Everyone knows the names of the geniuses of science: Newton, Lavoisier, Darwin, Einstein. Revolutionaries who single-handedly changed the world and our understanding of it …
But, as those of you who have been paying attention to my column will know, that’s not quite how it works. Yes, there are definitely revolutions in science. But rarely, if ever, does one guy Kobe it and actually do all the work. So, it’s fitting that the discovery of the conservation of energy was a group effort.
Julius von Mayer was born in Heilbronn, Germany in 1814. He was a real party animal in university, part of a fraternity, and better known for being good at cards than for studying. When the university started cracking down on secret societies, he was arrested for his fraternity activities and got suspended from school for a year. Mayer went on a hunger strike to protest the decision, but it took six days for his friends to convince him that resistance was futile. Eventually, in 1838, he graduated with a degree in medicine.
After that, Mayer took a job as a ship’s doctor (quite the grad trip, eh?) One day, when he was taking a blood sample from a sailor off the coast of Indonesia, he noticed that the blood was a much brighter shade of red than usual. He started wondering: What if it was the tropical weather? Maybe the body gets its heat from chemical reactions when it consumes food. Maybe chemical changes can be converted into heat. Oh, then perhaps mechanical work can be too.
It was already known at the time that more heat input was required to heat a gas at constant pressure than at constant volume (in modern terms, C[p] > C[v]). Mayer’s theory was that in a constant-pressure heating process, part of the heat input was converted into mechanical work in order for the gas to expand and maintain the pressure. In 1842, after returning to Germany, he published his conclusions with an estimate for the work-heat conversion factor.
Unfortunately, Mayer, being an “outsider”, never really got much respect from the scientific community. To make matters worse, he saw three of his children die in their childhood. After attempting suicide, Mayer committed himself to an asylum, but that just seemed to make matters worse. Eventually, he went home and decided to retire from scientific work, which was bringing back bad memories. Slowly, he began to regain his sanity, and in the late 1860s, recognition finally arrived when the French and British scientific academies gave him awards.
Across the Channel, James Prescott Joule was born in Manchester in 1818, and his dad owned a brewery. He never went to university. His interest in physics began while trying to solve a very practical problem at the brewery: could an electric motor do the same job as a steam engine for cheaper? Joule soon discovered that the heat dissipated from electrical resistance was proportional to I²R, a result now known as Joule’s first law. By 1843, Joule was convinced from his experiments that energy was conserved and could be converted from one form to another. But other British scientists weren’t listening – I mean, what could someone who had no higher education really know?
Joule had to work extra hard to overcome his stigma. He designed another experiment, which would prove to have the most accurate conclusions. He hung some weights off a paddle wheel, which was in turn connected to a device which rubbed pieces of metal together. He could measure the work done by the weight (mgh) as well as the temperature increase in the metal (using some next-level thermometers), and calculated a conversion factor of 774 ft-lb/btu (which is within 1% of the true value).
Slowly, recognition from academia started coming. Joule had a huge boost when Lord Kelvin, an actual university professor, heard one of his lectures and announced that he was onto something big. In Germany, Herman von Heimholtz started coming up with mathematical equations based around conservation of energy. Another German, the physicist Rudolf Clausius, noticed a little problem with Joule and Mayer’s experiments: if you went backwards, converting heat into work, you didn’t get the same results. After some more research into reversibility, Clausius came out with an even better theory of heat, including the two Laws of Thermodynamics we know and love.
There is a bit of a debate about who “discovered” conservation of energy – most historians think Mayer published first, but Joule had the much more accurate experiments which finally convinced the scientific establishment to pay attention. But I don’t find these debates constructive. Joule and Mayer spent many years as outsiders, but eventually were vindicated. There’s enough credit to go around for both of them (and Kelvin, Heimholtz, and Clausius as well). Engineers (especially those of us in Mech who deal with energy conversion all the time) owe them a huge debt.
So if you’re failing in school or you party too much, don’t worry. There’s still hope for you. All you need is a lot of persistence and a bit of luck. And if you’re graduating? Don’t be a snob: other people without a formal education still have incredibly useful things to say.
Author’s Note: As I am graduating after this term, this is the last OTSOG article I will write. For the dozen of you who have actually read all of them, I appreciate it, thanks for the support. If you liked it, why don’t you become an Iron Warrior staff writer yourself, so this column can continue? It’s even better if you’re in a different program than me, so the audience of the IW wouldn’t have to read about fluids, materials, and energy all the time. Who wouldn’t want to learn about what Volta or Tesla did to galvanize the field of electricity? Or maybe you’re into computers, and you’ll introduce the world to the tragedies of Babbage or Turing. I promise you, the Iron Warrior staff doesn’t bite 🙂
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