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本文是2022年秋季学期北京大学通识核心课程“今日物理”的优秀作业，作者为北京大学历史学系2021级本科生张了了，授课教师为北京大学物理学院的李新征老师。通识联播经作者授权发布。  Vol.1529 Stories from the early days of quantum mechanics 量子力学发展初期的故事 原文作者：Isidor Isaac Rabi（伊西多·艾萨克·拉比[1] ） Transcribed and edited by R. Fraser Code（转录和编辑：R. Fraser Code） 翻译：北京大学历史学系2021级本科生 张了了 A colloquium delivered to the University of Toronto physics department on 5 April 1979 by the master of molecular beams offers a fresh look at an earlier era. In 1979, I. I. Rabi (1898–1988) was the Emeritus University Professor of Physics at Columbia University in New York City. Fraser Code is an emeritus professor of physics at the University of Toronto in Canada. 1979年4月5日，分子束大师拉比在多伦多大学物理系举行了一场学术报告，为我们认识量子力学初期的发展提供了一个崭新的视角。 在1979年，伊西多·艾萨克·拉比（1898-1988）是纽约市哥伦比亚大学的物理学荣誉教授。 Fraser Code是加拿大多伦多大学的物理学荣誉教授。 I have something in common with Ernest Rutherford, that distinguished physicist and professor at Canada’s McGill University, who deplored the fact that, although a physicist, he got a Nobel Prize in chemistry. My career is the opposite. I started at Cornell as a chemist, and got a degree of bachelor of chemistry, which has since been discontinued. So I’m an orphan like the DeSoto, one of those cars that are no longer manufactured. Anyway, after some years in which I tried various things that broadened my education but did not line my pocketbook, I went back to Cornell to study physical chemistry. But I’d taken all those courses so I said to myself “I’ll study physics, and put the two together.” You know, that is somewhat like the person who wanted to study Chinese philosophy, so he looked up Chinese in the encyclopedia, and then he looked up philosophy, and finally tried to combine them. But for me, when I started studying physics, I realized that the part of chemistry I liked was called physics. So that was the beginning of my career, and I entered the subject of physics more seriously around 1922. 我与欧内斯特·卢瑟福有共同之处，他是杰出的物理学家也是加拿大麦吉尔大学的教授。卢瑟福对于自己是一位物理学家，但却获得了诺贝尔化学奖而感到遗憾。[2] 我的职业生涯正好相反。我最开始在康奈尔大学学习化学，并获得了化学学士的学位，后来这个学位不再颁发了。所以我是像DeSoto汽车[3]一样是个孤儿，是那些不再生产的汽车之一。 总之，经过几年的时间，我尝试了各种各样的事情，扩大了我的学习范围，但并没有让我富裕起来。我回到康奈尔大学学习物理化学，但我已经上过那些课了，所以我对自己说：“我要学习物理学，并把物理与化学结合起来。” 这有点像想研究中国哲学的人，他在百科全书里查了“中国”，然后又查了“哲学”，最后试图将二者结合。 但对我来说，当我开始学习物理学时，我意识到化学中我喜欢的那部分被称为物理。因此，这是我职业生涯的开始，我在1922年左右以更严谨的姿态进入了物理学。 Learning quantum mechanics in America 在美国学习量子力学 The year of 1922 was very significant. In fact, that whole time from the early twenties onward was a period of great ferment in physics, enormous ferment, all over the world—by which one means Denmark, England, France, but not the United States. I remember one time when I was a graduate student at Cornell, sitting in the library amongst the students, just before the time when Professor [Arnold] Sommerfeld was to come and visit. And you could see one professor after another sneak in and take a look at Sommerfeld’s book Atombau und Spektrallinien (Atomic Structure and Spectral Lines, Friedr. Vieweg & Sohn, 1919). That was all the exposure they had to the quantum theory. That was 1922 in America. By contrast, in Europe, quantum theory had been extant for quite a number of years. But in America, it had not yet achieved full recognition as something suitable for graduate study at Cornell, or for that matter at Columbia [where Rabi completed his PhD]. I’m not even sure that quantum theory was working very well here at Toronto in 1922! Anyway, the faculty in America wasn’t very much concerned with quantum physics, except experimentally. But at Columbia, a number of graduate students formed a weekly discussion group that we called a “Sunday soviet,” by which I mean that we met every Sunday near 11 o’clock in the morning, and went on right through a Chinese dinner. We learned a great deal just by ourselves. I’d recommend this method of learning to all the graduate students in this audience: If any of the faculty are deficient in some subject that interests you, just form a little soviet and do it on your own. As a matter of fact, it worked so well that when the Austrian physicist Erwin Schrödinger’s paper first came out[6], we read it and worked through all the equations. Then, just as an exercise, Ralph Kronig and I decided to do something with this new thing, Schrödinger’s quantum theory. So we looked through [Max] Born’s book[7] and found that the symmetrical top problem had not yet been done. So we sat down and, according to Schrödinger’s prescription, formed the wave equation, separated the variables, got the angular momentum, as well as the various states, but then we ran into an equation that we didn’t know how to solve. 1922年是一个非常重要的年份。事实上，从二十世纪初开始，物理学进入了一个巨大的发酵期，世界各地都在发生着巨大的变革——这里的世界指的是丹麦、英国、法国，但不包括美国。[4] 当我还是康奈尔大学的研究生时，有一次，我混在图书馆的学生中，目睹在阿诺德·索末菲教授[5]来访之前，一个又一个教授溜进来，翻一翻索末菲的《原子结构和光谱线》（Atomic Structure and Spectral Lines, Friedr. Vieweg & Sohn, 1919）。这就是他们对量子理论的所有接触。那是1922年的美国。 相比之下，量子理论在欧洲已经存在了相当长的时间。但是在美国，量子理论还没有得到充分的认可，它不适合康奈尔大学或者哥伦比亚大学【拉比在哥伦比亚大学获得博士学位】的研究生进行学习。我甚至不确定量子理论在1922年的多伦多是否得到了认可！ 总之，除了实验方面，美国的高校教师们不太关心量子物理。但在哥伦比亚大学，一些研究生组成了一个每周讨论小组，我们称之为 “周日苏维埃”，[8] 我们每周日上午11点左右见面讨论，一直持续到吃完中式晚餐。 我们仅靠自己就学到了很多东西。我向在座的所有研究生推荐这种学习方法：如果任何教员在你感兴趣的某个课题上有所欠缺，就组成一个小“苏维埃”，自己去学习。事实上，这种方法非常有效，当奥地利物理学家埃尔文·薛定谔的论文刚出来时，我们就读了它，并研究了所有的方程式。 然后，作为一个练习，拉尔夫·克朗尼格[9]和我决定对薛定谔的量子理论加以运用。我们翻阅了马克斯·玻恩的书，发现对称陀螺分子[10]的问题还没有完成。于是根据薛定谔的处理方法，建立了波动方程，分离了变量，得到了角动量，以及各种态，但后来我们遇到了一个不知道如何解决的方程。 And here’s another lesson that I want you to hear from my own experience. Somehow or other after that Sunday soviet, I was sitting in the library reading the mathematical works of Carl Jacobi, who wrote beautifully in German. I understand that German is no longer required for graduate students here. Too bad, because in reading through that book, suddenly there appeared my equation—the one Kronig and I could not solve. It was the equation for the confluent hypergeometric series, which neither of us had ever heard of before. Using this reference, we were then able to solve the quantum mechanical problem of the symmetrical top molecule. But we did not have the faintest idea what the wavefunction ψ meant. It was a magical thing. What you got when you followed this prescription, as Schrödinger had done for the hydrogen atom, were the eigenvalues of the differential equation. These were the energy levels, which agreed with experiment. But we had no idea what the wavefunction was—what was this magic function ψ? Of course, it became clear soon thereafter when Born and others suggested that |ψ|2, the absolute value of ψ squared, represented the probability density for finding that particular thing at that particular place. Suddenly the wave function ψ acquired a great meaning. But it was so magical, that function ψ. You simply followed the formula, and out came real results. This was not a surprise. During the first period of its existence, quantum mechanics didn’t predict anything that wasn’t also predicted before by the old quantum mechanics plus that very magical abracadabra of the correspondence principle. There were real artists at work on the correspondence principle. For example, they were able to deduce many things from the Kramers–Kronig formula, or from the Kramers–Heisenberg dispersion formula. The development of physical relationships from the correspondence principle was all done by artistry, by imagination, and from certain kinds of symmetry ideas. So the results that came out of quantum mechanics had to a large degree been previously anticipated from this correspondence principle. 从我个人的经历中，还有一个教训可以吸取。在那次“周日苏维埃”之后，不知怎么的，我坐在图书馆里读着卡尔·雅可比 的数学著作，这本书用德语写成，文字优美。我知道现在这里的研究生不再要求学习德语了，这太遗憾了。在阅读那本书时，突然出现了克罗尼格和我无法解决的那个方程。那是合流超几何级数的方程，我们以前都没有听说过。利用这个参考资料，我们就能解决对称陀螺分子的量子力学问题。 尽管如此，我们对波函数ψ的含义没有丝毫概念。这是个神奇的东西。[14]当你按照这个方法，就像薛定谔对氢原子所做的那样，你得到的是微分方程的特征值。这些是能级，与实验一致。但我们不知道波函数是什么——这个神奇的函数ψ是什么？ 当然，此后不久，当波恩和其他人提出|ψ|2，即ψ的绝对值的平方，代表在某个特定的位置找到某个特定物体的概率密度时，一切都变得清晰了。突然间，波函数ψ获得了一个伟大的意义。 但它是如此神奇，那个函数ψ。你只要按照公式操作，就会出现真实的结果。这并不奇怪。在它存在的第一个时期，量子力学没有预测到任何没有被旧量子论加上对应原理这个神奇魔咒所预测过的东西。[15] 在对应原理方面，有真正的“艺术家”在工作。例如，他们能够从克雷默斯—克罗尼格公式[67]或克雷默斯—海森堡的色散公式[17]中推导出许多东西。从对应原理中发展出的物理关系都是通过艺术性、想象力和某些对称性的思想来完成的（对称性在量子力学中的作用）。所以，量子力学所产生的结果在很大程度上是以前从这个对应原理中预见到的。 But a very unfortunate thing happened to John Van Vleck, who wrote a remarkable book on the old quantum theory. [18] It was a wonderful book, a clear book, and he was a master. However, it was published and came out just at the time of the revolution in quantum mechanics. Unfortunately, it became obsolete almost on publication! The same was true with Wolfgang Pauli’s first volume. When the revolution came, it all changed. Now, it was the new quantum mechanics that was doing things and growing. Matrix mechanics, of course, was in many ways clearer, and in many ways more dense than Schrödinger’s equation. But the matrix mechanics of Heisenberg used a different kind of mathematics. Paul Dirac had been an engineer with a background in mechanics, rather than having been a physicist. So when he followed Heisenberg’s first paper on matrix mechanics, he particularly noticed the commutation exchange relationships, and saw a certain parallel between Poisson brackets and the commutation exchange relationships. As a result, Dirac started his approach to matrix mechanics from that direction. So that was a very great time because we could be the first to do something like the symmetrical top. And we were the first to do this important molecular problem, and just as graduate students! It was not for my dissertation, nor was it for Kronig’s, but we did learn some quantum theory. While I was a graduate student at Columbia, there were no professors of theoretical physics. I was doing an experimental dissertation, and my supervisor was Professor Albert P. Wills. In 1926, there was just our little group of serious thinkers, including Michael Pupin[23], sitting there trying to figure out Heisenberg’s matrix mechanics. Schrödinger’s formulation, of course, was our favorite. This was clear. It only required that you were familiar with differential equations, and it had a pictorial interpretation. In contrast, Heisenberg’s approach involved matrices, which were not difficult but were messy. In addition, there was Heisenberg’s use of abstract symbolism, which, of course, looked to us as the most mysterious of all. And this shows how limited one can be if one is provincial. Because in the United States, as far as theoretical physics was concerned, we were provincial. Definitely provincial.  约翰·范弗莱克（John Hasbrouck Van Vleck, 1899-1980） 图源维基百科 但是一件非常不幸的事情发生在约翰·范弗莱克身上，他写了一本关于旧量子理论的杰出著作。那是一本清晰、完美的书。范弗莱克是一位大师。然而，这本书正好在量子力学革命的时候出版和问世，几乎刚一出版就惨遭淘汰！沃尔夫冈·泡利的第一卷也是如此。当理论革命到来时，一切都变了。 现在，是新的量子力学在阐释世界、不断发展。矩阵力学在许多方面比薛定谔方程更清晰，也更简约[21]。但海森堡的矩阵力学使用了一种不同的数学方法。 保罗·狄拉克[22]是一名具有力学背景的工程师，而不是一名物理学家。当他关注海森堡关于矩阵力学的第一篇论文时，他特别注意到了对易关系，并看到了泊松括号和对易关系之间的某种类似。于是，狄拉克从这个方向开始了他对矩阵力学的研究。 因此，那是一个非常伟大的时刻，因为我们可以成为第一个研究对称陀螺这类问题的人。我们是第一个做这个重要的分子问题的人，而且只是作为研究生！这不是为了我的论文，也不是为了克罗尼格的论文，我们确实学到了一些量子理论。我在哥伦比亚大学读研究生时，没有理论物理学教授。我的学位论文还是实验类的，我的导师是Albert P. Wills教授。 1926年，只有我们这一小批严肃的思想家，包括迈克尔·普平[24]，坐在那里试图弄清海森堡的矩阵力学。当然，薛定谔的表述是我们最喜欢的，因为它很清晰。它只要求你熟悉微分方程，而且有一个图像解释。相比之下，海森堡的方法涉及矩阵，这虽不难，但却很混乱。此外，海森堡还使用了抽象的符号，这在我们看来是最神秘的。[26] 这就说明了如果一个人思想狭隘，会有多么局限。因为在美国，就理论物理而言，我们是狭隘的。绝对是狭隘的。 Visiting quantum physicists in Europe 访问欧洲的量子物理学家 So the time came when I had finished my dissertation. But there were no jobs around in the US, so I got a small Barnard fellowship to go to Europe. It was $1500 a year for two years, not paying for transportation.[25] And on this my wife and I went to Europe. Well of course, being an American, in many ways I was very naive. The first place I went was to Zürich, Switzerland, where I hoped to work with Professor Schrödinger. Of course, I hadn’t written a note beforehand to make arrangements to come. When I arrived in Zürich, I tried to find a pension [boarding house or small hotel] where I could stay. Afterwards, I went right down to the university, where there was a colloquium going on that afternoon. The man gave a fiery lecture, and I didn’t understand a single word. I was very depressed, and I came out full of sorrow for what was going to happen to me. Here I had come all the way over to Europe from America, and now I felt very discouraged. So I looked around in the audience for somebody that I might know. Well, I did find people in a very definite way. In 1927, the Russian revolution was about 10 years old. And Americans always wore white shirts, but with their collars attached. You could recognize an American anywhere that way. I looked around, and there at the colloquium was a man with a white shirt and collar attached. He turned out to be Linus Pauling. I told him of my sorrow that I didn’t understand what the lecturer was saying. He said “Don’t worry, he was not talking German, he was talking Schwitzerdeutsch,” which was the local German dialect. I was very pleased to hear that. Later, Linus invited me to where he was staying and gave me a drink. I don’t suppose you realize what this meant: In 1927, Prohibition was on in America and drink was a rare thing, especially when you had no money.He also recommended a good pension for me to stay at. 当我完成我的学位论文时，美国没有工作机会，所以我得到了一笔小的巴纳德奖学金就去欧洲了。每年1500美元，为期两年，不包括交通费。我和我的妻子就这样去了欧洲。当然，作为一个美国人，在很多方面我是很不成熟的。我去的第一个地方是瑞士的苏黎世，希望在那里与薛定谔教授一起工作。 当然，我没有事先告知，安排我的来访。当我到达苏黎世时，我试图找到一个可以住宿的公寓（寄宿家庭或者小旅馆）。 然后，我就直接去了大学，那天下午有一个学术讨论会。有人做了激情四射的演讲，但我一个字都没听懂。我很沮丧，对即将发生在我身上的事情十分悲观。我大老远从美国来到欧洲，现在我感到非常气馁。所以，我在观众席中四处寻找我可能认识的人。 我确实以一种非常明确的方式找到了人。在1927年，十月革命已经过去了约10年。而美国人总是穿着带领子的白衬衫。你可以通过这种方式在任何地方认出美国人。我环顾四周，在那个学术报告会上，有一个人穿着带领子的白衬衫。 他原来是莱纳斯·鲍林。[27]我告诉他我很难过，我不明白演讲者在说什么。他说：“别担心，他说的不是德语，他说的是瑞士德语，”那是当地的方言。我听到这话非常高兴。后来，莱纳斯邀请我去他住的地方，请我喝了一杯。我想你应该没有意识到这意味着什么：1927年，美国正在实行禁酒令，喝酒是一件很稀罕的事情，尤其是当你没有钱的时候。他还为我推荐了一家很好的公寓，让我住进去。 Well, the timing of my trip to Europe was not very good. I had just arrived in Zürich to visit with Schrödinger, and then Schrödinger left almost the same day. He’d gotten a good job in Berlin. But I was traveling lightly, except for a very heavy suitcase. So I went down to Munich to visit Sommerfeld. I arrived there, and just as I did in all these places, I came in and said, “My name is Rabi. I’ve come here to work.” I hadn’t written anything beforehand. So there it was—Sommerfeld’s office in Munich! I was shown to a room where some of his students worked, and there were Hans Bethe and Rudolf Peierls, who were graduate students at that time, and Albrecht Unsöld, who later became a well-known astrophysicist—that is, a theoretical astronomer. There were also two Americans who became very notable later. One was Edward Condon. You know the book, The Theory of Atomic Spectra, that he wrote with George Shortley (Cambridge U. Press, 1935), as well as Condon’s other books. The other American was Howard P. Robertson, who was very well known in circles that deal with relativity. So we were the three Americans in Sommerfeld’s group, who gave each other strength because we were worried that our German was not of the best quality. Every once in a while, Peierls and Bethe would go out in the hall and laugh, and we did have the suspicion that they were laughing at us. Anyway, in the Germany of 1927, the working conditions for graduate students were very interesting in a way when compared to now. Once, Sommerfeld showed me around his offices. In the basement was one place where there was a closet with a board across, and a naked incandescent bulb over it. Right there was where Bethe worked. So there was nothing very much in the way of conveniences. I think there were only three graduate students actually working with Sommerfeld. But you can see their character somehow by their selection. Two of those three were Peierls and Bethe. I don’t remember the third one. 好吧，我去欧洲的时机不是很好。我刚刚抵达苏黎世拜访薛定谔，薛定谔几乎在同一天离开。他在柏林找到了一份好工作。我轻装上阵，只带了一个非常沉的行李箱。所以我转道慕尼黑，拜访索末菲。我到了那里，就像我在所有这些地方一样，我走进去说：“我叫拉比。我是来这里工作的。”我事先没有出具任何纸面证明。 于是我就到了——索末菲在慕尼黑的办公室！我被带到了他的一些学生工作的房间！我被带到一个房间，他的一些学生在那里工作，有汉斯·贝特[28]和鲁道夫·佩尔斯[29]，他们当时是研究生，还有阿尔布雷希特·恩索尔德[30]，他后来成为著名的天体物理学家、理论天文学家。还有两个美国人，之后也很出名。 一个是爱德华·康顿[31]。你应该知道他和乔治·肖特利一起写的《原子光谱理论》一书（剑桥大学出版社，1935年），以及康顿的其他书籍。另一个美国人是霍华德·P·罗伯逊[32]，他在相对论的圈子里非常有名。因此，我们三个索末菲研究组中的美国人，互相帮助。我们常担心我们的德语不过关。每隔一段时间，佩尔斯和贝特就会到大厅里笑，我们确实怀疑他们是在嘲笑我们。 总之，与现在相比，1927年德国研究生的工作条件在某种程度上是非常有趣的。有一次，索末菲带我参观他的办公室。在地下室有一个地方，那里有一个壁橱，上面横着一块板，上面有一个裸露的白炽灯。那就是贝特工作的地方。因此，没有什么称得上便利的设施。当时只有三个研究生真正与索末菲一起工作。你可以从他们的选择中看出他们的性格。这三个人中的两个是佩尔斯和贝特。我不记得第三个人了。 Sommerfeld was a man with enormous dignity, a wonderful person. I was invited on Friday afternoons to the Englischer Garten to have tea with the Geheimrat [an honorary German title conferred on outstanding scientists]. It was very dignified. Sommerfeld had a very large office, and then there was the office of his assistant, a man named Becker, and finally the place for his students. All the journals were in Sommerfeld’s office. So if you wanted to look up something, you made your way to the assistant, who would then knock on the door of the Geheimrat, and then you walked in. Under those circumstances, you didn’t look things up very much. I am telling you these stories to show another way of life, which existed at that time, and to contrast it in a way from the one we have now. Of course, I don’t know how it is since I finished working [in 1967]. For example, I don’t know whether you need clearance [the need to make prior arrangements] at all to go from one place to another to work. I don’t know whether you could come in and say, as a fresh-corked postdoc could say, “My name is Rabi. I’ve come to work here.” The answer would probably be, “Who said your name isn’t Rabi?” Well, it was a wonderful way to live, in a place like Germany. And as an American, you weren’t part of it. You never expected to get a job there, so you were free.In the fall, I left Munich intending to go first to England and then to Copenhagen. In England, I discovered that six marks—equivalent to six shillings—which carried me through the day in Germany, wouldn’t quite give me a room in London. I saw financial disaster staring me in the face. So I went to Copenhagen. Copenhagen, of course, was the mecca for everybody at that time who was interested in theoretical physics. Everything good came out of Copenhagen in one way or another. And so my wife and I went off. When we arrived in Copenhagen, I checked my bag, and my wife and I took our map and walked over to the Institute for Theoretical Physics [renamed the Niels Bohr Institute in 1965]. I rang the bell and said my usual spiel: “My name is Rabi. I’ve come to work.” So the Institute’s secretary gave me a key. I asked her for a suggestion on where we might stay, and she gave us a good one. I brought my wife and my bag there, and then came back. In the course of time, several people were to appear. There was one gentleman with an enormous stutter. He tried to tell me his name, and I tried to help. And I said “Klein, Klein,” as I knew Oskar Klein was Bohr’s assistant, but when he came up with his name, it was Pascual Jordan, who later on became a professor and lecturer. And how he ever did it I don’t know, except that he did not have this stutter when he had enough beer in him, or when he spoke English. Then, after a while, others showed up: great names in physics like Ivar Waller, Kronig (who had been there before me), and finally the great Professor Bohr came back from his vacation. 索末菲有一个非常大的办公室，然后是他的助手，一个叫贝克尔的人的办公室，最后是他的学生的地方。所有的期刊都在索末菲的办公室里。所以，如果你想查什么，你就去找助理，然后他就会敲索末菲的门，然后你才能走进去查期刊。在这种情况下，你不会经常去查阅期刊。 我告诉你们这些故事，是为了展示那个时候存在的另一种生活方式，并与我们现在的生活方式形成对比。当然，我不知道自从我停止工作【1967年】后的情况如何。例如，我不知道你从一个地方到另一个地方去工作是否需要许可【事先安排】。我不知道你是否可以像一个刚毕业的博士后那样进来说：“我叫拉比。我是来这里工作的。” 答案可能是，“谁说你的名字不是拉比？”但，我经历的是一种美妙的生活方式，在德国这样的地方。作为一个美国人，你不是其中的一部分。你从未指望在那里得到一份工作，所以你很自由。 秋天，我离开慕尼黑，打算先去英国，然后去哥本哈根。在英国，我发现六马克——相当于六先令——在德国可以让我过一天，但在伦敦却不够给我一个房间。财务灾难逼视着我。所以我去了哥本哈根。 当然，哥本哈根是当时所有对理论物理学感兴趣的人的圣地。所有优秀的成果都是以这样或那样的方式从哥本哈根出来的，于是我和我的妻子出发了。当我们到达哥本哈根时，我检查了我的行李，我的妻子和我拿着地图，走到理论物理研究所【在1965年更名为尼尔斯·玻尔研究所[33]】。我按了一下门铃，用了我的惯用说辞： “我叫拉比。我是来这里工作的。”于是研究所的秘书给了我一把钥匙。我问她有没有什么好的住宿地点推荐，她给了我们一个不错的建议。我带着我的妻子，拿着我们的行李去了那里，然后回到了研究所。 那是九月，完全是假期的一个月。除了秘书和我，周围没有人。但是，哥本哈根里有一种氛围，你不能在那里闲着。你得坐在那里工作，并试图思考伟大的想法。我建议你试试。这可能是非常令人沮丧的。 过一段时间，有几个人来了。有一位先生有严重的口吃。他试图告诉我他的名字，而我试图帮助他。我说 “克莱因，克莱因”，因为我知道奥斯卡·克莱因[34]是玻尔的助手。当他说出他的名字时，他是帕斯卡·乔丹[35]，他后来成为一名教授和讲师，我不知道他是怎么做到的，只知道当他喝了足够多的啤酒或者说英语时，他就没有这种口吃。 然后，又过了一阵，其他人出现了：物理学界的大人物，如伊瓦尔·沃勒[36]、克罗尼格（他在我之前就来到了理论物理研究所），最后，伟大的玻尔教授[37]休假回来了。 My arrival in Hamburg 我抵达汉堡后 And now I come to the beginning of the real story of my life, that is, the direction of my life. Bohr had had a very difficult summer, and his assistants thought that he had been overworked and that he should not have any people there except for Kronig, who had come earlier. And here again a most fortunate thing happened. Without asking me, but making all the arrangements, they arranged for Yoshio Nishina and me to go to work with Pauli in Hamburg. This seemed disappointing at first, to go away from the center to a place like the University of Hamburg. But Hamburg actually was the greatest institution in the world for physics at that moment. Hamburg had Pauli; Walter Gordon [of the Klein–Gordon equation]; Wilhelm Lenz, who was in molecular theory, a brilliant man; and most of all, Otto Stern, in experiment. So there quite by accident, and partly against my will, I found myself in this very marvelous place. In addition, there was Ronald Fraser from Scotland, and John Taylor, who was an American. They had both done molecular beams before, and were working now with Stern. Pauli at that time, and this is toward the end of 1927, asked Nishina and me to write a paper with him. [42] I became aware of the necessity for me to talk some English. This was a real physical necessity. The three of us English-speaking people there—Fraser and Taylor and I—formed a little group that I crowned “the three for we who were abroad.” No matter what, you had to express yourself, and for me this was only possible in English. Shortly, I left Pauli’s group. I had an idea about how to do an interesting experiment concerning the magnetic refraction of molecular beams and was invited by Otto Stern to do it in his laboratory at Hamburg. [43] 现在，我来到了我生命中真正的故事的开始，也就是我生命的方向。玻尔度过了一个非常艰难的夏天，他的助手们认为他已经工作过度，因此除了提前来的克罗尼格，其他人都不应该留在理论所。 这时又发生了一件十分幸运的事情。他们没有征求我意见，直接做了所有的安排，安排我和仁科芳雄[38]去汉堡和泡利一起工作。最初，离开理论所去汉堡大学这样的地方似乎很令人失望。 但汉堡实际上是当时世界上最伟大的物理学研究中心。汉堡有泡利、沃尔特·戈登[39]【克莱因-戈登方程】、威廉·楞次[40]，楞次在分子理论方面是一个杰出的人；最重要的是，在实验领域还有奥托·斯特恩 。因此，我发现自己来到了这个非常神奇的地方，这完全是偶然的，甚至部分是违背我的意愿。此外，还有来自苏格兰的罗纳德·弗雷泽和美国人约翰·泰勒。他们以前都研究过分子束，现在正和斯特恩一起工作。当时，也就是在1927年年底的时候，泡利要求我和仁科和他一起写一篇论文。 我开始意识到，我有必要说一些英语。这是一种真正的实际需要。我们三个讲英语的人——弗雷泽、泰勒和我——组成了一个小团体，我称之为 “我们三个异乡人”。无论怎样，你必须表达自己，而对我来说，这只有用英语才能做到。不久后，我离开了泡利的小组。 我有一个想法，就是如何做一个关于分子束的磁性折射的有趣实验，奥托·斯特恩邀请我在他位于汉堡的实验室做这个实验。 Remember, back at Columbia I said we were provincial. To show you the degree to which we were provincial—and by “we” I am talking about the United States, that land south of the Canadian border—in Germany they subscribed to the Physical Review, but waited until the end of the year to get their 12 issues at once, to save postage. It wasn’t important enough to get each issue right away. We—and here I mean Condon, Robertson, and others among my friends—felt that this was very humiliating and vowed we would change it. I must say that we did, because 10 years later the Physical Review was the leading journal in the world. It didn’t take long. We came back and distributed ourselves among our various universities and began teaching students. Teaching was just like raising fish—there were a lot of eggs, which we began to fertilize. And so we had this time bomb of emerging physicists. In America, we had numerous colleges and universities, the students were there, and they needed teachers. And we came back from Germany with the magic of quantum theory. Indeed, by the time World War II came, physicists could man all of the American research laboratories. We were able to recruit hundreds or thousands of people, people with a very sophisticatededucational background. So it [the conversion of American physics from the provincial to the international] could be done. And this is what frightened me so about the Russians when the first Sputnik was launched. I thought they were on to this trick of raising fish. But you can’t do it unless you have a free society. This was done freely by the people themselves and was done without government support. There was no government money for physics before the war. But I’m getting ahead of my story. 还记得吗，在哥伦比亚大学时我说过我们是狭隘的。为了向你展示我们在多大程度上是在主流之外的——我说的“我们”是指美国，即加拿大边境以南的土地——在德国，他们订阅了《物理评论》，但为了节省邮费，他们要等到年底才一次性拿到12期。立即得到每期杂志，了解美国物理学界的动向对他们来说并不重要。 我们——这里我指的是康顿、罗伯逊和我朋友中的其他人——觉得这非常羞辱人，并发誓我们会改变它。我必须说，我们做到了，因为仅仅10年后，《物理评论》就成为世界领先的杂志。我们回来后，散布在各个大学里，开始给学生上课。 教学就像养鱼一样——有很多卵子，我们开始让它们受精。因此，我们有了一颗由新兴物理学家组成的定时炸弹。在美国，我们有许多学院和大学，学生在那里，他们需要教师。 而我们从德国回来，带着名为量子理论的魔法。事实上，在第二次世界大战到来时，物理学家可以在所有的美国研究实验室的实验室中工作。我们能够招募到成百上千的人，这些人有非常复杂的教育背景。因此，它【美国物理学从狭隘到国际性的转换】是可以做到的。 这就是第一颗人造卫星发射时让我对俄罗斯感到恐惧的原因。我以为他们很会玩这种养鱼的把戏。但除非你有一个自由的社会，否则你无法做到这一点。这是由人民自己自由完成的，是在没有政府支持的情况下完成的。战前政府没有为物理学提供资金。但是，我现在已经跑题了。 The magical role of experiment 实验的奇妙作用 And now I begin the experimental part of my talk. It is about those great days, and how people saw marvelous things and didn’t understand them. It is well known that Stern and [Walter] Gerlach did a famous experiment that was intended to demonstrate space quantization. They passed a beam of silver atoms through an inhomogeneous magnetic field. When silver was evaporated, the atoms were supposed to have magnetic moments, which could be deflected by external magnetic field gradients. Since the atomic beam of silver had a Maxwell distribution of velocities, the beam would be deflected and broadened by the field gradients. Some would be deflected one way depending on their orientation, some the other way, and some not at all, if their orientation was perpendicular to the magnetic field. Stern and Gerlach had a brilliant concept, and with very poor equipment they did the experiment. (See the article “Stern and Gerlach: How a Bad Cigar Helped Reorient Atomic Physics,” PHYSICS TODAY, December 2003, page 53.) And the experiment, as most of you have seen in elementary books, showed a split beam, plus and minus; some were deflected one way, some were deflected the other way. But what about the middle? What about the atoms that were perpendicular? [Rabi now refers to the old Bohr–Sommerfeld theory, in which ground-state silver had an erroneous orbital angular momentum (L = 1) and the electron’s spin and g factor were yet to be discovered.] And the story at that time was that you assigned quantum numbers that were equal to plus one, minus one, and zero. What about zero? There was no zero! Instead of that fact creating an enormous sensation, they just said, “Well, equal to zero is missing,” which was a great statement at that time, and nobody understood it. Since there was no logical theory available, you could play it by ear; it seemed obvious that the zero state was missing. And to support the argument, they appealed to the theory of the Stark effect, in which the = 0 orbit should hit the nucleus. So they said, “We can’t have it hitting the nucleus, so we can say that the = 0 quantum number is missing—you just don’t have it.” Now you begin to see why this strange experimental result was so useful. You didn’t have to resort to these odd forms of chicanery about why the = 0 state was missing. The whole point of the experiment was that they had seen atomic silver to have spin equal to one-half, and its orientation was either one way or the other. So it was right there in front of them, and because they had been so accustomed to glib talk, they didn’t recognize it. At that time, Stern was also doing experiments to show the wave nature of matter. First, he was scattering hydrogen atoms with a ruled surface, and then he successfully used another type of lattice. He showed that the scattering was associated with the de Broglie wavelength—not only for atoms, but also for molecules. 现在我开始我演讲中关于实验的部分。这关乎那些伟大的日子，关乎那些人们无法理解的神奇现象。  瓦尔特·格拉赫（Walther Gerlach，1889—1979） 图源维基百科 众所周知，斯特恩和【瓦尔特】格拉赫[44]做了一个著名的实验，旨在证明空间量子化。他们通过不均匀磁场传递银原子束。当银蒸发时，原子应该具有磁矩，可以被外部磁场梯度偏转。由于银原子束具有麦克斯韦速度分布，因此束流会被场梯度偏转和展宽。 一些会根据它们的方向被偏转到一边，一些会被偏转到另一边，而如果它们的方向垂直于磁场，则根本不会被偏转。 斯特恩和格拉赫有一个出色的概念，他们用非常差的设备做了这个实验。(见文章 “斯特恩和格拉赫：一支糟糕的雪茄如何帮助重新定位原子物理学”，《今日物理》，2003年12月，第53页）。而这个实验，正如你们大多数人在基础课本上看到的那样，显示出一个分裂的光束，有正有负；一些被偏转到一个方向，一些被偏转到另一个方向。但是中间的情况呢？那些垂直的原子呢？【拉比现在指的是旧的玻尔-索姆费尔德理论，其中基态银有一个错误的轨道角动量（L=1），电子的自旋和g因子尚未被发现。】而当时的说法是，你指定量子数等于 1、-1和0。那0呢？根本就没有0！ 这个事实并没有引起巨大的轰动，他们只是说：“好吧，等于0的不见了。”这在当时是一个伟大的声明，但没有人理解它。 由于没有可用的逻辑理论，你可以随意阐释；似乎很明显，零态是缺失的。而为了支持这一论点，他们诉诸于斯塔克效应的理论，在该理论中，=0的轨道应该撞击原子核。所以他们说：“我们不可能让它撞上原子核，所以我们可以说=0的量子数是缺失的——就是没有。” 现在你开始明白为什么这个奇怪的实验结果是如此有用。你不必诉诸于这些奇怪的诡计来解释为什么=0的状态会丢失。实验的全部意义在于，他们看到原子银的自旋等于1/2，而且它的方向要么是一个方向，要么是另一个方向。所以真相就在他们面前，但是因为他们已经习惯了花言巧语，他们没有认识到这一点。 当时，斯特恩也在做实验以显示物质的波性。首先，他是用一个有规则的表面来散射氢原子，然后他成功地使用了另一种类型的晶格。他表明散射与德布罗意波长有关——不仅对原子，而且对分子。 Now a molecule is not an atom, at least if you go back to the unsophisticated days. Once you have a de Broglie wavelength for a molecule with only two atoms, then why shouldn’t a grand piano have a de Broglie wavelength? Any collection of things should scatter in this way. In fact, these scattering experiments were really demonstrating the wave nature of matter. Not just electron scattering, or even atomic scattering, but also molecular scattering was consistent with the same de Broglie relationship. Later on [in 1933], pursuing the same idea, Stern and his collaborators measured the magnetic moment of the proton. This was done against the strong advice of his friend Pauli, among other theorists. They all said, “We know the moment of the proton, because we know the difference in mass between the proton and the electron, and we know the magnetic moment of the electron.” Stern went ahead and did the experiment anyway, and, of course, all of those theorists were wrong. 现在，一个分子不是一个原子，至少如果你回到量子物理尚未成熟的时代。一旦你有一个只有两个原子的分子的德布罗意波长，那么为什么三角钢琴不应该有一个德布罗意波长？任何事物的集合都应该以这种方式散射。事实上，这些散射实验真正证明了物质的波性。不仅仅是电子散射，甚至是原子散射，分子散射也与同样的德布罗格利关系一致。 后来[1933年]，为了追求同样的想法，斯特恩和他的合作者测量了质子的磁矩。这是违背他的朋友泡利和其他理论家的强烈建议的。他们都说：“我们知道质子的磁矩，因为我们知道质子和电子之间的质量差异，而且我们知道电子的磁矩。” 斯特恩还是继续做了这个实验，当然，所有这些理论家都错了。 Will physics ever come to an end? 物理学会不会走到尽头？ I’m coming to the end of my talk, and I just want to tell you one more small story. I could go on telling stories, as you see, for a long, long time. But this is one story that you should take to heart. I went with my mentor, Otto Stern, to visit the great Max Born, who was then at the very height of his glory, with his probabilistic interpretation of the wavefunction and so on. At that meeting, he told us very seriously that in six months’ time, physics as we knew it would be over. That was quite a blow! Born had an impressive personality, and he said this with a certain amount of reason because it was 1928, and Dirac had just given us his miraculous theory of the electron. Making no assumptions other than relativistic invariance, Dirac derived the correct spin and magnetic moment of the electron. Everything that one wanted to know about the electron came without any extra assumptions beyond relativistic invariance. So this was a terrific achievement, of course. And Born apparently felt that it wouldn’t take more than six months for these very bright boys around him to derive the spin and moment of the proton from a similar theory, and then it would be all over. As he explained, there would be a lot to do, of course, but physics as we knew it—more or less groping blindly around in our optimistic way, that portion of physics—would be behind us. 我的演讲就要结束了，我只想再给你们讲一个小故事。如你所见，我可以继续讲故事，讲很久，很久。但接下来的故事是一个你们应该记在心里的故事。 我和我的导师奥托·斯特恩一起去拜访了伟大的马克斯·波恩[46]，他当时凭借着他对波函数的概率解释等等，正处于辉煌的职业顶峰。在那次会面时，他非常严肃地告诉我们，在六个月后，我们所知道的物理学将会结束。 这是一个相当大的打击！波恩有着令人印象深刻的个性，他这样说是有一定道理的，因为当时是1928年，狄拉克刚刚给我们提供了他神奇的电子理论。 除了相对论不变量之外，狄拉克没有做任何假设，他得出了电子的正确自旋和磁矩。人们想知道的关于电子的一切，除了相对论不变量之外，没有任何额外的假设。因此，这当然是一项了不起的成就。波恩显然认为，他周围的这些非常聪明的后辈用不了六个月就能从类似的理论中推导出质子的自旋和动量，然后一切都会结束。正如他所解释的那样，当然会有很多事情要做，但我们所知道的物理学——或多或少地以我们的乐观方式盲目摸索，那部分物理学——将成为我们的过去。[47] Well, I found Born’s prediction very hard to believe. In fact, I couldn’t actually let myself believe it. At my stage in life, I had far too much at stake. On the other hand, you will hear and see such predictions again as your careers develop. Most probably this will be particularly true for the graduate students and young people in the audience, because at every past period of synthesis in physics, the future looked closed. In Newtonian times, physics was a closed book. There were central gravitational forces, and equations describing what they could do. People tried to come up with solutions to these equations, but some types of problems led them to invent other forces. And of course, along came Maxwell’s theory of electromagnetism—all very beautiful, set, done, and apparently closed. But occasionally Nature does something strange, such as the photoelectric effect, which appeared just at the peak, the very triumph, of the Maxwell theory. It was uncovered first by accident during Heinrich Hertz’s experiments on the detection of electromagnetic waves [48], but he missed its significance and was unable to explain it. And so I have come to think that physics is a never-ending quest. In closing, there is one other mystical thought that occurs to me. Now, in a day when we need all this big equipment for physics experiments, such as those vast accelerators that we have, I began to think: Will God reveal himself only to rich people? Would it really be true that you had to have a very wealthy country with a large population in order to get some basic information about how the universe is made? At this point I am a mystic, and I don’t believe that only the rich and powerful can achieve true understanding. And I suppose it is up to you to prove me right. Thank you. And I love questions. 好吧，我发现波恩的预言非常难以相信。事实上，我真的无法让自己相信。在我的人生阶段，我有太多的风险。另一方面，随着你们事业的发展，你们会再次听到和看到这样的预言。很可能这对研究生和观众中的年轻人来说尤其如此，因为在过去的每一个物理集大成之时，未来看起来都是封闭的。 在牛顿时代，物理学是一本封闭的书。有中心的引力，以及描述它们能做什么的方程式。人们试图想出这些方程的解，但某些类型的问题导致他们发明了其他力。麦克斯韦的电磁学理论也随之而来——所有这些都是非常优美、完备，而且显然是封闭的。但是，自然界偶尔也会做出一些奇怪的事情，例如光电效应，它出现在麦克斯韦理论登峰造极，冠绝天下的时候。它首先是在海因里希·赫兹[49]的电磁波探测实验中被偶然发现的，但赫兹错过了它的意义，无法解释它。所以我开始认为物理学是一个永无止境的探索。 最后，我还有一个迷思。现在，在我们需要所有这些大型设备进行物理学实验的日子里，比如我们拥有的那些巨大的加速器，我开始思考：上帝会不会只向富人揭示自己？难道真的要有一个非常富裕的国家，人口众多，才能得到一些关于宇宙如何形成的基本信息吗？在这一点上，我是一个神秘主义者，我不相信只有有钱有势的人才能达到真正的理解。而且我想应该由你来证明我是对的。[50] Discussion 讨论 Jan van Kranendonk: A very down-to-earth question, perhaps.When you worked with Otto Stern, from what funds were the experimental apparatus supplied? How was this research work funded? Rabi: That’s a very good question. There was something, I think, called “der Notgemeinschaft der Deutschen Wissenschaft.” Somebody might properly translate this, but it’s the Society of Need for grants, but I don’t know whether it came from rich people or from the government. But the greater part of researchers’ money, at least in some cases, came naturally from America. Didn’t we beat the Germans in 1918? And now we had to pay! The Rockefeller Foundation, and other foundations, supported students—people like Felix Bloch and Edward Teller. Many other people applied for and got Rockefeller fellowships and grants. They had equipment in the laboratories at Hamburg that we certainly didn’t have at Columbia—and it was funded by American money. And very wisely, the Rockefeller Foundation was interested in getting good research and the best science for its money. And that was to be found in Germany at that time. That’s where they spent it. My eyes boggled when I saw all the equipment they had in Hamburg that I couldn’t get in America. There were special kinds of vacuum pumps and other things. They had pumps which would cost $200 or $300, which was an enormous sum then. inferiority for American science. But when I came home and started doing research, I had to get pumps for $8. Jan van Kranendonk：一个非常朴素的问题，也许。 当您与奥托·斯特恩合作时，实验装置是由哪些资金支持的？这项研究工作是如何资助的？ Rabi：这是一个非常好的问题。有一个叫做“der Notgemeinschaft der Deutschen Wissenschaft”的机构。有人可能可以适当地翻译这个，我的翻译是德国科学需求协会，他们会获得一些资金资助，但我不知道这是来自富人还是政府。但至少在某些情况下，研究人员的大部分资金自然来自美国。我们不是在1918年打败了德国人吗？现在我们必须付出代价了！ 洛克菲勒基金会和其他基金会支持学生——像费利克斯·布洛赫 和爱德华·泰勒 这样的人。很多人申请并获得了洛克菲勒基金会的奖学金和资助。他们在汉堡的实验室里有我们哥伦比亚大学肯定没有的设备，而且是由美国资助的。洛克菲勒基金会非常明智地运用它的资金获得最好的科研条件。那时候，这些高级设备都可以在德国找到。这就是他们花钱的地方。 当我看到汉堡的所有设备时，我的眼睛都要瞪出来了，因为我在美国买不到这些设备。有一些特殊的真空泵和其他东西。他们有一些泵，要花费200或300美元，那时候是一笔巨款。但是当我到美国开始做研究时，我不得不花8美元买泵。 So you can see how research in Germany was funded: There was an enormous respect in the United States for German science, and an enormous feeling of inferiority for American science. I think, as [J. Robert] Oppenheimer once expressed it, “We went to Germany, so to speak, on our hands and knees.” But it took only a very short time, in the post–World War II period, for the whole flow to be reversed. In 1926 you couldn’t get anywhere with English in Germany, because they didn’t know any. I remember how surprised one German was to hear another German speak English. And if you wanted your research to be recognized, you would publish either in German or in the British journal Nature. And you can compare that with today; English has almost become a universal language. But I would like to warn you: From 1927, the year that I was talking about, to 1937 or the beginning of the 1940s was only about 10 years, and during that time there was a reversal. And some of you who are very proud of not knowing any other language but English have got to learn some foreign languages. One other point about that: I know at Columbia they have also And you can compare that with today; English has almost become a universal language. But I would like to warn you: From 1927, the year that I was talking about, to 1937 or the beginning of the 1940s was only about 10 years, and during that time there was a reversal. And some of you who are very proud of not knowing any other language but English have got to learn some foreign languages. One other point about that: I know at Columbia they have also abolished the language requirements for the PhD. This is an enormous mistake. If you want to read the originals of many important physics papers from the earlier part of the 20th century and most of the previous century, you won’t be able to read them in English. Most of these original papers have not been translated into English, and you don’t get the flavor of the original papers from textbooks. So I would suggest you take that very seriously to heart and learn some other languages. I don’t know which, it’s your guess . . . maybe Dutch [said with a kind smile toward van Kranendonk, referring to his slight accent]. Question: Could you elaborate further on how it was that you could appear, apparently unannounced, to work at the institute that you spoke about, and they knew that you would be acceptable? Is that what you intended to say? Rabi: I was intending to show another period of time, when the world was simpler, and despite the first great World War, it still had that simplicity. Ascholar could roam around and be accepted where he went. I didn’t mean to put this to the test. But being a romantic, and an American, it didn’t seem to me necessary to prearrange things. I mean that this favorable reception didn’t surprise me. I just thought it was normal. 所以你可以看到德国是如何资助的研究的：美国对德国的科研有着极大的尊重，而对本国的科研则有着极大的自卑感。 正如罗伯特·奥本海默曾经表达过的那样，“我们可以说是跪着去德国的。”但在二战后不久，整个过程就被逆转了。1926年，在德国你无法用英语去任何地方，因为他们不懂英语。我记得有一个德国人听到另一个德国人说英语时感到非常惊讶。如果你想让你的研究得到认可，你要么用德语发表，要么用英国期刊《自然》发表。 你可以将那个时代与今天进行比较；英语如今几乎已经成为一种通用语言。但是我想警告你：从1927年到1937年或40年代初，只有大约10年的时间，情况就发生了逆转。那些非常自豪地只会英语而不会其他语言的人必须学习一些外语。关于这一点还有一件事：我知道在哥伦比亚大学，他们取消了博士学位的语言要求。这是一个巨大的错误。 如果你想阅读20世纪早期和上个世纪大部分重要物理论文的原文，你无法用英语阅读它们。这些原始论文中的大多数都没有被翻译成英语，而且你无法从教科书中获得原始论文的韵味。所以我建议你认真对待这个问题，并学习一些其他语言。我不知道是哪种语言……也许是荷兰语（对van Kranendonk微笑着说，指他轻微的口音）。 问题：您能进一步阐述一下，您是如何在没有事先通知的情况下出现在你所说的研究所工作的，而且他们知道您是可以被接受的？这是您想要表达的吗？ 拉比：我打算向你介绍另一个时期，那时世界还很简单，尽管经历了第一次世界大战，但它仍然保持着那种简单。学者可以四处漫游，并被接受。我不是故意要测试这个的。但作为一个浪漫主义者和美国人，我觉得没有必要事先安排好。我的意思是，这种良好的接待并没有让我感到惊讶。我只是认为这很正常。 It is only when I look back on that time, especially with modern terms in mind, that I am surprised that nobody asked who funded me. At Hamburg, I had an idea for an experiment and I was invited to do it, and so I did it. But nobody asked me, “Are you funded?” No one at all. They gave me the equipment, and space, and so on. I had a marvelous time doing it. We showed the Germans something that we called the “Amerikanische Arbeitsmethode,” the American way of working. Usually the laboratory was opened strictly at 7am and then closed at 7pm—it was all so very un-American. We would come at 10am, and then, around 11 o’clock, the wives would come and make toast, crumpets, and so on while we went on doing our physics experiment. And we finished in very good time. It really worked. Also we were very happy while doing it. We’d have requests from the top floor of the building, “Would you please sing more quietly?” So it wasn’t a time when you gritted your teeth and did an experiment. It was a joy all the time. That’s the only way to do physics, I think. Van Kranendonk: Perhaps I can ask a different question. You said that you were associated with Pauli, and I know that Pauli had a big reputation for being quite vicious. How did you find him? How did you like him and interact with him? Did you understand how he was when he worked? Rabi: I have seen him being extremely vicious, as you say. I think I got along with him very well, but it was a result of a mistake that I made. Right after I came to Hamburg, I told him about some calculations I was making on the hydrogen molecule. And we had a misunderstanding between the Roman letter p and the Greek letter π [the latter is pronounced “pea” in both German and Greek]. When Pauli said “pea,” I though he meant the Roman letter p [momentum], but he meant the number π. And so I said, my German being pretty poor, “Aber das ist Unsinn!” (That’s nonsense!) Nobody ever said that to Pauli. He rolled around and he said “Um . . . ist das Unsinn?” Somehow I had gotten in the first blow! But, you know, I was so upset by the way he did talk to people, until I saw that he was completely democratic—he talked the same way to Bohr. This was just Pauli’s character, it was just Pauli’s own way. There was something called the “Pauli effect,” which states that wherever Pauli went, misfortune followed. Not for Pauli, but for others. 只有当我回顾那个时期时，特别是在现代条件下，我才会惊讶于没有人问过谁资助了我。在汉堡，我有一个实验的想法，然后被邀请去做它，所以我就做了。但没有人问我，“你有资助吗？”没有人。他们给了我设备、空间等等。我做得非常愉快。 我们向德国人展示了我们称之为“美国式”的工作方法。通常实验室严格在早上7点开门，然后在晚上7点关门——这一切都非常不符合美国作风。我们会在上午10点左右到达，然后在11点左右，妻子们会来烤面包、松饼等等，而我们则继续进行物理实验。我们很快就完成了。真的很有效。而且我们做实验的时候非常开心。我们曾收到楼上的请求，“请你们唱得更轻一些好吗？”所以那不是你咬紧牙关做实验的时候。那是一段很愉快的时光。我认为这是研究物理的唯一方法。 Van Kranendonk：也许我可以问一个不同的问题。你说你和泡利有关系，我知道泡利因为刻薄而闻名。你是怎么看待他的？你喜欢他吗？你是如何与他互动的？你了解他工作时的情况吗？ 拉比：正如你所说，我见过他极度刻薄的样子。我认为我和他相处得很好，但这是我犯的一个错误。我刚来到汉堡，就告诉他我正在对氢分子进行一些计算。我们之间有一个罗马字母p和希腊字母π之间的误解【后者在德语和希腊语中都发音为“pea”】。当泡利说“pea”时，我以为他是指罗马字母p【动量】，但他指的是数字π。所以我说，我的德语相当差，“Aber das ist Unsinn！”（那是胡说八道！） 没有人对泡利说过这样的话。他转过身来，说：“Um…ist das Unsinn？”（嗯…这是胡说八道吗？）不知怎么地，我先下手了！但是，你知道，他谈话的方式让我很不高兴，直到我看到他完全是一视同仁的——他对玻尔也是这样说话的。这只是泡利的性格，这只是泡利自己的方式。 有一种叫做“泡利效应”的东西，它表明无论泡利走到哪里，不幸都会随之而来。不是对泡利本人，而是对其他人。 Pauli had visited the astronomical observatory in Hamburg. The astronomers talked to him and then forgot about what they were doing, so the telescope hit the dome. Pauli caused things of that sort to happen. Stern would never let him into the laboratory. They were good friends, and Pauli would knock on the door and would usually want to borrow some money, and they would make their transaction right at the door. I saw one of the most remarkable examples of the Pauli effect at a Physical Society meeting in Leipzig. News had come from America about the invention of talking pictures, and this local professor, I forget his name, was going to give a demonstration of them. The equipment was all set up, and when the assistant threw the switch . . . bang! bang! bang! came out of the loudspeaker, and then smoke. Pauli was beside himself. He shouted out, “My effect!” And they brought up another projector, and the same thing happened. Then they had a third one set up in a balcony above, where I suppose they used to have music of some sort. They connected that projector, and it worked, which showed the relationship between distance and the Pauli effect. But the real explanation was given by Paul Ehrenfest. You see, Pauli was born in 1900, the beginning of the 20th century, which was just an illustration of the fact that misfortunes could never come up singly. The 20th century has been a terrible century. In terms of Pauli, misfortunes never did come singly. Derek York: Do you know anything more about why Sommerfeld never received the Nobel Prize? If so, is there any inside story on this? Rabi: I haven’t heard any inside story about it, and I don’t think anybody would have raised any objection if he had been given the prize. But you must remember that the Nobel Prize is given by a committee of the Swedish Academy, and they have their own idiosyncrasies. You know, there was a book published some 25 years ago about the various Nobel awards. It discussed many things, for example, about why didn’t Dmitri Mendeleyev get the Nobel Prize. It suggested some mistakes of the committee of the Swedish Academy. They were very human. When the Nobel Prize was established, the choice of the awards was up to the Royal Swedish Academy, and they had very sincere doubts that they had the capacity to make such judgments. They felt they didn’t have enough members that were au courant enough and mature enough to make good judgments. I must say that their early judgments were terrible. But they gave it to Albert Michelson, and they gave it to Pieter Zeeman. They really had a tremendous field to choose from, and I think that is what established the Nobel Prize with such prestige. In addition, the Nobel Prize is presented by the king and queen in royal fashion. All the Nobel recipients are able to live for a few days in the manner to which they would like to become ccustomed. Van Kranendonk:Well, perhaps on this note we should end, and may I then ask you to join me in thanking Professor Rabi for his visit, for his talk. And let’s send him our best wishes. 泡利曾经参观过汉堡的天文台。天文学家们和他交谈，然后忘记了他们正在做什么，所以望远镜撞上了圆顶。泡利常会引起这样的事情发生。斯特恩永远不会让他进入实验室。他们是好朋友，泡利会敲门，通常想借点钱，他们会在门口完成交易。 我在莱比锡的物理学会议上看到了最显著的泡利效应实例。从美国传来了有关发明说话影片的消息，当地的一位教授，我忘记了他的名字，要进行演示。设备都准备好了，当助手按下开关时……砰！砰！砰！从扬声器里传出声音，然后冒出烟雾。泡利失态了，他大喊：“我的效应！”他们拿来另一个投影机，同样的事情发生了。然后他们在一个楼上的包厢里安装了第三个投影机，在那里我想他们以前播放过某种音乐。他们连接了那个投影机，它终于正常运作了，这表明距离和泡利效应之间的关系。 但泡利效应真正的解释是由保罗·埃伦费斯特给出的。你看，保利出生于1900年，20世纪初，这只是说明不幸永远不可能单独出现的事实。20世纪是一个可怕的世纪。对于泡利来说，不幸从来没有单独出现过。 Derek York：你知道为什么索末菲没有获得诺贝尔奖吗？有没有更多信息？如果是这样，有没有内幕故事？ 拉比：我没有听说过任何内幕故事，我认为如果他获得了奖励，没有人会提出任何反对意见。但你必须记住，诺贝尔奖是由瑞典学院的委员会颁发的，他们有自己的怪癖。你知道，大约25年前出版了一本关于各种诺贝尔奖的书。它讨论了许多事情，例如，为什么德米特里·门捷列夫[54]没有获得诺贝尔奖。它指出了瑞典学院委员会的一些错误。他们也不过是人而已。 当诺贝尔奖成立时，奖项的选择由瑞典皇家科学院决定，他们非常真诚地怀疑自己是否有能力做出这样的判断。他们觉得自己没有足够的成员，也了解的不够充分，也不够成熟，无法做出好的判断。我必须说，他们早期的判断是糟糕的。 但是他们把诺贝尔奖颁给了阿尔伯特·迈克尔森[55]，给了彼得·塞曼[56]。他们真的在很大的范围内挑选，我想这就是诺贝尔奖的威望所在。此外，诺贝尔奖以皇家方式由国王和女王颁发。所有诺贝尔奖获得者都可以在几天内以自己想要的方式生活。 Van Kranendonk：好吧，也许我们应该就此结束，然后请大家和我一起感谢拉比教授的访问和他的演讲。让我们向他致以最美好的祝愿。 Another view of things 对事情的另一种看法 One thing that I learned contains a tremendous amount of anthropology in just one sentence. One of Otto Stern’s assistants was a man by the name of Fritz Knauer. One time I was telling Knauer that in my country you could travel from one place to another and you didn’t have to register with the police—you just traveled freely. Knauer looked shocked at this, and he said to me, “You mean to say that you can live and die in America, and nobody cares?” Now that may sound very funny to you, but it shows the other end of the telescope. Something that I thought was an awful imposition—registering with the police—was to him a great support. It takes quite a bit of training to live in a democratic country like America, it takes a lot of training indeed. Some people who came to America, such as Russian refugees, have been shocked to learn that they have to find a job by themselves. 我学到的一件事仅仅是一句话就包含了大量的人类学知识。奥托·斯特恩的一个助手叫Fritz Knauer。有一次我告诉克瑙尔，在我的国家，你可以从一个地方旅行到另一个地方，你不必向警察登记——你只是自由地旅行。Knauer看起来很震惊，他对我说:“你的意思是说，你可以在美国生活和死亡，没有人在乎?”这听起来可能很有趣，但它展示了望远镜的另一端。在我看来是一件可怕的事情——向警察登记——对他来说却是一种极大的支持。在美国这样的民主国家生活需要很多训练，确实需要很多训练。一些来到美国的人，比如俄罗斯难民，震惊地发现他们必须自己找工作。 注释 [1] 伊西多·艾萨克·拉比（1898.7.29—1988.1.11），美国犹太裔物理学家，因发现核磁共振（NMR）而获得1944年的诺贝尔物理学奖。基于核磁共振技术发展出的核磁共振成像普遍运用于医疗、科研领域。资料来源：https://en./wiki/Isidor_Isaac_Rabi。 [2]欧内斯特·卢瑟福（1871.8.30.—1937.10.19），新西兰物理学家，世界知名的原子核物理学之父。1908年，卢瑟福凭借他对元素的衰变以及放射化学的研究获得诺贝尔化学奖。资料来源：https://en./wiki/Ernest_Rutherford [3] DeSoto（有时也写作De Soto）是一种美国汽车品牌，由克莱斯勒公司的DeSoto部门从1928年到1961年生产和销售。现在已经不再生产。资料来源：https://en./wiki/DeSoto_(automobile) [4]二十世纪初，物理学经历了量子力学与相对论的重大变革。二十世纪二十年代左右玻尔、海森堡、薛定谔等人逐渐将量子理论形式化。相对论在1905（狭义）和1915（广义）年分别被爱因斯坦两次推进。由于学术底蕴较差等原因，这时候的大部分进展都不发生在美国。 [5]阿诺尔德·索末菲（1868.12.5—1951.4.26），德国物理学家，量子力学与原子物理学的开山始祖之一。他发现了精细结构常数，这是电磁相互作用中电荷之间耦合强度的无量纲度量。他也是一位杰出的老师，教导和培养了很多优秀的理论物理学家，如海森堡、泡利等。资料来源：https://en./wiki/Arnold_Sommerfeld。 [6]原注1：E. Schrödinger, Ann. Phys. (Leipzig) 79, 361 (1926). [7]原注2：M. Born, Vorlesungen über Atommechanik (Lectures on the Mechanics of Atoms), J. Springer, Berlin, Germany (1925). [8]学术小组的成员除拉比外，还有拉尔夫·克朗尼格、杰拉尔德·查卡洛斯以及中国最早的理论物理博士——王守竞。资料来源：https://mp.weixin.qq.com/s?__biz=MTg1MjI3MzY2MQ==&mid=401867619&idx=1&sn=3c21e8e52bca281e6bd8ab5247732f46&chksm=d45827f1e32faee753bac573ca95020868b612ab707ed71fbe1c383a1cd38c360d80d3ea192a&scene=27。 [9]拉尔夫·克朗尼格（1904.3.10—1995.11.16），德国/美国物理学家。克勒尼希因发现粒子的自旋和x-射线吸收谱理论而知名。他提出了克勒尼希-宾尼模型，科斯特-克勒尼希转变和克喇末-克勒尼希关系。资料来源：https://en./wiki/Ralph_Kronig。 [10] 分子的两个主轴的转动惯量相等情况下的转动薛定谔方程 [11]原注3：R.：D. Kronig, I. I. Rabi, Phys. Rev. 29, 262 (1927). [12]原注4：M. Born, Z. Phys. 37, 803 (1926). [13]卡尔·雅可比（1804.12.10- 1851.2.18）是一位德国数学家，为椭圆函数、动力学、微分方程、行列式和数论奠定了基础。资料来源：https://en./wiki/Carl_Gustav_Jacob_Jacobi [14]量子力学神奇与反常识的点在于整个世界变得不确定，我们只能描绘未来某事件的概率而不是直接预测未来。 [15]在波函数表示出来之前，旧量子论也能对一些量子力学中的现象进行唯相解释。 [16]解析的复变函数的实部和虚部有一定关系 [17]描绘光子和原子中的电子的散射截面 [18]原注5：J. H. Van Vleck, Quantum Principles and Line Spectra, National Research Council (US), Washington, DC (1926). [19]约翰·范弗莱克（1899.3.13—1980.10.27），美国物理学家。1977年，因为对磁性和无序体系电子结构的基础性理论研究，与菲利普·安德森、内维尔·莫特共同荣获诺贝尔物理学奖。资料来源：https://en./wiki/John_Hasbrouck_Van_Vleck。 [20]沃尔夫冈·泡利（1900.4.25—1958.12.15），奥地利理论物理学家，是量子力学研究先驱者之一。1945年，他因泡利不相容原理而获得诺贝尔物理学奖。泡利不相容原理涉及自旋理论，是理解物质结构乃至化学的基础。资料来源：https://en./wiki/Wolfgang_Pauli。 [21]比如说描绘宏观物理量对于时间的演化，很多情况下矩阵力学更方便。 [22] 保罗·狄拉克（1902.8.8—1984.10.20），英国理论物理学家，量子力学的奠基者之一.他统合了维尔纳·海森堡的矩阵力学和埃尔温·薛定谔的波动力学，发展出了量子力学的基本数学架构。资料来源： https://en./wiki/Paul_Dirac。 [22]原图注1：Michael Pupin (1858–1935) at Columbia University, probably in the late 1920s. Pupin and I. I. Rabi were part of asmall group at Columbia that was trying to figure out quantum mechanics in 1926. (Courtesy of AIP Emilio Segrè Visual Archives.) [23]翻译如下：迈克尔·普平（1858-1935）在哥伦比亚大学。20世纪20年代末左右。普平和I.I. 拉比是哥伦比亚大学的一个小团体的成员，在1926年，他们试图弄清量子力学。(由AIP Emilio Segrè视觉档案提供)： [24]米哈伊洛·普平（1858.10.9—1935.3.12），塞尔维亚物理学家。普平以专利闻名，其发明成功延长长途电话的通信范围。 [25]原注6：I. I. Rabi, Phys. Rev. 29, 174 (1927). [26]波动力学通过波函数的描述似乎更容易让人接受，是因为波动方程与波函数来描述这个世界看上去更像是一种从更基本的东西出发来构建整个体系。海森堡的矩阵力学则是从可观测量出发，通过与哈密顿算符对易来得到系统随时间演化，看上去更加抽象，考虑到当时物理学家并没有必修线性代数，可能对矩阵操作也不太熟悉。现在看来，两种量子力学表述是等价的，在一些情况下还可以互相弥补劣势。 [26]莱纳斯·鲍林（1901.2.28—1994.8.19），美国化学家，量子化学和结构生物学的先驱者之一。1954年因在化学键方面的工作取得诺贝尔化学奖，1963年因反对核弹在地面测试的行动获得1962年度的诺贝尔和平奖。资料来源：https://en./wiki/Linus_Pauling [27]汉斯·贝特（1906.7.2-2005.3.6），德国和美国犹太裔核物理学家，对于天体物理学，量子电动力学和固体物理学有很重要的贡献。由于恒星核合成理论研究成果，他获得了1967年诺贝尔物理学奖。资料来源：https://en./wiki/Hans_Bethe [28]鲁道夫·佩尔斯爵士（1907.6.5-1995.9.15），出生于德国的犹太裔物理学家，后加入英国籍。是英国核计划中的重要人物，为原子弹的制造奠定了理论基础。资料来源：https://en./wiki/Rudolf_Peierls [29]阿尔布雷希特·恩瑟尔德（1905.4.20-1995.9.23），德国天体物理学家，对恒星大气的光谱分析做了重要贡献。资料来源：https://en./wiki/Albrecht_Unsöld [30]爱德华·康登（1902.3.2.-1974.3.26），是一位美国杰出的核物理学家、量子力学的先驱，与二战期间参与发展核武器和雷达。资料来源：https://en./wiki/Edward_Condon。 [31]霍华德·珀西·罗伯逊（1903.1.27-1961.8.26），美国数学家和物理学家，对物理宇宙学和不确定性原理做出了贡献,独立提出了宇宙膨胀。资料来源：https://en./wiki/Howard_P._Robertson。 [32]尼尔斯·玻尔研究所是哥本哈根诠释的诞生地，在上世纪二三十年代是原子和量子物理研究的中心。 [33]奥斯卡·克莱因（1894.9.15—1977.2.7），瑞典物理学家。提出了蜷曲的额外维度概念，对弱相互作用力也有研究。资料来源：https://en./wiki/Oskar_Klein。 [34]帕斯库尔·约尔当（1902.10.18—1980.7.31），德国理论和数学物理学家，他在量子力学和量子场论方面做出非常重要的贡献。他对矩阵力学的数学形式贡献颇多，并且发展了费米子的正则反对易关系。资料来源：https://en./wiki/Pascual_Jordan。 [35]伊瓦尔·沃勒（1898.6.11-1991.4.12）是瑞典乌普萨拉大学的理论物理学教授。他在彼得-德拜之前的工作基础上，发展了晶体晶格振动对X射线的散射理论。资料来源：https://en./wiki/Ivar_Waller。 [36]尼尔斯·玻尔（1885.10.7—1962.11.18），丹麦物理学家，1922年因“他对原子结构以及从原子发射出的辐射的研究”而荣获诺贝尔物理学奖。资料来源：https://en./wiki/Niels_Bohr。 [37]仁科芳雄（1890.12.6—1951.1.10），日本物理学家，被誉为日本现代物理之父。他在第二次世界大战期间领导日本核研究计划。与奥斯卡·克莱因提出量子场论中的光子与电子散射的克莱茵－仁科方程式。资料来源：https://en./wiki/Yoshio_Nishina。 [38]沃尔特·戈登（1893.8.13-1939.12.24），是一位德国理论物理学家。奥斯卡·克莱因和沃尔特·戈登提出了克莱因·戈登方程，即在相对论的框架内描述量子粒子。资料来源：https://en./wiki/Walter_Gordon_(physicist)。 [39]威廉·楞次（1888.2.8-1957.4.30）是一位德国物理学家。发明了著名的伊辛模型。他应用拉普拉斯-龙格-楞次向量于氢原子的旧量子论，关键性地导引出氢原子的发射光谱。资料来源：https://en./wiki/Wilhelm_Lenz。 [40]奥托·施特恩（1888.2.17—1969.8.17），德国裔美国核物理学家及实验物理学家。他发展了核物理研究中的分子束方法并发现了质子磁矩，获得了1943年度的诺贝尔物理学奖。资料来源：https://en./wiki/Otto_Stern。 [41]原注7：Y. Nishina, I. I. Rabi, Verh. Deut. Phys. Ges. 9, 6 (1928). [42]原图注2:Yoshio Nishina and Rabi in 1948. The two men wrote a paper together as part of Wolfgang Pauli’s group in Hamburg, Germany, in 1927. (Courtesy of AIP Emilio Segrè Visual Archives.) 翻译如下：1948年，仁科芳雄与拉比。1927年，在德国汉堡，保利的小组中，两人一起写了一篇论文。(AIP Emilio Segrè视觉档案馆提供。) [43]原注8：I. I. Rabi, Nature 123, 163 (1929); Z. Phys. 54, 190 (1929). [44]瓦尔特·格拉赫（1889.8.1—1979.8.10），德国物理学家，于1921年与奥托·施特恩通过施特恩－格拉赫实验共同发现原子在磁场中取向量子化的现象，以此闻名。资料来源：https://en./wiki/Walther_Gerlach。 [45]原注9: P. A. M. Dirac, Proc. R. Soc. London, Ser. A 117, 610 (1928); 118, 351 (1928). [46]马克斯·玻恩（1882.12.11—1970.1.5）,德国理论物理学家与数学家，对量子力学的发展做出了重要贡献，在固体物理学及光学方面也有所建树。1954年，玻恩因“在量子力学领域的基础研究，特别是对波函数的统计诠释”而获得诺贝尔物理学奖。资料来源：https://en./wiki/Max_Born。 [47]在上世纪物理学的黄金时代，有很多新现象激发着人们去解释，而这一时代已经过去。 [48]原注10： H. Hertz, Ann. Phys. (Leipzig) 33, 983 (1887). [49]海因里希·赫兹（1857.2.22—1894.1.1），德国物理学家，于1887年首先用实验证实了电磁波的存在。他对电磁学有很大的贡献，故频率的国际单位制单位赫兹以他的名字命名。资料来源：https://en./wiki/Heinrich_Hertz。 [50]当今的物理学的确面临着实验所需人力财力越来越大的问题，为了研究基础物理理论需要进入更高的能标，而对撞机、大型的天文望远镜、引力波探测器等都很烧钱。 [51]费利克斯·布洛赫（1905.10.23至1983.9.10）,瑞士物理学家。他和爱德华·珀塞尔因“开发了核磁精确测量的新方法和新方法”而被授予1952年诺贝尔物理学奖。 资料来源：https://en./wiki/Felix_Bloch。 |
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