Figure 21.1 — Violation of the second law for microscopic systems Figure 21.1 — Violation of the second law for microscopic systems. Experimental confirmation of the fluctuation–dissipation theorem, which predicts measureable violations of the second law for small systems over short time scales. The histogram shows the dimensionless time-averaged entropy production from 540 experimental trajectories of a colloidal particle in an optical trap after initiation of stage translation: at short times (10 ms, black bars) the trajectories are distributed nearly symmetrically about zero with nearly equal numbers of trajectories consuming and producing entropy; at longer times (2000 ms), the entropy-consuming trajectories occur less often and the mean entropy production shifts towards more positive numbers.Reprinted figure from Wang et al., Phys. Rev. Lett. 89, 050601. Copyright (2002) by the American Physical Society.