Physics is...

Questions answered by Werner Heisenberg (1901 – 1976)(Sources: Armin Hermann, “Werner Heisenberg,” Reinbek bei Hamburg 1979/ Werner Heisenberg, “Der Teil und das Ganze. Gespräche im Umkreis der Atomphysik,” Munich 1981/ Werner Heisenberg, “Physik und Philosophie,” Frankfurt, Berlin, Vienna 1977/ Werner Heisenberg, “Das Naturbild der heutigen Physik,” Hamburg 1955)

1. What were your reasons for studying physics? After having read Weyl’s “Raum-Zeit-Materie,” the future professor of mathematics was said to have already been spoiled for mathematics anyway.” “This is why I gave up my intention to study mathematics. After disappointing discussions with my father, I decided that I could try to study mathematical physics just as well.”
2. What university did you go to? Munich
4. Your physical aha-experience? It was a revelation to Heisenberg “that mathematics goes with the things of our experience; a discovery which - as I learnt at school – had already been made by the Greek, by Pythagoras and Euclid. Stimulated by the classes of Mr. Wolff, I tried out the use of mathematics myself, and these changes from mathematics to visualization and vice versa for me were at least as amusing as most other games. Later on, the field of geometry was no longer sufficient as a playing ground for mathematical games. From some books I learned that in the field of physics I could investigate the characteristics of my self-made apparatuses also by mathematical means, and I started studying the mathematics one needs for the description of the physical principles with the aid of Göschen booklets and similar, somewhat primitive, textbooks.”
6. Are you also interested in a completely different speciality? Mathematics and philosophy
9. By what do you recognize a physicist? “Every natural scientist engaged in research work has the feeling that he is looking for something which is objectively true. His statements are not meant to depend on the conditions under which they can be verified.”
13. Do you understand quantum mechanics? “Wolfram once asked me – I think it was in the course of an evening we spent at a pub at Grainau – whether I had understood Einstein’s theory of relativity which played such an important part in the Sommerfeld seminar. I could only answer him that I didn’t know, as I was not sure to understand the meaning of the word “understand” in natural science. I did not have any difficulties in understanding the mathematical structure of the theory of relativity, but that did not mean that I had understood why the word “time” has a different meaning for an observer in motion than for an observer at rest. For me, this confusion around the term of “time” was weird and insofar I did not understand this term.”
17. Do you master a musical instrument? The piano
22. What is in your opinion most important in a measurement? With good reason, the old formula “Credo ut intellegam – I believe in order to understand – has been used in Europe’s world history recently depicted by Freyer [...], and Freyer has expanded it [when applying it to the voyages of Columbus] by adding a link: “Credo ut agam; ago ut intellegam – I believe in order to act; I act in order to understand.” This formula goes not only with the first circumnavigations of the global, but also with the whole of the natural science of the Occident. It encompasses education in the humanities and natural science.”
24. Would you tell us three important events of your biography? 1933 – Heisenberg is awarded the Nobel prize for physics for the year 1932, 1941 – (unsuccessful) discussions with Niels Bohr on the military use of nuclear energy and on how to prevent this, 1945 – 1956 – Heisenberg is interned by the Allies together with other German physicists at Farmhall near Cambridge.
28. Which physicist do you admire? “I was impressed by Einstein’s way of handling things.”
32. There was a time when certain physical experiments were suddenly regarded as politically undesired. How political can physics be in your opinion? “Otto Hahn and all of us have had a part in the development of the modern natural sciences. This development is a process of life in favour of which mankind, or at least the Europeans, have decided many years ago – or, to formulate it more carefully: in which mankind got involved. We know from experience that this process may lead to Good or Evil. But we were convinced – and this was the belief in progress of the 19th century – that with increasing knowledge, the Good would prevail and that the possible negative consequences might be controlled. Before Hahn’s discovery of nuclear fission, neither Hahn nor any other person could seriously think of the possibility of atomic bombs, as at that time physics did not show any road in that direction. No one can be made guilty of having participated in this process of scientific development.”
33. Is it possible to still discover something new in the field of physics? “If one asks in what the great achievement of Christopher Columbus when discovering America really consisted, one will have to answer that it was not the idea to make use of the world’s spherical shape to travel to India on the Western route; this idea had already been considered by others. Neither was it the expert preparation of his journey or the professional equipment of the ships – this could also have been done by others. The most difficult aspect of this journey certainly was the decision to leave his well-known land behind and to sail so far to the West that a return would not be possible with the provisions available. In a similar way, really new grounds can be found in science only if at a decisive point and time one is prepared to leave the ground on which science has so far been based.”
34. Is nature really as physics, biology and chemistry describe it? “Natural science describes and explains nature not just as it is “as such.” It rather is part of the interrelation between nature and ourselves. It describes the nature as exposed to our questions and methods.”
35. Try to find a definition for coincidence. “Is there a possibility for what is possible – that is the aim to be reached – to influence causal sequences? This, however, again leads us to the field of quantum theory, as the wave function represents what is possible and not what is factual. In other words: maybe coincidence, which plays such an important part in Darwin’s theory, is much more subtle than we imagine, because it submits itself to the laws of quantum mechanics.”