W. Heisenberg, 'Physics and Beyond: Encounters and Conversations'

I continued. "Besides that, the necessity for an extension of quantum mechanics is sometimes questioned regarding the existence of human consciousness. There is no doubt that the concept of 'consciousness' does not appear in physics or science, and it is actually unclear how one might construct something resembling it from quantum mechanics. However, consciousness should have a place within natural science, including living organisms, because it belongs to reality."

Here, I tried to join the conversation again and stated the following: "You have now accurately described the characteristic nature of today's quantum theory. If we intend to infer regularities from atomic phenomena, we can no longer connect objective processes in space and time—or, to use a more careful expression, an observational situation emerges. Only against this can we maintain empirical laws. The mathematical symbols we use to describe such observational situations represent possibilities rather than facts. They represent something intermediate between possibility and fact, and one could perhaps say they are objective in at most the same sense that temperature is spoken of in statistical thermodynamics. It is true that a certain knowledge of these possibilities allows for some certain and clear predictions, but in general, it only allows for probabilistic conclusions about future results. Kant could not foresee that in the realm of experience far removed from daily life, the order of perception can no longer be penetrated by models of 'things-in-themselves'—or 'objects,' if you prefer—and therefore, to summarize in one simple word, atoms are neither things nor objects."
"But then, what exactly is an atom?"
"To that, we cannot give an expression using language. This is because our language is formed in connection with daily experience, and atoms are certainly not objects of daily experience. However, if you wish for a paraphrase, let us say this: it is a constituent of an observational situation, and a constituent with high explanatory value for the physical analysis of phenomena."
Here, Carl Friedrich interjected. "If we are to talk about the difficulty of expression through language, the most important lesson we can draw from modern physics is perhaps that all concepts that allow us to describe experience have only a limited range of application. In the case of concepts such as 'thing,' 'object of perception,' 'point in time,' 'simultaneity,' and 'extension,' we can point to experimental situations where these concepts do not work well. Nevertheless, this does not mean that these concepts cannot be the premise of all experience; it shows that premises that should always be critically analyzed are important, and that no absolute claims can be derived from them."
Then she asked further, "This relativization of Kant's 'a priori' is just a matter of words, and it does not mean a complete resignation in the sense of 'we have learned that we cannot know anything,' does it? Then, from your point of view, is there no foundation of knowledge upon which we can establish anything?"
Then Carl Friedrich, this time very boldly, replied that one could take an optimistic view from the development of natural science.
"The progress of science is achieved not only by our learning and understanding new facts, but also by our repeatedly learning anew what the word 'understanding' means."

"One must think about the era that comes after the catastrophe," (Max) Planck said, and I understood that well. It was the task stated by Planck to build an island of invariance through the catastrophe, to gather young people, to let them survive the catastrophe as vividly as possible, and to start anew once the catastrophe is over.
When I returned to Leipzig, my mind was made up, at least for the time being, to remain in Germany and at the University of Leipzig, and to see where this path would lead me further.

When Euler returned, he was shaken and anxious. And he reported to us in detail about his experience. "There was a small group of young people to which the Hitler Youth leader you spoke of also belonged, and those people truly believed in Nazism and held the opinion that some good results must surely come from it. I now know how many terrible things have already arisen from this movement, and perhaps how much misfortune will be caused for Germany by it in the future. At the same time, I felt that many of these young Nazis were nevertheless seeking something similar to what I myself was seeking. They, too, find this rigid civil society, where material prosperity and superficial fame are accepted as the most important value standards, unbearable. They certainly wish to replace this hollowed-out skeleton with something full and vivid. They wish to make human relationships more human, and that is something I also desire at the root. Yet, I still do not understand why so many inhuman things are born from such attempts. All I know is that it is reality."

One day, I asked if I could apply for him (Hans Euler) as a collaborator on the uranium problem.
"In this world full of meaninglessness, I do not know what use it would be for me to work on the utilization of atomic energy here."
"We are all powerless against the catastrophe currently in progress," I countered. "You cannot do it, and neither can I. But life after that will continue everywhere—here, in Russia, and in America. By then, a great many people, whether capable or incapable, guilty or innocent, will have died. But those who survive must then strive to build a better world. That might not be particularly good either. And people will surely realize that the war solved almost nothing. But even so, some mistakes might be avoided, and things might be made even slightly better; why do you not want to be there?"
"I have no intention of criticizing anyone who takes such a task upon themselves. Anyone who has long been content with the inadequacy of their environment and has chosen constant, painstaking, small improvements over a great revolution will find that the correctness of their patience has been endorsed, and they will repeat those painstaking small steps after the war. In the long run, that is perhaps better than any revolution. However, I see it differently. Indeed, I had hoped that communist ideals could fundamentally renew human communal life.
Anyone who wishes to turn the world into a crucible should also be prepared to be thrown into the crucible themselves. You must surely understand this as well."
The war with Russia broke out. Euler's plane did not return from its first reconnaissance flight over the Sea of Azov.

It was the afternoon of August 6, 1945. Carl Wirtz suddenly came to me, saying he had just heard on the radio that an atomic bomb had been dropped on the Japanese city of Hiroshima. At first, I did not want to believe this news. This was because I knew well that manufacturing an atomic bomb would require enormous technical expenditure, likely amounting to billions of dollars. Also, psychologically, it seemed impossible to me that the American atomic physicists I knew so well would devote all their efforts to such a project.
Only in the evening, when the radio news commentator explained the enormous technical expenditure spent on it, did I have to face the fact that the progress of atomic physics, to which I had devoted my heart and soul for twenty-five years in an old red-brick building, had now become the cause of the deaths of well over one hundred thousand people.
The one who received the worst shock was, naturally, Otto Hahn. Nuclear fission of uranium was his most significant discovery, and it was the decisive and completely unforeseen first step toward atomic technology. And this step had now caused a terrible outcome for a large city and its citizens—people who were unarmed and most of whom should have had no responsibility for the war. Hahn's shock was severe, and he returned to his room in a distraught state. We were seriously worried that he might commit suicide.

Niels (Bohr) replied.
"On one hand, we formulate laws different from classical physics, but on the other hand, at the stage of observation where we measure or take photographs, we use classical concepts without any hesitation. We have no choice but to do so because we must rely on language to inform others of the results we have obtained."
"It belongs to the basic premise of our science that we speak about our measurements using language that has essentially the same structure as when we speak about the experiences of daily life."

" 'In the beginning was symmetry'—that is certainly more correct than Democritus's proposition, 'In the beginning was the particle.' Elementary particles are the simplest expression of symmetry that embodies symmetry, but elementary particles are merely a consequence of symmetry. In the development of the universe, chance begins to work later. However, even chance conforms to the form set at the beginning. It satisfies the frequency laws of quantum theory."

"Elementary particles can be compared to the regular polygons in Plato's 'Timaeus.' They are primordial images, the ideas of matter. Nucleic acids are the ideas of living things. These primordial images determine all broad events. They are representatives of a central order. And in the development of all creation, even if chance plays an important role later, this chance may also be connected to the central order in some way."

"Our thinking seems to be adapted to starting from the simplest things. And the simplest things are a kind of binary choice. Yes or no, existence or non-existence, good or evil.
However, we certainly know in quantum theory that even in a binary choice, there is not only a yes or no answer, but also other complementary answers. That is, the probabilities of yes and no are fixed within it, and furthermore, a certain kind of interference with a statement value is determined between yes and no."

"The dichotomy in the Aristotelian sense is, just as Pauli wrote in a letter, a symbol of the devil, and it only leads to mere chaos by continuing the repetition. However, the third possibility that emerged with quantum mechanical complementarity can be fruitful, and through repetition, it can lead to the space of the real world. In fact, in old mysticism, the number 'three' is connected to a divine principle. Without going back as far as mysticism, one can also think of Hegel's dialectic. Thesis, antithesis, synthesis. Synthesis will be fruitful only when something qualitatively new is born from the connection of thesis and antithesis, rather than being merely a mixture or a compromise between them."