Niels Bohr

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

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

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

“There is no quantum world. There is only an abstract physical description.”

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

“We are all agreed that your theory is crazy. The question which divides us is whether it is crazy enough to have a chance of being correct.”

“There are some things so serious that you have to laugh at them.”

“Our task is not to penetrate into the essence of things, the meaning of which we do not know anyway, but rather to develop concepts which allow us to talk about the phenomena of nature in a creative and consistent way.”

“No, no, you're not thinking; you're just being logical.”

“Prediction is very difficult, especially if it's about the future.”

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

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

“Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it.”

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

“It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about nature.”

“Your theory is crazy, but it's not crazy enough to be true.”

“It is the hallmark of any deep truth that its negation is also a deep truth.”