It's a truism of science that concepts and inventions are rarely attributed to the person who actually came up with them. Most concepts and inventions have several creators, from the Pythagorean theorem to the radio. But one particular concept — the first law of thermodynamics — has two creators who came up with it only a year apart. And here's the tragic tale of why we measure energy in joules instead of mayers.

The history of science is dense with historic rivalries. One of the most famous was the Tesla/Edison fight that ended with present success but lasting ignominy for Edison. Tesla, meanwhile, has become something of a scientific folk hero, for all the good it did him during his life. An earlier rivalry kicked up between two other scientists over the laws of thermodynamics, and it nearly cost one scientist his life.