Albert Einstein thought he had made the breakthrough of his career and wrote a letter to his son sharing the news. It turned out not to be so. But in his letter, the physicist took a rare moment to reflect on his life's work and offered a glimpse into his fond relationship with his son.
The one-page handwritten letter is being auctioned this week by Boston's RR Auction. It could fetch more than $100,000 US, company officials said.
In the letter, which is estimated to be from 1929, Einstein tells his son, Eduard Einstein, that he has made a major discovery.
"I am now very happy because I finally solved to my total satisfaction, after immensely intensive work, my gravitation-electricity problem," he wrote, according to a translation of the German letter. "This, in a way, concludes my life's work — the remainder simply is bonus material."
The problem became known as his Unified Field Theory, an attempt to explain gravity in terms of the laws of electromagnetism. Einstein published the theory in 1929, but it put him at odds with many in the physics community who disagreed with it, according to officials at the auction house.
Despite his excitement in the letter, Einstein continued to work on the problem and never fully solved it. It remains unsolved today.
"Einstein does not usually talk about his life's work — that's what makes the letter spectacular," Robert Livingston, executive vice-president at RR Auction, said in a statement.
The letter also depicts Einstein as a caring father to Eduard, who was finishing high school at the time. He writes about a "deep inner kinship" between them.
"It seems to me it has been so long since I have seen you, and I am longing to have you around me once again," Einstein wrote.
He later invites Eduard to visit for Easter and discusses his upcoming 50th birthday party. He calls Eduard by his nickname, Tetel, and recommends books to him.
Eduard was later diagnosed with schizophrenia, Livingston said, and had his first breakdown in 1930. He went on to live much of his life in psychiatric institutions.
Einstein signed the letter simply "Papa."