Maxwell's Demon

The demon sorts fast (red) and slow (blue) particles — decreasing entropy, but at the cost of information.

Click the door to open/close it manually

0.00
Left Entropy
0.00
Right Entropy
0
Info bits (kT ln2)
0%
Sorted
Maxwell's Demon (1867): The demon opens the door for fast particles heading left→right and slow ones right→left, creating a temperature gradient without work — violating the 2nd law?

Landauer's Resolution (1961): The demon's memory must be erased each cycle. Erasing 1 bit costs ≥ kT ln2 of energy. Information IS physical — the entropy cost is paid by the demon's memory.