Maxwell — Boltzmann Statistics

The original explanation of the action of a thermal engine was a very mechanistic one: heat or phlogistic fluid falls from a higher to a lower temperature. This model was developed by the French scientist Sadi Carnot who actually himself found it to be not completely correct: it leads to the principle of conservation of heat (which in fact does not hold). The correct answer was given later by Clausius: the temperature is not the coordinate playing the role of potential (the vertical coordinate in the case of falling material bodies) but rather an analogue of a force. Notwithstanding its incorrectness, the idea that the passing of heat from high temperature bodies to low temperature bodies must be connected with a kind of ‘work’ was very fruitful. Thermodynamics as a branch of physics explaining specific laws of the ‘movement’ and transformation of heat is based on this idea.