Werner Heisenberg

“The end of the First World War had thrown Germany's youth into great turmoil. The reins of power had fallen from the hands of a deeply disillusioned older generation, and the younger ones dr...”

“It is true that in quantum theory we cannot rely on strict causality. But by repeating the experiments many times, we can finally derive from the observations statistical distributions, and...”

“Although the theory of relativity makes the greatest of demands on the ability for abstract thought, still it fulfills the traditional requirements of science insofar as it permits a divisio...”

“This proving of such and such I found to be almost like cheating. You start somewhere, and then you go into a dark tunnel, and then you come out at another place. You find that you have prov...”

“It is generally believed that our science is empirical and that we draw our concepts and our mathematical constructs from the empirical data. If this were the whole truth, we should, when en...”

“Our house was destroyed in 1943, and I moved the family to a cottage I owned before the war in the Bavarian Alps. This cottage was meant for a very few people, and at the end of the war, the...”

“It is seen that both matter and radiation possess a remarkable duality of character, as they sometimes exhibit the properties of waves, at other times those of particles. Now, it is obvious...”

“The uncertainty relation does not refer to the past; if the velocity of the electron is at first known and the position then exactly measured, the position for times previous to the measurem...”

“I would like to mention astrophysics; in this field, the strange properties of the pulsars and quasars, and perhaps also the gravitational waves, can be considered as a challenge.”

“Whoever dedicates his life to searching out particular connections of nature will spontaneously be confronted with the question how they harmoniously fit into the whole.”

“One may say that in a state of science where fundamental concepts have to be changed, tradition is both the condition for progress and a hindrance. Hence, it usually takes a long time before...”

“Reports in Washington show that our reasoning was just like that of your physicists. With all this information available, at least to privileged persons, I cannot understand why it is genera...”

“The uncertainty principle refers to the degree of indeterminateness in the possible present knowledge of the simultaneous values of various quantities with which the quantum theory deals; it...”

“Natural science, does not simply describe and explain nature; it is part of the interplay between nature and ourselves.”

“I had imagined doing nuclear physics and cosmic ray work in greater style in peace time. To do modern physics in a small way is of no use of all.”

“If the lecture is good, then everything is too smooth. That's the same in music: if the performance is too good, you really don't enjoy it, because it just goes by, and you can never penetra...”

“In 1924, I became a Dozent in Gottingen and worked out the quantum mechanics during a holiday stay on Heligoland.”

“There is a great difference between discoveries and inventions. With discoveries, one can always be skeptical, and many surprises can take place. In the case of inventions, surprises can rea...”

“I would say that I was absolutely convinced of the possibility of our making an uranium engine, but I never thought that we would make a bomb; and at the bottom of my heart, I was really gla...”