{"id":878741,"date":"2025-12-18T23:27:09","date_gmt":"2025-12-19T05:27:09","guid":{"rendered":"https:\/\/newsycanuse.com\/index.php\/2025\/12\/18\/reality-exists-without-observers-boooo\/"},"modified":"2025-12-18T23:27:09","modified_gmt":"2025-12-19T05:27:09","slug":"reality-exists-without-observers-boooo","status":"publish","type":"post","link":"https:\/\/newsycanuse.com\/index.php\/2025\/12\/18\/reality-exists-without-observers-boooo\/","title":{"rendered":"Reality Exists Without Observers? Boooo!"},"content":{"rendered":"
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I<\/span>\u2019ve never been a sports fan, let alone a rabid one, but I think I finally know what it feels like. I was reading a new book, Portals to a New Reality<\/em> <\/em>by Vlatko Vedral, when I found myself shouting at the page the way sports fans scream at TVs. When Vedral, a physicist at the University of Oxford, wrote that the Copenhagen interpretation of quantum mechanics \u201ccontains a great number of misconceptions about what the world is made of and how to understand its most fundamental processes,\u201d I felt my blood pressure spike. When he claimed, \u201cQuantum physics does not need observers,\u201d I leapt out of my seat. \u201cYeah? Try saying that to Niels Bohr\u2019s face<\/em>!\u201d<\/p>\n

Vedral\u2019s is one in a slew of recent books that cast Bohr, Werner Heisenberg, and colleagues as cartoonish villains looming over quantum physics, making the theory seem more woo-woo than it needs to be. Vedral is basically Team Many Worlds (though he doesn\u2019t like the name), which pits him against Team Copenhagen\u2019s insistence that observers play a fundamental role. In Copenhagen, one needs an observer to get a measurement outcome (the particle is either here or<\/em> there; Schr\u00f6dinger\u2019s cat is either alive or<\/em> dead), while in Many Worlds, there\u2019s never a single outcome, only an alive cat in one world and a dead cat in another. Since every possible outcome happens, there\u2019s no special part for observers to play. \u201cMaking measurements in quantum physics is like any other quantum process, nothing more,\u201d Vedral writes. Or, as I once heard physicist Brian Greene (another Many Worldser) put it, quantum measurement is \u201cjust stuff interacting with stuff.\u201d<\/p>\n

This no-nonsense take (if believing in infinite branching parallel realities in which every possible version of you is having every possible experience can be considered no-nonsense) is intended to sound more scientific and staider than their caricature of Copenhagen, in which, as Vedral puts it, \u201creality does not exist when no one observes it.\u201d<\/p>\n

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Only here\u2019s the thing. Every time an interpretation of quantum mechanics claims to banish observers, it ends up hiding them somewhere in the theory or sneaking them in through the back door. Which, if we\u2019re trash-talking, might lead a spectator to suggest that these theorists pack up their many worlds in their many suitcases and go crawling back to Denmark.<\/p>\n

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I leapt out of my seat. \u201cYeah? Try saying that to Niels Bohr\u2019s face<\/em>!\u201d<\/p>\n<\/blockquote>\n

Here\u2019s what the Copenhagen interpretation<\/a> actually says. When two objects interact\u2014say, a measuring device and the thing it\u2019s measuring\u2014there\u2019s no way to neatly decompose that combined system back into two individual objects. They\u2019re entangled. Enmeshed. That\u2019s thanks to the finite value of Planck\u2019s constant\u2014the smallest possible unit of \u201caction,\u201d a quantity in physics that measures how a system\u2019s potential and kinetic energy trade off over time. Because Planck\u2019s constant can\u2019t be further divided, it imposes a kind of graininess on the situation that prevents us from being able to carve up the interaction in an unambiguous way, as if it\u2019s possible to know which part belongs to which. In fact, it prevents us from talking as if there were ever two independent objects at all. We don\u2019t start with objects, which then interact; we start with interactions, which we then have to dissect into objects. Only there\u2019s no clear way to do it.<\/p>\n

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It\u2019s a situation not unlike that in relativity, where, thanks to the finite speed of light, there\u2019s no preferred way to decompose spacetime into space and time. In quantum theory, thanks to the finite Planck\u2019s constant, there\u2019s no preferred way to decompose an interaction into anything. To get a specific measurement outcome\u2014the particle\u2019s position is x<\/em> or its momentum is p<\/em>\u2014we have to decide which part of the interaction to call the \u201cparticle\u201d and which part to call the \u201capparatus.\u201d Since nature offers no single True-with-a-capital-T way to do that, we just have to wing it and remember that the outcome we get doesn\u2019t reveal some pre-existing fact about the world, but creates a new fact relative to the context of the measurement and our arbitrary decision as to how to divvy it up.<\/p>\n

So when Team No Observers say that quantum measurements are \u201cjust stuff interacting with stuff,\u201d what they mean is, we don\u2019t have to make that decision. A particle hits a measuring device, the two become entangled, and that\u2019s the end of the story. Only that can\u2019t <\/em>be the end of the story. It can\u2019t even be the beginning of the story. Because who decided which part to call the \u201cparticle\u201d and which to call the \u201cmeasuring device\u201d if all that exists is one big, entangled mess? If you already sectioned off a piece of world and labeled it \u201cmeasuring device\u201d before you ran the experiment, then you snuck in an observer at the start. If not\u2014if all you have is entanglement\u2014there\u2019s simply no measurement outcome at all<\/em>. Not in this world, and not in any other.<\/p>\n

At this point, the Many Worlds fans in the bleachers might start chanting \u201cDecoherence!\u201d But decoherence\u2014the process by which quantumness leaks out into the larger world, leaving behind the appearance of an objective thing\u2014requires, you guessed it, an observer. It\u2019s the observer who partitions the world into the system under study and its environment, which is defined as whatever part of the world the observer chooses to ignore. Only then can quantum correlations from the system slip away into the crowded environment and disappear out of sight. Should the observer decide to keep tabs on the environment, too, there\u2019s no more decoherence.<\/p>\n

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That\u2019s the trouble with the \u201cno observers\u201d story\u2014you can\u2019t tell it from the inside out. You can\u2019t start with a world, already divvied up into space and time, containing distinct systems and measuring apparatuses and environments, and then talk about objects interacting and getting entangled, because in the \u201cno observers\u201d story, none of those things can be defined in the first place. As a Many Worldser, you can\u2019t even define a \u201cworld\u201d or a \u201cbranch of the wavefunction\u201d without bringing in an observer. That\u2019s why American physicist Hugh Everett, when he proposed what\u2019s now known as Many Worlds, didn\u2019t talk about worlds branching into parallel realities so much as observers <\/em>branching into parallel states of having observed or not observed different outcomes. It\u2019s why Vedral dislikes the name \u201cMany Worlds.\u201d<\/p>\n

S<\/span>o why does Vedral want so badly to banish observers from quantum physics? He works in quantum information theory, where he designs experiments to show that quantum effects, which we usually observe in microscopic systems, operate at larger scales still\u2014in molecules, viruses, even people. But for that to work, he says, observers can\u2019t play a special role; they have to be treated quantum mechanically, like everything else. When we \u201ctake seriously the idea that the world is even more quantum than most physicists realize,\u201d Vedral writes, we will finally make progress in physics, ultimately uniting quantum mechanics with our understanding of spacetime and gravity. But Copenhagen and its observers, he says, are standing in the way.<\/p>\n

\u201cThe Copenhagen interpretation has contributed a great deal of force to the consensus in physics today that quantum physics is too \u2018weird\u2019 to work at macroscopic scales, and that quantum effects at the macro level are not accessible by experimentation,\u201d Vedral writes.<\/p>\n

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This is a total misunderstanding. Bohr made it clear that the macroscopic measuring device, even the observers themselves, can always be described by quantum mechanics. Quantumness, Bohr wrote, \u201cequally affects the description of the agency of observation and the object.\u201d Likewise, \u201cAn independent reality in the ordinary physical sense can neither be ascribed to the phenomena nor to the agencies of observation<\/em>.\u201d It\u2019s quantum all the way up. The point of Copenhagen was never to deny that, only to explain, given <\/em>that, why we still seem to get measurement outcomes. I\u2019m sitting here. The cup is over there. There are no half-dead-half-alive house cats half-walking around.<\/p>\n

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If we\u2019re trash-talking, theorists might pack up their many worlds and go back to Denmark.<\/p>\n<\/blockquote>\n

Team Many Worlds, on the other hand, can\u2019t account for why anything seems like anything. Because without observers, the only ingredient left is a single, universal wavefunction\u2014a giant entangled state\u2014which, technically speaking, is just a vector endlessly rotating in an abstract mathematical void for eternity. Nothing happens. There\u2019s nothing in it. No particles, no physicists, no cups, no cats. Not the appearance of measurement outcomes. Not the branching of worlds. Nothing to see, and no one to see it. Giving up observers, then, amounts to giving up empirical science. And regardless of one\u2019s feelings about a certain Danish physicist, that\u2019s a weird move to make, considering the very theory you\u2019re using to posit the existence of your eternal vector was arrived at through experiment and observation.<\/p>\n

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Of course, Vedral wants his own experiments to have outcomes, so he\u2019s forced to do what everyone does and sneak observers back into the picture. He assures us this is no big deal, no threat to the inherent quantumness of reality. Where we draw the line between observer and observed, he insists, is \u201ccompletely arbitrary.\u201d Well, yes. That was Copenhagen\u2019s whole point. These divisions aren\u2019t objectively given. Observers have to make choices, to forge the fault lines of the world.<\/p>\n

But words like \u201cchoice\u201d make physicists nervous, so they soothe themselves by making Copenhagen seem more mystical than it is. Surely the moon\u2019s<\/em> there when no one\u2019s looking, they love to say with a roll of the eyes.<\/p>\n

Let\u2019s put this moon thing to rest. It\u2019s true. We can\u2019t say the moon is there if no one\u2019s observing it. Neither can we say that the moon\u2019s not<\/em> there if no one\u2019s observing it. It\u2019s not as if the sky is empty until someone gazes upward and a moon suddenly pops into existence. It\u2019s that we can\u2019t say anything about the moon as an independent object, because quantum theory doesn\u2019t grant us independent objects, only measurements that we can slice into moons. We are no longer \u201cin a position to speak of the autonomous behavior of a physical object,\u201d Bohr wrote. \u201cSuch an analysis is in <\/em>principle excluded.\u201d<\/p>\n

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Our very concept of a thing<\/em>\u2014an atom, a chair, a planet\u2014is rooted in the assumption, Bohr said, \u201cthat it is possible to distinguish sharply between the behavior of objects and the means of observation,\u201d which, in quantum mechanics (given the finite value of Planck\u2019s constant), it\u2019s not.<\/p>\n

So, the issue isn\u2019t that objects in the world are out there doing weird quantum things until they meet the stern gaze of an observer and magically fall into line. The issue is that our entire framework of a world that comes pre-carved into objects was wrong from the start. Copenhagen\u2019s rivals are right to suggest that the interpretation is radical\u2014but not for the reasons they\u2019d have you believe. It\u2019s not radical because it ascribes some reality-creating power to the minds of observers. It\u2019s radical because it undermines the very categories according to which we\u2019ve organized the world ever since the 17th-century origins of modern science.<\/p>\n

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Interpretations that banish observers end up sneaking them in through the back door.<\/p>\n<\/blockquote>\n

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Vedral seems to think we could get back to those categories\u2014to a fully objective world of \u201cstuff interacting with stuff\u201d\u2014if only we could re-engineer our brains to perceive the world\u2019s quantumness directly. \u201cWe would need to integrate specially designed microchips that carry out these quantum measurements in conjunction with the existent machinery of our brain,\u201d Vedral suggests, noting that this would provide \u201can experience that corresponds more closely to fundamental reality than drugs could ever offer.\u201d<\/p>\n

Of course, one would need observers to define objects like brains, microchips, and measurements before our new quantum perception could take effect. But then what? Would we apportion the world differently\u2014defining different objects, blurring their borders, redrawing the very boundaries of ourselves? Trippy, sure\u2014but still in the Danish spirit.<\/p>\n

I agree with Vedral that there are deep questions still in need of answers. That no interpretation of quantum mechanics has quite yet won the game. So, while there\u2019s no universe in which you\u2019ll catch me wearing the Many Worlds\u2019 team jersey, I\u2019m not rocking Team Copenhagen\u2019s either.<\/p>\n

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Personally, I\u2019m rooting for QBism<\/a> (formerly Quantum Bayesianism), an interpretation that starts in Copenhagen by way of Texas and ends up, among other places, in Boston, with Christopher Fuchs, co-captain of the team, taking heed of the profound metaphysical lesson in Copenhagen\u2014that we can\u2019t think of ourselves as standing apart from a ready-made, objective world describable in third person\u2014and putting observers and their decision making front and center.<\/p>\n

The QBists added to Copenhagen elements of decision theory, personalist Bayesian probability, quantum information theory, and early American pragmatist philosophy until, as Fuchs puts it, \u201cWe were left with an interpretation of quantum theory that was very different from Bohr\u2019s, though the roots have always remained visible.\u201d At its heart, QBism is about how agents, by acting on the world, by carving up reality, participate in the incessant churn of novelty and creativity that spills out of a universe that\u2019s ever on the make.<\/p>\n

But QBism is an unfinished project, which means I\u2019m still watching the game, still shouting at the TV. Does the observer carve herself out of the world through her actions? Is that the very essence of what it means to be an observer? How do different observers, carving along different seams, navigate their differences? \u201cI believe that if the development of atomic physics has taught us anything,\u201d Bohr told Heisenberg, \u201cit is that we must learn to think more subtly.\u201d I suppose that\u2019s not only the art but the sport of it. <\/p>\n

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Lead image by Tasnuva Elahi; with images by Natalya Kosarevich, cybermagician, and zombiu26 \/ Shutterstock<\/em><\/p>\n