How Einstein struggled with his grand theory - and the maths

To many he is the greatest scientist who ever lived, but a unique collection of Albert Einstein's letters and papers has revealed a history of struggle and failure made worse by an apparently shaky grasp of maths.

An archive which goes on sale in London next month with a price tag of $1.5m (£800,000) shows how after transforming physics and securing unprecedented celebrity status with his general theory of relativity in 1916, Einstein suffered years of frustration as he failed to top that with "a grand theory of everything". The 15 manuscripts and 33 letters penned between 1933 and 1954 give a glimpse into a period in Einstein's life when he strayed away from mainstream physics and grappled with the most fundamental questions in the universe.

"At the time, a lot of his colleagues, the theoretical physicists, felt that he was completely off the beaten path and so they didn't really take him seriously," said Howard Rootenberg, of B&L Rootenberg Books in California, who is handling the sale. Although manuscripts dealing with Einstein's earlier work and his social and political views are relatively common, the collection is unique in helping to document the latter half of his life, when he moved to Princeton University in New Jersey and embarked on a struggle to unite all branches of physics.

Little impact

But his work in this period made very little impact on contemporaries and he never found his grand theory - something physicists are still grappling with.

The archive was collected by Einstein's colleague Ernst Gabor Straus, a young mathematician whom the great physicist selected to help him during his Princeton years. "A lot of people think of Einstein as a mathematical genius - he wasn't," said David McMullan, a physicist at Plymouth University. He said Einstein used Straus as he had used other mathematically gifted colleagues in his early career. "Straus's mathematical virtuosity gave a framework to Einstein's intuitive vision of the universe."

He said it was fascinating to see breakthroughs not coming easily to Einstein. "I do think it is interesting, the way you see him groping around. He's just trying anything. Here we see the greatest scientist who ever lived struggling and being honest about it."

In one sequence of 16 letters Straus criticises a line of inquiry that Einstein is pursuing and eventually persuades him to abandon it. "It would take somebody with real balls to say to Einstein, 'look, this is wrong'," said Peter Coles, a physicist at Nottingham University.

The papers have never been studied because they have been held by Straus and his family since they were written. Einstein scholars were not even aware they existed until Straus's wife and son decided to put them on the market. They tell the story of the two men's evolving thought process in the vain search for the unified field theory, as the grand theory was called.

Einstein hoped to unite the forces of gravity and electromagnetism under one theoretical framework, which would at the same time incorporate quantum mechanics. But the search turned out to be a series of blind alleys.

"It's a part of Einstein's life that we know comparatively little about," said Tilman Sauer, a senior editor at the Einstein Papers Project at the California Institute of Technology. "There is a general image of Einstein in Princeton that he was sitting in a kind of golden cage, having lost contact with mainstream physics and doing esoteric calculations. These documents paint a much more nuanced picture of Einstein's later life."

There are lighter moments too. For example, a set of scribbled equations describes a card trick, and there is a grumble familiar to many academics about inconvenient teaching duties. "Even if the professional work is not fully satisfactory in certain regards, it is most important that one is somehow normally integrated into the curious machinery of economics," Einstein wrote on October 28 1948. "On the side, one can also do something of permanent value."

Colossus

There is also a three-page letter from another colossus of 20th century physics, Erwin Schrödinger, dated spring 1946. In it he describes the degree of concentration he needed in order to solve an equation relating to Einstein's general relativity. "I have used the involuntary house arrest around Easter to solve the equation," he wrote.

Simon Roberts, an expert on rare books and manuscripts at Bonhams auctioneers in London, said that individual manuscripts or papers written by Einstein typically fetched £10,000 to £50,000 at auction, but selling the papers together would command a higher price.

The Straus family decided not to sell the papers at auction because they would inevitably be broken down into individual lots. They have already approached the Hebrew University in Jerusalem, which houses the largest collection of Einstein's papers, but it was unable to raise the sale price.

An intriguing possibility is that the manuscripts might contain ideas that Einstein abandoned but could still have mileage today in the light of subsequent discoveries. Prof McMullan said the scientific doodles and scribbled equations that cover many of the papers "are often just ways of developing ideas and quite often you just chuck them away. Of course, when it's Einstein you just feel that it must be more than that."

The life

1879 Born in Ulm, Germany, March 14

1901 Acquired Swiss citizenship and took a post as a technical assistant in the Swiss patent office

1903 Married Mileva Maric. The couple had one daughter and two sons

1905 Published his paper on special relativity

1914 Appointed director of the Kaiser Wilhelm Physical Institute and professor in the University of Berlin. Became a German citizen

1916 Published his paper on general relativity

1919 Marriage was dissolved. In the same year he married his cousin, Elsa Löwenthal

1933 Left Germany because of the rise of fascism and moved to Princeton, New Jersey

1940 Became a US citizen

1945 After the second world war he became a leading figure in the World Government Movement. He was offered the presidency of the state of Israel, but turned it down

1955 Died April 18

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