This 1934 photograph shows Einstein in front of a blackboard, deriving Special Relativity for a group of students and onlookers. Although Special Relativity is now taken for granted, it was revolutionary when Einstein first put it forth, and it isn’t his most famous equation; E = mc² is. (Credit: public domain)

The true meaning of Einstein’s most famous equation: E=mc²

More than any other of Einstein’s equations, E = mc² is the one that most people can name. But what does it all mean?



The Universe is out there, waiting for you to discover it.

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Ethan Siegel

The Universe is: Expanding, cooling, and dark. It starts with a bang! #Cosmology Science writer, astrophysicist, science communicator & NASA columnist.