Fluctuation Theorems

Fluctuation Theorems describe how the probability of observing temporary, small violations of the second law of thermodynamics—like a system spontaneously becoming more ordered—fits within our understanding of physics. While the second law states that entropy (disorder) tends to increase overall, these theorems show that tiny, brief decreases in entropy can happen randomly, especially in small systems or over short times. They quantify how likely these fluctuations are, demonstrating that such events are rare but not impossible, and help deepen our understanding of thermodynamics at microscopic scales.