Thomas Edison and Albert Einstein crammed so much awesome into their days that they could go to lunch with their friends and be like “Oh hey, I just changed everything you thought you knew about everything today. I’ll have the turkey on whole wheat.” That was more or less what they both did on this date, albeit 28 years apart.

It was 137 years ago on November 21, 1877, that Edison announced he had invented the phonograph. It was apparently as much a surprise to him as anyone else. Devices that recorded sound had already been invented, but Edison had been working on a method of capturing sound through grooves on a cylinder that would also play it back. (How earlier devices could claim to have recorded “sound” in any meaningful sense when they couldn’t reproduce it is a problem for philosophers, I guess.) Edison’s work apparently came along much quicker than he had hoped for. After a worker produced the first phonograph from Edison’s sketches, Edison prepared to test it.

“I didn’t have much faith that it would work, expecting that I might possibly hear a word or so that would give hope of a future for the idea,” he said later. But when he shouted “Mary had a little lamb” into the device’s recorder and played it back, it reproduced his words exactly. “I was never so taken aback in my life. … I was always afraid of things that worked the first time,” Edison said. And just like that, recording and playing back sound was a thing.

Nearly three decades later, Einstein created what was later called the Annus Mirabilis, or “miracle year,” for physics in 1905 by contributing four extraordinary papers to the “Annalen der Physik” (“Annals of Physics”) journal. The journal had already published three of the papers by November, covering topics like the photoelectric effect and special relativity, but on this date 109 years ago they published the paper containing the idea that would be most associated with Einstein’s name.

It was called "Does the Inertia of a Body Depend Upon Its Energy Content?" and it tackled ideas about the relationship between energy and mass that had been around for centuries. In it, Einstein built upon previous speculation and said that all energy and mass within a body had a constant relationship whose proportion could be determined by multiplying the mass by the speed of light squared. Einstein explained the idea in depth in this paper, but after World War II, he derived a simpler equation to express it to the average person: E = mc^2. The equation helped explain how nuclear reactions could give off massive amounts of energy with such a relatively small loss of mass. The equation doesn’t fully account for the energy lost in nuclear reactions, but it gets at the idea broadly enough that TIME put Einstein, the equation, and a mushroom cloud on its cover to help people understand the atomic bomb in 1946.

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