Macroscopic time-asymmetry emerging from time-reversible microscopic dynamics
Newton's laws (and quantum mechanics) are time-reversible: if you flip all velocities, the system retraces its path. Yet macroscopically, gas never spontaneously unmixes. The "reverse" movie looks wrong.
The resolution lies in initial conditions and phase space volume: states that look "ordered" occupy an exponentially tiny fraction of phase space. A randomly chosen microstate from a "mixed" macrostate will almost never be one that leads to unmixing.