137 - Arthur I. Miller [61]
Käthe Deppner and Pauli in the countryside, 1929.
For even before the marriage had taken place, it was clear it was going to be a disaster. Käthe made it known that she had already fallen in love with someone else, but for some reason she decided to go through with the marriage to Pauli. Maybe she hoped it would work out in the end. After the ceremony the couple moved into a flat in Hadlaubstrasse, 41, a three-story house with large French windows on a pleasant tree-lined street.
Letters of congratulation poured in. But only two months later, Pauli was already confessing to a friend that he was married only in a very “loose way.” He was clearly unhappy. “He used to walk around like a caged lion in our apartment,” Käthe recalled, “formulating his answers [to letters] in the most biting and witty manner possible. This gave him great satisfaction.” Pauli’s profession demanded that he sit at a desk alone for hours on end. It must have been stifling for someone like her.
In November 1930, less than a year after they had married, the two divorced. Käthe had walked out on Pauli. What he most resented, he always said wryly, was that she had left him for a mere chemist. “If it had been a bullfighter—with someone like that I could not have competed—but with an average chemist?” he would complain. “In spite of his theories he is, like other mortals, at times vehemently plagued by jealousy,” a colleague observed. Soon afterward Käthe married her chemist, Paul Goldfinger.
The lonely neutrino—Pauli’s second breakthrough
Through all this tumult, Pauli’s scientific creativity never flagged. The problem absorbing him at the time was, What happens when the nuclei of certain atoms give off excess energy by emitting an electron? Precise measurements of this process—known as beta-decay—showed, inexplicably, that the energy contained in the nucleus before the electron was emitted was greater than the combined energies of the nucleus afterward plus the discharged electron.
Somewhere, somehow, some energy had been lost. Could it be that beta-decay violated the law of conservation of energy, which holds that these energies must be equal? The law of conservation of energy was a mainstay of physics and engineering, and theories that violated it invariably turned out to be wrong.
Yet, in 1929, Niels Bohr had gone so far as to suggest that this fundamental law might not hold precisely for processes inside the nucleus, but only on average. “We must still be prepared for new surprises” in the atomic world, he wrote. Pauli and most other physicists strongly disagreed.
Pauli jokingly suggested to Bohr, “What if someone owed you a great deal of money and offered to pay it back in instalments, but each time the agreed instalment was not met? Would you consider this to be a statistical error or that something was missing?” In other words, Bohr was trying to make out that the missing energy was a matter of statistics and so was only missing on average.
In the papers on quantum electrodynamics that Pauli wrote with Heisenberg in 1929, he had demonstrated that the law of conservation of energy was built into its equations. Now he pondered long and hard over the loss of energy in beta-decay. Then he came up with an audacious suggestion. Perhaps something really was missing. Could it be that the nucleus undergoing beta-decay emitted another as-yet-undetected particle, along with the electron, that would balance the books?
From the mathematics of beta-decay Pauli inferred that this particle’s mass must be not more than the electron’s, its spin must be one-half and it must have no electric charge. He was later to write