Posts Tagged ‘reality’
“Reality is that which, when you stop believing in it, doesn’t go away”*…
Reality is tough. Everything eats and is eaten. Everything destroys and is destroyed.
In a way that challenges lots of our deeply-seated conceptions (your correspondent’s, anyway), philosopher (and self-proclaimed pessimist) Drew Dalton invokes the laws of thermodynamics to argue that it is our moral duty to strike back at the Universe…
Reality is not what you think it is. It is not the foundation of our joyful flourishing. It is not an eternally renewing resource, nor something that would, were it not for our excessive intervention and reckless consumption, continue to harmoniously expand into the future. The truth is that reality is not nearly so benevolent. Like everything else that exists – stars, microbes, oil, dolphins, shadows, dust and cities – we are nothing more than cups destined to shatter endlessly through time until there is nothing left to break. This, according to the conclusions of scientists over the past two centuries, is the quiet horror that structures existence itself.
We might think this realisation belongs to the past – a closed chapter of 19th-century science – but we are still living through the consequences of the thermodynamic revolution. Just as the full metaphysical implications of the Copernican revolution took centuries to unfold, we have yet to fully grasp the philosophical and existential consequences of entropic decay. We have yet to conceive of reality as it truly is. Instead, philosophers cling to an ancient idea of the Universe in which everything keeps growing and flourishing. According to this view, existence is good. Reality is good.
But what would our metaphysics and ethics look like if we learned that reality was against us?…
Read on for his provocative argument that philosphers must grapple with the meaning of thermodynamics: “Reality is evil,” from @dmdalton.bsky.social in @aeon.co.
Dalton further explores these ideas in his book The Matter of Evil: From Speculative Realism to Ethical Pessimism (2023)
* Philip K. Dick
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As we wrestle with reality, we might send somewhat sunnier birthday greetings to Stephen William Hawking CH CBE FRS FRSA; he was born on this date in 1942. A theoretical physicist and cosmologist, he is probably best known in his professional circles for his work with Roger Penrose on gravitational singularity theorems in the framework of general relativity, for his theoretical prediction that black holes emit radiation (now called Hawking radiation), and for his support of the many-worlds interpretation of quantum mechanics.
But Hawking is more broadly known as a popularizer of science. His A Brief History of Time stayed on the British Sunday Times best-seller list for over four years (a record-breaking 237 weeks), and has sold over 10 million copies worldwide.
“We have this one life to appreciate the grand design of the universe, and for that, I am extremely grateful.”
“The world of reality has its limits; the world of imagination is boundless”*…
Still, it’s useful to know the difference… and as Yasemin Saplakoglu explains, that’s a complex process– one that science takes very seriously…
As I sit at my desk typing up this newsletter, I can see a plant to my left, a water bottle to my right and a gorilla sitting across from me. The plant and bottle are real, but the gorilla is a product of my mind — and I intuitively know that this is true. That’s because my brain, like most people’s, has the ability to distinguish reality from imagination. If it didn’t, or if I had a condition that disrupts this distinction, I’d constantly see gorillas and elephants where they don’t exist.
Imagination is sometimes described as perception in reverse. When we look at an object, electromagnetic waves enter the eyes, where they are translated into neural signals that are then sent to the visual cortex at the back of the brain. This process generates an image: “plant.” With imagination, we start with what we want to see, and the brain’s memory and semantic centers send signals to the same brain region: “gorilla.”
In both cases, the visual cortex is activated. Recalling memories can also activate some of the same regions. Yet the brain can clearly distinguish between imagination, perception and memory in most cases (though it is still possible to get confused). How does it keep everything straight?
By probing the differences between these processes, neuroscientists are untangling how the human brain creates our experience. They’re finding that even our perception of reality is in many ways imagined. “Underneath our skull, everything is made up,” Lars Muckli, a professor of visual and cognitive neurosciences at the University of Glasgow, told me. “We entirely construct the world in its richness and detail and color and sound and content and excitement. … It is created by our neurons.”
To distinguish reality and imagination, the brain might have some kind of “reality threshold,” according to one theory. Researchers recently tested this by asking people to imagine specific images against a backdrop — and then secretly projected faint outlines of those images there. Participants typically recognized when they saw a real projection versus their imagined one, and those who rated images as more vivid were also more likely to identify them as real. The study suggested that when processing images, the brain might make a judgment on reality based on signal strength. If the signal is weak, the brain takes it for imagination. If it’s strong, the brain deems it real. “The brain has this really careful balancing act that it has to perform,” Thomas Naselaris, a neuroscientist at the University of Minnesota, told me. “In some sense it is going to interpret mental imagery as literally as it does visual imagery.”
Although recalling memories is a creative and imaginative process, it activates the visual cortex as if we were seeing. “It started to raise the question of whether a memory representation is actually different from a perceptual representation at all,” Sam Ling, a neuroscientist at Boston University, told me. A recent study looked to identify how memories and perceptions are constructed differently at the neurobiological level. When we perceive something, visual cues undergo layers of processing in the visual cortex that increase in complexity. Neurons in earlier parts of this process fire more precisely than those that get involved later. In the study, researchers found that during memory recall, neurons fired in a much blurrier way through all the layers. That might explain why our memories aren’t often as crisp as what we’re seeing in front of us…
“How Do Brains Tell Reality From Imagination?” from @yaseminsaplakoglu.bsky.social in @quantamagazine.bsky.social.
* Jean-Jacques Rousseau
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As we parse perception, we might send mindful birthday greetings to a man whose work figures into the history of science’s struggle on this issue, Franz Brentano; he was born on this date in 1838. A philosopher and psychologist, his 1874 Psychology from an Empirical Standpoint, considered his magnum opus and is credited with having reintroduced the medieval scholastic concept of intentionality into contemporary philosophy and psychology.
Brentano also studied perception, with conclusions that prefigure the discussion above…
He is also well known for claiming that Wahrnehmung ist Falschnehmung (‘perception is misconception’) that is to say perception is erroneous. In fact he maintained that external, sensory perception could not tell us anything about the de facto existence of the perceived world, which could simply be illusion. However, we can be absolutely sure of our internal perception. When I hear a tone, I cannot be completely sure that there is a tone in the real world, but I am absolutely certain that I do hear. This awareness, of the fact that I hear, is called internal perception. External perception, sensory perception, can only yield hypotheses about the perceived world, but not truth. Hence he and many of his pupils (in particular Carl Stumpf and Edmund Husserl) thought that the natural sciences could only yield hypotheses and never universal, absolute truths as in pure logic or mathematics.
However, in a reprinting of his Psychologie vom Empirischen Standpunkte (Psychology from an Empirical Standpoint), he recanted this previous view. He attempted to do so without reworking the previous arguments within that work, but it has been said that he was wholly unsuccessful. The new view states that when we hear a sound, we hear something from the external world; there are no physical phenomena of internal perception… – source
“Tennyson said that if we could understand a single flower we would know who we are and what the world is”*…
Reality feels “stable” enough to talk about it– though all logic seems to point away from that possibility. Marco Giancotti unpacks what he suggests is the only line of reasoning that resolves that paradox…
What is the source of what we call order? Why do many things look too complex, too perfectly organized to arise unintentionally from chaos? How can something as special as a star or a flower even happen? And, for that matter, why do some natural phenomena seem designed for a purpose?
We live in a universe of forces eternally straining to crush things together or tear them apart. There is no physical law for “forming shapes”, no law for being separated from other things, no law for staying still.
Boundaries are in the eye of the beholder, not in the world out there. Out there is only tumult, clashing, and shuffling of everything with everything else.
And yet, our familiar world is filled with things stable and consistent enough for us to give them names—and to live our whole lives with.
In this essay we’ll tackle these questions at the very root. We need good questions to get good answers, so we’ll begin by clarifying the problem. It has to do with probabilities—we’ll see why those natural objects seem so utterly unlikely to happen by chance, and we’ll find the fundamental process that solves the dilemma.
This will take us most of the way, but we’ll have one final obstacle to overcome, a cognitive Last Boss: living things still feel a little magical in some way, imbued with a mysterious substance called “purpose” that feels qualitatively different from how inanimate things work. This kind of confusion runs very deep in our culture. To remove it, I’ll give a name to something that, as far as I know, hasn’t been named before: phenomena that I’ll be calling—enigmatically, for now—“Water Lilies.”…
Applying systems dynamics, complexity, and emergence to understanding reality itself: “Recursion, Tidy Stars, and Water Lilies,” from @marco_giancotti (the second in a trilogy of essays: part one here; subscribe to his newsletter for Part Three when it drops).
* Jorge Luis Borges, “The Zahir“
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As we explore existence, we might spare a thought for Francis Simpson; he died on this date in 2003. An English naturalist, conservationist, and chronicler of the countryside and wild flowers of his native Suffolk, he became a botanist at Ipswich Museum, where he worked until his retirement in 1977.
He published one of the most highly regarded county floras, simply entitled Simpson’s Flora of Suffolk, and in 1938 saved a small meadow, famous for its snakeshead fritillaries, from being drained and ploughed into farmland. Using donations amounting to £75, he was able to purchase the field, Mickfield Meadow, for the Society for the Promotion of Nature Reserves. Today, it is one of the oldest nature reserves in the country, protecting the meadow flowers now surrounded by farmland.
“What happens when you get to the end of things?”*…
Charlie Wood introduces a remarkable new collection in Quanta…
A couple of years ago, I was chatting about black holes with Dan Harlow of the Massachusetts Institute of Technology when he made a casual comment that left a deep impression on me. I asked if some new work he’d been doing strengthened the case that space-time was “emergent.” Without missing a beat he replied, “Sure, if it needed strengthening.”
Harlow isn’t the only physicist with serious doubts about what reality is made of. For more than a decade now, Nima Arkani-Hamed of the Institute for Advanced Study has been delivering a polished lecture arguing that space-time is “doomed.” Time and again, I’ve heard theorists in high-energy physics make similar-sounding statements, and I’ve always been struck by their confidence. We don’t have the faintest idea what the next theory of physics will look like, whether it will involve strings, loops, triangles or something entirely new that no one has thought to propose. And yet so many theorists seem rather convinced that whatever it will be, it won’t involve space or time.
Why? What does that statement mean? What would it look like to do physics without referring to space or time? I’ve spent most of this year trying to find out. The results have just been published in “The Unraveling of Space-Time,” a massive package that includes articles, videos and interactive animations from me and my colleagues Mark Belan, Emily Buder, Amanda Gefter and Joseph Howlett.
Over the course of more than 40 interviews with nearly 30 physicists, I learned that there are many ways to define emergent space-time. But at the most basic level, “emergent space-time” means that space and time are the outputs of a theory instead of the inputs. A classic analogy is heat. To explain why a teacup cools, scientists of the 1700s put heat into their theory of the world as a substance that repels itself and naturally spreads out. But this “caloric theory” was ultimately replaced by thermodynamics, a theory where a primary input is molecules that buzz around with some energy. As molecules crash into each other, their energy spreads, and we now recognize this process as the origin of heat transfer. Heat is an output — a prediction — of thermodynamics. It is an emergent phenomenon.
Space-time is the ultimate input. If physics is largely about predicting what happens where and when, you need a stage upon which things can happen. Albert Einstein became a household name for revealing that this stage acts like a fabric that bends in ways we experience as gravity. He described in spectacular detail how space-time behaves, much as 19th-century scientists described how heat behaves with caloric theory. The idea that space-time is emergent is the idea that space-time will eventually go the way of heat, water, air and so many other substances before it; we will someday understand it to be the inevitable consequence of the behavior of simpler entities. Call them the “atoms” of space-time.This week’s series explores the mind-bending notion of emergent space-time from a number of angles. There is, of course, the why of it all. This mostly boils down to the strange things that happen when Einstein’s theory of space-time collides with quantum mechanics, the theory of the subatomic world. When we combine features from both theories, we see that any experiment that tries to probe reality a little too closely will get thwarted by the appearance of a black hole, an enigma that undermines the familiar picture of space-time in its own way.
For this and other reasons, physicists are pushing to escape our familiar space-time, often referred to as the “bulk,” in search of alien environments conducive to new ways of doing physics.
Where else might one do physics, if not in the bulk? A few ideas are being developed, including one that goes by the name of holography. This is roughly the idea that any gravitational system — even the entire universe — can have an alternative description as a collection of quantum particles moving around a flat surface. From these gravity-free surfaces, a bulk world with gravity somehow pops out. It’s a remarkable theoretical claim, and over the past few years, holographers have developed a suite of tools that have helped them decode the bulk from the behavior of these surface particles.Another research program, spearheaded by Arkani-Hamed, has even more ambitious aims — getting both space-time and quantum mechanics as outputs from even more alien inputs. His group has recently developed an entirely new language for making predictions, one that makes no reference to space-time. Instead, it uses only geometric shapes and primitive counting tasks.
Is space-time, at least in its current form, definitely doomed? The idea tortured one of the pioneers of gravitational theory, John Wheeler. And today, the end of space-time is even more widely accepted. Most of the theorists I spoke with struggled to think of colleagues in the quantum gravity community who would defend space-time as a fundamental ingredient of reality. However, some researchers are pursuing alternatives. I spoke at length with Latham Boyle about patterns in particle physics that have led him and his collaborators to the more conservative notion that space-time might come in two “sheets.”
The various proposals under development are unlikely to see experimental tests this century, so a conclusive answer doesn’t seem near. But if it were someday established that space-time does break down, what would that mean for us?
On a practical level, not much. Einstein’s fabric of space-time is so sturdy that little short of a black hole would put a noticeable dent in it. But at a conceptual level, it’s hard to imagine a more dramatic rethinking of reality. When Democritus suggested that matter emerges from tiny barbed “atoms” more than 2,000 years ago, he couldn’t possibly have foreseen that parts of his proposal would ultimately be realized in the form of quantum theory — a framework asserting that reality is an ocean of overlapping waves of possibility that resolve into fixed objects only in certain situations.
If the void itself emerges from something, that something will be at least as alien. Just as individual molecules don’t themselves have a well-defined notion of heat, the base level of reality could lack marquee features of our existence that we take for granted. Places. Times. The ability to influence only nearby objects. The requirement that causes precede effects. Physicists are already finding that these notions seem unlikely to be present in a more precise accounting of the world. They seem to be the approximate outputs of something stranger.“One of the most spectacular aspects of these new findings is the emergence of causality can only happen in the approximate description,” Elliott Gesteau, a quantum gravity researcher at the California Institute of Technology, told me over Zoom earlier this year. If there is gravity, he continued, “which is what we have in our world, then this causal structure is only approximate and must break down.”…
Are we on the verge of a new physics? “Why Space-Time Looks Doomed,” from @walkingthedot in @QuantaMagazine.
The full interactive collection is here, and eminently worth reading in full.
* John Wheeler
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As we wrestle with reality, we might spare a thought for a physicist whose work helped move the questions we face forward– Max Karl Ernst Ludwig Planck; he died on this date in 1947. A theoretical physicist, he is best remembered as the originator of quantum theory. It was his discovery of energy quanta that won him the Nobel Prize in Physics in 1918.
“Those who are not shocked when they first come across quantum theory cannot possibly have understood it”*…
A scheduling note: your correspondent is headed onto the road for a couple of weeks, so (Roughly) Daily will be a lot more roughly than daily until September 20th or so.
100 years ago, a circle of physicists shook the foundation of science. As Philip Ball explains, it’s still trembling…
In 1926, tensions were running high at the Institute for Theoretical Physics in Copenhagen. The institute was established 10 years earlier by the Danish physicist Niels Bohr, who had shaped it into a hothouse for young collaborators to thrash out a new theory of atoms. In 1925, one of Bohr’s protégés, the brilliant and ambitious German physicist Werner Heisenberg, had produced such a theory. But now everyone was arguing with each other about what it implied for the nature of physical reality itself.
To the Copenhagen group, it appeared reality had come undone…
[Ball tells the story of Niels Bohr’s building on Max Planck, of Werner Heisenberg’s wrangling of Bohr’s thought into theory, of Einstein’s objections and Erwin Schrödinger’s competing theory; then he homes in on the ontological issue at stake…]
Quantum mechanics, they said, demanded we throw away the old reality and replace it with something fuzzier, indistinct, and disturbingly subjective. No longer could scientists suppose that they were objectively probing a pre-existing world. Instead, it seemed that the experimenter’s choices determined what was seen—what, in fact, could be considered real at all.
In other words, the world is not simply sitting there, waiting for us to discover all the facts about it. Heisenberg’s uncertainty principle implied that those facts are determined only once we measure them. If we choose to measure an electron’s speed (more strictly, its momentum) precisely, then this becomes a fact about the world—but at the expense of accepting that there are simply no facts about its position. Or vice versa…
…A century later, scientists are still arguing about this issue of what quantum mechanics means for the nature of reality…
[Ball recounts subsequent attempts to reconcile quantum theory to “reality,” including Schrödinger’s wave mechanics…]
… Schrödinger’s wave mechanics didn’t restore the kind of reality he and Einstein wanted. His theory represented all that could be said about a quantum object in the form of a mathematical expression called the wave function, from which one can predict the outcomes of making measurements on the object. The wave function looks much like a regular wave, like sound waves in air or water waves on the sea. But a wave of what?
At first, Schrödinger supposed that the amplitude of the wave—think of it like the height of a water wave—at a given point in space was a measure of the density of the smeared-out quantum particle there. But Born argued that in fact this amplitude (more precisely, the square of the amplitude) is a measure of the probability that we will find the particle there, if we make a measurement of its position.
This so-called Born rule goes to the heart of what makes quantum mechanics so odd. Classical Newtonian mechanics allows us to calculate the trajectory of an object like a baseball or the moon, so that we can say where it will be at some given time. But Schrödinger’s quantum mechanics doesn’t give us anything equivalent to a trajectory for a quantum particle. Rather, it tells us the chance of getting a particular measurement outcome. It seems to point in the opposite direction of other scientific theories: not toward the entity it describes, but toward our observation of it. What if we don’t make a measurement of the particle at all? Does the wave function still tell us the probability of its being at a given point at a given time? No, it says nothing about that—or more properly, it permits us to say nothing about it. It speaks only to the probabilities of measurement outcomes.
Crucially, this means that what we see depends on what and how we measure. There are situations for which quantum mechanics predicts that we will see one outcome if we measure one way, and a different outcome if we measure the same system in a different way. And this is not, as is sometimes implied (this was the cause of Heisenberg’s row with Bohr), because making a measurement disturbs the object in some physical manner, much as we might very slightly disturb the temperature of a solution in a test-tube by sticking a thermometer into it. Rather, it seems to be a fundamental property of nature that the very fact of acquiring information about it induces a change.
If, then, by reality we mean what we can observe of the world (for how can we meaningfully call something real if it can’t be seen, detected, or even inferred in any way?), it is hard to avoid the conclusion that we play an active role in determining what is real—a situation the American physicist John Archibald Wheeler called the “participatory universe.”..
… Heisenberg’s “uncertainty” captured that sense of the ground shifting. It was not the ideal word—Heisenberg himself originally used the German Ungenauigkeit, meaning something closer to “inexactness,” as well as Unbestimmtheit, which might be translated as “undeterminedness.” It was not that one was uncertain about the situation of a quantum object, but that there was nothing to be certain about.
There was an even more disconcerting implication behind the uncertainty principle. The vagueness of quantum phenomena, when an electron in an atom might seem to jump from one energy state to another at a time of its own choosing, seemed to indicate the demise of causality itself. Things happened in the quantum world, but one could not necessarily adduce a reason why. In his 1927 paper on the uncertainty principle, Heisenberg challenged the idea that causes in nature lead to predictable effects. That seemed to undermine the very foundation of science, and it made the world seem like a lawless, somewhat arbitrary place….
… One of Bohr’s most provocative views was that there is a fundamental distinction between the fuzzy, probabilistic quantum world and the classical world of real objects in real places, where measurements of, say, an electron with a macroscopic instrument tell us that it is here and not there.
What Bohr meant is shocking. Reality, he implied, doesn’t consist of objects located in time and space. It consists of “quantum events,” which are obliged to be self-consistent (in the sense that quantum mechanics can describe them accurately) but not classically consistent with one another. One implication of this, as far as we can currently tell, is that two observers can see different and conflicting outcomes from an event—yet both can be right.
But this rigid distinction between the quantum and classical worlds can’t be sustained today. Scientists can now conduct experiments that probe size scales in between those where quantum and classical rules are thought to apply—neither microscopic (the atomic scale) nor macroscopic (the human scale), but mesoscopic (an intermediate size). We can look, for example, at the behavior of nanoparticles that can be seen and manipulated yet are small enough to be governed by quantum rules. Such experiments confirm the view that there is no abrupt boundary of quantum and classical. Quantum effects can still be observed at these intermediate scales if our devices are sensitive enough, but those effects can be harder to discern as the number of particles in the system increases.
To understand such experiments, it’s not necessary to adopt any particular interpretation of quantum mechanics, but merely to apply the standard theory—encompassed within Schrödinger’s wave mechanics, say—more expansively than Bohr and colleagues did, using it to explore what happens to a quantum object as it interacts with its surrounding environment. In this way, physicists are starting to understand how information gets out of a quantum system and into its environment, and how, as it does so, the fuzziness of quantum probabilities morphs into the sharpness of classical measurement. Thanks to such work, it is beginning to seem that our familiar world is just what quantum mechanics looks like when you are 6 feet tall.
But even if we manage to complete that project of uniting the quantum with the classical, we might end up none the wiser about what manner of stuff—what kind of reality—it all arises from. Perhaps one day another deeper theory will tell us. Or maybe the Copenhagen group was right a hundred years ago that we just have to accept a contingent, provisional reality: a world only half-formed until we decide how it will be…
Eminently worth reading in full: “When Reality Came Undone,” from @philipcball in @NautilusMag.
See also: When We Cease to Understand the World, by Benjamin Labatut.
* Niels Bohr
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As we wrestle with reality, we might spare a thought for Ludwig Boltzmann; he died on this date in 1906. A physicist and philosopher, he is best remembered for the development of statistical mechanics, and the statistical explanation of the second law of thermodynamics (which connected entropy and probability).
Boltzmann helped paved the way for quantum theory both with his development of statistical mechanics (which is a pillar of modern physics) and with his 1877 suggestion that the energy levels of a physical system could be discrete.
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