How the World Works

When I was a child, my father – who was a materials scientist, and used sometimes to make gunpowder in the back garden – told me that the study of physics was simply the study of how the world works. Optics and glass were his particular field. Occasionally he’d stand at the kitchen sink attempting to hand-grind a lens for a telescope or fetch a microscope and persuade my mother to supply a drop of blood for a slide. Observing the moon, or the bloody smear we could never quite resolve into cells, he’d be as fascinated by the means of procuring these images as by the images themselves and would try to teach me the principles of focal length.

At that time I was prone to wearing peculiar dresses I’d sewn myself, and playing Chopin by candlelight. I was interested in physics, because I was interested in everything; but I didn’t especially want to understand how the world worked. I felt it was altogether more appealing to wander about in a state of enchanted ignorance. I didn’t want to see a rainbow reduced to photons and refractive indices; I longed for comets, and resented being informed that HaleBopp – to which I devoted hours of loving observation as it hung over the garden shed for several nights in 1997 – was nothing but a dirty snowball. Time passed. I grew up. I abandoned Chopin for the beautiful organizations of Bach, and if my father wanted to explain laws regarding the motion of planetary bodies I listened carefully and made notes. I’d discovered life arrived in a succession of shocks and surprises, and that order was something to be sought, not shunned. The idea that the world’s matter was subordinate to laws even I might comprehend was a comfort and one afternoon, having seen an exhibition of clocks at the Science Museum in London, I became fascinated by the sight and significance of a pendulum’s swing. On the train home, fortified by a plastic cup of wine, I looked up the formula for calculating exactly the time it takes a pendulum to complete a sweep from side to side: T = 2π√(L/g) – no doubt nearby schoolchildren could have told me this, but to me these symbols contained the power and mystery of runes. I drew a number of theoretical pendulums of different lengths and weights in the back of the novel I ought to have been reading and calculated over and over the period of their imaginary swings. I remember laughing with pleasure: I understood almost nothing of myself and my own life, but perhaps I might be able to understand a little of how the world works. Some years after this, I encountered the theoretical physicist Carlo Rovelli in his work Seven Brief Lessons on Physics, and my tentative fondness for the science was more or less immediately consolidated into downright love. Rovelli was born in Verona in 1956 and was once arrested for ‘crimes of opinion’ related to his leftist political activity – and it was a youthful fondness for LSD that first aroused in him a fascination with theoretical physics. The drug’s effects insisted on the subjective nature of the order of time: ‘things were happening in my mind’, he wrote, ‘but the clock was not going ahead; the flow of time was not passing any more . . . how do I know that the usual perception is right, and this is wrong? If these two ways of perceiving are so different, what does it mean that one is the correct one?’ Over the course of an extraordinarily illustrious career, Rovelli has written both scholarly and popular works on subjects including Anaximander, Quantum Gravity and White Holes, but it is the Seven Brief Lessons that has most gripped the world. It is a curiously warm and generous book, so that reading it is rather like being in the author’s company, and it began as a series of articles in an Italian newspaper ‘for those who know little or nothing about science’. These ‘lessons’ were published in a single volume in 2014, and they are indeed brief. The paperback runs to fewer than one hundred pages and wouldn’t trouble the pocket of a silk frock; but it contains the universe, and everything in it. The key principles of post-Newtonian physics are explored with the rigour of a scholar and the questing wisdom of a philosopher. The first lesson is entitled ‘The Most Beautiful of Theories’ and explores the ‘absolute masterpiece’ of the General Theory of Relativity with such clarity and precision that within four pages I persuaded myself that I understood all that Einstein had conceived (within six pages, of course, I knew I did not). By p.10, the reader is introduced to quantum mechanics, and the moment Niels Bohr comprehended that electrons perform a ‘quantum leap’ between atomic orbits. There are lessons on the nature of particles, and on loop quantum gravity, and on black holes; a lesson on the nature of time begins with the image of a teaspoon cooling in a saucer. The shelves are not lacking in physics primers for the layperson, but what distinguishes the Seven Brief Lessons is the voice of Rovelli himself, in which absolute authority in his subject is matched by a sense of both awe and humility. The reader grasps that the study of theoretical physics is capable of arousing as much wonder and mystery as the study of art, or of religion. Doubt and mystery appear as intrinsic to the process of discovery as certainty or observing the outcome of a laboratory experiment or mathematical problem: ‘Reality is not as it appears to us: every time we glimpse a new aspect of it, it is a deeply emotional experience. Another veil has fallen.’ The experience of reading the book is curiously both enlarging and humbling. Rovelli’s gifts as tutor confer on the reader more knowledge than they likely will ever have hoped to gain; but the maddening scale of his subject entails repeated encounters with one’s own ignorance. I had thought, for example, that in accordance with Newtonian laws, objects were propelled by forces through space, but discovered instead that objects move through an electromagnetic field which is effectively a stream of particles: there is no ‘nothing’. The lesson on time and chance corrected my apparently childish belief that a heated object will certainly, in due time, become cool: now I understand (or think I understand) that in physics there is only the probability that it will do so. But I never felt chastened, or foolish – gradually I saw the qualities of ignorance and doubt as intrinsic to learning, and the awe that sometimes attends it. The popular idea that science and faith of all kinds are intractably at odds, and that the principles of sciences are calculable and immutable against the insubstantial hopefulness of faith, dissipated. This is not to say the study of physics and the pursuit of faith are entirely congruent – physicists doggedly seek out the mathematical or physical proofs of their ideas, while priests needn’t bother – only that in reading Rovelli I found the border between the two fields was here and there both unmarked and unmanned. I wish I could remember who commended the Seven Brief Lessons to me, but I’m unable to; nor could I tell you where I was when I first read it, but it seems absurd to me that I was ever without it. Three or four copies have passed through my hands since then, because I press them on friends, or lose them on trains, or drop them in the bath – the book arrived in my life more or less as the rigid faith of my childhood departed, and I suppose in some ways it has become a substitute sacred text. Then, in time, I met Rovelli in person. I’d been asked to speak with him at the London launch of his new book on Werner Heisenberg, whose hay fever drove him to spend a summer on the treeless island of Heligoland to wrestle with the earliest ideas of quantum. Though generally immune to celebrity, I found myself reduced briefly to a stammering girl as I attempted to explain what his writing had done for my mind and my spirits. It had inspired me, I said, to attempt to teach myself A-level physics, but that had been a hopeless case: I was more or less innumerate, and the maths was perpetually beyond my grasp. With the generosity so evident in the Seven Brief Lessons, Rovelli told me that though he was unable to read a musical score, he loved and understood music – he took part in it, and it enriched his life. Physics, in that case, could be to me what music was to him: an endlessly unfolding avenue of learning and wonder, and never mind the inscrutable marks on the page. There, he wrote, ‘shines the mystery and the beauty of the world. And it’s breathtaking.’

Extract from Slightly Foxed Issue 86 © Sarah Perry 2025