Helgoland Rovelli, Erica (cat reading book .TXT) 📖

world. At times, radically new. It is the capacity to constantly call our concepts into question. The visionary force of a rebellious, critical spirit, capable of modifying its own conceptual basis, capable of redesigning our world from scratch.

If the strangeness of quantum theory confuses us, it also opens new perspectives with which to understand reality. A reality that is more subtle than the simplistic materialism of particles in space. A reality made up of relations rather than objects.

The theory suggests new directions in which to rethink great questions, from the structure of reality to the nature of experience, from metaphysics to perhaps even the very nature of consciousness. Today this is all a matter of the liveliest debate among scientists and among philosophers. I speak about it all in the following pages.

On the island of Helgoland—barren, extreme, battered by the winds of the north—Werner Heisenberg lifted a veil. An abyss opened. The story that this book has to tell starts from the island where Heisenberg conceived the germ of his idea, and progressively widens to take in ever bigger questions opened by the discovery of the quantum structure of reality.

I have written this book primarily for those who are unfamiliar with quantum physics and are interested in trying to understand, as far as any of us can, what it is and what it implies. I have sought to be as concise as possible, omitting every detail that is not essential to grasping the heart of the issue. I have tried to be as clear as possible, about a theory that is at the center of the obscurity of science. Perhaps rather than explaining how to understand quantum mechanics, I explain why it is so difficult to understand.

But I have also written it thinking of my colleagues—scientists and philosophers, who, the more they delve into the theory, the more they are perplexed—to continue the ongoing conversation on the significance of this astonishing physics. The book has notes intended for those who are familiar with quantum mechanics. They add a bit of precision to what I try to say in a more readable form in the text.

The objective of my research in theoretical physics has been to understand the quantum nature of space and time: to make quantum theory cohere with Einstein’s discoveries. For this, I have found myself thinking continually about quanta. This book represents where I have gotten to so far. It does not ignore other opinions, but it is shamelessly partisan: centered on the perspective that I consider the most effective and that I think opens up the most interesting paths: the “relational” interpretation of quantum theory.

A warning before we begin. The abyss of what we do not know is always magnetic and vertiginous. But to take quantum mechanics seriously, reflecting on its implications, is an almost psychedelic experience: it asks us to renounce, in one way or another, something that we cherished as solid and untouchable in our understanding of the world. We are asked to accept that reality may be profoundly other than we had imagined: to look into the abyss, without fear of sinking into the unfathomable.

—Lisbon, Marseille, Verona, and London, Ontario 2019–20

PART ONE

I

A STRANGELY BEAUTIFUL INTERIOR

How a young German physicist arrived at an idea that was very strange indeed, but described the world remarkably well—and the great confusion that followed.

THE ABSURD IDEA OF THE YOUNG HEISENBERG: OBSERVABLES

It was around three o’clock in the morning when the final results of my calculations were before me. I felt profoundly shaken. I was so agitated that I could not sleep. I left the house and began walking slowly in the dark. I climbed on a rock overlooking the sea at the tip of the island, and waited for the sun to come up . . .1

I have often wondered what the thoughts and emotions of the young Heisenberg must have been as he clambered over that rock overlooking the sea, on the barren and windswept North Sea island of Helgoland, facing the vastness of the waves and awaiting the sunrise, after having been the first to glimpse one of the most vertiginous of Nature’s secrets ever looked upon by humankind. He was twenty-three.

He was on the island seeking relief from the allergy that afflicted him. Helgoland—the name means Sacred Island—has virtually no trees, and very little pollen. (“Heligoland with its one tree,” as James Joyce has it in Ulysses.) Perhaps the legends of the dreadful pirate Störtebeker hiding on the island, which Heisenberg loved as a boy, were in his mind as well. But Heisenberg’s main reason for being there was to immerse himself in the problem with which he was obsessed, the burning issue handed to him by Niels Bohr. He slept little and spent his time in solitude, trying to calculate something that would justify Bohr’s incomprehensible rules. Every so often, he would take a break to climb over the island’s rocks or learn by heart poetry from Goethe’s West–Eastern Divan, the collection in which Germany’s greatest poet sings his love for Islam.

Niels Bohr was already a renowned scientist. He had written formulas, simple but strange, that predicted the properties of chemical elements even before measuring them. They predicted, for instance, the frequency of light emitted by elements when heated: the color they assume. This was a remarkable achievement. The formulas, however, were incomplete: they did not give, for instance, the intensity of the emitted light.

But above all, these formulas had about them something that was truly absurd. They assumed, for no good reason, that the electrons in atoms orbited around the nucleus only on certain precise orbits, at certain precise distances from the nucleus, with certain precise energies—before magically “leaping” from one orbit to another. The first quantum leaps. Why only these orbits? Why these incongruous “leaps” from one orbit to another?