The handwritten letter of Albert Einstein that contains his famous E=mc2 equation was sold at auction for more than $1.2 million on Saturday.
The Boston-based PR auction house stated that the letter was sold for about three times more than the estimate.
The one-page handwritten letter in German to the Polish American physicist Ludwik Silberstein is dated Oct. 26. 1946.
The E = mc² equation, which was first published in a scientific journal in 1905 and explains the mass-energy equivalence in physics, is accepted as the basic concept of modern physics.
Considered one of the most important scientists in the world history, Albert Einstein was awarded the Nobel Prize in Physics in 1921 "for his services to Theoretical Physics, and especially for his discovery of the law of the photoelectric effect."