A century ago, a man with curly black hair and a moustache left his Berlin apartment and changed the world. I think of him often as I hurry to the U-Bahn, down my street and past his old address. The man is long gone, as is his former apartment building: blown away in the war and replaced with a 1950s block.
But it’s fun to think it was from my street, golden leaves crunching underfoot then as now, that Albert Einstein began his journey from scientist to icon. His general theory of relativity that still eludes most of us but, a century ago, it almost eluded Einstein, too.
“One thing is for sure, that I’ve never been so plagued in my life,” wrote Einstein at the time. “Smoking like a chimney, working like a steed, eating without thought, sleeping irregularly.”
One morning over breakfast, his wife Elsa watched her husband stare blankly into space, drift over to the piano to play absently for a while before locking himself into his study.
Two weeks later Einstein emerged and – exhausted and stinking of cigarettes – presented himself in November 1915 to colleagues at the Prussian Academy of Sciences, today the state library on Unter den Linden.
The 1915 theory was Einstein’s attempt to improve on his decade-old “special relativity theory”, which demonstrated that the laws of physics are identical at non-accelerating points in the universe and the speed of light in a vacuum is constant.
This meant that how you perceive the world around you depends on your state of motion, he said, and, if you’re moving at the speed of light, even time is relative and will slow down relative to a static observer.
This 1905 theory demonstrated that space and time were part of a “space-time” fabric; but the theory was “special” because it applied only to a special case where an observer was moving at a constant velocity.
Two years later he began thinking about gravitation theory. Someone travelling in an elevator feels their own weight, he began. But what if the elevator rocketed out of the Earth's gravitational field and into space – like in Charlie and the Chocolate Factory? The passenger could feel their weight again, even in zero-gravity space – if the elevator accelerated enough.
As a result of this, Einstein said accelerational force and gravitational force are one and the same thing.
This equivalence principle lead him to the most important part of his theory: that objects and the space-time fabric around them can influence – even distend – one other and influence how they move.
He presented his results over four Thursdays in November 1915 to a reserved reaction from colleagues. Independent scientific confirmation came four years later, in May 1919, when the astronomer Arthur Eddington observed during a solar eclipse how the sun distorted the light from faraway stars.
The news caused a sensation at a joint session of the Royal and Astronomical Societies of London on November 6th , 1919. Two days later, The Irish Times praised Einstein as one of the few "unassuming and apologetic men" still upholding Germany's best scientific traditions – in contrast to the majority who had "joined the hysterical apologists of Prussianism".
The newspaper noted that Einstein’s theory was “vague and hardly intelligible even to mathematicians” – some things haven’t changed – but the theory “threatens the fundamental axioms of physical science” because it “challenges Newton’s laws, which are based on the assumption that space is invariable”.
The newspaper said it was “not impossible” that the German professor would leave the structure of human scientific thought to date “in ruins about our feet”.
Not everyone was impressed. On November 12th, the newspaper published a letter from WFA Ellison of the Armagh Observatory arguing that space time could not be “distended” as it was “not an entity, but the absence or negation of an entity”.
"You cannot twist, distort or distend nothing," he wrote. "Professor Einstein has certainly 'scored one' but ... I prefer to wait rather than jump to hasty conclusions."
A century on, the conclusions are clear: without Einstein we couldn’t even begin to understand black holes or the Big Bang theory. And without his general theory of relativity, drafted a few doors down from me in Berlin, the world would tick very differently indeed.
