Tatiana and Paul Ehrenfest's work on the foundations of statistical mechanics and statistical thermodynamics was important to the development of those fields. "In 1911 the Ehrenfests gave an incisive analysi of the conceptual and logical status of Boltzmann's efforts to explain thermodynamics and irreversibility on a mechanical basis. In so doing they made extensive use of the phase-space representation of mechanical systems - the behavior of systems as expressed by the time a trajectory spends in certain regions of the energy surface. They also clarified how conjectures about this behavior translated into physical statements: the original ergodic theorem would justify Boltzmann's procedure, while the quasi-ergodic theorem (the statement that the trajectory comes arbitrarily near any point) would not be sufficient to do so. ... {Their] analysis made crystal clear that the introduction of suitable probability notions was esssential for a consistent implementation of Boltzman's program." --- , [tcp1995lmp] p. 599.

She performed research on the modern foundations of statistical mechanics. Of special interest to her were questions associated with the concepts of entropy and the role of chance in physical processes. Her specialty was the rigorous investigation of fundamental issues.   --- Professor Joseph Rudnick, UCLA

"Ehrenfest-Afanaseva took a professional interest in questions of education, publishing a number of monographs and articles in German, Russian, and Dutch that discussed such issues as axiomatization, randomnes and entropy, geometrical intuition and physical reality, and teaching method. ...... her writings substantially enriched physics in the Netherlands."   --- Lewis Pyenson [1T N20]

"Begriffliche Grundlagen der statistischen Auffassung in der Mechanik" (with P. Ehrenfest) , Encyklopädie der mathematischen Wissenschaften, vol. 4, part 32 (1911); English translation by Michael J. Moravcsik published by Cornell University Press (1959) as "The Conceptual Foundations of the Statistical Approach in Mechanics".

"On the Use of the Notion "Probability" in Physics," Am. J. of Phys. 26: 388 (1958).To read this article click here.

Wiskunde: Didactische opstellen. Zutphen, 1960. (This is a 164-page treatise on the teaching of mathematics; cf. [1T N20].)

Tatiana Afanaseva lived in St. Petersburg before she married Ehrenfest. Then, in Russia, women were not admitted to universities.   There were, however, special university-level institutions that allowed women to take courses in engineering, medicine, and teaching.   She attended the women's pedagogical school and the Women's Curriculum which shadowed the imperial university. [1T N20]

Sources and references consulted:

Professor Robert Finkelstein and [1T N20], [tcp1995lmp], [pe1970mk]

Regarding her impact on her husband's career, historian Martin Klein wrote the following:

"Paul Ehrenfest was not the kind of thinker who develops his ideas slowly in the solitude of his study. He had to talk about them, to work them out by by discussing and arguing them with a critical and competent colleague, and Tatyana was willing and able to play this role. Her quick and extraordinarily logical mind was a natural foil for hi more inventive one, and her urge to probe to the very bottom of an idea was as deep as his own. Even when the physical problems for which a theory was invented were not known to her, Tatyana Ehrenfest could sometime strike directly to the nub of the matter and raise a question of logical structure that set her husband off on the right track." [pe1970mk]

Ehrenfest-Afanaseva traveled to the University of Göttingen in 1902 where she met, and later married Paul Ehrenfest. For the first few years of their marriage they lived in Germany and Austria and then settled in St. Petersburg, Russia, in 1907. Russian law forbade Jews and Christians to marrry, and since Tatiana was Russian-Orthodox and Paul was a Jew, they could only live together legally by declaring that they did not have religion. [1T N20]

Later, when Einstein tried to appoint Paul to replace him in Prague, at the University's Institute of Physics, Paul faced another religiously-related law. All universities in the Austro-Hungary Empire refused to appoint any professors who did not have religious affiliations. Since Paul had announced that he did not have a religion, in order to live with Tatiana in Russia, he could not suddenly announce that he was once again Jewish. Despite Einstein's recommendation that he declare his religious affiliation again, Paul refused to do so and, thus, lost the opportunity to work in Prague. [pe1970mk]

Field Editor: Joseph Rudnick

Original citer's name: