C of L49...Maxwell 's Demon: a history

[Mark Kohut]

p. 86 hc...I won't link here to wikipedia or anything re JCMaxwell, you can....I just want to add the personal association of the bearded Victorian that he was with the bearded Smith Brothers of the famous coughdrops. (No P connection;  thanks for indulging me)
 
He was raised and remained a VERY Christian-believing scientist and was anti-Darwin's theory. 
 
Maxwell is widely acknowledged as the nineteenth century scientist whose work had the greatest influence on twentieth century physics. His electromagnetic theory and its associated field equations 'paved the way for Einstein's special theory of relativity, which established the equivalence of mass and energy. Maxwell's ideas also ushered in the other major innovation of 20th century physics, the quantum theory.  ----from an online bio, not wikipedia
 
Maxwell's Demon---wikipedia: 
Maxwell conceived a thought experiment as a way to explain the statistical nature of the second law. He described the experiment as follows[2]:
... if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are as essentially finite as our own, would be able to do what is impossible to us. For we have seen that molecules in a vessel full of air at uniform temperature are moving with velocities by no means uniform, though the mean velocity of any great number of them, arbitrarily selected, is almost exactly uniform. Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower molecules to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics.
 
Schematic figure of Maxwell's demon
In other words, Maxwell imagines one container divided into two parts, A and B. Both parts are filled with the same gas at equal temperatures and placed next to each other. Observing the molecules on both sides, an imaginary demon guards a trapdoor between the two parts. When a faster-than-average molecule from A flies towards the trapdoor, the demon opens it, and the molecule will fly from A to B. The average speed of the molecules in B will have increased while in A they will have slowed down on average. Since average molecular speed corresponds to temperature, the temperature decreases in A and increases in B, contrary to the second law of thermodynamics.