Werner Heisenberg

The quantum theory is a complete and consistent theory, even if it challenges our intuition.

The idea of a 'hidden variable' that would restore determinism is incompatible with quantum mechanics.

The quantum world is not a miniature version of the classical world.

The concept of 'identity' for elementary particles is problematic.

The quantum theory has shown us that the world is more subtle and complex than we imagined.

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

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

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.

The violent reaction on the recent development of modern physics can only be understood when one realizes that here the foundations of physics have started moving.

The ontology of materialism rested upon the illusion that the kind of existence, the direct 'actuality' of the world around us, can be extrapolated into the atomic range.

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 conception of objective reality... has thus evaporated... into the transparent clarity of a mathematics that represents no longer the behavior of particles but rather our knowledge of this behavior.

The path of progress can no longer be measured by the yardstick of classical physics.

The history of physics is not only a sequence of experimental discoveries and inventions, it is also a history of the very concepts of human thought.

The physicist may be satisfied when he has the mathematical scheme and knows how to use it for the interpretation of the experiments.

The closed-off theories of the past are like the individual pictures in a mosaic; they are meaningful only when seen together.

Science clears the fields on which technology can build.

The space-time of quantum theory is not the space-time of classical physics.

We cannot ignore the fact that science has a history, and that it is embedded in a cultural and social context.

The demand for 'understanding'... sometimes means nothing more than the reduction to the familiar.