Скачать или смотреть Entropy and irreversibility [Difficulty: 1/4]

What is entropy? And what exactly does it measure? These are very important questions that are foundational to the theory of thermodynamics, and yet, it's not always so easy to find satisfactory answers. In this video, I will give a simple and clear definition of thermodynamic entropy, and show that it measures irreversibility.

Difficulty level: 1/4 (green).

This is based on work by E.H. Lieb and J. Yngvason. They have several publications on the subject, which present the material in various levels of detail (and complexity).
For general audiences: "A Fresh Look at Entropy and the Second Law of Thermodynamics", Physics Today 53 (4), 32–37 (2000), https://doi.org/10.1063/1.883034 (Free)

More mathematical, but without proofs: "A Guide to Entropy and the Second Law of Thermodynamics", Notices of the AMS 45 (5), 571-581 (1998), https://www.ams.org/journals/notices/... (free)

Mathematical, with all proofs and details: "The physics and mathematics of the second law of thermodynamics", Physics Reports 310 (1), 1-96 (1999), https://doi.org/10.1016/S0370-1573(98... (Free)

This video was filmed at the Department of Mathematics, Rutgers University in Piscataway, NJ, on July 22, 2023.

Very special thanks go to Sasha Pohle for helping me produce this video, as well as to Sheldon Goldstein and Joel Lebowitz for their useful feedback and comments.

00:00 Introduction
01:50 Irreversibility
03:26 Experiment: an irreversible process
04:19 Thermodynamic Entropy
07:55 Boltzmann Entropy
09:41 Experiment: time scales of irreversibility
14:50 Boltzmann Entropy and Irreversibility
19:42 Conclusion