Werner Karl Heisenberg was born on December 5, 1901, in Würzburg, Germany, into an academic family. His father was a professor of medieval literature and modern Greek studies. During his early education, Werner displayed an aptitude for mathematics and physics, and during his late teenage years immersed himself in the study of philosophy, with a special focus on Plato’s Timaeus. This would later influence his thinking about “reality” as it applied to the microcosm of elementary particle physics.
In 1920, Heisenberg embarked on the study of mathematics and physics at the Ludwig Maximillian University of Munich under the guidance of Arnold Sommerfeld and Wilhelm Wien. In June, 1922 Sommerfeld took Heisenberg to the Bohr Festival where he met Niels Bohr, who was lecturing on quantum physics. Although Heisenberg was eager to pursue his interest in quantum physics, he followed in Sommerfeld’s footsteps, devoting the next year to his study of turbulence. In 1923, he was awarded his doctorate for his the thesis on the nature of laminar flow and turbulence. A year later, he completed his habilitation thesis on the anomalous Zeeman effect (splitting of spectral lines under a magnetic field) under the supervision of Max Born at the University of Göttingen.
In 1924, Heisenberg began his working career as a Privatdozen at the University of Göttingen. Then, in September of that year, he received a Rockefeller Foundation fellowship that enabled him to spend the academic year of 1924–25 at the University of Copenhagen to conduct research with Niels Bohr. On his return to Göttingen, Heisenberg published his celebrated paper, Quantum theoretical re-interpretation of kinematic and mechanical relations. During the next six months, he worked with Max Born and Pascual Jordan in formulating quantum physics using matrix mechanics.
On May, 1 1926, Heisenberg was appointed lecturer and assistant to Niels Bohr at the University of Copenhagen. On February 23, 1927, Werner Heisenberg wrote a letter to fellow physicist Wolgang Pauli, about a new principle he had formulated, that is known today as the Uncertainty Principle:
…Could it not be true that nature only allows for such situations which can be described with a mathematical scheme? …We had asked, given the situations in nature like the orbit in a cloud chamber, how can it be described with a mathematical scheme? But that wouldn’t work, because by using such a word like “orbit”, we of course assumed already that the electron had a position and had a velocity. …If I say nature only allows such situations as can be described with a mathematical scheme, then you can say, well, this orbit is really not a complete orbit. Actually, at every moment the electron has only an inaccurate position and an inaccurate velocity, and between these two inaccuracies there is this uncertainty relation. And only by this idea it [is] possible to say what such an orbit [is].
In its mathematical formulation, the Uncertainty Principle asserts that it is impossible to measure simultaneously and precisely certain pairs of properties (like position and momentum) of a particle. For example, to determine the momentum of an electron in a particular position, we must bombard it with another particle, thereby moving it to an unknown position. The Copenhagen interpretation of this quandary is that the particle does not have a definite position or momentum until it is measured. Hence, we can never know its position and momentum simultaneously.
In 1927, Heisenberg was appointed head of the department of physics at the University of Leipzig. In early 1929, he and Pauli submitted the first of two papers laying the foundation for relativistic quantum field theory, in which they combined quantum physics with Einstein’s Special Theory of Relativity. In that same year, Heisenberg went on a lecture tour of China, Japan, India, and the United States. His celebrity as a researcher on the frontier of quantum physics led to his appointment as visiting lecturer In the spring of 1929, at the University of Chicago.
For his development of quantum mechanics, and in particular his formulation of the Uncertainty Principle, Werner Heisenberg was awarded the Nobel Prize in Physics in 1932 However, with the rise of Hitler in 1933, Heisenberg, an Aryan by heredity, was accused of being a “white Jew” and denied the opportunity to succeed his mentor, Arnold Sommerfeld, as head of the Institute for Theoretical Physics at the University of Munich.
Amidst rising political tensions in Europe, elementary particle theory continued to evolve, and in 1938 the German chemists Otto Hahn and Fritz Strassmann split the uranium nucleus by bombarding it with neutrons. In January 13 of the following year, Frisch confirmed by experiment this technique for splitting the atom, and revealed the potential of a nuclear bomb. In the summer of 1939, Heisenberg traveled to the University of Michigan in Ann Arbor, US to collaborate with Samuel Goudsmit, but refused an offer to become a US citizen. On September 1 of that year, World War II began, and 16 days later, the German nuclear energy project, dedicated to the development of a nuclear bomb was launched.
In April 1942, Heisenberg was appointed Director of the Kaiser Wilhelm Institute but the nature of his contributions to the building of an atomic bomb during this period remain a subject of historical debate. Some accounts depict him as heading up the Nazi program to build an atomic bomb, while others depict him as a scientist who was apolitical, and focussed entirely on the investigation of nuclear fission as a source of energy.
At the end of the war, Heisenberg was captured by the British who detained him and nine other German scientists in London, where they examined the extent to which each participated in the Nazi war effort. In the absence of hard evidence of Heisenberg’s participation in the Nazi agenda, Heisenberg was released and enabled to continue his scientific research in the part of Germany that was under Allied control. He held various academic positions, including the directorship of the Max Planck Institute for Physics and Astrophysics. In the subsequent years, Heisenberg published papers on turbulence, superconductivity, and the theory of ferromagnetism.
In his later years, Heisenberg became more involved in the philosophy of science and in promoting more communication between scientists and the public so that politicians are held more accountable for their applications of scientific discoveries. During his late sixties, he wrote his autobiography and on February 1976, at the age of 74, he died of kidney cancer at his home in Munich.
Werner Heisenberg’s work laid the groundwork for much of modern quantum mechanics, and his Uncertainty Principle had profound implications for our understanding of the fundamental nature of the physical world. Werner Heisenberg will be remembered as one of the great founders of quantum physics.
