# Herbert Wagner (physicist)

Herbert Wagner (born 6 April 1935) is a German theoretical physicist, who mainly works in statistical mechanics. He is a professor emeritus of Ludwig Maximilian University of Munich.

## Biography

Wagner was one of the last students of German theoretical physicist and Nobel prize winner Werner Heisenberg, with whom he worked on magnetism.[1]

As a postdoc at Cornell University, he and David Mermin (and independently of Pierre Hohenberg) proved a "no-go theorem", otherwise known as the Mermin–Wagner theorem. The theorem states that continuous symmetries cannot be spontaneously broken at finite temperature in systems with sufficiently short-range interactions in dimensions $d \le 2$.[2]

Wagner is the academic father of a generation of statistical physicists. Many of his students and junior collaborators now occupy chairs in German universities, including Hans Werner Diehl (Essen), Siegfried Dietrich (Wuppertal, then Stuttgart), Klaus Mecke (Erlangen), Reinhard Lipowsky (Max Planck Institute of Colloids and Interfaces, Berlin), Hartmut Löwen (Düsseldorf) and Udo Seifert (Stuttgart).

## Awards

In 1992, Wagner was awarded an honorary degree by the University of Essen (now University of Duisburg-Essen).[3]

## References

1. ^ W. Heisenberg, H. Wagner, K. Yamazaki: "Magnons in a model with antiferromagnetic properties", Il Nuovo Cimento 59, 377-391 (1969), doi:10.1007/BF02755024.
2. ^ N.D. Mermin, H. Wagner: "Absence of Ferromagnetism or Antiferromagnetism in One- or Two-Dimensional Isotropic Heisenberg Models", Phys. Rev. Lett. 17, 1133–1136 (1966).
3. ^ Ehrenpromotionen in der Theoretischen Physik an der Universität [Duisburg-]Essen