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 to note that the lowest temperatures are obtained when the ratio of cold air to hot, regulated by means of the valve on the hot end, is approximately 1 :3.

These effects would seem to indicate that the Second Law of Thermodynamics is being successfully violated, and this in turn suggests that the demon proposed by Clerk Maxwell has been found and put to useful work!

The Second Law has often been dressed up in fancy terminology, but all it really says is (1) that water naturally flows down hill, not up, and (2) that heat naturally flows from hot bodies to cold, not the reverse. In other words, all actions that take place spontaneously tend to bring a system to equilibrium or to rest. As a secondary point, it may be noted that any process starting of and by itself—whether or not it is allowed to proceed to equilibrium—is accompanied by some loss of capacity for self-starting. This loss of capacity for spontaneous change is measured by its gain in entropy, indeed can serve as a basic definition of entropy. It will be noted that no loss of energy is involved; only the degree of availability of the energy to do useful work has been lessened.

A little reflection brings out an interesting corollary to the above: Any action that starts of itself represents a tendency to achieve a state of maximum probability, and the achievement of maximum probability is also the attainment of maximum entropy. When heat flows from a hot body to a colder one; when water flows down hill, both maximum probability and maximum entropy are being attained. Similarly with any other such action you care to name.

It seemed that Monsieur Ranque's device violated this law. Air is certainly a well mixed substance, and the number of molecules in a unit volume is fantastically large. A tremendous aggregation of gaseous molecules in completely random movement simply must arrive at the most probable configuration of complete randomness in short order. Yet the device Monsieur Ranque patented in 1934 apparently effects a separation of hot molecules from cold with consequent loss of entropy from the system as a whole. The action is strikingly similar to that of the demon first conceived by Clerk Maxwell.

Clerk Maxwell, remarkable physicist of the last century, recognized the statistical nature of temperature. In a gas of a certain observed temperature, a large percentage of molecules will have a kinetic energy content greatly higher than that corresponding to the thermometer reading, and a large percentage will have a much lower kinetic energy content. The temperature reading is merely the average value. That the same reading is obtained at all points in the system simply means that the

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