2025 Volume 34 Pages 35-68
One of the key objectives in the study of time in physics is to understand the emergence of macroscopic irreversibility from microscopic reversible dynamics. Prigogine proposed a worldview based on the probabilistic picture, in which irreversibility appears as a fundamental property of the dynamical system itself. This idea was formulated through the use of the complex spectral representation. On the other hand, contemporary physics in the study of isolated quantum systems with a small number of degrees of freedom explains irreversibility from the trajectory picture by using the concept of typicality. This paper reviews Prigogine's theory of irreversibility and compares it with the concept of typicality. By placing Prigogine's approach at the center, it provides a conceptual overview of how irreversibility is treated in physics, focusing on the contrast between probabilistic and trajectory pictures.
