JERUSALEM - Hebrew University is expanding and digitizing a catalog of Albert Einstein's documents that now contains more than 80,000 of the scientist's writings and private correspondence from over the years.

Some of the 2,000 documents that have been scanned total about 7,000 pages and are now published on the updated site - alberteinstein.info - for the public to see. They include one of the original manuscripts for his famous formula E=mc², a postcard to his mother in her final days and a letter from his mistress 21 years his junior in which she addresses him as "Highly-regarded Professor!"

The update doubles the number of cataloged Einstein documents from 40,000 to 80,000.

"The renewed site is another expression of the Hebrew University's intent to share with the entire cultural world this vast intellectual property which has been deposited into its hand by Einstein himself," Professor Hanoch Gutfreund, the academic head of the Einstein archive, said in a statement.

When he died in 1955, Einstein left all his writings and the rights to his image to the university.

"Dear Mother, Today some happy news," he writes to his sick mom Pauline in a letter September 1919. "The British expeditions have definitely verified the deflection of light by the sun. Maja [Einstein's sister] writes me, to my dismay, that you're not only in a lot of pain but that you have gloomy thoughts as well. How much I would like to keep you company again so that you aren't left to such nasty musing…"

The twice-married Einstein has several affairs and is known to have believed that "Marriage is the unsuccessful attempt to make something lasting out of an incident."

During his second marriage to first cousin Elsa Lowenthal, he fell in love with Betty Neumann in 1923. Fifteen years later, she would write him in Princeton, N.J., from Austria asking for help immigrating to the United States as life got tougher for Jews in Europe before World War II.

"I lost my brother," she explains to Einstein who would help her get to the U.S.

The archives curator tell ABC News there are many more letters from Neumann that, along with thousands of other pages,  will be scanned and published online during the course of the year.