HAPPY 100th ANNIVERSARY….Here’s the way Einstein originally wrote it ? in English translation, of course. The full text of his (short) article “Does the Inertia of a Body Depend on Its Energy Content?” published on September 27, 1905, is here.

In case you’re wondering how this becomes the famous e = mc?, K (on the left side of the equation) is kinetic energy (mv?/2) and L (on the right side) is energy of radiation. So it becomes:

A little bit of arithmetic, and it assumes its more famous form. And that’s all it takes to become the most famous physicist of the 20th century.