Three Pages That Changed the World

In 1905, a twenty-six-year-old clerk in the Swiss patent office in Bern did something extraordinary in his spare time: he rewrote physics. Four times.

Albert Einstein's "miracle year" produced a paper on the photoelectric effect (the work that would win him the Nobel Prize in 1921), a paper explaining Brownian motion, and the special theory of relativity. But the quietest of the four may have been the most profound. On September 27, 1905, the journal Annalen der Physik received a three-page paper titled "Does the Inertia of a Body Depend Upon Its Energy Content?"

The argument was disarmingly simple. Imagine a body that emits two equal flashes of light in opposite directions. The light carries energy away — and Einstein showed, with a few lines of reasoning from his relativity principle, that the body must lose mass in exact proportion to the energy radiated. Mass and energy, he concluded, were two forms of the same thing.

Here is a detail worth getting right: the paper did not print E=mc². Not in that form. Einstein wrote the relationship in the notation of his day, and the now-famous shorthand emerged only later, as others polished the idea. What the September paper established was the principle itself — that a body's mass is a measure of its energy content — in three pages, by a man with no university post, working evenings after evaluating patent applications.

The paper was published on November 21, 1905. At the time, almost no one noticed. There was no press conference, no headlines — just another article in a physics journal. It would take decades for the world to grasp what had been set loose: the energy locked inside the atom, the power of stars, the physics of nuclear weapons and nuclear power alike.

The miracle year had been building quietly. That same year Einstein also submitted his doctoral thesis to the University of Zurich, and all four landmark papers appeared in the same journal, Annalen der Physik. Almost nobody noticed at first — but Max Planck, one of Germany's leading physicists, was among the earliest to grasp what relativity meant, and he championed the unknown clerk's work. Within a few years, the patent examiner was the most talked-about physicist in Europe.

Einstein later regarded the mass-energy relation as the most significant consequence of special relativity. A clerk wondering what light does to matter had found the exchange rate between mass and energy — the idea that would define the twentieth century — and mailed it to a journal on a September day in 1905.

No verified public-domain or Creative Commons image of Einstein from this period could be confirmed for this story, so it appears without one.