Einstein's Proof of E=mc²

Ever wonder how Einstein proved E=mc²? This is how.
Pi day (3.14) is Albert Einstein's Birthday! To celebrate, we'll explain 4 of his most groundbreaking papers from 1905, when he was just 26 years old.
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Minute Physics provides an energetic and entertaining view of old and new problems in physics -- all in a minute!
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Thanks to Nima Doroud and Alex Yale for contributions and to Perimeter Institute for support. Created by Henry Reich