An expert is someone who knows some of the worst mistakes that can be made in his subject and how to avoid them.

The existing scientific concepts cover always only a very limited part of reality, and the other part that has not yet been understood is infinite.

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

I think that modern physics has definitely decided in favor of Plato. In fact the smallest units of matter are not physical objects in the ordinary sense; they are forms, ideas which can be expressed unambiguously only in mathematical language.

The physicist may be satisfied when he has the mathematical scheme and knows how to use for the interpretation of the experiments. But he has to speak about his results also to non-physicists who will not be satisfied unless some explanation is given in plain language. Even for the physicist the description in plain language will be the criterion of the degree of understanding that has been reached.

Not only is the Universe stranger than we think, it is stranger than we can think.

[T]he atoms or elementary particles themselves are not real; they form a world of potentialities or possibilities rather than one of things or facts.