When Peter Sarstedt was wondering where his lovely Marie-Claire would go to when she was alone in her bed, the answer was the sorts of memories that occupy the minds of ordinary mortals – her indigent roots as a child begging in rags in the back streets of Naples, a far cry from her fancy apartment off the Boulevard St Michel, her embassy parties and the painting she stole from Picasso (allegedly). But what if we really could see inside a head – and that mind was Einstein’s.

*E *= *mc*^{2}. Of course it does! Everybody knows that … hey? Well, most of us know how to *say* it, because we’ve heard it all our lives. What does E equal? And everybody yelled: “mc^{2}!” But what does that mean? Hmmm, now that’s another matter altogether.

And there need be no embarrassment in not knowing, given how much time Einstein spent on reaching that particular conclusion. A little heads-up would seem apposite at this point. This inveterate truant, even on the rare occasions when he was at school, was dreadful at maths, if sufficiently interested in science to get through. But it’s never too late to learn something new, which is why the occasional illuminating and elucidating documentary on Netflix gets swallowed up and chewed over.

It turns out, who knew, that while old Einstein was extremely good at maths and science, “he was very bad at other classes, mostly because he kept cutting class”, as the commentary of *Inside Einstein’s Mind* notes. So, that’s two things we have in common. (The other is the, you know, hair thing.) A University of Life education does not teach you everything, but my erstwhile maths teachers must all be long dead by now so have no further need to tear their hair out.

Not long ago I watched Netflix’s *The Secret Rules of Modern Living: Algorithms*, in which Prof Marcus du Sautoy explains how algorithms work and what they are in such a way that you wish he’d been your own maths teacher because if he had been your entire life would have been different. (I’m looking at you, Dr Gilloway. By the way, are you still stuck on Page 219? You were stuck on Page 219 of our Standard 8 maths text book for an Entire School Term. I can’t remember a single thing from the page but boy do I remember the number. Okay, maybe that was the problem.)

So let’s turn to the academics who populate *Inside Einstein’s Mind*, which runs for just 53 minutes. A highly valuable 53 minutes because so much is explained so clearly, cleverly and swiftly. Oh and super accessibly. Now isn’t that what good teaching is about?

How to make the General Theory of Relativity relatively captivating? Generally speaking.

The commentary starts off in awed tones.

“It’s a mysterious force that shapes our universe. It feels familiar, but is far stranger than anyone ever imagined. And yet, one man’s brilliant mind tamed it. Gravity.”

Concluding to a suitably awed world that time and space are shaped by matter. Never quite understood that before, but this documentary does its job: you’ll get it, even if you’re not a maths nut.

The narrative has some rather poetic ways of explaining certain things. That gravity “is in fact the push and pull of space and time itself”. Which brings into relief the truth that words, well chosen and well placed, can explain mathematical and scientific discoveries in ways that indecipherable scrawlings on a blackboard can’t. The perfect mind, perhaps, can do the equation and then find the right words to explain it. Which is more or less where this documentary comes in.

From the perspective of our deeply technological present, it pulls us backwards a century and more to when Einstein was first formulating his theories, which he was to do his entire life, and then walks us back to our time, and the persistently unfathomable nature of Black Holes.

The seeds of his thinking were germinated when he was a boy playing with a train set. He was “slow to learn to speak” as a child, and used to occupy himself erecting card towers. He was an inveterate daydreamer who wondered about things such as how things can be forced to move even when nothing’s touching them. He developed “a new way of thinking about the physical world … to think visually”.

Einstein’s “thought experiments” were forming – “the defining feature of his thinking”. As a teenager he tried to imagine what would happen if he could catch up with a light wave – “what if he could propel himself really quickly? What would he see?” This “dreamlike thought about the nature of light was Einstein’s first stop on the path to his great theory”.

In 1902, when he was 23, he worked in a patent office, assessing the originality of new devices, just as time zones had been introduced in central Europe and the accurate synchronisation of clocks had become important. He’d theorise quietly in his spare time, scribbling in notebooks. Isaac Newton, for whom “all there is in the world is matter, moving”, showed that the motion of falling apples and moving planets are governed by the same force – gravity. Which, many of us tend to think, is the earth’s force pulling us down. Which is not so, we learn much later in the documentary.

Einstein hated a contradiction, and he saw one between James Maxwell’s theory that light is an electromagnetic wave that travels at a fixed speed – yet in Newton’s world, the speed of light is not fixed. This is bringing us to a beautiful illustration of how Einstein’s “thought experiments” evolved. It was a sign that “something’s not right and needs fixing”.

After months of mind-wrestling with this he alights on a key element of speed – time – and how it relates to simultaneity, as in the relationship between two events seemingly happening at the same time. But are they?

“In a brilliant thought experiment he questions what ‘simultaneous’ actually means and sees that the flow of time is different for an observer that is moving versus one that is standing still.”

He pictures a man on a railway platform. Two bolts of lightning strike, one each side of him. In the man’s view, they strike simultaneously. But then he imagines a woman on a train travelling close to the speed of light.

“As the light travels out from the (lightning) strikes, the train is moving towards one, and away from the other.”

Light from one strike reaches her eyes first which means that for the woman on the train, time elapses between the two strikes. Yet for the man on the platform there is no time between them.

This is mindblowing in its significance, says the narrator, because “the simultaneity of the flow of time itself depends on how you’re moving”.

Questions as to what this means, or could mean, for the relationship between time, place and history, at the very least, can take one in all sorts of directions from this point. And this isn’t even Quantum Physics.

The concept, not to put too fine a point on it, that time and space are relative “become known as special relativity” – *E *= *mc*^{2}, an equation relating energy to mass. (See, Dr Gilloway – I finally had my “Eureka!” moment.)

But wait, there’s more: what if the train begins to speed up or slow down? Which, after much more thought-experimentation, leads to what Einstein called “the happiest thought of his life” – if gravity and acceleration *feel* the same, perhaps they *are* the same.

How happy he must have been in his endless thinking. There’s very, very much more of great fascination in this documentary, so get to it for some happy brain moments of your own.

The happiest thoughts of my life? That’s usually something like the beauty of a rose, a smile on my girl’s face or an extra chuckle around the braai. But right now a strong contender is that I might have finally worked out what was on Page 219. __DM__

- 23 JULY 2018
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Magenta has no physical wavelength. It thus does not "exist" strictly speaking. Rather our brains are telling us that we are seeing "not green".