Best 538 quotes in «physics quotes» category

Unassuming in manner, genial and kindly in his intercourse with his fellow-men, never showing impatience or irritation, devoid of personal ambition of the baser sort or of the slightest desire to exalt himself... In the minds of those who knew him, the greatness of his intellectual achievements will never overshadow the beauty and dignity of his life. [H.A. Burnstead's comments on the life of esteemed scientist J. Willard Gibbs]

Until now, I've been writing about "now" as if it were literally an instant of time, but of course human faculties are not infinitely precise. It is simplistic to suppose that physical events and mental events march along exactly in step, with the stream of "actual moments" in the outside world and the stream of conscious awareness of them perfectly synchronized. The cinema industry depends on the phenomenon that what seems to us a movie is really a succession of still pictures, running at twenty-five [sic] frames per second. We don't notice the joins. Evidently the "now" of our conscious awareness stretches over at least 1/25 of a second. In fact, psychologists are convinced it can last a lot longer than that. Take he familiar "tick-tock" of the clock. Well, the clock doesn't go "tick-tock" at all; it goes "tick-tick," every tick producing the same sound. It's just that our consciousness runs two successive ticks into a singe "tick-tock" experience—but only if the duration between ticks is less than about three seconds. A really bug pendulum clock just goes "tock . . . tock . . . tock," whereas a bedside clock chatters away: "ticktockticktock..." Two to three seconds seems to be the duration over which our minds integrate sense data into a unitary experience, a fact reflected in the structure of human music and poetry.

Using freshman level calculus you can show that the one and only shape that has the smallest surface area for an enclosed volume is a perfect sphere. In fact, billions of dollars could be saved annually on packaging materials if all shipping boxes and all packages of food in the supermarket were spheres. For example, the contents of a super-jumbo box of Cheerios would fit easily into a spherical carton with a four-and-half inch radius. But practical matters prevail - nobody wants to chase packaged food down the aisle after it rolls off the shelves.

Very high altitude astronomy only works by ignoring established biological science

We also find *physics*, in the widest sense of the word, concerned with the explanation of phenomena in the world; but it lies already in the nature of the explanations themselves that they cannot be sufficient. *Physics* is unable to stand on its own feet, but needs a *metaphysics* on which to support itself, whatever fine airs it may assume towards the latter. For it explains phenomena by something still more unknown than are they, namely by laws of nature resting on forces of nature, one of which is also the vital force. Certainly the whole present condition of all things in the world or in nature must necessarily be capable of explanation from purely physical causes. But such an explanation―supposing one actually succeeded so far as to be able to give it―must always just as necessarily be burdened with two essential imperfections (as it were with two sore points, or like Achilles with the vulnerable heel, or the devil with the cloven foot). On account of these imperfections, everything so explained would still really remain unexplained. The first imperfection is that the *beginning* of the chain of causes and effects that explains everything, in other words, of the connected and continuous changes, can positively *never* be reached, but, just like the limits of the world in space and time, recedes incessantly and *in infinitum*. The second imperfection is that all the efficient causes from which everything is explained always rest on something wholly inexplicable, that is, on the original *qualities* of things and the *natural forces* that make their appearance in them. By virtue of such forces they produce a definite effect, e.g., weight, hardness, impact, elasticity, heat, electricity, chemical forces, and so on, and such forces remain in every given explanation like an unknown quantity, not to be eliminated at all, in an otherwise perfectly solved algebraical equation. Accordingly there is not a fragment of clay, however little its value, that is not entirely composed of inexplicable qualities. Therefore these two inevitable defects in every purely physical, i.e., causal, explanation indicate that such an explanation can be only *relatively* true, and that its whole method and nature cannot be the only, the ultimate and hence sufficient one, in other words, cannot be the method that will ever be able to lead to the satisfactory solution of the difficult riddles of things, and to the true understanding of the world and of existence; but that the *physical* explanation, in general and as such, still requires one that is *metaphysical*, which would furnish the key to all its assumptions, but for that very reason would have to follow quite a different path. The first step to this is that we should bring to distinct consciousness and firmly retain the distinction between the two, that is, the difference between *physics* and *metaphysics*. In general this difference rests on the Kantian distinction between *phenomenon* and *thing-in-itself*. Just because Kant declared the thing-in-itself to be absolutely unknowable, there was, according to him, no *metaphysics* at all, but merely immanent knowledge, in other words mere *physics*, which can always speak only of phenomena, and together with this a critique of reason which aspires to metaphysics." ―from_The World as Will and Representation_. Translated from the German by E. F. J. Payne. In Two Volumes, Volume II, pp. 172-173

We are at the dawn of a new era, the era of 'molecular biology' as I like to call it, and there is an urgency about the need for more intensive application of physics and chemistry, and specially of structure analysis, that is still not sufficiently appreciated.

We are made of atoms. With each breath you inhale a million billion billion atoms of oxygen, which gives some idea of how small each one is. All of them, together with the carbon atoms in your skin, and indeed everything else on Earth, were cooked in a star some 5 billion years ago. So you are made of stuff that is as old as the planet, one-third as old as the universe, though this is the first time that those atoms have been gathered together such that they think that they are you.

We are the last generation of humans on Earth!

We can measure the fine structure constant with very great precision, but so far none of our theories has provided an explanation of its measured value. One of the aims of superstring theory is to predict this quantity precisely. Any theory that could do that would be taken very seriously indeed as a potential 'Theory of Everything'.

We have learnt that the exploration of the external world by the methods of physical science leads not to a concrete reality but to a shadow world of symbols, beneath which those methods are unadapted for penetrating. Feeling that there must be more behind, we return to our starting point in human consciousness - the one centre where more might become known. There we find other stirrings, other revelations than those conditioned by the world of symbols... Physics most strongly insists that its methods do not penetrate behind the symbolism. Surely then that mental and spiritual nature of ourselves, known in our minds by an intimate contact transcending the methods of physics, supplies just that... which science is admittedly unable to give.

We have found that the values of the constants of nature have not been fine-tuned for life by accident, but that these values are constrained by and logically follow from the fundamental space-time organization of the Cosmic Tree of Life.

We have one real candidate for changing the rules; this is string theory. In string theory the one-dimensional trajectory of a particle in spacetime is replaced by a two-dimensional orbit of a string. Such strings can be of any size, but under ordinary circumstances they are quite tiny, ... a value determined by comparing the predictions of the theory for Newton's constant and the fine structure constant to experimental values.

We have written the equations of water flow. From experiment, we find a set of concepts and approximations to use to discuss the solution--vortex streets, turbulent wakes, boundary layers. When we have similar equations in a less familiar situation, and one for which we cannot yet experiment, we try to solve the equations in a primitive, halting, and confused way to try to determine what new qualitatitive features may come out, or what new qualitative forms are a consequence of the equations. Our equations for the sun, for example, as a ball of hydrogen gas, describe a sun without sunspots, without the rice-grain structure of the surface, without prominences, without coronas. Yet, all of these are really in the equations; we just haven't found the way to get them out. ...The test of science is its ability to predict. Had you never visited the earth, could you predict the thunderstorms, the volcanoes, the ocean waves, the auroras, and the colourful sunset? A salutary lesson it will be when we learn of all that goes on on each of those dead planets--those eight or ten balls, each agglomerated from the same dust clouds and each obeying exactly the same laws of physics. The next great era of awakening of human intellect may well produce a method of understanding the qualitative content of equations. Today we cannot. Today we cannot see that the water flow equations contain such things as the barber pole structure of turbulence that one sees between rotating cylinders. Today we cannot see whether Schrodinger's equation contains frogs, musical composers, or morality--or whether it does not. We cannot say whether something beyond it like God is needed, or not. And so we can all hold strong opinions either way.

We know that energy can not be created nor destroyed but can be changed in it's form. If it can not be formed then it can not exist. We may not exist.

We must realize that growth is but an adolescent phase of life which stops when physical maturity is reached. If growth continues in the period of maturity it is called obesity or cancer. Prescribing growth as the cure for the energy crisis has all the logic of prescribing increasing quantities of food as a remedy for obesity.

We need science education to produce scientists, but we need it equally to create literacy in the public. Man has a fundamental urge to comprehend the world about him, and science gives today the only world picture which we can consider as valid. It gives an understanding of the inside of the atom and of the whole universe, or the peculiar properties of the chemical substances and of the manner in which genes duplicate in biology. An educated layman can, of course, not contribute to science, but can enjoy and participate in many scientific discoveries which as constantly made. Such participation was quite common in the 19th century, but has unhappily declined. Literacy in science will enrich a person's life.

We present a series of hypotheses and speculations, leading inescapably to the conclusion that SU(5) is the gauge group of the world — that all elementary particle forces (strong, weak, and electromagnetic) are different manifestations of the same fundamental interaction involving a single coupling strength, the fine-structure constant. Our hypotheses may be wrong and our speculations idle, but the uniqueness and simplicity of our scheme are reasons enough that it be taken seriously.

We walked up and down in the snow, I on skis and she on foot (she said and proved that she could get along just as fast that way), and gradually the idea took shape that this was no chipping or cracking of the nucleus but rather a process to be explained by Bohr's idea that the nucleus was like a liquid drop; such a drop might elongate and divide itself. {On his aunt and fellow science Lise Meitner}

What we are proposing,' Alicia said, 'is that the laws of physics are such that causality violation is subject to a form of version control, one that prevents a forking of history. That instead of causality violation creating an alternate universe, one version of history is outright overwritten by another. One past is replaced with another future. Which means that the memories of the past of the people in that future are replaced with memories of a different past.' Carson interrupted. 'Including the memories of any—' 'Purely hypothetical—' '—time travelers.' 'So take our time traveler from the traditional story,' Carson continued. 'He leaves his utopian future for the past. He kills the butterfly. The Magna Carta is never written. He returns to the dystopian future that his misstep created. But he doesn't see it as a dystopia: he sees it as home, the world he grew up in, the world he left to go back in time. Because he doesn't remember that first future, and has no other world to which he can compare this one. Maybe he even sees it as a utopia. Maybe everyone does. Maybe everyone in this dark place believes that they live in the best of all possible worlds.

When {Born and Heisenberg and the Göttingen theoretical physicists} first discovered matrix mechanics they were having, of course, the same kind of trouble that everybody else had in trying to solve problems and to manipulate and to really do things with matrices. So they had gone to Hilbert for help and Hilbert said the only time he had ever had anything to do with matrices was when they came up as a sort of by-product of the eigenvalues of the boundary-value problem of a differential equation. So if you look for the differential equation which has these matrices you can probably do more with that. They had thought it was a goofy idea and that Hilbert didn't know what he was talking about. So he was having a lot of fun pointing out to them that they could have discovered Schrödinger’s wave mechanics six month earlier if they had paid a little more attention to him.

When Einstein died, his greatest rival, Bohr, found for him words of moving admiration. When a few years later Bohr in turn died, someone took a photograph of the blackboard in his study. There’s a drawing on it. A drawing of the ‘light-filled box’ in Einstein’s thought experiment. To the very last, the desire to challenge oneself and understand more. And to the very last: doubt

When I was lecturing recently to a group of cardiologists at the Mayo Clinic I said... Why is it that from the moment you enter medical school to the moment you retire, the only disorder that you will ever diagnose with a physics textbook is obesity? This is biology folks, it's endocrinology, it's physiology - physics has nothing to do with it. The laws of thermodynamics are always true, the energy balance equation is irrelevant. If someone's getting fatter I guarantee you they're taking more energy than they expend (as long as they're getting heavier). And if they're getting leaner I guarantee they're expending more than they're taking in. [It's] given, let's never discuss it again. And if you say it to your patients you're telling them nothing (University Of Colorado Medical School, May 9th 2013 - via YouTube)

When I was young, I thought it is thunder that kills people. But when I learnt physics in the high school, I discovered that it is rather the lightning that does the killing. The voice of the thunder itself is just a noise. The lightning is the poise!

Within the immense ocean of galaxies and stars we are in a remote corner; amidst the infinite arabesques of forms which constitute reality we are merely a flourish among innumerably many such flourishes.

A careful analysis of the process of observation in atomic physics has shown that the subatomic particles have no meaning as isolated entities, but can only be understood as interconnections between the preparation of an experiment and the subsequent measurement.

After Montesquieu, the next great addition to Sociology (which is the term I may be allowed to invent to designate Social Physics) was made by Condorcet, proceeding on the views suggested by his illustrious friend Turgot.

All the standard equations of mathematical physics can be separated and solved in Kerr geometry.

A lot of my theories were not applicable as a closer

Until Einstein (roughly), THE universe of Newton was, for us, THE universe. With Einstein, it became A universe. Something similar happen to man. A new 'man' was produced, just as good, certainly contraditory to the old one. THE man became A man, otherwise a 'conceptual construction', one among the infinity of possible ones.

When I was young, I thought it was thunder that kills people. But when I learnt physics in St. Paul's High School, I discovered that it is rather the lightning that does the killing. The voice of the thunder itself is just a noise. The lightning is the poise. I learnt to take the course of my life, not by violence but rather with intelligence.

When left alone, quantum particles behave as multiple images of themselves (as waves, really), simultaneously moving through all possible paths in space and time. Now, again, why do we not experience this multitude around ourselves? Is it because we are probing things around us all the time? Why do all experiments that involve, say, the position of a particle make the particle suddenly be somewhere rather than everywhere? No one knows. Before you probe it, a particle is a wave of possibilities. After you've probed it, it is somewhere, and subsequently it is somewhere for ever, rather than everywhere again. Strange, that. Nothing, within the laws of quantum physics, allows for such a collapse to happen. It is an experimental mystery and a theoretical one. Quantum physics stipulates that whenever something is there, it can transform into something else, of course, but it cannot disappear. And since quantum physics allows for multiple possibilities simultaneously, these possibilities should then keep existing, even after a measurement is made. But they don't. Every possibility but one vanishes. We do not see any of the others around us. We live in a classical world, where everything is based on quantum laws but nothing resembles the quantum world.

[..] when we get down to the subatomic level, the solid world we live in also consists, again rather worryingly, of almost nothing and that wherever we do find something it turns out not to actually something, but only the probability that there may something there.

When you look deeply into yourself you may be able to see that there is, in this moment, a quality of aliveness that is animating you that is not philosophical and is not abstract. It's independent of what you think about it, what you believe about it and what you feel about it. It's always there! it is animating your breath, It is coursing the spirit, it is what makes it possible for you to think and speak and see and hear. This is the Invisible Touch.

Whether we like it or not, modern ways are going to alter and in part destroy traditional customs and values.

Which do you think is more valuable to humanity? a. Finding ways to tell humans that they have free will despite the incontrovertible fact that their actions are completely dictated by the laws of physics as instantiated in our bodies, brains and environments? That is, engaging in the honored philosophical practice of showing that our notion of "free will" can be compatible with determinism? or b. Telling people, based on our scientific knowledge of physics, neurology, and behavior, that our actions are predetermined rather than dictated by some ghost in our brains, and then sussing out the consequences of that conclusion and applying them to society? Of course my answer is b).

Why are black holes so different from all other objects in the macroscopic Universe? Why are they, and they alone, so elegantly simple? If I knew the answer, it would probably tell me something very deep about the nature of physical laws. But I don’t know.

Why is it so difficult for us to think in relative terms? Well, for the good reason that human nature loves absoluteness, and erroneously considers it as a state of higher knowledge.

...Why is it, that from the moment you enter medical school to the moment you retire, that the only disorder you will ever diagnosis with a physics book - is obesity? This is biology folks, it's endocrinology, it's physiology - physics has nothing to do with it. The law of thermodynamics is always true, [but] the energy balance equation is irrelevant...

...Why is it that from the moment you enter medical school to the moment you retire, the only disorder that you will ever diagnose with a physics textbook is obesity? This is biology folks, it's endocrinology, it's physiology - physics has nothing to do with it. The laws of thermodynamics are always true, the energy balance equation is irrelevant...

With only one proton in its nucleus, hydrogen is the lightest and simplest element, made entirely during the big bang. Out of the ninety-four naturally occurring elements, hydrogen lays claim to more than two-thirds of all the atoms in the human body, and more than ninety percent of all atoms in the cosmos, on all scales, right on down to the solar system. Hydrogen in the core of the massive planet Jupiter is under so much pressure that it behaves more like a conductive metal than a gas, creating the strongest magnetic field among the planets.

Wolfgang Pauli, in the months before Heisenberg's paper on matrix mechanics pointed the way to a new quantum theory, wrote to a friend, "At the moment physics is again terribly confused. In any case, it is too difficult for me, and I wish I had been a movie comedian or something of the sort and had never heard of physics." That testimony is particularly impressive if contrasted with Pauli's words less than five months later: "Heisenberg's type of mechanics has again given me hope and joy in life. To be sure it does not supply the solution to the riddle, but I believe it is again possible to march forward.

You want a physicist to speak at your funeral. You want the physicist to talk to your grieving family about the conservation of energy, so they will understand that your energy has not died. You want the physicist to remind your sobbing mother about the first law of thermodynamics; that no energy gets created in the universe, and none is destroyed. You want your mother to know that all your energy, every vibration, every Btu of heat, every wave of every particle that was her beloved child remains with her in this world. You want the physicist to tell your weeping father that amid energies of the cosmos, you gave as good as you got. And at one point you'd hope that the physicist would step down from the pulpit and walk to your brokenhearted spouse there in the pew and tell him that all the photons that ever bounced off your face, all the particles whose paths were interrupted by your smile, by the touch of your hair, hundreds of trillions of particles, have raced off like children, their ways forever changed by you. And as your widow rocks in the arms of a loving family, may the physicist let her know that all the photons that bounced from you were gathered in the particle detectors that are her eyes, that those photons created within her constellations of electromagnetically charged neurons whose energy will go on forever. And the physicist will remind the congregation of how much of all our energy is given off as heat. There may be a few fanning themselves with their programs as he says it. And he will tell them that the warmth that flowed through you in life is still here, still part of all that we are, even as we who mourn continue the heat of our own lives. And you'll want the physicist to explain to those who loved you that they need not have faith; indeed, they should not have faith. Let them know that they can measure, that scientists have measured precisely the conservation of energy and found it accurate, verifiable and consistent across space and time. You can hope your family will examine the evidence and satisfy themselves that the science is sound and that they'll be comforted to know your energy's still around. According to the law of the conservation of energy, not a bit of you is gone; you're just less orderly. Amen.

A consistent pursuit of classical physics forces a transformation in the very heart of that physics.

All of science can be divided into physics and stamp-collecting.

As an undergraduate, I did maths and physics. That doesn't make me a scientist. So I try to read and understand and talk to scientists.

As physics is a mental reconstruction of material processes, perhaps a physical reconstruction of psychic processes is possible in nature itself.

Cambridge was the place for someone from the Colonies or the Dominions to go on to, and it was to the Cavendish Laboratory that one went to do physics.

A scenario is suggested by which the universe and its laws could have arisen naturally from nothing. Current cosmology suggests that no laws of physics were violated in bringing the universe into existence. The laws of physics themselves are shown to correspond to what one would expect if the universe appeared from nothing. There is something rather than nothing because something is more stable.

Classical physics has been superseded by quantum theory: quantum theory is verified by experiments. Experiments must be described in terms of classical physics.

Digital mechanics predicts that for every continuous symmetry of physics there will be some microscopic process that violates that symmetry.