“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 this were the whole truth, we should, when entering into a new field, introduce only such quantities as can directly be observed, and formulate natural laws only by means of these quantities.

It is generally believed that our science is empirical and that we draw our concepts and our mathematical constructs from the empirical data.

Reports in Washington show that our reasoning was just like that of your physicists.

In America, it was decided to attempt the production of atomic bombs with an effort that would constitute a large part of the collective American war effort.

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 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.

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.

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.

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.

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.

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.

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

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

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.

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.

Certainly, in the course of time, the splendid things will separate from the hateful.

It had no practical application in his lifetime, but today, thanks to computers, is routinely used in the modelling of climate change, astrophysics and stock-market analysis.