Harry Kroto

A fascination with puzzles developed into an intellectual quest that led from the breathtaking revelations of spectroscopy into organic chemistry and quantum mechanics

I sometimes wonder how I ended up as a scientist. I was originally attracted to organic chemistry for reasons I could not quite fathom - perhaps it was something to do with the innate fascination humans have for solving puzzles.

Maybe I saw the same challenge in elaborating a sequence of individual synthetic chemical reactions, the stepping stones to a target compound, that others find in playing games. I remember as an adolescent attempting the Manchester Guardian crossword puzzle every day for a week and getting the hang of it - or about a quarter to half of it - by Friday. I then gave up on crosswords.

The challenge of devising the overall synthesis of an exotic molecule, say a steroid, seemed a significantly more useful activity. Why play at play, I thought, when you could play at work? Chemistry - at least on paper - provided a similar satisfaction to games. Crossword puzzles required a knowledge of the appropriate literature; chess depended on forward thinking; and jigsaws brought the catharsis of seeing a grand design completed in a simple final act.

Science and engineering are also games - but ones that have saved humanity from the drudgery of working 12 hours a day seven days a week merely to survive.

One day on my way to becoming an organic chemist or perhaps a graphic artist - my other passion - I was waylaid. In a lecture, I learnt how the subtle ballet that tiny molecules perform is revealed by spectroscopy.

Spectroscopy is in essence the study of the causes of colour. When light passes through aqueous copper sulphate solution, only the blue component emerges - other components such as red and yellow are absorbed. That pure transparent blue, once seen, is never forgotten.

The classic album cover for Pink Floyd's Dark Side of the Moon shows how a prism splits a beam of white light into components that emerge at different angles, depending on their colour (pity they got the physics wrong on the back). If copper sulphate solution is placed in the beam, only the blue component gets through. The resulting graph of light intensity against wavelength or colour is the "spectrum".

Spectroscopy is useful as we can tell what a substance is by its colour. There is more, however, much more, in a spectrum.It can reveal the structures and motions of molecules, too. If we apply the elegant abstract relations of quantum mechanics, we can interpret the spectral patterns in terms of subtle motions of a molecule's constituent atoms and electrons.

So here I was, a practical sort of guy, brought up in the nuts-and-bolts, hands-on world of Meccano, suddenly fascinated by a world too small to see and intrigued by the mathematical relationships that described it. Molecules counted. I decided that I just had to understand quantum mechanics.

From time to time in my quest, I would call a close friend, whose seemingly innate understanding of ubiquitous quantum concepts left me in awe, to say that I didn't understand something or other. Each time I would be presented with an erudite explanation, but after putting down the phone, I found that I was none the wiser.

Then I realised that for these discussions to be useful, I had to determine exactly what it was that I didn't understand and frame the question far more precisely. After a while, I made an empirical discovery: I never again rang up with questions. I stumbled on a fascinating rule: the act of framing a question precisely was the key to understanding.

Some time later, I found a parallel in what was, at the time, my favourite magazine, the old Radio Times , which is now illustrated by unimaginative spotty halftone photos. In earlier times, it carried superb black-and-white images, which I so loved and collected. Among those images was a headline advertising the next episode in a kung fu series. I still have the cutting; it proclaimed in Celtic font: "I seek not the answer - but to understand the question." Dammit, Confucius got there first - but at least I know more quantum mechanics than he did.

Sir Harry Kroto is professor of chemistry at Sussex University. He won the Nobel prize for chemistry in 1996.