Irreversibility and the quantum arrow of time
Irreversibility is one of the most intriguing concepts in physics. While microscopic physical laws are perfectly reversible, macroscopic average behavior has a preferred direction in time. According to the second law of thermodynamics, this arrow of time is associated with a positive mean entropy production. We will discuss the physics of the quantum arrow of time and present results of recent experimental investigations of irreversibility in a nuclear magnetic resonance setup.