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Quantum theory via 40-tonne trucks: How science writing became popular

Wave-particle duality may sound complicated – but the basics of quantum theory can be explained by matchboxes and trucks, says Marcus Chown. As can the surge in popularity of science writing...

Richard Feynman was arguably the greatest post-war American physicist. He worked on the Manhattan Project to build an atomic bomb and won the Nobel Prize for his work on the theory of quantum electrodynamics which, by describing how light interacts with matter, explains pretty much all everyday phenomena, from the way that sunlight glints on a lake to the attraction that glues together the atoms in your body. But, though Feynman was top of the academic tree, a magician in the manipulation of arcane mathematical equations, he had an interesting criterion for whether he really grasped something. Could he explain it to someone with no science background? If he could, then he understood it; if he could not, it was back to the drawing board.

In the mid-1980s, I was lucky enough to be taught by Feynman as a student at the California Institute of Technology in Pasadena. Before arriving at Caltech, I had watched a BBC TV Horizon programme about the man. For 50 minutes, the camera simply focused on Feynman while he talked engagingly about his life, his children and his father, who had no formal education but had nevertheless infected Feynman with a deep curiosity about the world. Unusually, my mum watched the whole thing, declaring when it was finished: "What an interesting man."

Now my mum had no interest whatsoever in science, and I was forever trying to explain to her why, for instance, people in Australia did not fall off the other side of the world. So when I arrived at Caltech, I had an idea: plucking up my courage, I knocked on Feynman's office door and asked, nervously, whether he would write to my mum.

He did. "Dear Mrs Chown," he wrote. "Please ignore your son's attempts to teach you physics. Physics is not the most important thing. Love is. Richard Feynman."

It wasn't quite what I had expected. It is not every day, after all, that the world's greatest living physicist announces that physics is not the most important thing. But I was not discouraged. Although my attempt to explain science to my mum had ended in abject failure, I persisted in trying to communicate the fun things I had learnt at Caltech, eventually becoming a science writer. These days, instead of explaining things to my mum, I explain them to my wife, who is a nurse and has no physics background. If her eyes glaze over and she starts scrabbling for the TV remote control, I give up and look for another explanation.

In no way would I compare myself with Feynman. His book, QED: The Strange Theory of Light and Matter, in which he describes the work that earned him his Nobel Prize, is a masterclass in the communication of the most complex science known to man in simple words and pictures. Like Feynman, my criterion of whether I understand something is whether I can explain it to someone waiting for a number 52 bus. (If you are ever waiting for a number 52 bus or unlucky enough to be sitting next to me on a train, run a mile, my wife says.)

My quest to understand things at a deep level leads me to paint mental pictures that hopefully shed light on fundamental things. For instance, for my last book, We Need to Talk about Kelvin: What Everyday Things Tell Us About the Universe, I wanted to explain why people invented quantum theory – our current best description of the microscopic world of atoms and their constituents. Quantum theory has literally created the modern world – not only giving us computers and lasers and nuclear reactors but also an explanation of why the sun shines and why the ground beneath our feet is solid.

Quantum theory arose, phoenix-like, from the ashes of a conflict between two great theories: our theory of matter, which said that matter is ultimately made of atoms, and our theory of light, which said that light is a wave. The conflict is apparent whenever light is emitted by an atom (for instance, in the filament in a light bulb), or absorbed by an atom (for instance, in the retina of your eye). The conflict arises because a wave, like a ripple on a pond, is fundamentally a big, spread-out thing, whereas an atom is a tiny, localised thing. That doesn't communicate in any way the essence of the conflict. So, to try to make it concrete, I thought, "Imagine you have a matchbox and you open it and out drives a 40-tonne truck." An atom absorbing light is like a matchbox eating a 40-tonne truck. Hopefully, that does highlight the paradox that had physicists in the early 20th century tearing their hair out, and the resolution of which ultimately led to the new world-view of quantum theory.

My attempt to communicate to non- scientists the amazing things I learnt has led me down unexpected avenues. For instance, I have written children's fiction. Although Felicity Frobisher and the Three-Headed Aldebaran Dust Devil is just very, very silly, it does use "wormholes" – shortcuts through space-time which are permitted to exist by Einstein's general theory of relativity – as a plot device.

Then, last year, I appeared on several episodes of BBC4's comedy-science series, It's Only a Theory, with Andy Hamilton and Reginald D Hunter. Among other things, we explained gravity with the aid of a trampoline, a bowling ball and a bucket of maggots. Comedy puts people at their ease. If you laugh at something, it is no longer scary. As QI has shown, comedy has largely untapped potential for communicating science to a wide audience.

I have also found that comedy feeds back into my science writing. Recently, I performed on the London stage alongside comedians such as Robin Ince and Chris Addison, and science writers including Simon Singh and Richard Dawkins. My contribution to the show, Nine Lessons and Carols for Godless People, was a mock awards ceremony for the unsung heroes of science: "And the award for Most Baffled by the Concept of a Cat flap goes to... Isaac Newton."

Probably you know that Newton was famously bad-tempered and had long- running and bitter feuds with other scientists of his day. But maybe you didn't know that he loved his cat. And, to let his cat in and out of his study, he cut a hole in his study door – a kind of 17th-century cat flap without the flap. But then his cat had kittens. So Newton cut a whole row of small holes, one for each kitten.

The audience liked the Newton's cat flap anecdote, which was related in a popular science book by the Ukrainian-American physicist George Gamow. Comedy, it seems, provides instant audience feedback.

There is a great tradition in Britain of popularising science. Charles Darwin himself was a popular science writer, for what else was On the Origin of Species but a summary in plain English of the evidence for the theory of evolution by natural selection? In the 20th century, there has been a tradition at Cambridge of science popularisers, with Arthur Eddington, James Jeans and Fred Hoyle all disseminating the biggest cosmic ideas to the general public. Hoyle even coined the term "Big Bang"during a 1949 BBC radio broadcast.

And the genre remains healthy, with the big writers including Richard Dawkins, most famous for The Selfish Gene, Simon Singh for Fermat's Last Theorem and Matt Ridley for Genome. This month came the news that Graham Farmelo won the Costa Biography Award for The Strangest Man, his brilliant biography of the Spock-like physicist Paul Dirac.

Science writing has come a long way since Darwin, and I have come a long way from trying to explain to my mum that the Earth is round. Perhaps the best thing to have happened along the way was a letter I received from the wife of a south London taxi driver, who said she had been brought to tears at the end of chapter two of my book The Magic Furnace. (Hopefully, it wasn't the thought of having to read chapter three.) Pam, who was in her forties with three children, had left school at 14 with no qualifications. She was inspired by my book to get educated. In fact, she ended up with a first-class degree.

Who would have thought that a science book could change anyone's life? But, incredibly, it can.

The extract

Afterglow of Creation By Marcus Chown (Faber £8.99)

'...At the time it didn't bother me that we had been scooped. I was young. I thought this was just one of a series of wonderful things that was going to happen to me in my career. But, of course, discoveries like this come along only every decade or so – Dave Wilkinson on missing out on the discovery of the "afterglow" of the Big Bang'