To a Would-Be Scientific Revolutionary

Dear Mr X,

I am sorry you did not appreciate my reply to your long essay pointing out the errors in the laws of thermodynamics as stated in textbooks. As I said, thermodynamics is a mature subject. College students repeat the classical experiments as part of their courses. If there were significant errors in college level textbooks they would have been found and corrected years ago.

You accuse textbooks of excessive reverence for the statements of early scientists. However, you seem to be unaware that those very books point out that Sadi Carnot, the founder of thermodynamics, was mistaken in thinking that heat energy was indestructible. Perhaps you missed this because you too have made the same mistake. Despite your declaration to the contrary, heat energy can be transformed into mechanical energy. I suggested, as gently as I could, that the immensely complicated device which you had built to prove your point was not suitable for that purpose.

As have many other people, you have failed to appreciate that the equation which relates thermodynamic efficiency to the input and output temperatures of an engine makes no reference to the type of the engine. The measured efficiency of any engine is its potential thermodynamic efficiency multiplied by its actual mechanical efficiency. Carnot envisioned a heat engine having 100% mechanical efficiency. Remarkably, he also showed how, at least in principle, one could be built. It runs on the so-called Carnot cycle.

This does not in the least imply that the thermodynamic efficiency equation applies only to engines with reciprocating parts or that some other type of engine, such as a turbine, can be more efficient than a Carnot engine. The Carnot limit applies to all conceivable engines. The mechanical efficiency of an engine can be improved but cannot exceed 100%. Thus the overall efficiency of no engine can, even in theory, exceed the limits set by its input and output temperatures.

By writing a long, detailed response I was trying to help you. I didn't need to do that and you could have been more appreciative. I regret that you have put so much effort into a vain attempt to prove the textbooks wrong. The next time you find something in a textbook which you do not understand, please consider that this is because you have failed to grasp the principles involved, not that the writer of the textbook didn't know what he was talking about.

Tom Napier

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