Albert Einstein's letter on relativity fetches $106,250

LONDON: A signed letter written by German scientist Albert Einstein to his closest friend Michele Besso, expressing joy at the success of his theory of relativity, has fetched $106,250 at an auction.

The letter is postmarked Berlin and dates December 10, 1915. It was originally estimated to be worth $30,000.

"The boldest dreams have now been fulfilled," Einstein wrote in the letter, rejoicing in his theory's success.

Einstein had set out the key elements of the general theory of relativity in four magisterial papers submitted to the Prussian Academy of Sciences between November 4 and 25, according to the British auction house Christie's.

The postcard was a part of a collection of letters written by Einstein to his college friend Besso that was auctioned online at Christie's. The collection of 63 letters was sold for a total of $1,234,625.

Einstein's general theory of relativity is one of most important developments of 20th-century physics.

Published in 1916, it explains that gravity is in fact curvature of space and time.

The postcard, written in German, opens with news of an intended journey to Switzerland, after Einstein was assured that his eldest son, Hans Albert, wished to spend time with him.

Einstein signed off the letter with 'greetings from your happy but rather worn out Albert'.