Comment by roywiggins
4 years ago
Hard to see how this works when Brownian ratchets don't.
Also: "Léon Brillouin in 1950 discussed an electrical circuit analogue that uses a rectifier (such as a diode) instead of a ratchet. The idea was the diode would rectify the Johnson noise thermal current fluctuations produced by the resistor, generating a direct current which could be used to perform work. In the detailed analysis it was shown that the thermal fluctuations within the diode generate an electromotive force that cancels the voltage from rectified current fluctuations. Therefore, just as with the ratchet, the circuit will produce no useful energy if all the components are at thermal equilibrium (at the same temperature); a DC current will be produced only when the diode is at a lower temperature than the resistor."
But if the diode at a lower temperature than the resistor can generate current, then the current should raise the temperature of the resistor, meaning that it will stay running.
That seems unlikely, as I understand thermodynamics. Can anyone explain?
Current in a resistor will raise the resistor's temperature.
Current in a diode also raises the diode's temperature.
It takes work to keep the diode at a lower temp.
The diode won't be at a lower temperature for very long.