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.
In 1843, James Joule set up a little experiment that changed how people saw the world. One on side of a pulley he tied a heavy weight. On the other side, he tied a little paddle wheel. He dunked the paddle wheel in water, which he had previously taken the temperature of, and dropped the weight. As the weight fell, its energy turned the paddle wheel and stirred the water. After the weight had hit the ground, he took the temperature of the water again. It was warmer. Joule demonstrated one of the most fundamental relationships of all thermodynamics. He proved that mechanical motion and heat could be interchangeable. He started a process that got his name installed as a famous unit of energy. More importantly Joule had just come up with the e = mc^2 of his day. Mechanical energy and heat seemed like completely different things, but he proved they were equivalent, and that in thermodynamics, energy didn't just disappear. It was translated to different forms. This became the first law of thermodynamics.
And it became the torment of a man who, in an 1842 scientific paper about the interchangeability of mechanical and heat energy, had written the words, "Energy is neither created nor destroyed." Julius Robert von Mayer did not get too many breaks in life, but he did make the most of every opportunity. He was one of the younger sons of an apothecary. He went off to college, and trained in medicine. He set sail as a surgeon on a Dutch merchant vessel. There are conflicting accounts of what he learned on the voyage. Some say that he noticed that blood was a slightly different color in the tropic heat - because not as much nutrition and oxygen was required to warm the body in the tropics compared to colder climes. Some say that he put his hand to storm-churned waves and noticed they were warmer than calmer waves. Some say the trip had nothing to do with it and he first noticed a temperature shift due to motion when watching a horse stir a cauldron of paper pulp. Whatever his first inspiration was, it got him thinking about how energy can be transferred from one medium to another, and when he got back home, he started doing research on it.
By reading up on other people's experiments, and doing some observations of his own, Mayer came up with the theory of the indestructibility of energy, as well as a rough estimate of what it would take to bring a certain amount of water up a certain temperature. He sent off his scientific papers on the subject - and saw them largely ignored. At the time, he was a physician, not a physicist. He didn't have the training to present his paper in a properly academic way. He extrapolated from other people's experiments, rather than devising his own. He also was relatively unconnected in the physics community. Although Mayer kept working and refining his observations, he was not paid any heed.
Which is why the realization that Joule was getting credit for everything he had been advocating for hit him so hard. It's true, Joule did his own experiments, and those experiments were refined. Joule also met with resistance, and he wasn't able to rally acceptance for his theories until the late 1840s. That didn't help Mayer's mental well-being. As Joule's fame grew, Mayer's mental stability declined. He nearly committed suicide, and ended up in a mental institution - which in the mid-1800s was exactly as nice as it sounded. To the end of his days, he never recovered from the dismissal of his ideas and the steadily increasing praise for Joule.
Fortunately, this story has a semi-happy ending. After Mayer had recuperated, he threw himself into his scientific studies again, and became one of the first people to write about photosynthesis. Towards the end of his life, he was even honored - though primarily locally - for his ideas about thermodynamics, and was given an honorary degree by the university where he worked. Today, he is given credit as one of the founders of thermodynamics. It's still Joule's name that's most remembered, though.
Top Image: Jason Woodhead