bobbycaputo:

The Only Known Photograph of Einstein Deriving his Famous E=mc² Equation

At a public lecture in Pittsburgh in 1934, four hundred lucky students were privy to a lecture by Albert Einstein, in which the great man mathematically derived his famous mass-energy equivalence equation: E=mc². What you see above is a photo from that lecture, and what is thought to be the only surviving photo that shows Einstein working on that derivation.

The photo was pulled from a halftone newspaper clipping by David Topper and Dwight Vincent of the University of Winnipeg, who discovered it in 2007. Sadly, everything is a bit fuzzy so you can’t really make out the famed equation itself. And even though the original article had a crisp picture of Einstein posing next to one of his blackboards, he’s next to the wrong one.

Here’s a closer look at the man and the math. If you look closely, you’ll see the mass-energy equivalence in the lower left hand corner of the blackboard on the right:

Fortunately, Topper and Vincent managed to take the blurry photo and reproduce both blackboards in their original paper. Here’s the math behind the magic, the derivation of mass-energy equivalence as presented by Albert Einstein.

In case you’re wondering why the famous equation says Δ