Exactly one hundred years ago today, Albert Einstein, delivered a speech on his General Theory of Relativity to the prestigious Prussian Academy of Sciences in Berlin, a lecture nearly 10 years in the making. Then 36 years old, the patent-clerk-turned-theoretical-physicist, a genius with a messy coiff, spoke to a brilliant audience and contradicted everything the modern world understood about space and time. Like how a body dents a mattress, matter dents space and time; or The New York Times described, like Santa Claus’s belly:

Space-time could curve, fold, wrap itself up around a dead star and disappear into a black hole. It could jiggle like Santa Claus’s belly, radiating waves of gravitational compression, or whirl like dough in a Mixmaster. It could even rip or tear. It could stretch and grow, or it could collapse into a speck of infinite density at the end or beginning of time.

Sir Isaac Newton, two hundred years prior, discovered an invisible force called gravity, but beyond that, he didn’t know how it worked. And Einstein filled in the blanks. He would later refer to his theory as one of “incomparable beauty,” and if anyone’s earned the right to toot his own horn, it’s Einstein, who also happened to be a decent violinist.

“He did not have great respect for authority,” said Hanoch Gutfreund, the academic director of the Albert Einstein Archives at Hebrew University, home to the largest and most comprehensive Einstein archives in the world. “When he doubted something, he had the courage to question the most basic dogmas. That allowed him to think, as we say, ‘out of the box,’” he continued over Skype, a piece of technology that I’m pretty sure exists because of Einstein. But, I’m not a physicist, so don’t quote me.

It took a lot of chutzpah for Einstein, the son of a German engineer, to arrive at his conclusions, which outright defied the then-accepted status quo of physics, which had then been based on Isaac Newton’s 200-year-old (apple) theories. To Newton and Galileo, time and space were absolute entities, but not to Einstein (hence, space and time’s malleability compared to Santa’s paunch). And playing the part, it’s no surprise that the Jewish wiz was as eccentric as his claims.

To celebrate 100 years since his gravity-shifting lecture, here’s a list of some facts about the genius that you might not know.

1) Einstein didn’t wear socks…ever, making him prone to athlete’s foot and these other unfortunate perils.

2) He couldn’t drive or swim, but loved to sail, smoke pipes, and was a big fan of yo-yos and violins.

3) A rockstar of his era, he had his fair share of extramarital lovers within two marriages.

4) He had his first wife, Mileva, sign a bullet-pointed contract when their marriage was failing, demanding that she cook three meals a day, abstain from intimate relations with him, and stop talking when he requested. For for his second marriage he pulled a Jerry Lee Lewis (or vice versa) when he married his cousin.

5)  Einstein was the proud owner of a cat named Tiger that got depressed when it rained. According to Albert Einstein: A Biography, written by Alice Calaprice and Trevor Lipscombe, Einstein reportedly commiserated with the cat: “I know what’s wrong, dear fellow, but I don’t know how to turn it off.”

6) Einstein once started a riot.

7) He co-invented a fridge in 1926.

8) Einstein almost became president of Israel in 1952. Offered the position after the death of Chaim Weizmann, he declined the seat. According to Gutfreund, Einstein’s relationship with Israel was more intellectual than political. In fact, Einstein was one of the founders of the Hebrew University and he left his entire literary estate to the institution in his will: over 55,000 articles of manuscripts, love letters and speeches.

Gutfreund admitted sure, Einstein was ordinary, likely to indulge in the occasional pipe or romantic fling, but on this given day, marking a century since his groundbreaking speech, what we’re celebrating is lost on figuring out the man behind the theory. “We are a tiny little dot and this is what we celebrate,” the professor said.

There’s no way to find out what he was thinking November 25, 1915, or if he would have been able to foresee the magnitude of such a theory, that his work would eventually furl the world forward and bring about the Atomic Age, modern technology, and nuclear warfare.

But it’s safe to say that when he gave that fateful lecture a century ago, he definitely wasn’t wearing socks.

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