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.

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 division of the world into subject and object (observer and observed) and, hence, a clear formulation of the law of causality.

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.

Werner Heisenberg Quotes