Uncertainty: The Life and Science of Werner Heisenberg
by David C. Cassidy
W. H. Freeman, 669 pp., $29.95
Werner Heisenberg was undoubtedly one of the greatest physicists of this century. In 1925, at the age of twenty-three, he wrote the paper that laid the foundations of quantum mechanics on which all subsequent generations have built. This was not just an extension or elaboration of the work of others, but an unexpected, radical new departure, which abandoned the basic notions of the old “classical” physics, such as that of electrons moving in orbits, replacing them by a much more abstract description.
In the public mind many advances in science are attributed to famous scientists, but in most cases the famous discoverer has completed a structure that was already developing, and without him someone else would sooner or later have done the same. Heisenberg’s paper was so original that, if he had not been around, it might have taken a very long time for the idea to occur to some other physicist; so this is one of the cases in which the personal attribution is justified. It is true that less than a year later Erwin Schroedinger published his theory of wave mechanics, which turned out to be identical in content to Heisenberg’s quantum mechanics. But we needed both points of view to develop a real understanding of the physical world.
Heisenberg was born in 1901 into an academic family. He was in his teens in Munich after the First World War, when a strong youth movement was emerging, and he became an enthusiastic member. Long hikes and campfire discussions of poetry, philosophy, religion, and music appealed to him. He learned to appreciate the beauty of nature: love for the countryside was part of the patriotism that was a strong emotion throughout his life. He became a youth leader, and formed a close friendship with a group of younger boys with whom he continued his long walks well after he became a famous and established scientist.
Another early interest was music; he was a highly gifted pianist, and it was even suggested that he might choose music as a career. But he was more strongly attracted to mathematics and physics; as a schoolboy he was fascinated by the theory of relativity. At the University of Munich he first tried to enroll in the study of mathematics, but he was put off by the mathematics professor, Ferdinand Lindemann, and he joined instead the theoretical physics group under Arnold Sommerfeld, then the greatest teacher of the subject. Sommerfeld immediately recognized Heisenberg’s unusual ability. Another student in the group, Wolfgang Pauli, a year his senior, became a lifelong friend.
Heisenberg was introduced to the intricacies of the quantum theory of Niels Bohr and Arnold Sommerfeld, which had successfully explained many facts about atoms, but had also had many failures and contained internal inconsistencies. He wrote his first paper in 1922, barely a year after entering the university. During Sommerfeld’s absence on leave he went to Göttingen to work with Max Born, and later returned there as Born’s assistant …