Это интервью Quanta Magazine, адаптированное под читателя, знающего английский на среднем уровне(я добавил перевод сложных слов и несколько пояснений). Так вы сможете прочитать и понять текст без постоянных заглядываний в словарь. Оригинал по ссылке.
Если вам понравится такой формат, пожалуйста, поставьте отметку "Палец вверх". Приятного чтения!
Among (среди) the brilliant theorists cloistered ( уединённый, от cloister - монастырь) in the quiet woodside (на опушке) campus of the Institute for Advanced Study in Princeton, New Jersey, Edward Witten stands out as a kind of high priest (первосвященник, т.е. в этом "монастыре" физиков он выше всех). The sole (единственный) physicist ever to win the Fields Medal, mathematics’ premier prize, Witten is also known for discovering M-theory, the leading (первый, лидирующий) candidate for a unified (единая, обобщенная) physical “theory of everything.” A genius’s genius, Witten is tall and rectangular (прямоугольный, метафорически), with hazy eyes and an air of (на вид) being only one-quarter tuned in to reality (кажется, что он почти оторван от реальности) until someone draws him back from more abstract thoughts .
During a visit this fall, I spotted (заметил) Witten on the Institute’s central lawn and requested (попросил) an interview; in his quick, alto voice, he said he couldn’t promise to be able to answer my questions but would try. Later, when I passed him on the stone paths (дорожки из камня в кампусе), he often didn’t seem to see me.
Physics luminaries (буквально светило, светоч) since Albert Einstein, who lived out his days in the same intellectual haven (имеется в виду, что Эйнштейн тоже у себя в голове жил), have sought to (искали способы) unify (объединить) gravity with the other forces (силы, законы) of nature by finding a more fundamental quantum theory to replace (заменить) Einstein’s approximate (приблизительная) picture of gravity as curves (искривления) in the geometry of space-time. M-theory, which Witten proposed (предложил) in 1995, could conceivably (убедительно) offer this deeper description, but only some aspects of the theory are known. M-theory incorporates (соединяет) within a single mathematical structure all five versions of string theory (теория струн), which renders (представляет, интерпретирует) the elements of nature as minuscule (крошечные, микроскопические) vibrating (колеблющиеся) strings. These five string theories connect to each other through “dualities,” (двойственности) or mathematical equivalences (тождественности). Over the past 30 years, Witten and others have learned that the string theories are also mathematically dual to quantum field theories — descriptions of particles (частицы) moving through electromagnetic and other fields that serve (служат, выступают) as the language of the reigning (господствующей) “Standard Model” of particle physics. While he’s best known as a string theorist, Witten has discovered many new quantum field theories and explored (исследовал) how all these different descriptions are connected. His physical insights (идеи, открытия) have led time and again (снова и снова, приводили и все ещё приводят) to deep mathematical discoveries.
Researchers pore over (корпеть) his work and hope he’ll take an interest in theirs. But for all his scholarly influence (влияние, авторитет в академической среде), Witten, who is 66, does not often broadcast (публично высказывает) his views on the implications (следствия) of modern theoretical discoveries. Even his close colleagues eagerly (настойчиво) suggested questions they wanted me to ask him.
When I arrived at his office at the appointed hour (назначенный час) on a summery Thursday last month, Witten wasn’t there. His door was ajar (приоткрыта). Papers covered his coffee table and desk — not stacks (стопки), but floods (кучи, горы): text oriented every which way (т.е. тексты были повернуты во все стороны), some pages close to spilling (вот-вот соскользнут) onto the floor. (Research papers get lost in the maelstrom (водоворот) as he finishes with them, he later explained, and every so often he throws the heaps (кучи) away.) Two girls smiled out from a framed photo on a shelf; children’s artwork decorated the walls, one celebrating Grandparents’ Day. When Witten arrived minutes later, we spoke for an hour and a half about the meaning of dualities in physics and math, the current prospects (перспективы, потенциал) ( of M-theory, what he’s reading, what he’s looking for, and the nature of reality. The interview has been condensed (сжато, сокращено) and edited for clarity (для чистоты, удобочитаемости).
Physicists are talking more than ever lately about dualities, but you’ve been studying them for decades. Why does the subject interest you?
People keep finding new facets (грани, аспекты) of dualities. Dualities are interesting because they frequently answer questions that are otherwise out of reach (недоступны). For example, you might have spent years pondering (обдумывая) a quantum theory and you understand what happens when the quantum effects are small, but textbooks don’t tell you what you do if the quantum effects are big; you’re generally in trouble if you want to know that. Frequently (часто) dualities answer such questions. They give you another description, and the questions you can answer in one description are different than the questions you can answer in a different description.
What are some of these newfound facets of dualities?
It’s open-ended (открытая, неразрешенная проблема) because there are so many different kinds of dualities. There are dualities between a gauge theory (калибровочная теория) [a theory, such as a quantum field theory, that respects (объясняет) certain symmetries (симметрии, инвариантности)] and another gauge theory, or between a string theory for weak coupling (слабое взаимодействие) [describing strings that move almost independently from one another] and a string theory for strong coupling (сильное взаимодействие). Then there’s AdS/CFT duality, between a gauge theory and a gravitational description. That duality was discovered 20 years ago, and it’s amazing to what extent (до какой степени) it’s still fruitful (приносит плоды). And that’s largely (по большей части) because around 10 years ago, new ideas were introduced that rejuvenated (оживили) it. People had new insights about entropy (энтропия, запутанность) in quantum field theory — the whole story about “it from qubit.” (it from qubit - коллаборация учёных с целью соединить квантовой теорию микромира и теорию гравитации макрокосмоса в единую согласованную картину на основе квантовой теории информации).
That’s the idea that space-time and everything in it emerges (проявляется, происходит из, выводится) like a hologram out of information stored in the entangled quantum states of particles (запутанное квантовое состояние).
Yes. Then there are dualities in math, which can sometimes be interpreted physically as consequences (следствия) of dualities between two quantum field theories. There are so many ways these things are interconnected that any simple statement I try to make on the fly, as soon as I’ve said it I realize it didn’t capture the whole reality. You have to imagine a web of different relationships (связей), where the same physics has different descriptions, revealing (отражая) different properties (свойства). In the simplest case, there are only two important descriptions, and that might be enough. If you ask me about a more complicated (сложный, трудный) example, there might be many, many different ones.
Given this web of relationships and the issue of how hard it is to characterize all duality, do you feel that this reflects a lack of understanding of the structure, or is it that we’re seeing the structure, only it’s very complicated?
I’m not certain what we should hope for. Traditionally, quantum field theory was constructed by starting with the classical picture [of a smooth field (гладкое поле)] and then quantizing (квантовать) it. Now we’ve learned that there are a lot of things that happen that that description doesn’t do justice to (отдавать должное). And the same quantum theory can come from different classical theories. Now, Nati Seiberg [a theoretical physicist who works down the hall] would possibly tell you that he has faith (вера) that there’s a better formulation of quantum field theory that we don’t know about that would make everything clearer. I’m not sure how much you should expect that to exist. That would be a dream, but it might be too much to hope for; I really don’t know.
There’s another curious (занимательный) fact that you might want to consider, which is that quantum field theory is very central to physics, and it’s actually also clearly very important for math. But it’s extremely difficult for mathematicians to study; the way physicists define it is very hard for mathematicians to follow with a rigorous (строгая) theory. That’s extremely strange, that the world is based so much on a mathematical structure that’s so difficult.
What do you see as the relationship between math and physics?
I prefer not to give you a cosmic (всеобъемлющий) answer but to comment on where we are now. Physics in quantum field theory and string theory somehow has a lot of mathematical secrets in it, which we don’t know how to extract (извлекать, раскрывать) in a systematic way. Physicists are able to come up with things that surprise the mathematicians. Because it’s hard to describe mathematically in the known formulation (формулировке), the things you learn about quantum field theory you have to learn from physics.
I find it hard to believe there’s a new formulation that’s universal. I think it’s too much to hope for. I could point to theories where the standard approach really seems inadequate (несоответствующий), so at least for those classes of quantum field theories, you could hope for a new formulation. But I really can’t imagine what it would be.
You can’t imagine it at all?
No, I can’t. Traditionally it was thought that interacting (взаимодействующая) quantum field theory couldn’t exist above four dimensions (измерения), and there was the interesting fact that that’s the dimension we live in. But one of the offshoots (вариант, ответвление) of the string dualities of the 1990s was that it was discovered that quantum field theories actually exist in five and six dimensions. And it’s amazing how much is known about their properties.
I’ve heard about the mysterious (2,0) theory, a quantum field theory describing particles in six dimensions, which is dual to M-theory describing strings and gravity in seven-dimensional AdS space. Does this (2,0) theory play an important role in the web of dualities?
Yes, that’s the pinnacle (вершина, венец). In terms of conventional (общепринятый) quantum field theory without gravity, there is nothing quite like it above six dimensions. From the (2,0) theory’s existence and main properties, you can deduce (вывести) an incredible amount (большую часть) about what happens in lower dimensions. An awful lot of important dualities in four and fewer dimensions follow from this six-dimensional theory and its properties. However, whereas what we know about quantum field theory is normally from quantizing a classical field theory, there’s no reasonable (разумной) classical starting point of the (2,0) theory. The (2,0) theory has properties [such as combinations of symmetries] that sound impossible when you first hear about them. So you can ask why dualities exist, but you can also ask why is there a 6-D theory with such and such properties? This seems to me a more fundamental restatement (пересмотр).
Dualities sometimes make it hard to maintain a sense (сохранить понимание) of what’s real in the world, given that there are radically different ways you can describe a single system. How would you describe what’s real or fundamental?
What aspect of what’s real are you interested in? What does it mean that we exist? Or how do we fit into our mathematical descriptions?
The latter.
Well, one thing I’ll tell you is that in general, when you have dualities, things that are easy to see in one description can be hard to see in the other description. So you and I, for example, are fairly (довольно) simple to describe in the usual approach (подход) to physics as developed by Newton and his successors. But if there’s a radically different dual description of the real world, maybe some things physicists worry about would be clearer (понятнее), but the dual description might be one in which everyday life would be hard to describe.
What would you say about the prospect of an even more optimistic idea that there could be one single quantum gravity description that really does help you in every case in the real world?
Well, unfortunately, even if it’s correct I can’t guarantee it would help. Part of what makes it difficult to help is that the description we have now, even though it’s not complete, does explain an awful lot. And so it’s a little hard to say, even if you had a truly better description or a more complete description, whether it would help in practice.
Are you speaking of M-theory?
M-theory is the candidate for the better description.
You proposed M-theory 22 years ago. What are its prospects today?
Personally, I thought it was extremely clear it existed 22 years ago, but the level of confidence (уверенности) has got to be much higher today because AdS/CFT has given us precise (точные) definitions, at least in AdS space-time geometries. I think our understanding of what it is, though, is still very hazy (туманно). AdS/CFT and whatever’s come from it is the main new perspective compared to 22 years ago, but I think it’s perfectly possible that AdS/CFT is only one side of a multifaceted (многогранный) story. There might be other equally important facets.
What’s an example of something else we might need?
Maybe a bulk description of the quantum properties of space-time itself, rather than a holographic boundary (пограничное) description. There hasn’t been much progress in a long time in getting a better bulk (масса) description. And I think that might be because the answer is of a different kind than anything we’re used to. That would be my guess.
Are you willing to speculate (предполагать, делать догадки) about how it would be different?
I really doubt I can say anything useful. I guess I suspect that there’s an extra layer (уровень, слой) of abstractness compared (в сравнение) to what we’re used to (привыкли). I tend (склоняюсь) to think that there isn’t a precise quantum description of space-time — except (за исключением) in the types of situations where we know that there is, such as in AdS space. I tend to think, otherwise, things are a little bit murkier (загадочнее, темнее, туманнее) than an exact quantum description. But I can’t say anything useful.
The other night I was reading an old essay by the 20th-century Princeton physicist John Wheeler. He was a visionary, certainly. If you take what he says literally, it’s hopelessly vague (общее, расплывчатое, неконкретное) . And therefore (следственно), if I had read this essay when it came out 30 years ago, which I may have done, I would have rejected (отклонил) it as being so vague that you couldn’t work on it, even if he was on the right track (направление).
You’re referring to Information, Physics, Quantum, Wheeler’s 1989 essay propounding (предлагающее, ставящее) the idea that the physical universe arises from information, which he dubbed “it from bit.” Why were you reading it?
I’m trying to learn about what people are trying to say with the phrase “it from qubit.” Wheeler talked about “it from bit,” but you have to remember that this essay was written probably before the term “qubit” was coined (придуман, изобретен) and certainly before it was in wide currency (в широком обращении). Reading it, I really think he was talking about qubits, not bits, so “it from qubit” is actually just a modern translation.
Don’t expect me to be able to tell you anything useful about it — about whether he was right. When I was a beginning grad student, they had a series of lectures by faculty members to the new students about theoretical research, and one of the people who gave such a lecture was Wheeler. He drew a picture on the blackboard of the universe visualized as an eye looking at itself. I had no idea what he was talking about. It’s obvious to me in hindsight (в ретроспективе) that he was explaining what it meant to talk about quantum mechanics when the observer (наблюдатель) is part of the quantum system. I imagine there is something we don’t understand about that.
Observing a quantum system irreversibly (необратимо) changes it, creating a distinction (различие) between past and future. So the observer issue (проблема) seems possibly related to the question of time, which we also don’t understand. With the AdS/CFT duality, we’ve learned that new spatial (пространственные) dimensions can pop up (появляться, рождаться из, возникать из) like a hologram from quantum information on the boundary (границе). Do you think time is also emergent (возникающее) — that it arises from a timeless complete description?
I tend to assume (предполагать) that space-time and everything in it are in some sense emergent. By the way, you’ll certainly find that that’s what Wheeler expected in his essay. As you’ll read, he thought the continuum was wrong in both physics and math. He did not think one’s microscopic description of space-time should use a continuum of any kind — neither a continuum of space nor a continuum of time, nor even a continuum of real numbers (вещественные числа). On the space and time, I’m sympathetic to that. On the real numbers, I’ve got to plead ignorance (сослаться на незнание) or agnosticism. It is something I wonder about, but I’ve tried to imagine what it could mean to not use the continuum of real numbers, and the one logician I tried discussing it with didn’t help me.
Do you consider Wheeler a hero?
I wouldn’t call him a hero, necessarily, no. Really I just became curious (любопытно) what he meant by “it from bit,” and what he was saying. He definitely had visionary ideas, but they were too far ahead of their time. I think I was more patient (терпеливый) in reading a vague but inspirational (вдохновляющее) essay than I might have been 20 years ago. He’s also got roughly (приблизительно) 100 interesting-sounding references (отсылки) in that essay. If you decided to read them all, you’d have to spend weeks doing it. I might decide to look at a few of them.
Why do you have more patience for such things now?
I think when I was younger I always thought the next thing I did might be the best thing in my life. But at this point in life I’m less persuaded (убежден) of that. If I waste a little time reading somebody’s essay, it doesn’t seem that bad.
Do you ever take your mind off physics and math?
My favorite pastime is tennis. I am a very average but enthusiastic tennis player.
In contrast to Wheeler, it seems like your working style is to come to the insights through the calculations, rather than chasing (преследуя) a vague vision.
In my career I’ve only been able to take small jumps. Relatively (относительно) small jumps. What Wheeler was talking about was an enormous (огромный) jump. And he does say at the beginning of the essay that he has no idea if this will take 10, 100 or 1,000 years.
And he was talking about explaining how physics arises from information.
Yes. The way he phrases it is broader (шире): He wants to explain the meaning of existence. That was actually why I thought you were asking if I wanted to explain the meaning of existence (существование).
I see. Does he have any hypotheses?
No. He only talks about things you shouldn’t do and things you should do in trying to arrive (прийти) at a more fundamental description of physics.
Do you have any ideas about the meaning of existence?
No. [Laughs.]