Bohr Quotes

To resolve the discrepancy between waves of probability and our commonsense notion of existence, Bohr and Heisenberg assumed that after a measurement is made by an outside observer, the wave function magically "collapses," and the electron falls into a definite
state - that is, after looking at the tree, we see that it is truly standing. In other words, the process of observation determines the final state of the electron. Observation is vital to existence. ~ Michio Kaku

Chemistry, until my childhood, not that long ago, was regarded as a calculating device. Because you couldn't reduce to physics. So it's just some way of calculating the result of experiments. The Bohr atom was treated that way. ~ Noam Chomsky

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. ~ Niels Bohr

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. ~ Niels Bohr

Physics is not about how the world is, it is about what we can say about the world ~ Niels Bohr

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

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

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

And so, whereas Bohr and the Copenhagen gang would argue that only one of these universes would exist (because the act of measurement, which they claim lies outside of Schrodinger's purview, would collapse away all the others), and whereas a first-pass attempt to go beyond Bohr and extend Schrodinger's math to all particles, including those constituting equipment and brains, yielded dizzying confusion (because a given machine or mind seemed to internalize all possible outcomes simultaneously), Everett found that a more careful reading of Schrodinger's math leads somewhere else: to a plentiful reality populated by an ever-growing collection of universes. ~ Brian Greene

The withdrawal of philosophy into a "professional" shell of its own has had disastrous consequences. The younger generation of physicists, the Feynmans, the Schwingers, etc., may be very bright; they may be more intelligent than their predecessors, than Bohr, Einstein, Schrödinger, Boltzmann, Mach and so on. But they are uncivilized savages, they lack in philosophical depth – and this is the fault of the very same idea of professionalism which you are now defending. ~ Paul Karl Feyerabend

The bridge between the electron and the other elementary particles is provided by the fine structure constant, a ~ 1/137, as manifested in the factor-of-137 spacings between the classical electron radius, electron Compton radius, and Bohr orbit radius. ... An a-quantized mass-generation grid extends accurately from the electron all the way to the top quark t, and leads to a corresponding a-quantized particle lifetime grid. ~ Malcolm H. Mac Gregor

Bohr Before we can lay our hands on anything, our life's over.
Heisenberg Before we can glimpse who or what we are, we're gone and laid to dust.
Bohr Settled among all the dust we raised.
Margrethe And sooner or later there will come a time when all our children are laid to dust, and all our children's children. ~ Michael Frayn

In March 1950, in New York City, I was married to Marietta Soffer. We have three children: Vilhelm, Tomas, and Margrethe. ~ Aage Bohr

when does an electron know when to jump, and how does it decide where to jump? Reasonably enough, Rutherford wanted to know what underlying process controlled the quantum jumping: "Bohr's answer was remarkable. Bohr suggested that the whole process was fundamentally random, and could only be considered by statistical methods: every change in the state of an atom should be regarded as an individual process, incapable of more detailed description. We are here so far removed from a causal description that an atom may in general even be said to possess a free choice between various possible transitions. ~ Andrew Thomas

Niels Bohr brainwashed a whole generation of theorists into thinking that the job (interpreting quantum theory) was done 50 years ago. ~ Murray Gell-Mann

It is difficult to predict, especially the future. ~ Niels Bohr

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

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

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

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

Today, all physicists know from studying Einstein and Bohr that sometimes an idea which looks completely paradoxical at first, if analyzed to completion in all detail and in experimental situations, may, in fact, not be paradoxical. ~ Richard P. Feynman

Sommerfeld's fine-structure theory was generally considered to be excellently and unambiguously confirmed by experiment. Because the theory rested on the foundation provided by Bohr, the experiments were also taken as strong support for his theory of atomic structure. ~ Helge Kragh

Despite the earnest belief of most of his fans, Einstein did not win his Nobel Prize for the theory of relativity, special or general. He won for explaining a strange effect in quantum mechanics, the photoelectric effect. His solution provided the first real evidence that quantum mechanics wasn't a crude stopgap for justifying anomalous experiments, but actually corresponds to reality. And the fact that Einstein came up with it is ironic for two reasons. One, as he got older and crustier, Einstein came to distrust quantum mechanics. Its statistical and deeply probabilistic nature sounded too much like gambling to him, and it prompted him to object that "God does not play dice with the universe." He was wrong, and it's too bad that most people have never heard the rejoinder by Niels Bohr: "Einstein! Stop telling God what to do. ~ Sam Kean

Planck ... and Bohr ... have invented systems containing electrons of which the motion produces no effect upon external charges ... [N]ot only [is this] inconsistent with the accepted laws of electromagnetism, but I may add, is logically objectionable, for that state of motion which produces no physical effect whatsoever may better be called a state of rest. ~ G.N.Lewis

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

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

Using the word much as it is used in atomic physics to characterize the relationship between experience obtained by different experimental arrangements and visualized only by mutually exclusive ideas, we may truly say that different human cultures are complimentary to each other ... each such culture represents a harmonious balance of traditional conventions by means of which latent potentialities of human life unfold themselves in a way which reveals to us new aspects of its unlimited richness and variety. ~ Niels Bohr

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

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

I did not like the man [Niels Bohr] when you showed him to me, with his hair all overhis head ... ~ Winston Churchill

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

Truth and clarity are complementary ~ Niels Bohr

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

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. ~ Niels Bohr

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

Stop telling God what to do with his dice. ~ Niels Bohr

The Stone Age didn't end because the World ran out of stones ~ Niels Bohr

[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. ~ J. Robert Oppenheimer

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. ~ Niels Bohr

I go into the Upanishads to ask questions. ~ Niels Bohr

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

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 ~ Niels Bohr

Everett's approach, which he described as "objectively deterministic" with probability "reappearing at the subjective level," resonated with this strategy. And he was thrilled by the direction. As he noted in the 1956 draft of his dissertation, the framework offered to bridge the position of Einstein (who famously believed that a fundamental theory of physics should not involve probability) and the position of Bohr (who was perfectly happy with a fundamental theory that did). According to Everett, the Many Worlds approach accommodated both positions, the difference between them merely being one of perspective. Einstein's perspective is the mathematical one in which the grand probability wave of all particles relentlessly evolves by the Schrodinger equation, with chance playing absolutely no role. I like to picture Einstein soaring high above the many worlds of Many Worlds, watching as Schrodinger's equation fully dictates how the entire panorama unfolds, and happily concluding that even though quantum mechanics is correct, God doesn't play dice. Bohr's perspective is that of an inhabitant in one of the worlds, also happy, using probabilities to explain, with stupendous precision, those observations to which his limited perspective gives him access. ~ Brian Greene

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. ~ Niels Bohr

In a sense the debate between Penrose and Hawking is a continuation of that earlier argument, with Penrose playing the role of Einstein and Hawking that of Bohr. ~ Stephen Hawking

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

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

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. ~ Niels Bohr

[About describing atomic models in the language of classical physics:]
We must be clear that 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 and establishing mental connections. ~ Niels Bohr

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

For Bohr the theory came first, then the philosophical position, the interpretation constructed to make sense of what the theory says about reality. Einstein knew that it was dangerous to build a philosophical worldview on the foundation of any scientific theory. If the theory is found wanting in the light of new experimental evidence, then the philosophical position it supports collapses with it. 'it is basic for physics that one assumes a real world existing independently from any act of perception', said Einstein. 'But this we do not know'. ~ Manjit Kumar

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

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. ~ Niels Bohr

Every great and deep difficulty bears in itself it's own solution. It forces us to change our thinking in order to find it. ~ Niels Bohr

Perhaps I have found out a little about the structure of atoms. ~ Niels Bohr

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

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. ~ Niels Bohr

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 ~ Niels Bohr

Which is to say that culture is not a reflex of political economy, but
that society is now a reflex of key shifts in music theory and practice ...
[Sampladelia is] the sound made by those early-twentieth-century discoveries
in particle physics and relativiity theory, the projection of the minds of
Einstein, Heisenbery, and Bohr, their fateful explorations of liquid time,
curving space, uncertainty fields and relativity theorems, into densely
configured and fully ambivalent android music tracks ~ Arthur Kroker

You are not thinking, you are just being logical. ~ Niels Bohr

Prediction is very difficult, especially about the future. ~ Niels Bohr

Margrethe: And when all our eyes are closed, when even the ghosts have gone, what will be left of our beloved world? Our ruined and dishonoured and beloved world? ~ Michael Frayn

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. ~ Niels Bohr

Predition is risky, especially of the future. ~ Niels Bohr

I know of no actor who is so pure onstage that he thinks only what his character thinks. If he did, he would presumably become the character: a form of madness. This may be of course what happens to Hamlet--he puts on an antic disposition, and gets stuck with it.
[...]
Acting is mostly a twin-track mental activity. In one track runs the role, requiring thoughts ranging from, say, gentle amusement to towering rage. Then there is the second track, which monitors the performance: executing the right moves, body language, and voice level; taking note of audience reaction and keeping an eye on fellow actors; coping with emergencies such as a missing prop or a faulty lighting cue. These two tracks run parallel, night by night. If one should go wrong, then it is likely that the other will misbehave too.
[...]
But there is a third and wholly subversive track that intrudes itself at intervals, full of phantom thoughts and feelings that come and go of their own volition. This ghost train of random musings is, of course, to be discouraged, but it can never be entirely denied. As Bohr and his wife, Margrethe, say in the play: "So many things we think about at the same time. Our lives and our physics...All the things that come into our heads out of nowhere. ~ David Burke

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

Heisenberg and Bohr and Einstein strike me as being like gifted retriever dogs. Off they go, not just for an afternoon, but for ten years; they come back exhausted and triumphant and drop at your feet ... a vole. It's a remarkable thing in its way, a vole - intricate, beautiful really, marvellous. But does it ... Does it help? Does it move the matter on?
When you ask a question that you'd actually like to know the answer to - what was there before the Big Bang, for instance, or what lies beyond the expanding universe, why does life have this inbuilt absurdity, this non sequitur of death - they say that your question can't be answered, because the terms in which you've put it are logically unsound. What you must do, you see, is ask vole questions. Vole is - as we have agreed - the answer; so it follows that your questions must therefore all be vole-related. ~ Sebastian Faulks

My interpretation of scientific knowledge, for example, was a triviality for physicists like Mach, Boltzmann, Einstein and Bohr. But the ideas of these great thinkers were distorted beyond recognition by the rodents of neopositivism and the competing rodents of the church of 'critical' rationalism. ~ Paul Feyerbend

And at that age, the only boys I didn't think were gross were dead scientists – and it's not like I wanted to kiss those guys. (No offense, Niels Bohr.) ~ Sarah Cross

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. ~ Niels Bohr

An expert is a man who has made all the mistakes which can be made in a very narrow field. ~ Niels Bohr

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

Chinese dialectical reasoning had an impact on the physicist Niels Bohr, who was highly knowledgeable about Eastern thought. He attributed his development of quantum theory in part to the metaphysics of the East. There had been a centuries-long debate in the West about whether light consists of particles or waves. Belief in one was assumed to contradict and render impossible belief in the other. Bohr's solution was to say that light can be thought of in both ways. In quantum theory, light can be viewed either as a particle or as a wave. Just never both at the same time. ~ Richard E. Nisbett

One must always do what one really cannot. ~ Niels Bohr

A. Douglas Stone, a physicist who has spent his life using quantum mechanics to explore striking new phenomena, has turned his considerable writing skills to thinking about Einstein and the quantum. What he finds and makes broadly understandable are the riches of Einstein's thinking not about relativity, not about his arguments with Bohr, but about Einstein's deep insights into the quantum world, insights that Stone shows speak to us now with all the vividness and depth they had a century ago. This is a fascinating book, lively, engaging, and strong in physical intuition. ~ Peter Galison

In quantum mechanics...an observation here and now changes in general the 'state' of the observed system....I consider the unpredictable change of the state by a single observation...to be an abandonment of the idea of the isolation of the observer from the course of physical events outside himself. ~ Niels Bohr

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

Bohr's standpoint, that a space-time description is impossible, I reject a limine. Physics does not consist only of atomic research, science does not consist only of physics, and life does not consist only of science. The aim of atomic research is to fit our empirical knowledge concerning it into our other thinking. All of this other thinking, so far as it concerns the outer world, is active in space and time. If it cannot be fitted into space and time, then it fails in its whole aim and one does not know what purpose it really serves. ~ Erwin Schrodinger

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. ~ Niels Bohr

Nothing exists until it is measured. ~ Niels Bohr

But it is necessary to insist more strongly than usual that what I am putting before you is a model-the Bohr model atom-because later I shall take you to a profounder level of representation in which the electron instead of being confined to a particular locality is distributed in a sort of probability haze all over the atom. ~ Arthur Eddington

The founders and grand theorists of modern (quantum and relativity) physics: Einstein, Schroedinger, Heisenberg, Bohr, Eddington, Pauli, de Broglie, Jeans, and Planck. ~ Ken Wilber

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

Our deepest description of physical reality, in quantum theory and in the four Core Theories of forces (gravitation, electromagnetism, strong and weak forces), bring in concepts that call to mind yin and yang. Niels Bohr, an influential founder of quantum theory, saw strong parallels between his concept of complementarity and the unified duality of yin-yang. He designed a coat of arms for himself, in which the yin-yang figures centrally (see figure 42, page 324). Our Core Theories center on the interplay between lightlike space filling fluids (yang) and substances (yin) they both direct and respond to. ~ Frank Wilczek

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

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

The opposite of a plain truth, Neils Bohr liked to repeat, is a plain falsehood. But the opposite of a deep truth is another deep truth. ~ Rebecca Goldstein

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

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.' ~ Niels Bohr

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

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

It is often asserted that, in view of the situation in quantum theory, object and subject can no longer be sharply separated. 1 To use Heitler's words, the 'separation of the world into an "objective outside reality", and "us", the self-conscious onlookers, can no longer be maintained. Object and subject become inseparable from each other'. 2 This, according to Bohr, is due to 'the impossibility of any sharp separation between the behaviour of atomic objects and the interaction with the measuring instruments which serve to define the conditions under which the phenomena appear'. 3 Heitler elaborates the point in some detail. 'One may ask', he writes, 'if it is sufficient to carry out a measurement by a self-registering apparatus or whether the presence of an observer is required.' And he arrives at the conclusion that the self-registering apparatus is insufficient, and that 'the observer appears, as a necessary part of the whole structure, and in his full capacity as a conscious being'. ~ Karl Popper

Prediction is difficult, especially the future. ~ Niels Bohr

Bohr advanced a heavyhanded remedy: evolve probability waves according to Schrodinger's equation whenever you're not looking or performing any kind of measurement. But when you do look, Bohr continued, you should throw Schrodinger's equation aside and declare that your observation has caused the wave to collapse.

Now, not only is this prescription ungainly, not only is it arbitrary, not only does it lack a mathematical underpinning, it's not even clear. For instance, it doesn't precisely define "looking" or "measuring." Must a human be involved? Or, as Einstein once asked, will a sidelong glance from a mouse suffice? How about a computer's probe, or even a nudge from a bacterium or virus? Do these "measurements" cause probability waves to collapse? Bohr announced that he was drawing a line in the sand separating small things, such as atoms and their constituents, to which Schrodinger's equation would apply, and big things, such as experimenters and their equipment, to which it wouldn't. But he never said where exactly that line would be. The reality is, he couldn't. With each passing year, experimenters confirm that Schrodinger's equation works, without modification, for increasingly large collections of particles, and there's every reason to believe that it works for collections as hefty as those making up you and me and everything else. Like floodwaters slowly rising from your basement, rushing into your living room, and threatening to engulf your attic, the math ~ Brian Greene

There are some things so serious that you have to laugh at them. ~ Niels Bohr

There's a quote from the famous physicist Niels Bohr, who posits that the way you become an expert in a field is to make every mistake possible in that field. ~ Sebastian Gutierrez

The opposite of every great idea is another great idea. ~ Niels Bohr

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

Niels Bohr believed that the complementarity that existed between the wave and the particle aspects of nature were indications of a much deeper complementarity in which irreconcilable pairs of opposites need not be contradictory. As he once said, "the opposite of a small truth may be a lie, but the opposite of a great truth is also a great truth." Thus the ring i may be a symbol of the reconciliation of complementary parts of the whole. ~ Fred Alan Wolf

Somebody once asked Niels Bohr why he had a horseshoe hanging above the front door of his house. Surely you, a world famous physicist, can't really believe that hanging a horseshoe above your door brings you luck? Of course not, Bohr replied, but I have been reliably informed that it will bring me luck whether I believe in it or not. ~ Arthur Koestler