Werner Heisenberg

Quantum mechanics has taught us that the world is not as we thought it was.

The task is...not so much to see what no one has yet seen; but to think what nobody has yet thought, about that which everybody sees.

Every sentence I utter must be understood not as an affirmation, but as a question.

The world thus appears as a complicated tissue of events, in which connections of different kinds alternate or overlap or join together, to form a variety of complex structures.

But the term, too, is not quite free from ambiguity, as is seen in the fact that the ancients preferred to speak of 'moving' rather than of 'free' fall.

The 'paradox' is only a conflict between reality and your feeling of what reality 'ought' to be.

If you hate a person, you hate something in him that is part of yourself. What isn't part of ourselves doesn't disturb us.

The end of all our exploring will be to arrive where we started and know the place for the first time.

Science clears the field on which civilization may develop.

The older a man gets, the more he likes dogs.

In such a case the individual is staggered by the profound shock of the collapse of the reality to which he has been clinging.

The mathematical structure of the theory has its own inner logic, which is deeper than the logic of everyday language.

We must be prepared to find that the other states of matter are as different from the present as the present is from the past.

The very concept of empty space becomes a problem.

The world is not deterministic; it is probabilistic.

I believe that the existence of the quantum of action is the fundamental riddle of the world.

The development of physics during the last few decades has shown that the idea of a mechanical model is not adequate for the description of reality.

The Copenhagen interpretation is an attitude towards the uncertainty in our knowledge.

Nature allows only probabilistic statements.

The laws of quantum physics cannot be visualized in space and time.