Ehrenfest, Paul

Library of Congress Cataloging-in-Publicaiion Data Ehrenfest, Paul, 1880-1933. 

Ehrenfest, Paul, and Tatiana Ehrenfest. The Concep tual Foundations of the Statistical Approach in Mechanics. Mineola, N.Y Dover, 2002. 

In his book States of Matter, [(1985), Prentice Hall, Dover] David L. Goodstein writes Ludwig Boltzmann, who spent much of his life studying statistical mechanics, died in 1906, by his own hand. Paul Ehrenfest, carrying on the work, died similarly in 1933. Now it is our turn to study statistical mechanics. Perhaps it will be wise to approach the subject cautiously. ... 

Lewis wrote to Paul Ehrenfest that he thought he had "hit upon something pretty fundamental." But Lewis had difficulty publishing his paper, "On the Theory of Reaction Rate," which the editor and referees of the Journal of the American Chemical Society worried was too speculative and insufficiently oriented toward experimental verification.96 Lewis ended by rejecting the radiation hypothesis, even issuing a press release to announce that a decision now had been made between the two rival theories of violent collision and radiation absorption in favor of the former. 97... 

Letter from G. N. Lewis to Paul Ehrenfest, undated but probably 1925, G. N. Lewis Correspondence, BL.UCB. G. N. Lewis and D. F. Smith promised in their paper, "The Theory of Reaction Rate," JACS 47 (1925) 15081520, to publish a demonstration that a range of frequencies of radiation affecting degrees of freedom in a molecule is responsible for chemical reaction. This paper was the subject of the letter, with anonymous referee s report, from Arthur B. Lamb to G. N. Lewis, 28 February 1925, G. N. Lewis Papers, BL.UCB. The referee said "No real unimolecular reaction has actually been observed they have been shown to be merely catalytic the idea that a unimolecular reaction is due to collision between a quantum and a molecule is not original with Lewis."... 

Paul Ehrenfest initiated a famous physics colloquium series in 1912 where he encouraged students to ask questions, and he said that no questions were stupid. ... 

Occasionally, some of the topics or puzzles in this book will seem simple or frivolous, including dropping pennies from the Empire State Building or wondering if Jesus could calculate 43 x 31. However, these are questions that fans have often posed to me, and I love some of these quirkies the best. I agree with the Austrian physicist Paul Ehrenfest who said Ask questions. Don t be afraid to appear stupid. The stupid questions are usually the best and hardest to answer. They force the speaker to think about the basic problem. ... 

Paul Ehrenfest suggested a widely used classification of thermodynamic transition phenomena according to the lowest derivative of Gibbs free energy that exhibits a mathematical discontinuity at the phase transition. 

In this concise classic, Paul Ehrenfest, one of the 20th century s greatest physicists, reformulated the foundations of the statistical approach in mechanics. Originally published in 1912 as an article for the German Encyclopedia of Mathematical Sciences , it has lost little of its scientific and didactic value, and no serious student of statistical mechanics can afford to remain ignorant of this great work. 

The conceptual foundations of the statistical approach in mechanics / by Paul and Tatiana Ehrenfest translated by Michael J. Moravcsik. p. cm. 

Adiabatic process (quantum mechanics) — In quantum mechanics a process is called adiabatic if electrons equilibrate with nuclei as they move. The concept of quantum adiabaticity was introduced by Paul Ehrenfest (1880-1933) as early as 1917, using pre-Heisenberg quantum mechanics [i]. The idea survived the advent of post-Heisenberg quantum mechanics, and was brought into its modern form by -> Born [ii]. The existence of adiabatic processes is readily proved by considering... 

Sep. 29, 1901, Rome, Italy - Nov. 28, 1954, Chicago, USA) Fermi studied at the University of Pisa, receiving his Ph.D. in 1922. Later he worked with - Max Born in Gottingen, Germany (1923) and Paul Ehrenfest in Leyden, Holland. In 1924 he returned to Italy occupying the position of lecturer in mathematical physics and mechanics at the University of Florence. He became professor of theoretical physics at the University of Rome in 1927 and professor of physics at Columbia University, USA (1939-1942). During the Second World War he participated in the Manhattan project. In 1939, Fermi and Leo Szilard (1898-1964) invented the nuclear reactor at Columbia University. They assembled the first full-scale pile , as Fermi dubbed it, and executed the first... 

Samuel Abraham Goudsmit (1902-1978). Dutch-American physicist. While a student of Paul Ehrenfest at the University of Leiden in 1925, he and fellow student George Uhlenbeck postulated the existence of intrinsic electron spin. Goudsmit was the scientific leader of Operation Alsos at the end of World War 11, whose mission was to determine the progress of German efforts toward an atomic bomb. 

George Eugene Uhlenbeck (1900-1988). Dutch-American physicist. Born in Indonesia (then a Dutch colony), Uhlenbeck studied at the University of Leiden with Paul Ehrenfest, where he, with fellow student Samuel Goudsmit, postulated the existence of intrinsic electron spin. In addition to his work on quantum mechanics, Uhlenbeck made fundamental advances in statistical mechanics and the theory of random processes. 

Introduced by Paul Ehrenfest in 1917, the adiabatic principle allows one to find the quantum conditions when an adiabatic or gradual change is imposed on a system. However, it depends on the possibihty of deriving the new motion from the known one by means of an adiabatic transformation. For example, the quantum states of a particular system are known, the new quantum states that result from a gradual change, such as the apphcation of an electric or a magnetic field, can be calculated. The quantities that preserve their values after such a transformation are known as adiabatic invariants. Ehrenfest showed that for any arbitrary periodic motion, the following quantity is an adiabatic invariant ... 

Paul Ehrenfest I have read your article in Nature with eager interest Of course... 

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