# Geek Trivia: Eye for an Einstein

How did Albert Einstein express his infamous energy-mass equivalence equation in its original 1905 publication, wherein the mathematical construct bore little resemblance to its most famous incarnation, E=mc<sup>2</sup>?

On Nov. 9, 1921, Albert Einstein won the Nobel Prize in Physics for his 1905 paper on the photoelectric effect, just one of five seminal papers he published in what history would call his Annus Mirabilis or "Year of Wonders." Einstein's other four 1905 papers touched on molecular dimensions, Brownian motion, and -- to ensure Uncle Albert's everlasting fame -- special relativity and energy-mass equivalence.

While all five of these papers bear some interrelation beyond sharing the same genius author -- after all, they're conjoined by the principles of modern physics -- special relativity and energy-mass equivalence are particularly and rather famously intertwined.

Without getting too technical (mostly because this Trivia Geek is no quantum physicist), Einstein's special relativity made the bold assertion that the speed of light is a fixed constant and that the progress of time is variable -- rather than the other way around. This refuted the rules laid down by the godfather of physics, Isaac Newton, which held that speed is relative and time is a constant.

When observed as a fixed constant, the speed of light can unlock other key characteristics of space and time -- namely, the relationship between matter and energy. Again, to grossly simplify, all matter is merely bound energy. With a simple formula, you can thus convert all matter in the universe into the currency of energy, which makes untold calculations possible by virtue of a simple equation. You've probably heard of it: E=mc2.

Technically speaking, E=mc2 is the core equation for an object's rest energy, which is to say the energy possessed by an object when it isn't moving and isn't in a position to move. (It's actually a rather minor component of Einstein's larger theory of General Relativity.) That is, rest energy is separate from kinetic or potential energy, which were the bread-and-butter forces of classical Newtonian mechanics.

Einstein proved that even apart from movement, all objects that possess mass also possess energy. You can find out exactly how much energy with the simple calculation of mass multiplied by the square of the speed of light, E=mc2.

The crazy thing is, you won't find this famous equation in any of Einstein's papers published before, during, or after 1905. That's because Einstein never wrote his most famous equation in its most famous form.