Niels Bohr

"Nothing exists until it is measured."

"Niels is always entertaining—he makes friends with everyone."

"We must learn to live with uncertainty."

"The greatest challenge facing humanity is the challenge of distinguishing appearance from reality."

"I cannot say what I do not know with certainty."

"Religion and science are not adversaries but rather complementary aspects of human experience."

"The most important thing is not knowledge but imagination."

"We are suspended in language in such a way that we cannot say what is up and what is down."

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

"The task is not so much to see what no one has yet seen, but to think what nobody has yet thought."

"Nature is like a book written in mathematical language."

"The fundamental paradox of science is that facts alone do not constitute knowledge."

"We cannot know both the position and momentum of a particle with perfect precision."

"Atoms must be somewhat like little planetary systems."

"I would not call it knowledge, but rather a description of observations."

"The present generation has inherited a world of unprecedented complexity."

"One should as a rule respect public opinion in so far as is necessary to avoid starvation and to prevent oneself from being jailed, but anything that goes beyond this is voluntary submission to an unnecessary tyranny."

"The purpose of physics is not the compilation of mere facts and laws, but an understanding of nature."

"The beauty of the physical world lies in its unity and coherence."

"Measurement affects reality in ways we are only beginning to understand."

"The world is not only strange; it is stranger than we can imagine."

"One must not work on semiconductors, that is a filthy mess."

"If I could remember the names of all these particles, I would have been a botanist."

"The very act of observation disturbs the system being observed."

"Nature speaks in the language of mathematics."

"We must be prepared to undergo profound changes."

"The structure of the atom is one of the great mysteries of nature."

"It is the tension between creativity and skepticism that produces scientific advance."

"The universe does not reveal its secrets easily."

"An important discovery is often a surprise."