In thermodynamics, Arnold Sommerfeld (1868-1951) (IQ=180) was a German theoretical physicist note for several famous quotations loosely connected to the manuscript Thermodynamics and Statistical Mechanics he was working on at the time of his death. [1] As the story goes, in the late 1940s, Sommerfeld had previously written a series of books in physics: mechanics (1943), electrodynamics (1948), optics (1950), etc., and was asked why he had never written a book on thermodynamics? The following is his humorous and frequently quoted answer: [2]

“Thermodynamics is a funny subject. The first time you go through it, you don't understand it at all. The second time you go through it, you think you understand it, except for one or two small points. The third time you go through it, you know you don't understand it, but by that time you are so used to it, it doesn't bother you anymore.”

In an odd twist of fate to this quote, in April of 1951, while in the midst of writing a book on thermodynamics (Thermodynamics and Statistical Mechanics), and having been nominated 81 times for the Nobel Prize (more than any other physicist), but not yet having won, Sommerfeld was killed from injuries after a traffic accident while walking his grandchildren. The book was published post-humorously the following year. [3] The following is another noted quote from his thermodynamics book: [4]

“Reversible processes are not, in fact, processes at all, they are sequences of states of equilibrium. The processes which we encounter in real life are always irreversible.”

References
1. Sommerfeld, Arnold. (1956). Thermodynamics and Statistical Mechanics: Lectures on Theoretical Physics (pg. 19). Vol. V., trans. by Joseph Kestin. Academic Press.
2. Angrist, Stanley W. and Helper, Loren G. (1967). Order and Chaos – Laws of Energy and Entropy (pg. 215). New York: Basic Books.
3. (a) Sommerfeld, Arnold. (1952). Thermodynamik und Statistik - Vorlesungen über theoretische Physik Band 5 Herausgegeben von Fritz Bopp und Josef Meixner. Diederich sche Verlagsbuchhandlung.
(b) Sommerfeld, Arnold, edited by F. Bopp and J. Meixner, and translated by J. Kestin. (1964). Thermodynamics and Statistical Mechanics - Lectures on Theoretical Physics Volume V. Academic Press.
(c) Crawford, Elisabeth. (2001). “Nobel Population 1901-50: Anatomy of a Scientific Elite”, November 15, 2007, PhysicsWorld.com.
4. Hokikian, Jack. (2002). The Science of Disorder: Understanding the Complexity, Uncertainty, and Pollution in Our World (pg. 25). Los Feliz Publishing.

External links
● Arnold Sommerfeld – Wikipedia.
● Arnold Sommerfeld – NNDB.