Helgoland by Rovelli, Erica (ebook reader below 3000 .txt) 📗

felt great admiration for Heisenberg when, at just twenty-three, he managed it in one swoop.”11

Except for Born, who is in his forties, Heisenberg, Jordan, Dirac and Pauli are all twentysomethings. In Göttingen they call their physics Knabenphysik, or “boys’ physics.”

Sixteen years later, Europe is in the throes of another world war. Heisenberg is by now a famous scientist. Hitler has assigned to him the task of using his knowledge of the atom to construct a bomb that will win the war. Heisenberg takes a train to Copenhagen, in a Denmark occupied by the German army, and visits his old teacher. The old master and the young man talk together, before parting without having understood each other. Heisenberg will later say that he sought out Bohr to discuss the moral problem entailed by the prospect of a terrifying weapon. Not everyone will believe him. Shortly afterward, with his consent, Bohr is kidnapped in a British commando raid and taken out of occupied Denmark. He is taken to England and received personally by Churchill—then to the United States, where his knowledge is put to work with the generation of young physicists who have learned how to use the new quantum theory to manipulate atoms. Hiroshima and Nagasaki are annihilated. Two hundred thousand human beings—men, women and children—killed in a fraction of a second. Today we live with tens of thousands of nuclear warheads aimed at our cities. If anyone were to lose their head, or make a mistake, there is ample capacity to destroy life on our planet. The devastating power of the “boys’ physics” is evident for all to see.

Thankfully, there is much more than weapons. Quantum theory has been applied to atoms, atomic nuclei, elementary particles, the physics of chemical bonds, the physics of solid materials, of liquid and gas, semiconductors, lasers, the physics of stars such as the Sun, neutron stars, the primordial universe, the physics of the formation of galaxies . . . and so on and so forth. The list could go on for pages. Quantum theory has allowed us to understand whole areas of nature, from the form of the periodic table of elements to medical applications that have saved millions of lives. It has predicted new phenomena never previously imagined: quantum correlations over a distance of kilometers, quantum computers, teleportation. All predictions have turned out to be correct. The astonishing run of quantum theory’s successes has been uninterrupted for a century, and it continues today.

The calculation scheme by Heisenberg, Born, Jordan and Dirac, the strange idea of “limiting yourself to only what’s observable,” and to substituting physical variables with matrices,12 has never yet been wrong. It is the only fundamental theory about the world that until now has never been found wrong—and whose limits we still do not know.

But why is it that we are not able to describe where the electron is and what it is doing when we are not observing it? Why must we speak only of its “observables”? Why is it that we can speak of its effect when it leaps from one orbit to another, and yet we cannot say where it is at any given moment? What does it mean to replace numbers with tables of numbers?

What does it mean that “everything is still very vague and unclear to me, but it seems that electrons no longer move in orbits”? His friend Pauli wrote of Heisenberg: “He reasoned in a terrible way, he was all about intuition; he did not pay any attention to elaborating clearly the fundamental assumptions and their relation to existing theories.”

The spellbinding article by Werner Heisenberg, with which everything started, conceived on the island in the North Sea, opens with the phrase: “The objective of this work is to lay the foundations for a theory of quantum mechanics based exclusively on relations between quantities that are in principle observable.”

Observable? What does Nature care whether there is anyone to observe or not?

The theory does not tell us how the electron moves during a leap. It only tells us what we see when it leaps. Why?

THE MISLEADING Ψ OF ERWIN SCHRÖDINGER: PROBABILITY

In the following year, 1926, everything seems to come clear. The Austrian physicist Erwin Schrödinger manages to obtain the same result as Pauli, calculating the Bohr energies of the atom, but in a completely different way.

Curiously, this result, too, is not obtained in a university department or lab: Schrödinger achieves it during a getaway with a secret lover in the Swiss Alps. Raised in the libertarian and permissive atmosphere of Vienna at the beginning of the century, the brilliant and charismatic Schrödinger always kept a number of relationships going at once—and made no secret of his fascination with preadolescent girls. Years later, despite being a Nobel laureate, Schrödinger had to leave his position at Oxford because of a lifestyle too unconventional even for the supposed English accommodation of eccentricity. He was living at the time with his wife, Anny, and his pregnant lover, Hilde, the wife of his assistant. Things did not go much better in the United States: at Princeton, Erwin, Anny and Hilde wanted to live together with little Ruth, who had been born in the meantime—but the Ivy League was not ready for a ménage such as this. In search of somewhere more liberal, they moved to Dublin—but there, too, Schrödinger ended up at the center of a scandal, after fathering children with two of his students. His wife commented: “You know it would be easier to live with a canary bird than with a race horse, but I prefer the race horse.”13

The identity of whoever accompanied him into the mountains in those first days of 1926 remains a mystery. We only know that she was an old Viennese friend. Legend has it that he’d headed there taking just his lover, two pearls to place in his ears to isolate himself when he wanted to think about physics, and