Albert Einstein's handwritten letter has recently been reported to have been sold to an anonymous collector at auction, for $1.2 million.

The so-called "lost letter," a Live Science report specified, was written to the physicist's rival in the field, contained the former's famous equation, E=mc2, which is one of Einstein's four known examples of the equation in his own handwriting.

This was according to archivists from the Einstein Papers Project at Caltech and the Hebrew University of Jerusalem.

Written in German on paper with a blind-stamped personal Princeton letterhead of Einstein, the one-page letter was sent to Ludwik Silberstein, a Polish American and well-known critic of some of the theories of this great physicist at that time.

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(Photo: David Silverman/Getty Images)
A detail from Albert Einstein's General Theory of Relativity which is on display in its entirety for the first time, at the Israeli Academy of Sciences and Humanities on March 9, 2010, in Jerusalem, Israel.

The 'E=mc2' Equation

This Live Science report also specified that the document has an "A. Einstein" signature, and it's dated October 26, 1946. It stayed in the archive of Silberstein and was auctioned off recently by his family.

Moreover, the document was expected to sell amounting to $400,000, but it ended up going for thrice the expected cost that following a late bidding war between two parties in mid-May, said RR Auction, the Boston-based firm that sold Einstein's handwritten letter.

RR Auction executive vice president, Bobby Livingston said the E=mc2 equation is the world's most famous equation and for that reason, it is an essential letter from a physics point of view.

Einstein initially published this equation, energy equals mass times the speed of light squared, in a 1905 scientific research.

The notion behind this equation is that energy and mass are vitally just different forms of the same thing, and can shift from one to the other, though the conditions needed to do so, are extreme.

A Handwriting That Changed the Notion on Mass and Energy Forever

Before the E=mc2 equation got published, physicists considered mass and energy as two distinct entities that were just loosely related to each other.

However, in only a few strokes of Einstein's pen, he changed this notion forever by proving that they were in fact, two sides of a similar coin, a Discover Magazine article specified.

The equation enabled Einstein as well, to prove his special relativity theory, stating that nothing can travel than the speed of light in a vacuum as an object that travels at the speed would have infinite mass and thus need infinite energy to move.

Special relativity changed physics too, by introducing the idea of space-time, which set the groundwork for the later theory of Einstein for general relativity, published in 1915.

Specifically, this presented that gravity is the outcome of distortion in space-time, resulting from objects that move through it.

Emphasis on Energy Between Masses

In Einstein's handwritten letter, he wrote the famous equation to emphasize the energy difference between a pair of masses at both infinite and specified distance from each other, as a response to Silberstein's query.

Translated from the German language, in his letter, Einstein wrote, the question can be answered from the E=mc2 formula minus any erudition.

Meanwhile, collectors were drawn as well, to Einstein's one-page handwritten letter as it mentioned the necessity for a unified field theory, a single concept that ties all fundamental forces of nature together, presently regarded as modern physics' holy grail.

Scientists recently reported too, the discovery of another handwritten letter by Einstein, this one suggesting that there could be a connection between birds' migration and an unidentified process of physics.

A similar report is shown on Outpost News's YouTube video below:

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