A letter written by Albert Einstein with his famous E = mc2 equation has sold at auction for more than USD 1.2 million. Boston-based RR Auction which cracked the deal said on Friday that the money generated is about three times more than the amount it was expected to get.

Archivists at the Einstein Papers Project at the California Institute of Technology and the Hebrew University of Jerusalem say there are only three other known examples of Einstein writing the world-changing equation in his own hand.

This fourth example, the only one in a private collection, only became public recently, according to RR Auction, which had expected it to sell for about USD 400,000.

The equation was first published in a scientific paper by Einstein in 1905. It explains the interchangeability of energy and mass. The equation, energy equals mass times the speed of light squared is a fundamental concept in modern physics.

The one-page letter in German is dated back to October 26, 1946, and addressed to Polish-American physicist Ludwik Silberstein, who challenged some of Einstein’s theories.

“Your question can be answered from the E = mc2 formula, without any erudition,” Einstein wrote in the letter written on Princeton University letterhead, according to a translation provided by RR Auction.

According to dnaindia.com. Source of photos: internet