Michael Cohen

Michael Cohen

Professor of Physics Emeritus

(215) 898-8161



  • Prof. Emeritus
  • Postdoctoral positions al CalTech and the Institute for Advanced Study (Princeton)


Honors include:

Honorary Trustee (co-founder), Aspen Center for Physics

Fellow, American Physical Society


Ph.D., CalTech (1956)
B.A. Cornell (1951)

Research Interests

Condensed Matter Physics


I have investigated the quantum mechanics of liquid helium, calculating properties of the bulk fluid as well as the surface (density profile and surface excitations).

I am interested in applying statistical mechanics to the analysis of simple models of real-world systems. An analysis of a simple model of displacive ferroelectrics led to an interesting phase diagram and an understanding of mode softening as the precursor of a displacive transition. With a biologically-oriented coworker, I have studied the equilibrium between a membrane (wilh sites which can adsorb molecules) and a fluid containing those molecules. We have studied fairly complicated membranes, taking account of the geometrical competition for sites and also including electrostalic effecls in a mean-field approximation.

In September 2011 I completed an elementary text, or supplementary text, on Classical Mechanics. The book incorporates my ideas on how to present the basic concepts, and is available (free) online. (See link above).


Selected Publications


  • (with T.J. Einstein), "Statistical Mechanics of a Simple Model of a Displacive Ferroelectric," Phys. Rev. B, 7, 1932 (1973).
  • (with C.C. Chang), "Microscopic Theory of Surface Excitations in Superfluid Helium," Phys. Rev. B 11, 1059 (1975).
  • (with J.A. Cohen), "Adsorption of Monovalent and Divalent Cations by Phospholipid Membranes: the Monomer-Dimer Problem," Biophys. Journal 36, 623 (1981).
  • (with A.B. Harris), "Scaling of Negative Moments of the Growth Probability of Diffusion Limited Aggregates" , Phys. Rev. A41, 971 (1990)
  • (with A.B.Harris), "Multiple Species of Noninteracting Molecules Adsorbed on a Bethe Lattice", Phys.Rev.E78, 041116 (2008)
  • "Classical Mechanics: a Critical Introduction" online 2011 (see link above)