On the Equality of All Things by Carlo Rovelli: A sceptical eye on humanity’s grand claims
It is a misconception widely entertained, even by some of its cleverest practitioners, that science is engaged in the pursuit of ultimate, foundational truths about the nature of reality. Science, unlike art, has rigour, and makes rigorous pronouncements on the nature of things. An equation cannot be gainsaid. So it is believed. This delusion is a relatively modern phenomenon. Even at the height of what we call the Renaissance, scientists – or natural philosophers, as they were called then – did not imagine that they were figuring the world and the heavens as they actually are. Rather, they were content to “save the phenomena”, as they put it, that is, to devise systems that would agree with the evidence presented to them by the physical world. To know how things really are was God’s business, certainly not ours. With the Renaissance, with the Enlightenment, with the industrial revolution, human arrogance, not to say hubris, inexorably set in. Isaac Newton (d.1747), one of the greatest minds our species has produced, and one of the most unappetising personalities, discovered, or better say invented, a set of laws governing the mechanics of the quotidian world, laws that are still valid, in the quotidian world, at our scale, despite Einstein’s theory of relativity, despite quantum theory, and despite whatever mind-boggling theory is to come next. We live in a Newtonian world. The table we eat at is made up of a countless number of unimaginably tiny particles, yet it stoutly sustains our plates, our knives and forks, and our elbows. As Carlo Rovelli writes: “We are in the world. We are here. And we are home.” But are we content, here at home? Do we not, in what the poet Wallace Stevens called our “rage for order”, still hanker after simple, stable, incontrovertible proofs of the world’s workings? Indeed we do. But Rovelli is here, gently, to dash our hopes: “Respectful of all philosophies, but a humble devotee of the so-called exact sciences, I find it wiser to abandon the goal of certainty altogether, in all aspects of knowledge.” Read that sentence again, and feel the foundations of our most cherished and most aspirational beliefs crumble to dust. And do not imagine that Rovelli is some new age guru urging us to chill out and stop worrying about ultimate truths. Born in Verona 70 years ago, he has had a brilliant career as a theoretical physicist, doing his main work in the field of loop quantum gravity, as well as being one of the most stimulating popularisers of science and the philosophy of science. His books include Seven Brief Lessons on Physics, The Order of Time and Reality Is not What It Seems: The Journey to Quantum Gravity. He is emeritus professor at the Centre of Physics Theory in Marseilles, and works at the Western University in Canada and the Santa Fe Institute in New Mexico. On the Equality of All Things is his most ambitious work so far. It is written in clear, crisp prose studded with gems of poetic insight, and ventures deeply into the realms of western and eastern philosophy, quoting as freely from the great second-century Buddhist teacher Nāgārjuna and the 19th-century American pragmatist Charles Saunders Peirce, as from Ludwig Wittgenstein and Martin Heidegger. Significantly, the book was written in response to an invitation to deliver a series of lectures, or “lessons”, as Rovelli calls them, to the Department of Philosophy at Princeton University late in 2024. One might imagine it would have been discomforting for a physicist to be thrown into such an arena, but if Rovelli was daunted he certainly hides it well. His tone is sure, his assertions are bold, and he has not the slightest hesitation in taking an occasional swipe at what he sees as the complacency, and in some cases the plain stupidity, of professional philosophers. They must have been lively, those couple of months in Princeton, when this obstreperous savant – Rovelli was a student activist in the 1970s – was rattling the branches in that venerable grove of academe. It would be a disservice to the reader to pretend that this is an easy book, but the labour we are required to give to it is amply rewarded by the excitement of the venture, by the richness of the lessons we are offered, and by moments of pure aesthetic bliss, when this or that knotty concept is suddenly, silkily unravelled for us by the ever-accommodating Prof Rovelli. For the nervous ones among us, such as this reviewer, it might easiest to read the very short preface and jump straight to the afterword, take a breather, and then tackle the main text, which begins with the cheering observation that “We are united by our curiosity.” From the archive: Carlo Rovelli on Schrödinger, God and physics being ‘better than LSD’ However, we are united too, even the brightest of us, by our stubbornness and complacency, and scientists are no exception. For instance, from the very beginning, when mankind began to take the measure of the skies, it was held as axiomatic that the orbits of the planets trace out perfect circles, if for no other reason than that God cannot abide imperfection. This mistaken belief led many of the ancient cosmologists into awful muddles. One of the most influential of those ancients was Claudius Ptolemy, born in Egypt in the second century AD. His astronomical treatise Almagest sought to solve the puzzle of the planets – and save the phenomena – by adding to their orbits a juggler’s bagful of epicycles, that is, small circles on larger circles, and smaller circles on the small circles, like Jonathan Swift’s little fleas upon the backs of bigger fleas. Even Copernicus (d.1543), in devising his model of a sun-centred planetary system, had to preserve the Ptolemaic pieties. Then along came Johannes Kepler (d.1630), who among many doubts and after deep heart-searching, announced to the world that in fact the planets move in elliptical orbits. Had the world been listening harder, he might have been burnt at the stake for such an outrageous notion. This is how science works, now in slow accretions, now in fits and starts, now in blind conformity, now in sudden breakthroughs. Always the fog persists, though shafts of light strike through it here and there, and now and then. Rovelli quotes from a speech by Max Born, whom he believes to be the true creator of quantum mechanics, on the need for us to curb our grand notions of ourselves and of our ability to know for certain the nature of reality: “I believe that ideas such as absolute certitude, absolute exactness, final truth, etc are figments of the imagination that should not be admissible in any field of science ... This loosening of thinking seems to me to be the greatest blessing modern science has given to us. For the belief in a single truth and in being the possessor thereof is the root cause of all evil in the world.” And it is not just in science that we should show humility. Like Wittgenstein, like the Danish quantum theorist Niels Bohr, like the poet Reiner Maria Rilke, Rovelli not only acknowledges but celebrates the ambiguity of language in which we frame scientific concepts, the ambiguity that “allows [us] to express ever more subtle things in the infinite process that has given rise to the vastness and richness of language and culture”. But why is Rovelli so much concerned with verbal language, when science has the language of numbers – mathematics – in which to address nature’s secrets? It was Niels Bohr (1885-1962) who recognised that many of the problems encountered in quantum theory derived from the imprecision of the language spoken by quantum scientists. “We must never forget,” Bohr cautioned, “that ‘reality’ too is a human word just like ‘wave’ or ‘consciousness’. Our task is to learn to use these words correctly ...” But note: “correctly” is not the same as “unambiguously”. To some, and not just scientists, Rovelli’s ideas will seem subversive, even anarchic. Are we to have no solid scientific ground on which to set our feet? No, we are not, and a good thing too; if there is nowhere to stand, we shall just have to fly. Rovelli writes: “To say, as I often hear, that if we know the world’s fundamental physical equations then we know everything about the world, is, I believe, nonsense ... Physics is overrated.” And later he adds: “Even thunderstorms are not yet completely understood.” The Equality of All Things is a marvellous, insouciant and liberating book. It celebrates our extraordinary ingenuity – we invented agriculture, we flew to the moon – and at the same time turns a sceptical eye upon our grand claims to be the lords of the universe. In closing, Rovelli quotes Milton’s image of Adam and Eve, having been driven out of Paradise, but with “the world all before them”. And he adds: “We are still like this.” Further reading Carlo Rovelli has also just published 85 Seconds to Midnight: A Physicist’s Argument against Rearmament (Allen Lane), in which he traces the history of the development of nuclear weapons, and the various efforts that have been made to prevent their proliferation. It makes for salutary but sober reading. One of the most accessible surveys of the latest theories on the nature of things is Jim Al-Khalili’s The World According to Physics (Princeton). The author, who works at the University of Surrey, has an easy style and knows his stuff. And there is not an equation in sight. As the great physicist Richard Feynman famously remarked, “I think I can safely say that nobody understands quantum mechanics.” In Beyond Weird (Vintage), Philip Ball does not claim to understand it, but he does lay out clearly and entertainingly many of the mysteries at the heart of the quantum version of reality. A bracer of a book. John Banville’s latest novel is Venetian Vespers