Before arriving astatine the quanta to which this archetypal acquisition is devoted, let maine to statesman with a elemental observation. We humans inhabit the aboveground of the satellite Earth, and this is simply a alternatively peculiar place: it has aspects that are not astatine each communal successful the universe. They are not unique—most apt determination are plentifulness of planets akin to Earth—but astir of the immense cosmos is precise antithetic from our constrictive home. The peculiarities of the aboveground of our satellite pb america to prejudices that marque it hard for america to recognize that vaster world. Here are immoderate of them.
The aboveground of the Earth is precise small. So tiny so that it takes airy a specified tenth of a 2nd to question astir it: a mea-sure smaller than we are susceptible of perceiving with our senses. This is wherefore we pass successful a mode that seems instantaneous to us: we talk by telephone betwixt Paris and Shanghai arsenic if we were lasting adjacent to each other. We could not bash this with a person who lived successful a antithetic star system. It takes years for a awesome to question backmost from adjacent the nearest of stars. The smallness of the Earth gives america the content that determination is simply a shared communal Time; that it ever makes consciousness to inquire what is happening determination other close now; that we could conscionable marque a telephone to find out. But it is not truthful successful the larger, immense world. The thought of a shared, communal clip works good here, betwixt ourselves, neighbors connected the aforesaid planet. But it does not enactment successful the remainder of the universe.
A kid calved successful a colony people thinks that the full satellite is similar that village.
On Earth determination are objects. A stone, a pen, a house—these are objects, things. Solid entities, well-defined, unchangeable implicit time. This leads america to judge that quality is made up of specified things. But we lone request deliberation of Jupiter oregon Saturn, oregon of our Sun, to go alert that not everyplace is similar this. Jupiter and Saturn are worlds vaster than Earth. All sorts of phenomena hap there—but they are fluid. There, phenomena cannot beryllium understood successful presumption of objects. There are nary “things” connected Saturn.
The aboveground of the Earth is surrounded by air. Air is simply a unusual substance; we dainty it arsenic if it was not there. We accidental “this solid is empty,” erstwhile successful information it is full—of air. The evanescence of aerial leads america to ideate that determination is thing similar bare space. But determination is thing successful the beingness that is wholly empty.
One 4th of the aboveground of the Earth is precise rigid. Earthquakes and bradyseisms are precise rare; the continents determination highly slowly. This condition offers america a peculiar accidental to find ourselves: we springiness names to the regions of the Earth and we usage them to accidental wherever things are—“I americium successful Princeton,” oregon “I americium connected Ponte Pietra successful Verona.” If determination was lone sea, with h2o that ne'er stands still, locating thing would beryllium overmuch much complicated—as mariners cognize afloat well. The beingness of places fixed with respect to 1 different by the rigidity of the continents causes america to deliberation astir abstraction successful a mode that simply does not enactment elsewhere. It allows america to accidental “I’m staying successful the aforesaid place,” erstwhile what we really mean is “I’m not moving successful narration to the coagulated aboveground of the Earth.” On Jupiter the meaning of “staying successful the aforesaid place” is unclear.
On Earth gravity is much oregon little the aforesaid everywhere. This is wherefore the clip betwixt erstwhile we abstracted from idiosyncratic and erstwhile we conscionable them again is the aforesaid for everyone. This is not the lawsuit successful the wider universe. Time passes astatine antithetic speeds for antithetic travelers: erstwhile they conscionable again, they person mostly not aged by the aforesaid fig of years. The information that present connected Earth the aforesaid magnitude of clip lapses for 2 radical betwixt a separation and reunion gives america a peculiar intuition astir temporality—an intuition that does not enactment elsewhere.
A kid calved successful a colony people thinks that the full satellite is similar that village. He expects to brushwood extracurricular it the aforesaid mores, the aforesaid mode of dressing, the aforesaid language. When helium finds that the satellite is otherwise, helium is amazed. This amazement is the quality of learning. And this is science.
It is not ever easy, however, to escaped ourselves from the ideas and outlook of our autochthonal village. Even learning that successful Rome cats are called gatti, and successful New Delhi billee, does not forestall america from having a hard clip reasoning that the proper, existent sanction of the feline is not “cat.”
Reality is much analyzable and much varied than we think.
We instinctively mistake section peculiarities for cosmopolitan truths. We bash not easy recognize that the things which look evident to america are conscionable aspects of “the plot that makes america truthful ferocious,” arsenic Dante calls the Earth erstwhile helium views it, astatine the extremity of Paradiso, acold beneath and tiny, from the heights of the heavens of fixed stars.
The peculiarity of the aboveground of the Earth, the colony successful which we hap to beryllium born, generates prejudices successful america that are not casual to recognize. If we bash not privation to beryllium similar the kid that lone knows its ain village, we indispensable larn to abstracted ourselves from these prejudices.
In the wider universe, determination are nary objects, bare space, ways of definitively locating events—and it is meaningless to accidental thatsomething “stays successful the aforesaid place.” It means thing to talk of a “now” successful distant places; nary communal clip exists . . . Reality is much analyzable and much varied than we think.
Allow me, earlier dealing with twentieth-century science, to dwell upon 1 much simple fact.
Consider, if you will, beloved reader, an entity that is adjacent to you. The seat connected which you are sitting, for instance—or the sofa connected which you are lying. Look astatine it carefully, and inquire yourself whether it is still, oregon moving. If it is not still, inquire yourself astatine what velocity it is moving.
Our archetypal intuitive effect is that, if cipher moves it, past the seat is evidently still. Always given, of course, that you are not speechmaking these lines connected a train, oregon an airplane, successful which lawsuit the spot connected which you are sitting volition beryllium moving astatine the velocity of the bid oregon the plane, and could adjacent beryllium going astatine hundreds of meters per second.
Perhaps, though, it has already occurred to you that the Earth itself is moving, turning connected its axis and orbiting astir the Sun. We are each moving with it, astatine a sizeable speed. Therefore, the seat is moving with the Earth, adjacent if you are not connected a bid oregon an airplane.
But this is not all. Our postulation is besides turning, and the full star strategy with it. The seat moves, with the galaxy, astatine a tremendous speed. And the postulation itself? Is it not moving astatine a definite velocity successful narration to thing else? In narration to what?
Is it imaginable to halt this series of references with respect to which it is imaginable to accidental astatine what velocity the seat is moving? Is there, successful different words, an ultimate reference point, 1 that is really still, and that volition yet let america to find what is the objective speed of the chair?
The reply to this question is good known to immoderate bully physics student. The reply is no. There is nary ultimate reference point, thing really still, and nary meaning to an objective (in the consciousness of non-relative) conception of velocity. This facet of quality was intuited by Galileo immoderate 4 centuries ago, and clarified successful extent by the consequent past of mechanics. There is nary ultimate, absolute reference constituent which would let america to accidental that thing is inactive and thing is moving, but successful narration to thing else. It lone makes consciousness to inquire whether oregon not an entity is stationary relative to thing else. The question arsenic to whether an entity is moving oregon stationary in itself is meaningless.
We usually acceptable a notation constituent implicitly, without saying so. The Earth, being solid, large, and accessible, offers a precise conve-nient reference. When we accidental “still,” we commonly mean inactive with respect to the Earth’s surface. But not always. If connected a bid the antheral successful the spot successful beforehand of america tells his lad who is moving astir to “keep still,” helium is not suggesting that the mediocre kid should propulsion himself retired of the model successful bid to beryllium inactive with respect to the Earth. He means that the kid should not determination with respect to the train. When studying the movements of the planets, we instrumentality the Sun arsenic a convenient notation point: arsenic noticed by Copernicus, it is amended than the Earth for this purpose. An implicit notation point, successful our existent knowing of the world, simply does not exist.
But I judge we bash not bespeak capable upon conscionable however precise extremist a find it is—the information that velocity is simply a relative property.
But fixed that we are utilized to seeing the Earth arsenic a constituent of reference, it seems earthy to america to deliberation that determination inactive must be a final, existent one, adjacent if the Earth moves successful narration to the Sun, and the galaxies determination successful narration to each other.
It comes instinctively to america to deliberation that, ultimately, the information that an entity is moving oregon not is fundamentally meaningful, inde-pendently of wherever different objects are, oregon what they are doing. But we are wrong. It is similar reasoning that adjacent though the connection for feline is antithetic successful antithetic languages, determination indispensable nevertheless beryllium a true name for feline that tin ultimately be referenced.
Forgive me, beloved reader, if I look to beryllium laboring a constituent that is already wide to you. One that you studied astatine school, arsenic portion of simple physics. But I judge we bash not bespeak capable upon conscionable however precise extremist a find it is—the information that velocity is simply a relative property. It is not casual to digest an thought which, if we deliberation astir it properly, is astonishing.
A fewer years ago, portion connected a lecture tour, I made friends with a superb young antheral who was moving successful the Princeton doctrine department. Talking with him, I realized that helium was afloat alert of physics—but besides that helium did not truly judge it. One day, portion discussing this, helium said to me: “But travel on, Carlo. There must, successful the end, beryllium an implicit consciousness successful which a happening is either moving oregon not.” While accepting the thought that it is not imaginable to measure whether an entity is moving, helium nevertheless insisted connected reasoning that whether thing is moving oregon not moving indispensable beryllium a existent fact, adjacent if it cannot beryllium measured. In different words, a young philosopher successful the Department of Philosophy successful 1 of the astir prestigious universities successful the satellite had failed to digest what Galileo had understood 4 centuries ago!
What led him to judge that determination is thing fundamentally existent astir implicit motion, adjacent though it is not observable? The reply that helium gave to this question is 1 of the reasons that I wrote this book: “Because,” helium said to me, “it is the precise quality of the full concept of question that a happening is either moving oregon still.” The world, to his mode of thinking, indispensable conform to our concepts.
Where does the mistake lie? There is nary uncertainty that successful the quality of his concept of question everything is either moving oregon stationary. A philosopher susceptible of precise conceptual investigation sees intelligibly what a definite conception of question implies.
The mistake lies elsewhere: successful not knowing that this peculiar concept of question is inadequate for describing the existent world. My friend, successful different words, considered his intuition, based connected the conception of motion, to beryllium much reliable than the cognition accumulated by humanity implicit the past 4 centuries.
His mistake was to not instrumentality into relationship the information that his intuition, connected which his conception of question is based, is the effect of acquisition that is limited, and that arsenic specified is adapted to describing a constricted portion of reality: the portion that is acquainted to us, slow-moving ants connected the coagulated aboveground of our tiny planet.
What my person failed to see is that concepts are the products of experience, and that erstwhile that acquisition is limited, arsenic ours inevitably is, concepts tin beryllium inadequate to giving a due relationship of the existent world. What helium failed to spot is that successful bid to recognize the satellite amended it is indispensable to let our concepts to evolve, adjacent if this seems astatine archetypal to beryllium counterintuitive.
I consciousness that determination is simply a full subdivision of modern doctrine that is trapped wrong this mistake. The mistake is to judge that the concepts we person are needfully capable for knowing reality, adjacent beyond the discourse successful which these concepts were shaped.
The mistake is to stay attached to a conceptual framework, without realizing that it mightiness nary longer beryllium moving successful the airy of what we tin spot erstwhile we look a small further.
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From On the Equality of All Things. Used with the support of the publisher, Scribner. Copyright © 2026 by Carlo Rovelli
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