Niels Bohr quotes:

Technology has advanced more in the last thirty years than in the previous two thousand. The exponential increase in advancement will only continue. Anthropological Commentary The opposite of a trivial truth is false; the opposite of a great truth is also true.

If anybody says he can think about quantum physics without getting giddy, that only shows he has not understood the first thing about them.

Address to Albert Einstein: You are not thinking. You are merely being logical.

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

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

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

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

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

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.

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

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. My own feeling is that it is not crazy enough.

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

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

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

The opposite of a fact is falsehood, but the opposite of one profound truth may very well be another profound truth.

Einstein, stop telling God what to do!

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

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

You must come to Copenhagen to work with us. We like people who can actually perform thought experiments!

A physicist visits a colleague and notices a horseshoe hanging on the wall above the entrance. 'Do you really believe that a horseshoe brings luck?' he asks. 'No,' replies the colleague, 'but I've been told that it works even if you don't believe in it.'

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

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

Of course I don't believe in it [pointing to horseshoe on his office wall]. But I understand that it brings you luck whether you believe in it or not.

A visitor to Niels Bohr's country cottage, noticing a horseshoe hanging on the wall, teasing the eminent scientist about this ancient superstition. "Can it be true that you, of all people, believe it will bring you luck?' 'Of course not,' replied Bohr, 'but I understand it brings you luck whether you believe it or not.'

It is, indeed, perhaps the greatest prospect of humanistic studies to contribute through an increasing knowledge of the history of cultural development to that gradual removal of prejudices which is the common aim of all science.

The great extension of our experience in recent years has brought light to the insufficiency of our simple mechanical conceptions and, as a consequence, has shaken the foundation on which the customary interpretation of observation was based.

The meaning of life consists in the fact that it makes no sense to say that life has no meaning.

The old saying of the two kinds of truth. To the one kind belongs statements so simple and clear that the opposite assertion obviously could not be defended. The other kind, the so-called 'deep truths', are statements in which the opposite also contains deep truth.

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

[About the great synthesis of atomic physics in the 1920s]It was a heroic time. It was not the doing of any one man; it involved the collaboration of scores of scientists from many different lands. But from the first to last the deeply creative, subtle and critical spirit of Niels Bohr guided, restrained, deepened and finally transmuted the enterprise."

We are trapped by language to such a degree that every attempt to formulate insight is a play on words.

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.

There are two sorts of truth: trivialities, where opposites are clearly absurd, and profound truths, recognised by the fact that the opposite is also a profound truth

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

When asked ... [about] an underlying quantum world, Bohr would answer, 'There is no quantum world. There is only an abstract quantum physical description. 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.'

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

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.]

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

Prediction is very difficult, especially about the future.

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

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.

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

When we measure something we are forcing an undetermined, undefined world to assume an experimental value. We are not measuring the world, we are creating it.

A deep truth is a truth so deep that not only is it true but it's exact opposite is also true.

A person who wasn't outraged on first hearing about quantum theory didn't understand what had been said.

Accuracy and clarity of statement are mutually exclusive.

All rising curves that show unwelcome trends in human affairs will approach infinity if extended far enough, but it is we who dictate the curve and not vice versa.

An independant reality in the ordinary physical sense can neither be ascribed to the phenomenon nor to the agencies of observation.

And anyone who thinks they can talk about quantum theory without feeling dizzy hasn't yet understood the first thing about it.

Anybody who is not shocked by this subject has failed to understand it. [of quantum mechanics]

Anyone not shocked by quantum mechanics has not yet understood it.

Every valuable human being must be a radical and a rebel, for what he must aim at is to make things better than they are

I go into the Upanishads to ask questions.

If an idea does not appear bizarre, there is no hope for it.

If we couldn't laugh at ourselves, that would be the end of everything.

If you aren't confused by quantum mechanics, you haven't really understood it.

If you have a correct statement, then the opposite of a correct statement is of course an incorrect statement, a wrong statement. But when you have a deep truth, then the opposite of a deep truth may again be a deep truth.

If you think you understand it, that only shows that you don't know the first thing about it.

In our description of nature the purpose is not to disclose the real essence of the phenomena but only to track down, so far as it is possible, relations between the manifold aspects of our experience.

In physics we deal with states of affairs much simpler than those of psychology and yet we again and again learn that our task is not to investigate the essence of things-we do not at all know what this would mean&mash;but to develop those concepts that allow us to speak with each other about the events of nature in a fruitful manner.

In the great drama of existence we are audience and actors at the same time.

Isolated material particles are abstractions, their properties being definable and observable only through their interaction with other systems .

It is a great pity that human beings cannot find all of their satisfaction in scientific contemplativeness.

It is difficult to predict, especially the future.

It is not enough to be wrong, one must also be polite.

It is very difficult to make an accurate prediction, especially about the future.

No paradox, no progress.

Nothing exists until it is measured.

Oh what idiots we have all been, this is just as it must be

One must always do what one really cannot.

One thought spectra are marvellous, but it is not possible to make progress there. Just as if you have the wing of a butterfly then certainly it is very regular with the colors and so on, but nobody thought one could get the basis of biology from the coloring of the wing of a butterfly.

Opposites are not contradictory but complementary.

Our task is not to penetrate the essence of things, the meaning of which we do not know anyway, but rather to develop concepts which allow us to talk in a productive way about phenomena in nature

Physics is the belief that a simple and consistent description of nature is possible.

Physics is to be regarded not so much as the study of something a priori given, but rather as the development of methods of ordering and surveying human experience. In this respect our task must be to account for such experience in a manner independent of individual subjective judgement and therefore objective in the sense that it can be unambiguously communicated in ordinary human language.

Prediction is difficult, especially the future.

Predictions are hard, especially abot the future.

Predition is risky, especially of the future.

Some subjects are so serious that one can only joke about them.

Some things are so serious, they can only be joked about.

Sometimes the child in one behaves a certain way and the rest of oneself follows behind, slowly shaking its head.

The measurement we get when we measure something is not a property of the thing measured.

The opposite of every great idea is another great idea.

The present state of atomic theory is characterized by the fact that we not only believe the existence of atoms to be proved beyond a doubt, but also we even believe that we have an intimate knowledge of the constituents of the individual atoms.

There is no hope for any speculation that does not look absurd at first glance.

Truth and clarity are complementary

Truth is something that we can attempt to doubt, and then perhaps, after much exertion, discover that part of the doubt is not justified.

We all know your idea is crazy. The question is whether it is crazy enough.

We depend on our words...Our task is to communicate experience and ideas to others. We must strive continually to extend the scope of our description, but in such a way that our messages do not thereby lose their objective or unambiguous character...We are suspended in language in such a way that we cannot say what is up and what is down. The word 'reality' is also a word, a word which we must learn to use correctly.

What is that we human beings ultimately depend on? We depend on our words. We are suspended in language. Our task is to communicate experience and ideas to others.

When it comes to atoms, language can be used only as in poetry.

When searching for harmony in life one must never forget that in the drama of existence we are ourselves both actors and spectators.

Rutherford is a man you can rely on; he comes regularly and enquires how things are going and talks about the smallest details - Rutherford is such an outstanding man and really interested in the work of all the people around him.

Anyone who can contemplate quantum mechanics without getting dizzy hasn't understood it.