Arquivo da tag: Wittgenstein

Confessions of a Theoretical Physicist (Nautilus)

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My life among the elementary particles has made me question whether reality exists at all.

By Vijay Balasubramanian

August 19, 2024

Iremember the day when, at the age of 7, I realized that I wanted to figure out how reality worked. My mother and father had just taken us shopping at a market in Calcutta. On the way back home, we passed through a dimly lit arcade where a sidewalk bookseller was displaying his collection of slim volumes. I spotted an enigmatic cover with a man looking through a microscope; the words “Famous Scientists” were emblazoned on it, and when I asked my parents to get it for me, they agreed. As I read the chapters, I learned about discoveries by Antonie van Leeuwenhoek of the world of microscopic life, by Marie Curie about radioactivity, by Albert Einstein about relativity, and I thought, “My God, I could do this, too!” By the time I was 8, I was convinced that everything could be explained, and that I, personally, was going to do it.

Decades have passed, and I am now a theoretical physicist. My job is to work out how all of reality works, and I take that mission seriously, working on subjects ranging from the quantum theory of gravity to theoretical neuroscience. But I must confess to an increasing sense of uncertainty, even bafflement. I am no longer sure that working out what is “real” is possible, or that the reality that my 7-year-old self conceived of even exists, rather than being simply unknown. Perhaps reality is genuinely unknowable: Things exist and there is a truth about them, but we have no way of finding it out. Or perhaps the things we call “real” are called into being by their descriptions but do not independently exist.

The theories and concepts we build are like ladders we use to reach the truth.

I am steeped in the cultural traditions of physics, a field that is my calling and trade, and in the philosophies of India with which I was raised. As a physicist, I remain committed to a system of thought which posits that: (1) things we observe are definitely real, (2) the details may be unknown, (3) bounded resources may slow progress, but (4) physical inquiry can lead us to the real truth, as long as we have time and proceed with patience. On the other hand, I am also acutely aware of philosophical traditions to the effect that: (1) there may be a reality, but (2) measurements from the world are inherently misleading and partial, so that (3) the real may be formally indescribable, and that (4) we may not have a systematic way to reach the fundamentally real and true.

The idea that the real may be unknowable is very old. Consider the creation hymn in the Rig Veda, composed around 1500 to 1000 B.C., called the “Nasadiya Sukta.” This verse addresses fundamental questions of cosmology and the origin of the universe. In a beautiful translation by Juan Mascaró, it asks: 

Who knows the truth? Who can tell whence and how arose this universe? The gods are later than its beginning: Who therefore knows whence comes this creation? Only he who sees in the highest heaven: He only knows whence came this universe and whether it was made or un-created. He only knows, or perhaps he knows not.

The poet who wrote this verse points out the fundamental problem of epistemology: We don’t know some things and may not even have any way of determining what we don’t know. Some questions may be intrinsically unanswerable. Or the answers may be contradictory. The “Isha Upanishad,” a Sanskrit text from the first millennium B.C., attempts to describe a reality that escapes common sense: “It moves and it moves not, it is far and it is near, it is inside and it is outside.”

A second problem is that perception fundamentally limits our ability to apprehend reality. A prosaic example is the perception of color. Eagles, turtles, bees, and shrimp sense more and different colors than we humans do; in effect, they see different worlds. Different perceptual realities can create different cognitive or conceptual realities.

Jorge Luis Borges pushed this idea to the limit in his story “Funes the Memorious,” about a man who acquires a sort of infinite perceptual capacity. Borges writes: “A circle drawn on a blackboard, a right triangle … are forms that we can fully grasp; … [Funes] could do the same with the stormy mane of a pony … with the changing fire and its innumerable ashes.” Funes’ superpower sounds wondrous, but there is a catch. Borges writes that Funes was “almost incapable of ideas of a general, Platonic sort. Not only was it difficult for him to comprehend that the generic symbol dog embraces so many unlike individuals of diverse size and form; it bothered him that the dog … (seen from the side) should have the same name as the dog … (seen from the front).” The precision of Funes’ perception of reality prevents him from thinking in the coarse-grained categories that we associate with thought and cognition—categories which, necessarily rough, texture our imagined reality.

The arbitrariness of categories was the subject of another Borges story, “The Analytical Language of John Wilkins,” in which Wilkins imagined dividing animals into those belonging to the Emperor, those that are crazy-acting, those painted with the finest brush made of camel hair, those which have just broken a vase, those that from a long way off look like flies, and other oddly specific groupings.

In Body Image
SKETCHY: Students and the public are often told the world consists of real particles called quarks and leptons. Yet these are only concepts that approximate a certain sketch of the structure of the world. Image by Fouad A. Saad / Shutterstock.

The philosopher Michel Foucault, in his book The Order of Things, drew inspiration from Borges’ stories to reflect on the nature of categorization. He suggested that the categories and concepts that we define control our bounded cognition and, in their intrinsic arbitrariness, structure the realities that reside in our minds.

Foucault’s analysis resonates with me because it reminds me of categories in physics. For example, we routinely tell our students and the public that the world consists of particles called quarks and leptons, along with subatomic force fields. Yet these are concepts that reify a certain approximate sketch of the structure of the world. Physicists once thought that these categories were fundamental and real, but we now understand them as necessarily inexact because they ignore the finer details that our instruments have just not been able to measure.

If our categories determine the reality we perceive, can having an idea call a reality into being? This question is a version of the “simulation hypothesis,” whereby all of reality as we know it is simply a simulation in some computational engine, or perhaps a version of the idealism of Plato, where things that we can conceive in the world echo imperfectly an ideal that is the true reality.

Consider, for example, Mymosh the Self-begotten, the tragic hero of a story by Polish writer, Stanislaw Lem, in his volume The Cyberiad. Mymosh, a sentient machine self-organized by accident from a cosmic garbage heap, conjures up entire worlds and peoples just by imagining them. Are those people real, or are they all in his head? In fact, is there a difference? After all, Mymosh’s imagination is a physical process—electrical impulses in his brain. So perhaps the people he imagines are real in some sense.

Things exist and there is a truth about them, but we have no way of finding it out.

Some of these philosophical conundrums have concrete avatars in theoretical physics. Consider the notion of “duality” between physical theories. In this context, a “theory” means a mathematical description of a hypothetical universe, which we develop as a stepping-stone to understanding the actual universe in which we live. Two theories are said to be “dual,” or equivalent, if every observable in one matches some observable in the other. In other words, the two theories are different representations of the same physical system. Often in these dualities the elementary variables, or particles, of one theory become the collective variables, or lumps of particles, of the other, and vice versa. Dual theories scramble some of the most basic categories in physics, such as the difference between “bosonic” particles (any number of which can be in the same place at the same time) and “fermionic” particles (no two of which can be in the same place at the same time). These two kinds of particles have entirely different physical properties, so you would think that they could not be equivalent. But through dualities, it turns out that lumps of bosons can act like fermions, and vice versa. So, what’s the reality here?

Even more dramatic are dualities involving the force of gravity. On one side, we have theories of matter and all the forces except gravity; on the other, we have theories of matter and forces including gravity. These theories look very different. They are couched in terms of different forms of matter, different types of forces, and even different numbers of spacetime dimensions. Yet they describe precisely the same fundamental physics. So, what is “real” here? If one theory says the force of gravity operates and the other says it doesn’t, what do we conclude about the reality of gravity? Perhaps we can use my sketch to visualize the situation—we are able to tell stories about the corners of this diagram of possible worlds, where simplifications and approximations suffice, but the categories and concepts that we have been capable of, at least to date, fail to describe the interior where reality is actually located.

In Body Image
Sketch by Vijay Balasubramanian

Quantum mechanics makes things even more confusing. Quantum-mechanical states of a system can be combined, or superposed, in seemingly contradictory ways. So, the spin of an electron can be in a superposition of pointing up and down—an idea that might seem akin to suggesting that, say, a cat can be in a superposition of alive and dead. Does that mean these objects are in both states or neither state? Some theories suggest that measuring a cat (to continue with this metaphor) could cause it to collapse into a state of aliveness or deadness; others, evoking something like the many-worlds theory, suggest that the combined superposition continues through time. This is a casse-tête, a head breaker.

Where does this leave me? Perhaps we can reconcile all these ideas by following Ludwig Wittgenstein, who proposed in his Tractatus Logico-Philosophicus, possibly referencing previous ideas of Søren Kierkegaard, that the theories and concepts we build are like ladders or nets we use to reach the truth, but we must throw them away upon getting there. I myself am trying to find my way by working in multiple fields, both physics and neuroscience, studying both the world and the mind that perceives it, because I believe that the quest to understand the reality of the universe must contend with the truncations imposed by the perceptual and cognitive limitations of the mind.

Should we bother seeking truths about the world in light of the doubts I have set out? I am hardly the first to ask. Socrates, according to Plato, remarked to Meno: “I would contend … that we will be better [people], braver and less idle, if we believe that one must search for the things one does not know, rather than if we believe that it is not possible to find out what we do not know and that we must not look for it.”

I am with Socrates on this one—his attitude is wise and pragmatic. If there is a reality and a truth about it, we will be better off and more likely to find it by searching, rather than assuming that it is not there. And even if the search, and the ladders we use to climb obstacles, do not lead us to the truth, we will enjoy the journey.  

Lead image by Tasnuva Elahi; with photos by Vijay Balasubramanian

Wittgenstein’s forgotten lesson (Prospect Magazine)

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Wittgenstein’s philosophy is at odds with the scientism which dominates our times. Ray Monk explains why his thought is still relevant.

by Ray Monk / July 20, 1999 / Leave a comment

Published in July 1999 issue of Prospect Magazine

Ludwig Wittgenstein is regarded by many, including myself, as the greatest philosopher of this century. His two great works, Tractatus Logico-Philosophicus (1921) and Philosophical Investigations (published posthumously in 1953) have done much to shape subsequent developments in philosophy, especially in the analytic tradition. His charismatic personality has fascinated artists, playwrights, poets, novelists, musicians and even movie-makers, so that his fame has spread far beyond the confines of academic life.

And yet in a sense Wittgenstein’s thought has made very little impression on the intellectual life of this century. As he himself realised, his style of thinking is at odds with the style that dominates our present era. His work is opposed, as he once put it, to “the spirit which informs the vast stream of European and American civilisation in which all of us stand.” Nearly 50 years after his death, we can see, more clearly than ever, that the feeling that he was swimming against the tide was justified. If we wanted a label to describe this tide, we might call it “scientism,” the view that every intelligible question has either a scientific solution or no solution at all. It is against this view that Wittgenstein set his face.

Scientism takes many forms. In the humanities, it takes the form of pretending that philosophy, literature, history, music and art can be studied as if they were sciences, with “researchers” compelled to spell out their “methodologies”—a pretence which has led to huge quantities of bad academic writing, characterised by bogus theorising, spurious specialisation and the development of pseudo-technical vocabularies. Wittgenstein would have looked upon these developments and wept.

There are many questions to which we do not have scientific answers, not because they are deep, impenetrable mysteries, but simply because they are not scientific questions. These include questions about love, art, history, culture, music-all questions, in fact, that relate to the attempt to understand ourselves better. There is a widespread feeling today that the great scandal of our times is that we lack a scientific theory of consciousness. And so there is a great interdisciplinary effort, involving physicists, computer scientists, cognitive psychologists and philosophers, to come up with tenable scientific answers to the questions: what is consciousness? What is the self? One of the leading competitors in this crowded field is the theory advanced by the mathematician Roger Penrose, that a stream of consciousness is an orchestrated sequence of quantum physical events taking place in the brain. Penrose’s theory is that a moment of consciousness is produced by a sub-protein in the brain called a tubulin. The theory is, on Penrose’s own admission, speculative, and it strikes many as being bizarrely implausible. But suppose we discovered that Penrose’s theory was correct, would we, as a result, understand ourselves any better? Is a scientific theory the only kind of understanding?

Well, you might ask, what other kind is there? Wittgenstein’s answer to that, I think, is his greatest, and most neglected, achievement. Although Wittgenstein’s thought underwent changes between his early and his later work, his opposition to scientism was constant. Philosophy, he writes, “is not a theory but an activity.” It strives, not after scientific truth, but after conceptual clarity. In the Tractatus, this clarity is achieved through a correct understanding of the logical form of language, which, once achieved, was destined to remain inexpressible, leading Wittgenstein to compare his own philosophical propositions with a ladder, which is thrown away once it has been used to climb up on.

In his later work, Wittgenstein abandoned the idea of logical form and with it the notion of ineffable truths. The difference between science and philosophy, he now believed, is between two distinct forms of understanding: the theoretical and the non-theoretical. Scientific understanding is given through the construction and testing of hypotheses and theories; philosophical understanding, on the other hand, is resolutely non-theoretical. What we are after in philosophy is “the understanding that consists in seeing connections.”

Non-theoretical understanding is the kind of understanding we have when we say that we understand a poem, a piece of music, a person or even a sentence. Take the case of a child learning her native language. When she begins to understand what is said to her, is it because she has formulated a theory? We can say that if we like—and many linguists and psychologists have said just that—but it is a misleading way of describing what is going on. The criterion we use for saying that a child understands what is said to her is that she behaves appropriately-she shows that she understands the phrase “put this piece of paper in the bin,” for example, by obeying the instruction.

Another example close to Wittgenstein’s heart is that of understanding music. How does one demonstrate an understanding of a piece of music? Well, perhaps by playing it expressively, or by using the right sort of metaphors to describe it. And how does one explain what “expressive playing” is? What is needed, Wittgenstein says, is “a culture”: “If someone is brought up in a particular culture-and then reacts to music in such-and-such a way, you can teach him the use of the phrase ‘expressive playing.’” What is required for this kind of understanding is a form of life, a set of communally shared practices, together with the ability to hear and see the connections made by the practitioners of this form of life.

What is true of music is also true of ordinary language. “Understanding a sentence,” Wittgenstein says in Philosophical Investigations, “is more akin to understanding a theme in music than one may think.” Understanding a sentence, too, requires participation in the form of life, the “language-game,” to which it belongs. The reason computers have no understanding of the sentences they process is not that they lack sufficient neuronal complexity, but that they are not, and cannot be, participants in the culture to which the sentences belong. A sentence does not acquire meaning through the correlation, one to one, of its words with objects in the world; it acquires meaning through the use that is made of it in the communal life of human beings.

All this may sound trivially true. Wittgenstein himself described his work as a “synopsis of trivialities.” But when we are thinking philosophically we are apt to forget these trivialities and thus end up in confusion, imagining, for example, that we will understand ourselves better if we study the quantum behaviour of the sub-atomic particles inside our brains, a belief analogous to the conviction that a study of acoustics will help us understand Beethoven’s music. Why do we need reminding of trivialities? Because we are bewitched into thinking that if we lack a scientific theory of something, we lack any understanding of it.

One of the crucial differences between the method of science and the non-theoretical understanding that is exemplified in music, art, philosophy and ordinary life, is that science aims at a level of generality which necessarily eludes these other forms of understanding. This is why the understanding of people can never be a science. To understand a person is to be able to tell, for example, whether he means what he says or not, whether his expressions of feeling are genuine or feigned. And how does one acquire this sort of understanding? Wittgenstein raises this question at the end of Philosophical Investigations. “Is there,” he asks, “such a thing as ‘expert judgment’ about the genuineness of expressions of feeling?” Yes, he answers, there is.

But the evidence upon which such expert judgments about people are based is “imponderable,” resistant to the general formulation characteristic of science. “Imponderable evidence,” Wittgenstein writes, “includes subtleties of glance, of gesture, of tone. I may recognise a genuine loving look, distinguish it from a pretended one… But I may be quite incapable of describing the difference… If I were a very talented painter I might conceivably represent the genuine and simulated glance in pictures.”

But the fact that we are dealing with imponderables should not mislead us into believing that all claims to understand people are spurious. When Wittgenstein was once discussing his favourite novel, The Brothers Karamazov, with Maurice Drury, Drury said that he found the character of Father Zossima impressive. Of Zossima, Dostoevsky writes: “It was said that… he had absorbed so many secrets, sorrows, and avowals into his soul that in the end he had acquired so fine a perception that he could tell at the first glance from the face of a stranger what he had come for, what he wanted and what kind of torment racked his conscience.” “Yes,” said Wittgenstein, “there really have been people like that, who could see directly into the souls of other people and advise them.”

“An inner process stands in need of outward criteria,” runs one of the most often quoted aphorisms of Philosophical Investigations. It is less often realised what emphasis Wittgenstein placed on the need for sensitive perception of those “outward criteria” in all their imponderability. And where does one find such acute sensitivity? Not, typically, in the works of psychologists, but in those of the great artists, musicians and novelists. “People nowadays,” Wittgenstein writes in Culture and Value, “think that scientists exist to instruct them, poets, musicians, etc. to give them pleasure. The idea that these have something to teach them-that does not occur to them.”

At a time like this, when the humanities are institutionally obliged to pretend to be sciences, we need more than ever the lessons about understanding that Wittgenstein—and the arts—have to teach us.