Part of the fun of Rovelli’s book is that your immediate reaction to his ideas — repugnance or delight — isn’t meaningless. Without mathematics or experiment, by page 81 your thoughts are at the frontier of quantum theory, and it’s time for your second brain-cudgeling walk. If things exist only by virtue of their interaction with other things, what happens to them between times? Do they vanish? Do instants of time also not exist? Does it even make sense to talk this way? Oh dear, oh dear.
It is the genius of Carlo Rovelli — in my opinion the most poetic and lucid popular science writer since Richard Dawkins — to evoke the mystical aspect of physics. Rovelli owes his scientific fame to his role as one of the founders of quantum loop theory and his literary reputation to the slim book Seven Brief Lessons on Physics, which has sold more than a million copies. His new book, Helgoland (named after the island where Heisenberg discovered his uncertainty principle), is his most beautiful yet.
With the light touch of a skilled storyteller, Rovelli reveals that Heisenberg had been wrestling with the inner workings of the quantum atom in which electrons travel around the nucleus only in certain orbits, at certain distances, with certain precise energies before magically “leaping” from one orbit to another. Among the unsolved questions he was grappling with on Helgoland were: why only these orbits? Why only certain orbital leaps? As he tried to overcome the failure of existing formulas to replicate the intensity of the light emitted as an electron leapt between orbits, Heisenberg made an astonishing leap of his own.
There is so much in this short but rich book, including a fascinating detour through the dispute between Lenin and his fellow Bolshevik, the polymath Alexander Bogdanov. Rovelli concludes that for all the strangeness of quantum physics, it leaves everything we value not only in place, but more remarkable than ever. “Conventional, everyday existence is not negated.” When the world of enduring objects dissolves, to be replaced by one of processes and interactions, we are left in a world that is not disenchanted by science, but even more magical. As Rovelli puts it: “Precisely because of its impermanence, because of the absence of any absolute, the now has meaning and is precious.”
Nobody said that post-Newtonian physics was easy, but Rovelli’s gift is to bring difficult ideas down a level. His books continue a tradition of jargon-free popular scientific writing from Galileo to Darwin that disappeared in the academic specialisations of the past century. Only in recent years has science become, in publishing terms, popular and attractive again... Undeniably, the book is hard going at times. (“I hope I have not lost my reader,” Rovelli says at one point.) The American physicist Richard Feynman presumably meant it when he said that “nobody understands quantum mechanics”. In his trademark lucid prose, Rovelli does his best to explain why this might be so. Known for his work on loop quantum gravity theory and the pre-Socratic Greek philosopher Anaximander, Rovelli is a deep-thinking, restlessly inquiring spirit who sees no incompatibility between physics and philosophy – only mutual attraction.