it is the most revolutionary idea in physics after relativity and quantum theory. But is she truthful?

Article by Prof.Eduard WITTEN (1987)

From Isaac Newton to Albert Einstein and Niels Bohr, the luminaries of theoretical physics have tried to find connections between the fundamental forces of nature. Today, Edward Witten is a leading proponent of one of the most promising—and controversial—probable solutions to this problem, String Theory, a mathematical representation of a universe built not of billiard-ball-like particles of matter, but of tiny strings circular vibrating in ten dimensions.

If correct, this theory has the potential to provide a single, consistent explanation for everything in the universe, from the mechanisms inside the atom to the structure of the cosmos. But it may be a lifetime before scientists invent the means to test this theory.

In the present article, K.C. Cole paints a portrait of an extremely talented physicist toiling at the boundaries of mathematics and physics. <<Este extreme de important să crezi în ceea ce faci<<,spune Edward Witten. <<Totuși, e greu să-ți păstrezi credința când totul este atât de speculativ.

One of the lessons you learn is to not give up on good ideas - but how do you know they're good?

K. C. Cole has published numerous articles in Omni and The New York Times Magazine and is the author of the volume entitled "Sympathetic Vibration: Reflection on Physics as a Gay of Life".

Recently, she conducted a study commissioned by the Association of Science-Technology Centers and focusing on the work of women and members of ethnic minorities in the field of science.

Pacing the room with big, sure steps, he delivers his lecture like a conductor, the ra-ta-ta-ta of the chalk on the blackboard sounding like a counterpoint to his high-pitched voice that is sometimes almost imperceptible. He talks about «vector bundles», «trivial modules» and «free circular spaces». At one point he stops and says the following: "We have lived in a world of finite dimensions until now. And now I invite you to soar into a world of infinite dimensions».

The teacher is Eduard Witten from the Institute of Advanced Study in Princeton (New Jersey).

At the age of 36, Witten is among the most prominent contemporary physicists. He is currently in New York to lecture at Columbia University's Faculty of Mathematics on the applications of physics to mathematics «!» Mathematics "a discipline that deals with abstract, intangible relationships" has always been a useful tool in physics "a discipline that deals with the concrete forces and objects of the real world". Witten turned everything upside down, trying to demonstrate how physics can facilitate new insights into mathematics.

"It is not desirable to rush to make comparisons with Einstein," says one of the faculty members of the Faculty of Physics at Princeton University, "but when it comes to Witten" His arms open in a gesture of helplessness. "He is head and shoulders above everyone else. It has guided whole groups of people down new paths, created whole new fields. He displays elegant, formidable proofs that leave people speechless, that arouse in them overwhelming feelings of admiration».

Witten seems to be constantly everywhere, publishing scientific reports and lecturing on cosmology, mathematics, and various aspects of physics. Whenever he speaks, the physicists listen with rapt attention.

Their attention was probably never greater than a few years ago, when Witten tried to deal seriously with a seemingly bizarre and long-forgotten theory that radically changes our conception of the physical universal. Although it is difficult to pinpoint any one contribution that made Witten such a force in physics, his passion for this controversial theory makes him the foremost promoter of what may be the most revolutionary concept emerged in physics in the last 5 decades – as revolutionary, Witten claims, as relativity and quantum theory.

If this theory is correct (and Witten believes that its validity will probably eventually be proven), it could provide entirely new answers to the fundamental questions that philosophers, poets, and theologians have asked since the dawn of human civilization: Why is the universe as it is and what is the origin of matter?

"String Theory" , or "string theory", as it is usually called (some scholars call it "sueprstring theory"), it eliminates the well-known image of a universe made up of particles like billiard balls, repelled and attracted by well-known forces such as gravity and electricity. Quantum theory had already revealed, in the third decade of the current century, that billiard balls have certain strange properties that make them resemble waves – they are vibrations rather than defined points in space. Now, string theory assumes that these points are actually tiny circles, or closed "strings". The strings vibrate invisibly in subtle resonances. According to the theory, these vibrations build everything that exists in the universe - from light to fireflies, from gravity to gold.

Of course, these strings are not visible, nor can they be likened to garters or pieces of string. Since they cannot be detected with any of the means available to science today, they are mathematical curves. Talking about strings, like talking about billiard balls or waves, is a simple way of trying to understand the unknown in known terms. The truth is that physics has always had to resort to metaphors. "When it comes to atoms," the Danish physicist Niels Bohr, the father of quantum theory, once said, "language can be used in poetry. The poet is much more interested in creating images than describing realities".

Physicists broke apart the atom and discovered, first, electrons, protons, and neutrons, and then, more exotic elements, such as neutrinos and so-called quarks. They found out how the nuclear force, gravity and electromagnetic force build molecules and galaxies from these particles. But, among other things, no one knows why electrons exist or why particles are influenced by gravity. According to its adherents, string theory has the potential to provide a single, consistent explanation for absolutely everything, from the internal mechanisms of the single atom to the structure of the cosmos.

Unfortunately, string theory contains what some scientists consider to be a major flaw. The mathematical consistency that makes it so compelling is only relevant if we are willing to suspend our view that the physical world is defined by four well-known dimensions (height, length, width, and time) and assume the existence of six other hidden dimensions—so, ten sizes in total.

Imagine a closed string – a circle – of fundamental matter of one kind or another.

Then imagine that the circle rotates, twists and vibrates not only in the usual three spatial dimensions (plus the temporal dimension), but also in six other dimensions that we cannot perceive.

The circle vibrates in countless tonalities, like a deca-dimensional violin string emitting cosmic versions of A or E flat. If string theory is correct, these vibrations may determine all possible particles and forces in the universe.

If you ask him to give you a clearer explanation, Witten smiles and shrugs. "No one understands this much better than the way I explained it to you now," he says.

A ten-dimensional system doesn't bother Witten at all: "These added dimensions are no stranger than many other things that physicists think about." However, the notion of a deca-dimensional universe and the absence of any experimental data that could provide evidence in this sense made many physicists adopt a very skeptical position.

Obviously, string theory has a lot to explain. For example, she will have to explain how the six additional dimensions remain invisible. Adherents of this theory imagine these dimensions as tightly "wrapped" on scales billions of times smaller than that of the nucleus of an atom. However, they don't know why or when the six dimensions wrapped up. Some of these scientists think that it is simply possible that they did not expand billions of years ago with the rest of the physical universe.

Such doubts in no way diminish Witten's conviction. "It is quite possible that the proper understanding of string theory will lead to the dissolution of time-space continuity," he says. "String theory is a miracle after all".

Witten began getting offers of university professorships only a few years after graduating from Princeton University, where he was hired as a professor at the age of 28. He has been honored with many awards from institutions around the world, including a "genius grant" from the MacArthur Foundation and recently, the National Science Foundation's Outstanding Young Researcher Award.

In physics, the effort to find a definitive explanation has always been evident countless times, physics took a step forward with the discovery that apparently different phenomena were actually aspects of a single phenomenon. Newton's great discovery, for example, was that the same force that caused the apple to fall to the ground caused the moon to maintain its terrestrial orbit and the Earth to maintain its solar orbit. For a long time there was the opinion that there was no connection between magnetism, electricity and light, until, in the 19th century, James Clark Maxwell and Michael Faraday discovered that they were all manifestations of electromagnetism. The theory of relativity arose from Einstein's effort to reconcile electromagnetism with classical mechanics.

Recently, physicists are obsessed with trying to unify the fundamental forces of nature - gravity, electromagnetism, the "strong" force (that force that ensures the cohesion of the particles in the nucleus of an atom) and the "weak" force (which determines, among other things, radioactivity, the spontaneous disintegration of the atomic nucleus resulting in the emission of energy) - or to discover the connections between them.

Electromagnetism, the strong and weak forces, and all the particles known to be present in the universe can be explained according to quantum theory, something that Witten qualifies as "magic." This theory created a whole field of scientific research in which Witten himself made a number of important contributions. According to quantum theory, everything results from the interactions of energy fields. The fields vibrate but not only in certain patterns or resonances that correspond to certain amounts (hence the term "quanta") of energy. These resonances are the known particles and forces of the natural universe, in fact physicists, who use giant accelerators to smash atoms and find the particles that make them up, sometimes call their work "resonance hunting".

Quantum theory managed to clarify many phenomena and led to the understanding of subatomic processes, a fact that resulted in the production of many wonders, from lasers to semiconductors. However, quantum theory cannot explain gravity. Mathematical calculations that try to incorporate gravity into this theoretical framework give unusable results.

However, gravity interacts with all types of energy present in the universe, even a ray of light is influenced by it. Therefore, gravity must conform to the same laws of nature. But what are these laws?

Einstein tried for a long time to make a connection between gravity and electromagnetism so that he could still explain the whole system of nature within a single "unified theory". He failed to do so. In 1919, however, Einstein received a letter from a physicist of German origin, a certain Theodor F.E. Kaluza, who believed that electromagnetism could be understood as a manifestation of gravity in a fifth dimension. Kaluza does not explain why the fifth dimension could not be perceived. In 1926, however, a Swedish mathematician, Oskar Klein, assumed that this was due to the fact that the fifth dimension exists on such a tiny scale that it does not influence anything, not even the size of a subatomic particle.

Tstring theory is a new and much more complex version of Kaluza-Klein theory. Like the fifth dimension postulated by Klein, the six additional dimensions postulated by string theory have "contracted", somehow to the point of invisibility. String theory claims that if we accept the notion of these six hidden dimensions, the mathematical inconsistencies that have hindered previous attempts to reconcile quantum theory with gravity miraculously disappear.

However, we cannot be sure that string theory is a true representation of reality. Except for mathematical consistency, there is no evidence for the existence of the six additional dimensions. Witten notes, however, that throughout the last hundred years, mathematical consistency has been "one of the most reliable guides of physicists".

To some extent, the theorist's world is by definition a personal world. The work does not require test tubes or laboratories, cyclotrons or high-capacity electronic computers, nothing but pencil and paper, and sometimes not even that. Although Witten's students include some who are doing graduate studies, he hesitates to involve them in his projects in which scholarly speculation plays an important role, because, he says, he does not want to jeopardize their professional futures.

Listening to Witten talk about his own career, you might be convinced that becoming a physicist is almost commonplace. Although his father, Louis Witten, is a physicist specializing in the study of gravity, he says that he was not influenced by his family to a great extent. "I was on the verge of doing something else," he explains.

Witten grew up in Baltimore and graduated from Brandeis University in Massachusetts with a degree in history, although his main interest was in linguistics. Before beginning his graduate studies at Princeton, Witten wrote articles published in The Nation, The New Republic and other magazines. In 1972, he worked for six months on the campaign of presidential candidate George McGovern as a legislative assistant to one of his advisers. Witten claims today that he does not possess the qualities required for a career in advertising or politics, especially the "sense of reality". When he began his studies at Princeton University, he was very close to choosing mathematics before deciding on physics.

Witten's colleagues are much more generous with himself when it comes to his merits, especially his contribution to the attention that string theory enjoys today.

Physicists did not try to develop this theory, nor did they pay much attention to the Kaluza-Klein theory. What happened was that they stumbled upon it in the dark, after which they endlessly tried to give it a precise form. "I don't think any physicist would have been insightful enough to invent string theory on purpose," says Witten. "Fortunately it was invented by accident".

In 1968 an Italian physicist, Gabriele Veneziano, was doing studies on the strong force (the binder that unites the particles of the atomic nucleus) and simply came across what Witten calls "a formula that had some strange properties". A few years later, thanks to the research done by Yoichiro Nambu from the University of Chicago and others, physicists "realized that that bizarre formula defined the vibrations of some strings".

For several years, string theory has attracted a lot of interest. By the middle of the last decade, however, it had been largely abandoned, partly because other avenues of thought seemed more promising and partly because of the fallacy that this theory implied the unacceptable idea of ​​additional dimensions.

"When they realized it was only plausible in a 10-dimensional framework," says Witten, "most physicists left the field." His own interest in this theory had been sparked primarily by the research done by the physicists John H. Schwarz of la California Institute of Technology and Michael B. Green from Queen Mary College from London. Witten recalls that the effort to inform himself about this theory cost him "several months of hard work." "It was unlike anything anyone had seen before," he added. "There is no one to give you encouragement."

It seems that interest in string theory was revived by a series of reports issued by Schwarz and Green at the beginning of the current decade. In 1984 they published an important report that according to a Nobel laureate physicist Steven Weinberg of the University of Texas answered a question that had also been asked by Witten.

The question referred to the anomalies that appeared in theories that tried to unite gravity with quantum field theory. In the case of a theory anomalies are flaws that generate absurd results that annihilate the theory, Witten like Luis Alvarez-Gaumé from Harvard University discovered a new class of anomalies. At the same time, he demonstrated an even more important thing (...)

String theory assumes that, if we could see the universe in its ten-dimensional whole, a new symmetry would appear, and all forces and particles would appear to us as facets of a single coherent whole.

layer that the origin of the anomalies was topological, in other words, it was related to geometric properties that do not appear in the presence of four dimensions, but appear in the presence of ten dimensions.

Witten considers topology, which studies the properties of distorted or deformed geometric figures in different dimensions, as "mental fabric". The thought that topology might be unknown to specialists causes him astonishment. "It's like saying they don't know how to speak in prose," he says, borrowing a joke from Ia Moliere. A cup with a twist, for example, is the topological equivalent of a bagel. If the cup were made of soft clay, it could be reshaped into a pretzel without the material breaking. "It's so obvious," Witten says. "There are properties of objects that change when you break those objects, but they don't change when you change the shape of objects by bending them." He admits, however, that not even physicists took topology seriously in the past."

Witten attaches great importance to topology because the question of whether the real world can be explained by string theory depends not only on the existence of additional dimensions, but also on the shapes they take in space – whether they are, say, the shape of tubes, or bagels , or if they are spheres.

In Flatland, the famous Victorian science fiction writer, Edwin Abbott eloquently demonstrates that what seems confusing and obscure in one dimension can become crystal clear in another. In his hypothetical world of two-dimensional triangles and squares, a three-dimensional sphere was an incomprehensible object. As it traversed this flat space, the sphere first appeared as a point. then as a widening circle, and finally contracted again to the shape of a point and disappeared. A two-dimensional creature can only see one two-dimensional slice of a sphere at a time. Only a three-dimensional viewer can visually perceive the sphere as a whole.

String theory assumes that if we could see the universe as a decadyrnensional ensemble, a new symmetry would emerge, and the confusing multitude of forces and particles would prove to be but different facets of the same coherent whole.

Unfortunately, this alluring symmetry inherent in ten-dimensional space is not easily translated into four-dimensional particles and forces. Its perception requires incredibly subtle mathematical tools, tools that probably haven't been invented yet.

A few years ago, Witten had a conversation with a colleague, and this discussion deeply impressed him. "HE was talking about a very talented physicist who was not as productive as he could have been," Witten explains. "And his view was that the reason was that the physicist in question was never working on the kinds of problems for which he was really the right man" Witten took very seriously the advice implied by his colleague's remark. EI considers himself to be the right man to "take a physics problem and find a solution based on some bizarre mathematical operations". "String theory," he continues, "will require a great deal of new mathematics—and the application of bizarre mathematics to physics is my specialty." In the last few! years.

Witten claimed to be one of the protagonists of a new alliance between physicists and mathematicians, an alliance forged by string theory. "I for one consider him as the number one protagonist", says I.M. Singer, professor of mathematics at the Massachusetts Institute of Technology "His intuition is fantastic." Witten himself considers some of his most important contributions to be contributions to mathematics rather than physics.

Most of the great advances made by man in understanding the universe were due to close links between physics and mathematics. Newton had to invent a new type of mathematics - differential and integral calculus - to complete his theory of gravity. Einstein's theory of general relativity was based on a geometry of curved space invented by the German mathematician F.B. Riemann in the middle of the 19th century. Quantum theory required a tool called "functional analysis".

Witten says that string theory "takes us to the frontiers of mathematics". However, this does not intimidate them. "I realized that I could actually turn everything around." he adds, and to obtain with the help of physics some surprising insights regarding mathematics".

The new marriage of physics and mathematics made physics really difficult for Witten for the first time. This is one of the reasons that led him to accept the invitation to work at the prestigious Institute for Advanced Study, located a stone's throw from Princeton University, where he does not have to fulfill the duties of a chair. "I want to work more intensively on fewer things," he confesses. All the "things" Witten is currently working on are aspects of string theory.

Witten's conclusions cannot be verified in the laboratory today, and this will not be possible for the foreseeable future. In fact, everything he does is so far removed from observable reality that it may take a lifetime or more before the value of his theoretical insights—and their possible practical applications—become known. Theoretical physics is a risky business. "It's extremely important to believe in what you're doing," says Witten. "However, it's hard to keep your faith when everything is so speculative."

"One of the lessons you learn," he continued, "is not to make mistakes - but that's not of much use to you. Another lesson is don't give up on good ideas - but how do you know they're good?"

Witten notes that neutron stars and gravitational lensing—large concentrations of matter in outer space that, when observed from Earth, produce double images of the stars—were considered fanciful notions, pure speculation, until they were really discovered. "The history of science is full of predictions that the validity of new ideas will never be proven. But the history of physics shows that good ideas eventually turn out to be correct."

Witten believes that string theory is too good to be true. It seems difficult and complicated, only because it is not sufficiently well understood. String theory is for now, according to Witten, "A piece of physics belonging to the 21st century and accidentally dropped into the 20th century." Physicists today only work with "a few crumbs compared to the great feast that awaits us".

However, Witten sometimes fears that the difficulties will be too great. "The chances that this theory will lead us anywhere in the next few years are not very high", he admits, "but if I didn't try, I would have the feeling that my insight has left me."

John Ellis, one of the experts in theoretical physics of the European Center for Nuclear Research in Geneva, recently wrote the following: .”String phenomenology is still a young subject. There are many unanswered questions and technical problems, and it is easy to ridicule the totalitarian passion of the promoters of this theory. However, to quote what was written on a candy wrapper that I opened a few years ago, "only optimists achieve something in this world".

Or, in Witten's words: "If we're going to prove string theory, we'll probably need luck. But in physics there are many ways to be lucky."