Gas particles collide elastically. Starting from a non-equilibrium state, the velocity distribution evolves toward the Maxwell-Boltzmann curve while entropy increases.
Entropy: 0.000 T_eff: 0.000 Collisions: 0
Entropy S = -∫ f(v) ln f(v) dv increases toward equilibrium (H-theorem). MB: f(v) ∝ v² exp(-mv²/2kT)