Xiaogu Talks About Quantum Physics (Colloquial Version)
Lecture One: The Gains of Not Understanding
The reading salon has been eagerly anticipated for a long time. You all know that I am very fond of books: first I like buying books, and second I like reading books. Among students, I’m probably the one who buys the most books. Of course, they are not all just for show; I have read quite a few of them.
There are simply far too many books on the market now. There is a pile of bad books, but there are also far too many good books. If you asked me to pick two books from among so many good ones to recommend to everyone, that would be very easy. But if you asked me to spend an hour or so introducing one book in particular, that would be somewhat difficult, because my way of reading is “book-at-the-head” reading: I often take up a book, read the beginning, and then first put it back on the shelf. Of course, there are many books that need to be read over and over, line by line, but this “book-at-the-head” method has its advantages too: I get a rough initial sense of what topics each book touches on and what views it mentions. Then, when I suddenly need to think about some issue later, or when inspiration strikes, or when I need to write some paper, I can immediately remember where to find the relevant materials, and then pull the book out again and reread it. So although when I write papers I mainly rely on my usual accumulation and never muddle through by cramming at the last minute, I still often have to spend the week before a deadline frantically looking for books to read, and then stay up all night writing them in the day or two before submission…
But back to the point. I’m not here today to talk specifically about this one book. I’m mainly borrowing the name of this recommendation to talk about some topics concerning quantum physics and science popularization.
When it comes to science, everyone may not be interested; precisely for that reason, I think it is all the more necessary for me to talk to you about popular science.
Modern science and the humanities have become increasingly divided, just as our former mayor Xu Kuangdi, Academician Xu Kuangdi, sternly put it: scientists are generally uncultured, and humanities scholars generally do not understand science,
Granted, modern natural science and the humanities are both becoming increasingly specialized, and with one person’s energy limited, it is hard to learn everything comprehensively. However, Murray Gell-Mann once pointed out angrily—perhaps every now and then you will meet a scientist who does not know Shakespeare, but you will never meet a scientist who takes pride in not knowing Shakespeare—yet in the fields of art and the humanities, and even in the social sciences, there are often people who pride themselves on knowing almost nothing about science or mathematics! That is rather sharp, but we can observe and reflect on it: is the reason many people in the arts and humanities have no interest in science really because they lack the capacity to absorb it, or because they simply disdain learning about it? In China, this situation is even more serious—there is mutual contempt and mutual underestimation between the scientific community and the humanities community. In our own department, do the different specialties also have this kind of problem? Of course we cannot expect everyone doing Western philosophy to be as broadly conversant across Chinese and Western thought as Teacher Zhang Xianglong, but I do hope that those doing Western philosophy will not take pride in not understanding Chinese philosophy, those doing logic will not take pride in not understanding philosophy of science, and so on.
I do not expect everyone in the sciences to be like Schrödinger, who was thoroughly versed in classical literature and philosophy, and could read and write four modern languages—English, French, Italian, and Spanish—as well as he could Greek and Latin. He translated the Homeric epics into English and translated French poetry into German. He also published a personal poetry collection in 1949. He loved drawing and sculpture, had a special fondness for drama, loved nature, and enjoyed mountain climbing… Nor do I expect humanities scholars to have some terribly high level of scientific background. But at the very least there should be a bit more mutual respect. If you have never heard of Schrödinger, just as you have never heard of Whitehead, that is not strange—but it is certainly nothing to be proud of!
When ZXM heard that I not only wanted to talk about science, but also about quantum mechanics, he was frightened out of his wits and said that this topic was too deep and that it would be better to make it a bit more universally applicable and have a broader audience or something like that. I felt rather helpless. In fact, quantum physics is indeed profound; I’m afraid there is nothing more profound than quantum physics! But popular science books certainly cannot be called profound in that sense. Especially for us philosophy students, if we dare read Husserl, why should we fear these popular science books? The book I am recommending to everyone is one of the most vulgar books I have read recently. It is not only popular literature, but Internet literature as well. In my personal feeling, this book is simply vulgar to the point of excess. I personally do not especially like this style. My favorite popular science book on quantum mechanics is still John Gribbin’s *In Search of Schrödinger’s Cat*—this was the first popular science book on quantum mechanics I read. Although the quality of the Chinese translation is extremely poor, if you just read it casually in your spare time, the confusion of terminology does not matter too much. Gribbin’s book is excellent; in the Philosophers’ Stone series there are several of his books, all of them splendid. There is also a recent one, *The New Quantum World*, in the fourth installment of *The First Push* series, which is also good. Excellent popular science books on quantum physics are very rare both in China and abroad, because they are simply too hard to write!
Speaking of this sort of so-called “high-end popular science” book, the one everyone is most familiar with is probably Hawking’s *A Brief History of Time*. By the way, *A Brief History of Time* is actually rather ordinary. Of course Hawking wrote it very brilliantly, but I would not recommend it to everyone as my first choice. For topics like relativity, the best book I have read is Kip Thorne’s *Black Holes and Time Warps*; Gribbin’s *In Search of the Big Bang* is also excellent. Of course, the greatest merit of *A Brief History of Time* is that it is relatively slim, relatively accessible, and relatively short, but it is not as clear as Thorne or Gribbin.
People say that *A Brief History of Time* sells well but is read by few, and that even those who do read it cannot understand it because it is too profound. In fact, that is not quite right. Physics is profound, but those popular science books are not. Reading those popular science books with a junior-high-school foundation in physics is enough. I finished *A Brief History of Time* in two or three days when I was in the third year of junior high. In fact, you do not even need to master high school physics particularly well; you just need to know a few conservation laws. The first is mass-energy conservation; if you do not know this and keep thinking about building perpetual-motion machines, that won’t do. The second, for example, is charge conservation. Actually, it is enough just to know that besides mass-energy conservation there are other conservation laws as well. A few of the “amateur scientists” I have seen know about mass-energy conservation, but not the others; they think that pressing 1,800 electrons together makes a proton, and that won’t do. It is enough to have a rough grasp of such physical common sense; the main thing is not to read a popular science book and end up becoming an amateur scientist. I guarantee on my reputation that the popular science books I recommend are all very accessible—at least much more accessible than most people who have not read them imagine.
But why do people all say that *A Brief History of Time* is impossible to understand? That is perfectly normal too, because physics is profound, so it would be strange if you did understand it! If you read two popular science books and then say, “I’ve figured out relativity and quantum mechanics!”—congratulations, you have already become an amateur scientist!
It seems that Teacher Liu Bing of legend once came up with an advertising slogan for *A Brief History of Time*: “Reading Hawking: understanding or not understanding, both are gains.” This slogan was very successful. A certain Simpli objected to it and made some comments that were not without reason, but as for what gains one can possibly have from not understanding, I have my own view.
Actually, first of all, there is the issue of changing one’s habits of thought. Popular science on something like quantum mechanics is very different from the traditional kind people imagine. The goal of traditional popular science is to make you “understand.” If you look at popular science with that expectation, then naturally you will think that only if you understand it does that count as success, and if you do not understand it, that is failure. The more clearly the reader grasps it, the greater the gain. But in fact it is not like that.
The traditional popular science most familiar to us is exemplified by *Ten Thousand Whys*; from the title alone you can already tell the features of this kind of popular science:
The characteristic of this kind of popular science is that it first starts from “why.” People read popular science with questions of confusion and puzzlement, for example: “Why is there a rainbow? Why is the sky blue? Ah, what is going on here? Wow, and what about that?” Then the popular science book—often personified by a bald, white-bearded, bespectacled old man in a white lab coat—reveals the mystery to us: “This is because of this, that is due to that, because therefore scientific principles…” In the end the reader understands and says, “Oh, I see!”—and then the popular science has been successful.
But the situation with quantum popular science is exactly the reverse! We do not initially approach such books carrying any particular “why” questions. Most of the questions we can think of in life are perfectly well explained by classical mechanics; who would think to ask about blackbody radiation and such things? When we first hear the concept of quantum mechanics, although we do not understand it, perhaps we still do not take it seriously—“So-called quanta just mean that energy is discontinuous, that it comes in units, right? What’s the big deal?” But reading popular science on quantum mechanics does not make things clearer the more you read; on the contrary, it makes you more and more muddled! After you finish a quantum popular science book, if you slam the book down and say, “Good heavens! What on earth is all this chaos?”—that means the book has had a good effect!
The purpose of popular science like *Ten Thousand Whys* is to turn us from wonder and bewilderment into understanding; it is “de-wondering,” “demystifying” popular science. After reading those books, even if there is still wonder, it is only amazement at the power of science. Such popular science is of course very necessary; it frees people from ignorance and superstition. However, once you have had too much contact with *Ten Thousand Whys*-style popular science, it is easy to develop the habit of thinking that just as all ten-thousand-and-first whys or million whys can be scientifically explained, so too all questions can be answered by science, and thus it becomes easy to think science can solve everything—easy to become a scientific fanatic, a believer in the omnipotence of science, a scientismist.
Ordinary popular science is intended to dispel mystery, whereas popular science about quantum physics goes in the opposite direction: it hopes to present to readers the deepest and most baffling mysteries in the universe. It does not provide answers to mystery—or rather, it provides a dozen answers in one go; in any case, it is absolutely unlike ordinary popular science, which provides only a single, scientific, correct answer. It helps people understand what the scientists at the very frontier of scientific exploration are actually doing!
A few days ago I had just written a paper on the similarities between science and religion. When discussing the religious sentiments of great scientists, I cited statements about religion by many major scientists such as Planck, Einstein, Bohr, Heisenberg, Schrödinger, Born, Feynman, Bohm, and so on. Although their views differed from one another, their attitudes were all tolerant, receptive, even admiring. And astonishingly, every one of the names on the list I compiled turned out to be a major physicist who made outstanding contributions to the exploration of quantum physics! In fact, if you add just a few more names to that list—for example Dirac, Pauli, de Broglie, and so on—you almost arrive at the “dream team” of twentieth-century theoretical physicists. Besides their generally friendly attitude toward religion, these top physicists were often extraordinarily versatile. Einstein loved playing the violin; Planck, Heisenberg, Born, and others were skilled at the piano; and the scientific prankster Feynman need hardly be mentioned…
We know that physics can be said to be the purest of the natural sciences, and quantum physics is the most fundamental, the most “reductive,” and the most frontier field. Yet why is it that those who seem most “off-task” among scientists, those who like to “talk about the mysterious and discuss the Way,” and those most receptive to the humanities, arts, and religion are precisely the people doing quantum physics? Although among theoretical physicists there are also many who resist and dislike unscientific things such as religion, compared with other scientists in fields like biology and economics, it seems fair to say that quantum physicists are practically the class of scientists least given to scientism!
I believe this is by no means a coincidence. The exploration of quantum physics is the most fascinating; quantum physicists are the closest to the mysteries of nature; they are the most likely to feel the beauty and depth of nature,
Feynman once said:
Poets always say that as scientists we do not see the beauty of the stars—we only see a bunch of gathered gas atoms in the stars. There is no such thing as “only.” I can see the stars in the desert night sky, and I can feel them. But do I see less, or more, than others? The vast sky arouses my imagination—staring at this rotating dome of heaven, my little eyes can catch light that was emitted a million years ago… Or perhaps one can observe these stars through the big eyes on Mount Palomar (the telescope), which can focus together large amounts of light emitted from the same source. Maybe those rays were originally together. What kind of image is this, or what does it mean, or why is it like this? Knowing a little about the universe does not diminish its mystery. Because the universe is far more wondrous than any artist of the past could have imagined. Why don’t poets say this now?
The nature sung of by poets is of course beautiful, but the “nature” explored by scientists should likewise be beautiful, and this beauty ought to arrive at the same destination by different routes. We are too familiar with the cold, mechanical picture of nature depicted by Newtonian mechanics. If one wants to escape this coldness, one way is to forget science, reject science, and devote oneself to the humanities; another is to seek help from the pseudoscience of mysticism, to look at things like *The Complete Record of Unsolved Mysteries*; but a better way is simply to take a look at quantum physics!
It is worth noting that the “mystery” of nature revealed by quantum physics is entirely different from things like *A Complete Compendium of Unsolved Mysteries*, *The Mysterious Crop Circles*, or *The Mysterious Bermuda Triangle*. Those so-called popular science books are mostly just cheap sensationalism and contrived obscurity. Of course, I should also remind everyone not to over-mystify quantum physics. Science is certainly a search for understanding nature, and there can be no science that studies the “supernatural.” Quantum mechanics does not mean that nature is incomprehensible; quantum physicists are all persistently pursuing an understanding of nature. But quantum physics is indeed incomprehensible in another sense, because it probably cannot be understood by the ordinary habits of thought we use in daily life, and perhaps multiple different interpretations will emerge that are all simultaneously “correct.”
Reading popular science about quantum physics is not merely a matter of “understanding or not understanding, both are gains”; rather, it is precisely that “not understanding is the gain.” What I mean, of course, is not that one cannot understand the author’s written expression, but that after finishing the book one feels—“I don’t understand!”—and thus comes to sense something of nature’s profundity and the marvel of science. That would be enough. Bohr said: “Whoever is not astonished by quantum theory has not understood it.”
All right, next let us draw close to the bizarre and dazzling quantum world and see just how uncanny it really is. Before that, does anyone have any questions?
(To be continued)
April 4, 2006
Lecture Two: The Quantum World
Lecture Three: About This Book and Others
Afterword: Life Lessons from Quantum Physics
Translated from the Chinese original with AI assistance. The original text is authoritative.
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