Arrow of time

Arthur Eddington introduced the concept of the arrow of time, highlighting its significance in understanding time's directionality. The term "arrow of time" encapsulates the idea that time has a one-way direction or asymmetry, which remains an unsolved question in physics.

The arrow of time paradox emerged from the 1800s, revealing a discrepancy between microscopic and macroscopic descriptions of thermodynamics and statistical physics. At the microscopic level, physical processes are largely time-symmetric, meaning they would remain true if time's direction were reversed. However, at the macroscopic level, there is a clear direction or flow of time.