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Einstein ‘E=mc squared’ equation letter goes up for auction

A previous letter written by Einstein featuring the famous equation sold for $1.2 million in 2021

February 8, 2024 15:35
Copy of Albert Einstein
Albert Einstein

ByDaniel Ben-David, Daniel Ben-David

2 min read

An exceptionally rare letter written by Albert Einstein that includes the world’s most famous equation is up for auction.

The typed letter, dated April 21, 1946, showcases Einstein’s legendary scientific formula, energy equals mass times the speed of light squared, addressed to high school student Jack Monsted. In the letter, Einstein corrects Monsted’s understanding, stating: “In the formula E=mc2, M is measured in gram, E in erg and c in cm/sec.”

Notably, the equals sign and comma are handwritten by Einstein in pencil, with his signature handwritten in pen.

[Missing Credit]

Monsted, the original recipient, provided a letter of provenance explaining the context. He says that while studying physics during his senior year in high school he sent a letter asking Einstein for clarification on the units of measurements in the equation. Monsted’s letter also discussed the shrinking of a yardstick as it approaches the speed of light. Einstein’s response acknowledges the inaccuracies in Monsted’s information but indicates a lack of time for corrections.