Albert Einstein's Theory of Relativity was inspired by Scottish philosopher

Albert Einstein was inspired to propose his Theory of Relativity after reading the works of a 18th century Scottish philosopher, it has emerged.

A new letter, discovered at the University of Edinburgh shows that the German-born theoretical physicist had studied David Hume’s A Treatise of Human Nature just before proposing special relativity in 1905.

The groundbreaking theory suggested that the speed of light remained the same even if the observer was speeding up or slowing down, suggesting that time and space therefore could not be constant.

Yet it was Hume who had first questioned whether space and time were in fact fixed, and independent of each other, and had called for further scientific investigation to find out.

In a Treatise of Human Nature, published in 1738, Hume wrote: “The chief objection against all abstract reasoning is derived from the ideas of Space and Time. Ideas in everyday life may

appear clear and intelligible, but when they pass through the scrutiny of the profound Sciences...they seem full of absurdity and contradiction.”

In Einstein’s letter, written to Moritz Schlick, Professor of Physics at Vienna, in December 1915 he admits that it was Hume’s work which inspired general relativity.

“You have correctly seen that this line of thought was of great influence on my efforts and indeed Ernst Mach and still much more Hume, whose treatise on understanding I studied with eagerness and admiration shortly before finding relativity theory.”

He goes on to write that “It is very possible that without these philosophical studies I can not say that the solution would have come.”

The new letter was discovered by Professor David Purdie, if the Institute of Advanced Studies at the University of Edinburgh.

He said: “I was talking to the rector of Princeton University last year about how the Scottish scientists James Clerk Maxwell had been a huge inspiration for Einstein, and he said: “You know Hume was as well don’t you?”

“I was absolutely thrown. I have read all the Einstein papers and there is no mention of Hume. So he sent me to dig out the old letters of Einstein and there he was, filed away and forgotten. I had no idea.

“Einstein said that Hume more than anyone else had inspired him. It’s amazing to think that someone who lived 100 years before, in an entirely different place, could have had such an impact.”

In his twenties, Einstein worked as a clerk in the Swiss federal Patent Office in Bern

while developing his theories of relativity and was part of a group called The Olympic Academy which met weekly to discuss physics and philosophy.

It was here that Einstein was introduced to David Hume’s Treatise of Human Nature.

The work is generally considered to be one of the most important philosophical studies ever published and the first to seriously question God, and man’s place in the world, ahead of Darwin.