Uploaded September 2019 | Updated September 2026, 1 week ago
The Second Law of Thermodynamics is one of the most important laws in all of physics. But it is also one of the more difficult to understand. Central to it are the concepts of reversibility and entropy.
Note on the definition of a "closed system." I am using the term "closed system" in the sense of the following definition from Thermal Physics by Charles Kittel: "A closed system is defined as a system with constant energy, constant number of particles, and constant volume." Another term for such a system is "isolated system," in which case "closed system" may refer to a system that has a constant number of particles but can exchange energy with its surroundings.
The Second Law of Thermodynamics is one of the most important laws in all of physics. But it is also one of the more difficult to understand. Central to it are the concepts of reversibility and entropy.
Note on the definition of a "closed system." I am using the term "closed system" in the sense of the following definition from Thermal Physics by Charles Kittel: "A closed system is defined as a system with constant energy, constant number of particles, and constant volume." Another term for such a system is "isolated system," in which case "closed system" may refer to a system that has a constant number of particles but can exchange energy with its surroundings.
