WERNER HEISENBERG

What we observe is not nature itself, but nature exposed to our method of questioning.

Every word or concept, clear as it may seem to be, has only a limited range of applicability.

The problems of language here are really serious. We wish to speak in some way about the structure of the atoms. But we cannot speak about atoms in ordinary language.

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

The solution of the difficulty is that the two mental pictures which experiment lead us to form - the one of the particles, the other of the waves - are both incomplete and have only the validity of analogies which are accurate only in limiting cases.

The violent reaction on the recent development of modern physics can only be understood when one realises that here the foundations of physics have started moving; and that this motion has caused the feeling that the ground would be cut from science.

That was the work of some of the old officers embittered by the war, but we don’t take these groups very seriously!

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.

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 penetrate into the heart of it. Sometimes a poor performance is better for enjoyment, because you can look at those things that were wrong and analyze them.

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.

The Anglo-Americans want the balance of power in Eurasia. The only balance of power they can achieve now is the whole of Europe against Russia. The only choice for us is either to join this Western European bloc or join in with Russia.

I believe this uranium business will give the Anglo-Saxons such tremendous power that Europe will become a bloc under Anglo-Saxon domination. If that is the case, it will be a very good thing. I wonder whether Stalin will be able to stand up to the others as he has done in the past.

The single life is bearable to me only through my work in science, but for the long term, it would be very bad if I had to make do without a very young person next to me.

If we made atomic bombs, we would bring about a terrible change in the world. Who knows what would happen from this?

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 measurement may be calculated.

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 the new concepts are generally accepted.

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.

Bohr's influence on the physics and the physicists of our century was stronger than that of anyone else, even than that of Albert Einstein.

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, there were about 13 people in this very small house.

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 generally held in the United States that we completely missed the basic principle of the bomb until after Hiroshima.

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 drew together in larger and smaller groups to blaze new paths or, at least, to discover a new star to steer by.

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 really only occur for people who have not had anything to do with it.

I think that if a United States of Europe were to be formed, it would be in our interests to fight for it, as all our old traditions would remain in such a united Europe, whereas if we were to start now as part of the Russian Empire, everything that had ever been in Germany would disappear.

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 by repeating such series of experiments, we can arrive at objective statements concerning these distributions.

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