Helgoland by Carlo Rovelli: a short lesson in quantum physics

Popular books on quantum mechanics almost invariably dazzle and amaze, offering tantalizing glimpses of nature’s deepest mysteries, only to finally leave the reader baffled. The greatest popularizer of physics today, Carlo Rovelli, prepares the readers of his new book for this familiar destiny when he warns that if “what I have described seems perfectly clear, it means that I have not been clear enough.”

It is too modest. His previous books addressed to the general reader, including the international phenomenon Seven short physics lessonsThey have established him as a more literary heir to Stephen Hawking. In Helgoland puts his own interpretation of quantum physics center stage and the result is a book that allows us to share Werner Heisenberg’s almost religious “feeling that I had gone beyond the surface of things.” Quantum physics cannot be perfectly clarified, but Rovelli perfectly provides as much clarity as possible.

The incredible implications of quantum physics are well known. The properties of the objects seem to change depending on whether they are being observed or not. Quantum entanglement means that two objects appear to be able to affect each other when they are too far apart for information from one to reach the other – a photon on Venus could be switched by a photo taken in Venice. Yet this strange science finds practical use every day, forming “the foundation of our latest technologies: from computers to nuclear power.”

Rovelli finds the competing interpretations of quantum theory that aim to solve these puzzles anyway. So he ditches all our assumptions and starts over, following the principle that “everything should be based on what we see, not what we assume.” This rigorous empiricism guided both Einstein, whose theory of relativity was a kind of prequel to quantum mechanics, and Heisenberg, one of the first quantum pioneers, who made his first advances on the island of Heligoland in the North Sea. .

It sounds obvious, but even many scientists remain attached to metaphysical assumptions that are not based on observation at all. Chief among these is the idea that behind appearances there must be a “solid and well-defined image of the world” in which objects have inherent and immutable properties. Science has decomposed the world, first into atoms, then into elementary particles, but always assuming that deep down there was a reality with a stable and measurable nature.

The pre-Socratic philosopher Heraclitus challenged this assumption two and a half millennia ago by postulating an ever-changing world. The Western mind could have taken a very different form if its ideas had prevailed over those of its successor, Plato, who saw ultimate reality as unchangeable.

Outside the West, the illusion of solidity has been less prevalent. The richest prescientific articulation of the alternative worldview occurred in the writings of the second century BC. Of the Indian Mahayana Buddhist thinker Nagarjuna. His doctrine of sunyata, or emptiness, says that nothing exists complete in itself, but only in relation to other things. This was not quantum theory avant la lettreBut Rovelli argues that the Nagarjuna Middle Way provides the proper framework for understanding “a reality made up of relationships rather than objects.”

So it is not true that quantum theory forces us to accept the absurdity that the properties of objects change depending on whether they are observed or not. Rather, the properties of an object always depend on what it is interacting with. Think about how an air vibration can be invisible to one ear and an intolerable screech to another. Therefore, it is not that looking at reality has a special power to alter it, but that “any interaction between two physical objects can be seen as an observation.”

Quantum entanglement is explained in a similar way. The moment a third party, in this case, the observer, enters the scene, it is not that the image changes, but rather that we are seeing a different image.

Rovelli’s clarity of exposition would be enough to make the book a triumph. What elevates it even higher is the deep humanity it brings to its subject. Despite all his immense powers of rationality, this is still a man who always sniffs books before buying them.

It reminds us that many of the key players in the development of quantum theory had interests that went far beyond science. The young Heisenberg learned Goethe’s poems by heart ”, Schrödinger was“ fascinated by Asian thought ”and, like Einstein, he was“ passionate ”by Schopenhauer’s philosophy”.

There is much in this short but rich book, including a fascinating detour through the dispute between Lenin and his Bolshevik colleague, the scholar Alexander Bogdanov. Rovelli concludes that despite 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 denied.”

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 says: “Precisely because of its impermanence, because of the absence of an absolute, the now makes sense and is precious.”

Helgolandby Carlo Rovelli, Allen Lane, RRP £ 20, 208 pages

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