Niels Bohr

“An expert is a person who has made all the mistakes that can be made in a very narrow field.”

“The opposite of a correct statement is a false statement. But the opposite of a profound truth may well be another profound truth.”

“You can recognize a small truth because its opposite is a falsehood. The opposite of a great truth is another truth.”

“Prediction is very difficult, especially about the future.”

“There are trivial truths and there are great truths. The opposite of a trivial truth is plainly false. The opposite of a great truth is also true.”

“Every sentence I utter must be understood not as an affirmation but as a question. [A caution he gives his students, to be wary of dogmatism.]”

“Those who are not shocked when they first come across quantum theory cannot possibly have understood it.”

“Stop telling God what to do with his dice.”

“The very nature of the quantum theory ... forces us to regard the space-time coordination and the claim of causality, the union of which characterizes the classical theories, as complementar...”

“Technology has advanced more in the last thirty years than in the previous two thousand. The exponential increase in advancement will only continue.”

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

“A physicist is just an atom's way of looking at itself.”

“When it comes to atoms, language can be used only as in poetry. The poet, too, is not nearly so concerned with describing facts as with creating images.”

“Everything we call real is made of things that cannot be regarded as real.”

“Humanity will... be confronted with dangers of unprecedented character unless, in due time, measures can be taken to forestall a disastrous competition in such formidable armaments and to es...”

“Every description of natural processes must be based on ideas which have been introduced and defined by the classical theory.”

“The best weapon of a dictatorship is secrecy, but the best weapon of a democracy should be the weapon of openness.”

“Never express yourself more clearly than you are able to think.”

“If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet.”

“How wonderful that we have met with a paradox. Now we have some hope of making progress.”