Commemoration (Journal of Non-Equilibrium Thermodynamics)

On October 23, 2002 professor Istváan Gyarmati departed from life. The Hungarian and the international thermodynamic community lost a prominent member.

Professor Gyarmati was born in Szeged (Hungary) Sept 5, 1929. After maturation he went to learn for chemistry in József Attila University Szeged but graduated as a teacher for mathematics and physics from Kossuth Lajos University Debrecen. He was an assistant at the Department of Theoretical Physics there from graduation to 1955. In 1955 his life long job at the Technical University Budapest started with a three year scholarship. In 1958 he became fellow at the Department of Physical Chemistry; in 1964 professor. In 1968 he organized the Department of Physics in the Agricultural University Gödöllő and lead it until 1975 but kept his job at TU Budapest as a second one. In 1975 he went to the Central Research Institute for Chemistry of the Hungarian Academy of Sciences and remained there until retiring. He took great part in the organization of Institute of Physics TU Budapest 1973; he was the spiritual organizer of a chair for thermodynamics that was formally a group---later a department---of Institute of Physics. Finally, the chair was organized officially, too, with the name of Department of Chemical Physics and he was its first leader until 1994. He was an obliged scientist and teacher; renewed the education in physics of students for chemical engineering at TU Budapest and for mechanical engineering at Agricultural University Gödöllő. In the middle of the 80's he shared the interest between science and society; played initiating role of the later social changes in Hungary.

Professor Gyarmati's activity in thermodynamics of irreversible processes started in Debrecen. His contribution to the field theoretical formulation of non-equilibrium thermodynamics is important. He generalized the variational principles in irreversible thermodynamics and proposed a very general one---nowadays referred to as Gyarmati's principle---and developed its integral form called GPDP (General Principle of Dissipative Processes). His book made considerable influence on modern thermodynamics; appeared in Hungarian (1967), in English (Non-Equilibrium Thermodynamics, Springer, Berlin, 1970), and in Russian (1974). Gyarmati's variational principle applies generally in the realm of the linear Onsager theory and for some non-linear phenomena; a number of well known variational principles---e.g. those of plasticity---are special cases. The non-linear generalization of Onsager's reciprocal relations---the Gyarmati--Li reciprocal relations---proved rather a necessary and sufficient condition for the validity of the variational principle. GPDP is a background for numerical methods concerning dissipative processes, as well. Gyarmati's variational principle is particularly useful in the thermodynamic theory of liquid crystals, when Onsager's equations are clumsy to formulate both in tensorial and scalar form; the variational principle displays elegant and graceful expressions.

Nevertheless, he insisted on the original Onsagerian concept (not on the modified version referred to as "Classical Irreversible Thermodynamics"), he considerably contributed to the development of "Extended Irreversible Thermodynamics", too, with a term "Wave Approach of Thermodynamics". He made efforts to integrate chemical reaction kinetics into irreversible thermodynamics. Nevertheless, the usual theory of chemical reactions fits well---in linear order---to Onsager's thermodynamics, a general non-linear theory is desirable. These efforts remained incomplete. The rigorous and accurate wording makes even his early works valuable for advanced study.

Results were honored with Hungarian Academic Prize 1970 and Hungarian State Prize 1975; he was elected into the Hungarian Academy of Sciences 1982. He was member in the advisory board of Journal of Non-Equilibrium Thermodynamics (from its foundation), Zeitschrift für Physikalische Chemie, Acta Physica Hungarica, and Természet Világa (Hungarian scientific journal for the public).

Professor Gyarmati had no children but scientific children and grandchildren were thrown into mourning when attending the funeral together with coworkers, colleagues, friends, and family.