An example of analogy used by a scientist:
"Carnot had analogised heat engines to water mills. In the latter, water creates energy in the form of work as it streams downhill. In heat engines caloric fluid was supposed to do the same as it flows form hot furnace to cool sink. The same amount of both substances leaves their respective devices as enters. Neither water nor caloric fluid are destroyed.
Clausius abandoned this comparison. Though water enables a mill, it does not turn into work. That derives from gravity. Water at a height possesses potential energy that becomes work with downhill flow."
Paul Sen (2022) Einstein's Fridge. The science of fire, ice and the universe. William Collins.
[Note that energy cannot be created nor destroyed (the principle of conservation of energy) so the idea that energy was created in a mill is an alternative conception.]
Read examples of scientific analogies
