E + M = Ethel Michanowski, a previously unheard-of mistress of Albert Einstein, according to newly released papers of the world’s most famous scientist.

Mrs Michanowski, a Berlin socialite, was intimate with the German-Jewish physicist in the late 1920s and early 1930s and became so enamoured that she pursued him to England, according to letters made public yesterday by the Hebrew University of Jerusalem.

Covering the years 1912 until his death in 1955, the correspondence, between Einstein and his first and second wives and their children, consists of almost 3,500 pages.

Extraordinarily, his near-daily letters to Elsa, his second wife, and Margot, his stepdaughter, contain open discussions of his extramarital flings, and how his lovers — he is known to have had at least ten — showered him with “unwanted” affections.

Prominent among more than 1,300 letters released yesterday was Mrs Michanowski. Mentioned in three, she was a friend of Einstein’s stepdaughters and about 15 years younger than him.

In a letter to Elsa he wrote: “Mrs M. definitely acted according to the best Christian-Jewish ethics: 1) one should do what one enjoys and what won’t harm anyone else; and 2) one should refrain from doing things one does not take delight in and which annoy another person. Because of 1) she came with me, and because of 2) she didn’t tell you a word. Isn’t that irreproachable?”

To his stepdaughter in 1931 he confided: “It is true that Mrs M. followed me [to England] and her chasing after me is getting out of control . . .” Between the mid-1920s and the time that he emigrated to the United States, these affairs appeared to have included a Margarete, an Estella, two Tonis and Ethel, with all of whom he went sailing, read books and attended concerts.

The collection lay in the university’s Einstein Archives for years, but was not made public in accordance with the wishes of Margot, who stipulated that they should not be revealed until 20 years after her death in July 1986.

Barbara Wolff, an archivist, said that they painted a more complete portrait of the man.

“It added colours to the image we had of Einstein before. Now we have a high-resolution picture.”

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