseen symmetries, including those in a theory that led to a prediction of a new class of fundamental particles, died Aug. 8 in Hamburg, Germany. He was 72.

The cause of death was a stroke, said Bruno Zumino, an emeritus professor at the University of California, Berkeley, who collaborated with Dr. Wess.

In 1973, Dr. Wess and Dr. Zumino published a paper that extracted ideas from an obscure, abstract theory that regarded fundamental particles as vibrating strings and applied them to mainstream particle physics.

''They came up with quantities that you could measure and you could observe,'' said Roman W. Jackiw, a professor of physics at the Massachusetts Institute of Technology.

Fundamental particles fall into one of two groups known as fermions and bosons. The familiar constituents of matter like electrons, quarks and neutrinos are all fermions, while the particles that carry the fundamental forces like photons, which are particles of light, are bosons.

In the Wess-Zumino model, one of a group of theories more broadly known as supersymmetry, the distinction between fermions and bosons is blurred, with every fermion having a boson ''superpartner'' and vice versa. None of the supersymmetric partners, which would be much heavier, have been discovered yet, but that is one of the key targets for the Large Hadron Collider, which will be the world's most powerful accelerator when it starts operating next year at the CERN laboratory in Switzerland.

''Julius was very hopeful that something might be found there,'' Dr. Zumino said.

The supersymmetric particles are a leading candidate for filling in the dark matter of the universe, a component of the universe five times as plentiful as ordinary matter yet still undiscovered. Supersymmetry has also provided a way to tie gravity together with other fundamental forces.

''It has become the standard extension of what we think particle physics should be,'' said William A. Bardeen, a physicist at the Fermi National Accelerator Laboratory in Illinois.

Born in 1934 in Austria, Julius Wess received his Ph.D. in physics in 1957 at the University of Vienna. During his graduate studies, he met Dr. Zumino, who was a visiting scientist there, through Dr. Wess's adviser, Walter Thirring. ''Walter told me there was this very good student and could I take care of him,'' Dr. Zumino said. ''Thirring was right. He was a very good student.''

Dr. Wess worked at CERN, and later as an associate professor at the Courant Institute of New York University in 1966. Two years later, he became a professor at Karlsruhe University in Germany.

In 1990, he became director of the Max Planck Institute for Physics in Munich.

After retiring, he worked for DESY, a German particle physics research center in Hamburg.

1 of 2 09/14/2007 05:49 PM Julius Wess, 72, Theoretical Physicist - New York Times http://select.nytimes.com/search/restricted/article?res=F30E16FD3B5F...

Only two weeks before his death, Dr. Wess gave a talk at a supersymmetry conference at Karlsruhe, recounting the history of how he and Dr. Zumino introduced the idea of supersymmetry.

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