137 - Arthur I. Miller [116]
Through the Looking Glass
Dreams of reflections
IN NOVEMBER 1954 Pauli had a dream so curious that three years later he was still thinking about it. He sent a description of it to Jung. In his waking life Pauli was very preoccupied with issues of symmetry, both in physics and in psychology—the conscious and unconscious as mirror images of each other. It was not surprising that this preoccupation should seep into his dreams as well.
In the dream he is with a dark woman—his anima—in a room in which experiments are being carried out involving reflections. The “others” in the room think that the reflections are real objects, but Pauli and the dark woman know they are just mirror images. They keep this secret. “This secret fills us with apprehension.” From time to time the dark woman changes into the Chinese woman of Pauli’s earlier dreams, who had paraded Pauli before the “strangers.” The Chinese woman, according to Jung, represents the dark woman’s holistic side, in that Chinese philosophy seeks to reconcile opposites.
Pauli guessed that the “others” represented the collective opinion which he took to be his “own conventional objections…to certain ideas—and [his] fear of them.” The problem with which he is struggling is that “there is no symmetry of ‘objects’ and ‘reflections’ in this dream, since the whole point is about distinguishing between the two.” Even though he can see that what appear to be objects are simply reflections, the “others” cannot. In this dream there is no mirror symmetry. But this is impossible.
In the very first set of dreams he had presented to Jung in 1932, he had spoken of the conscious and the unconscious as mirror images of each other. When he was sure that the “left is the mirror image of the right,” he felt at one with himself because it meant his conscious and unconscious were in balance.
Charge, parity, and time reversal (CPT)—Pauli’s third great breakthrough
Pauli never worked out quite why it was that he started working on the mathematics of mirror images. The year was 1952. As he wrote, “between 1952 and 1956 there was not actually anything going on in the world of physics to justify focusing on that particular subject.” It was two years later that he dreamed about the Chinese woman and began to suspect that “there must have been psychological factors involved.”
Pauli began his investigation into mirror symmetry by looking at time reversal. Representing time with the symbol T, he placed a minus sign in front of it. In mathematical terms, he made time run backward. (Hard though it is to imagine, this can actually be done in the laboratory at a subatomic level.) When time is run backward, we look into a world in which a particle that was originally moving to the right is now moving to the left; the particle’s speed is also reversed. The law of time reversal asserts that the laws of physics remain the same when time is reversed—time-reversal invariance—which means that there is no difference between the state of a collection of moving elementary particles (or billiard balls or cannonballs) and the same collection in which time has been reversed. Time-reversal invariance is not a property of a specific state of a collection of objects, but of two different states. In other words, it is not intrinsic to any particular particle, like the spin of an electron is.
Pauli’s lectures on this inspired other physicists to look into the connection of time reversal (T) with two other symmetries, parity (P) and charge conjugation (C). Parity is the mirror-image effect, the interchange of left and right. In both prequantum and quantum physics, the law of parity conservation states that every physical system (that is, atoms, electrons, billiard balls, etc.) should be independent of any difference between right and left. Physicists believe that atomic systems have a particular parity independent of the system’s location in space and time and which must be maintained throughout all interactions. If an experiment