Feynman’s Flashing RatchetA gear that only turns one way sounds like it should let you harvest energy from random jiggling for free — Feynman showed that trick secretly fails. Below, specks of “dust” bounce around in the heat on a lopsided landscape. Leave the landscape switched on and they just settle into the nearest dip and sit there (blue line, flat). But flick that same landscape on and off in rhythm, and the identical random jitter turns into a steady one‑way drift (gold line, climbing) — order squeezed out of noise, just never for free.Feynman’s ratchet‑and‑pawl “paradox” (from Smoluchowski’s 1912 thought experiment) looks like it should extract useful work from pure heat, violating the second law — but a passive pawl sitting in the same heat bath is jostled exactly as randomly as the ratchet teeth, so on average it goes nowhere. Only by externally flashing an asymmetric potential on and off — actively pumping in energy and breaking time‑symmetry — does directed motion appear. It is the same trick believed to power real motor proteins like kinesin walking along microtubules, using chemical energy instead of a literal switch.