Helgoland: Making Sense of the Quantum Revolution

by Carlo Rovelli

At the time Dante was writing, in Europe we thought of the world as the blurred mirror of a great celestial hierarchy: a great God and His spheres of angels carried the planets in their course across the heavens and participated with trepidation and love in the lives of a fragile humanity which oscillated, at the center of the universe, between adoration, rebellion and guilt.

Not to fear rethinking the world is the power of science: ever since Anaximander removed the foundations on which the Earth rested, Copernicus launched it to rotate in the sky, Einstein dissolved the rigidity of space and of time, and Darwin demolished the separateness of humanity . . . reality is constantly being redrawn in images that are increasingly effective. Step by step, the fabulous strangeness and beauty of reality is unveiled. The courage to radically reinvent the world: this was the subtle fascination of science that first captivated me as a rebellious adolescent . . .

Bohr speaks of the “impossibility of neatly separating the behavior of atomic systems from their interaction with the measuring device used to define the conditions under which the phenomenon appears.”53 When he wrote this, in the 1940s, the applications of the theory were confined to the laboratories that measured atomic systems. Almost a century later, we know that the theory is valid for every object in the universe. We need to amend “atomic systems” to “all objects,” and “interaction with measuring equipment” to “interaction with any other thing whatsoever.”

The properties of an object are the way in which it acts upon other objects; reality is this web of interactions. Instead of seeing the physical world as a collection of objects with definite properties, quantum theory invites us to see the physical world as a net of relations. Objects are its nodes.

The world is the network of relative facts: relations realized when physical entities interact. A stone collides with another stone. The light from the sun reaches my skin. You read these lines.

The solidity of the world to which we have become accustomed in our daily lives does not reflect the actual grain of reality: it is the result of our macroscopic vision. A lightbulb does not emit continuous light, it emits a hail of evanescent photons. At small scale, there is no continuity, or fixity, in the real world: there are discrete events, interactions, gapped and discrete.

In the words of the nineteenth-century French philosopher Hippolyte Taine, we can say that “external perception is an internal dream which proves to be in harmony with external things; and instead of calling ‘hallucination’ a false perception, we must call external perception ‘a confirmed hallucination.’”134 Science, we may say, is only an extension of the way in which we see: we seek out discrepancies between what we expect and what we gather from the world. We have visions of the world, and if they don’t work, we change them. The whole of human knowledge is constructed in this way.

There is, of course, something bewildering about the vision of the world that emerges from this theory. We must abandon something that seemed most natural to us: the simple idea of a world made of things. We recognize it as an old prejudice, an old vehicle that we no longer have any use for.

passages in the history of literature. After taking us on such a flight of imagination, taking us temporarily outside ourselves, Prospero/Shakespeare comforts us for looking “in a moved sort” and “as if you were dismay’d”: “Be cheerful . . . / Our revels now are ended. These our actors, / As I foretold you, were all spirits and / Are melted into air, into thin air.” Only to then softly dissolve into that immortal whisper: “We are such stuff / As dreams are made on, and our little life / Is rounded with a sleep.”