Introduction.

that heat is a form of motion. This conception is, in fact, not strictly necessary for the general theory of heat Wärmelehre: the study of thermodynamics and, as is well known, was not shared by Robert Mayer Julius Robert von Mayer (1814–1878), one of the founders of the law of conservation of energy. Certainly, the further development of "Energetics" A 19th-century school of thought that sought to describe all physical phenomena through energy transformations alone, without assuming underlying mechanical or atomic models is highly significant for science; however, up to now its concepts are still far too unclear and its principles expressed with far too little precision for them to displace the sharply defined theorems of the old theory of heat, which are always clearly applicable to new, specific cases where the result is not yet known in advance.

Now, in the field of electrodynamics, the old mechanical explanation of the relevant phenomena based on "action-at-a-distance" forces Fernkräfte: forces acting across space without a mediating medium, common in German physics before Maxwell—which was particularly common in Germany—has suffered shipwreck. Indeed, although Maxwell himself speaks with the greatest respect of Wilhelm Weber's theory—who, by determining the conversion factor between electrostatic and electromagnetic units and discovering its relationship to the speed of light, had even provided the first stone for the edifice of the electromagnetic theory of light—some went so far as to claim that Wilhelm Weber's mechanical hypothesis regarding the effectiveness of electrical forces had actually been harmful to the progress of science.

In England, views on the nature of heat as well as on atomism remained fairly untouched by this. But precisely on the Continent, where previously the assumption of central forces between material points (so useful in astronomy) had been generalized into an epistemological requirement—and where, for that reason, Maxwell's theory of electricity had been scarcely noticed even a decade and a half ago (it was only this generalization that was harmful)—people now generalized the provisional character of every specific hypothesis once again. They concluded that the assumption that heat is a motion of the smallest particles would also, in time, be recognized as false and cast aside.

In opposition to this, it must be remembered that the entanglement of the kinetic theory with the doctrine of central forces is merely accidental. The gas theory Gastheorie: the kinetic theory of gases even shows a special kinship with Maxwell's theory of electricity in that it regards visible motion