Obituary of Stefan Machlup

Stefan Machlup spent 45 years as a member of the physics faculty, first of Western Reserve, and then of the combined department of Case Western Reserve University. His principal physics interest, the thermodynamic behavior of systems of large numbers of particles subjected to a variety of driving forces, had its roots in his graduate studies at Yale. With his research director, Lars Onsager, Machlup published in 1952 two frequently cited Physical Review papers on what became known as the Onsager-Machlup-Laplace approximation. The theory addresses losses in thermodynamic systems and applies to a very wide variety of constituents and forces: nuclei in magnetic fields, atoms in a laser, molecules in chemical reactions, ions passing through biological membranes. Throughout his long career, Machlup tackled many of these, including: formation of vacancies in crystal lattices, population inversions and “negative temperatures”, noise in semi-conductors, transport in frog-skin, biological effects of low-field electromagnetic radiation.

Stefan was born in Vienna in 1927 and brought as a child to America. He earned his BS at Swarthmore, PhD at Yale, and enjoyed a string of post-doctoral appointments, including positions at Cambridge, Bell Labs, U of I Urbana, and Amsterdam.

Stefan published an introductory text for pre-med physics students and was a frequent contributor to conferences of the AAPT. He enjoyed working with high school physics teachers and helped to develop new teaching materials. He was an accomplished, semi-professional cellist, who performed with great passion in chamber groups for many decades, from his college days to recent annual “university faculty galas”. Fluent in five modern languages, progressive in his views, Stefan was a delightful colleague and an asset to the institution.

Dr. Stefan Machlup

The Plain Dealer