Obituary of Michael J. Stephen

The world of condensed matter physics lost a major theorist when Michael Stephen had to retire from teaching and research in 2001 due to the onset of bone cancer. This disease finally claimed his life: he died on April 15 2007 at his home in Cambridge Massachusetts. He had a distinguished career, making major contributions in condensed matter and statistical physics.

Michael was born on April 7, 1933 in Johannesburg. He received BS and MS degrees in physics from the University of Witwatersrand and his D.Phil from Oxford in 1955, where he studied with C.A. Coulson. He had post-doctoral positions at Cambridge, Columbia, MIT and Oxford, before joining the faculty at Yale in 1962. From there, after a short stint at MIT, he went to Rutgers University in 1968, where he spent the rest of his career until his retirement, forced by his illness, in 2001.

Michael’s impressive mathematical skills and physical insight attracted many students, postdocs and senior collaborators. Among the latter were John Bardeen and Lars Onsager at Yale. Michael’s relationship with them inspired much of his later research activities. The range of Michael’s scientific interests and expertise is very impressive. He published on atomic and molecular physics, quantum optics, electronic properties of metals, plasma physics, turbulence, critical phenomena, disorder and localization, liquid helium, liquid crystals, and many topics in superconductivity.

Among Michael’s major accomplishments, often cited even today, are his work with Bardeen on vortices in type-II superconductors, the theory of noise in Josephson junctions and arrays, the theory of percolation in disordered magnets, the theory of the localization of light, and an important review article, with Straley, on liquid crystals. All of these results depended heavily on Michael’s characteristic ability to invent relatively simple mathematical methods to treat relatively complicated physics problems.

Michael was a very superior tennis player and an avid fisherman; he enjoyed salt water fishing and lobstering near the family cottage in Woods Hole. He also ran, swam and climbed rocks and mountains. Even after contracting multiple myeloma, he was able to keep himself in shape by taking long walks near his home in Cambridge. He had a refined appreciation of classical music and played the violin quite respectably, participating frequently in amateur chamber music activities.

Michael’s wife, Johanna Pallotta, is a professor at the Harvard Medical School. Somehow Michael was able to teach at Rutgers, commute back and forth to Cambridge, MA and to raise a wonderful family: four children, all physicians, as well as to have a terrific research career. In addition to his important contributions to physics, Michael is remembered for his self-effacing character, his dry wit and his caring personality.

Reminiscences of Marlan O. Scully:

Michael was a theoretical mainstay of the wonderful Yale low temperature physics group. Indeed the names associated that group of the 1960’s reads like a who’s who in the field: Bardeen, Fairbank, Lane, Lee, Onsager, Reppy, etc. But it was to Michael that everyone went to discuss theoretical ideas and subtle calculations. An expert in many body physics he was, a specialist he was not. I recall spending long hours in his office discussing the quantum theory of the laser, and he was co-author on the first such paper.

We all took his many body lecture (often more than once!). His complete mastery of the subject together with his dry wit was a winning combination. His absolute availability and his friendly open attitude were a joy to us all. One of the things I recall vividly was long silences at the board in his office. The conversation rate was often below 10 words/minute but the results of those discussions were pure gold. He would spend time with us explaining the delta function or quantum field theory—elementary or advanced, he was always there and his guidance was always on target.

Later we moved together to MIT. His MIT research interests were more quantum optics but his style continued to be “students first, others second, Michael Stephen third.” For example, after a hard day he would take us fishing, snowshoeing, or beat us on the racketball court.

Michael’s insights were often conveyed in one-liners:

When stuck: “We need to learn something new here.”

When tired: “We need to get some exercise.”

When writing a paper: “We will enjoy writing this up.”

When making the Markov approximation: “We can do this, but we should not forget that we did.”

And I would add:

When thinking of Michael: “We do it with a smile.”