Niels Bohr

“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.”

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

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

“I feel personally responsible for the universe's inevitable heat death.”

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

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

“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 complementary but exclusive features of the description, symbolizing the idealization of observation and description, respectively.”

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

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