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This article comes from the official account of Wechat: ID:fanpu2019, author: Eric. Johnson (Associate Professor, Department of Chemistry, Mount St. Joseph University of Cincinnati), translator | 1Compact 137

Paul Ellenfester, an Austrian physicist, was an important physicist in the early 20th century, but to some extent he has been forgotten by later generations. In his early years, he studied with giants such as Hilbert and Klein in Gottingen, and later became a student of Boltzmann. Ellen Fester made outstanding contributions in the fields of statistical mechanics, quantum mechanics and the theory of relativity. His clear expression of the problem, as well as his seriousness and dedication in teaching students, is regarded by his peers as the best teacher. Ellen Fester is also a good friend. He has established a deep friendship with Einstein, Bohr and others. Bohr's famous picture of quantum mechanics was taken at Ellenfester's home. However, because of his confusion about the rapid development of the "raging era" of physics and the changes in his family and society, Ellenfest finally took a tragic path similar to that of his mentor-only 53 years old. He committed suicide after shooting his son.

Ellen Fester is largely a forgotten figure, but he is loved by the smartest students and the most important scientists of the 20th century.

Ellen Fester's efforts are perhaps best recognized by what his peers privately call him: the conscience of physics (the conscience of physics). Photo Source: Wikipedia / The MIT Press Reader if we judge from the friends they make, Paul Ehrenfest must be a great scientist. Einstein once called him "the best teacher in our profession as far as I know". Niels Bohr, a pioneer in quantum physics, is a close friend and a regular in his family. The leaders of the Manhattan project, Enrico Fermi and Robert Oppenheimer, both received postdoctoral training at Ellenfester's lab at Leiden University, although Ellenfest's personal contribution was slightly lower. Today, he is largely a forgotten character, even among physicists. So why is he considered to be a great scientist?

Eric Johnson is the author of anxiety and equations: understanding Boltzmann Entropy (Anxiety and the Equation: Understanding Boltzmann's Entropy), which describes the work and life of Boltzmann, an anxiety-plagued physicist in the 19th century. Any greatness of Ellenfester in science is inextricably linked to the academic legacy of his doctoral mentor, Ludwig Boltzmann. As a 19th-century physics giant, Boltzmann played an important role in our understanding of gas-a theme that may not capture the imagination of people in the 21st century, but it played a key role in the development of thermodynamics. By modeling gases as a collection of atoms and following statistical rules, Boltzmann constructed a microscopic basis for the elusive second law of thermodynamics. The importance of this work was later found to go far beyond the study of gases, affecting the fields of cryptography and economics, and even the large-scale structure of the universe.

For Ellen Fester, however, the excitement about Boltzmann from these discoveries had faded long before he met his mentor. Although Boltzmann is still a famous scientist at home and abroad, he suffers from self-doubt and self-pity. He was an exhausted old man, no better than Ellen Fester's inner expectation, especially a mentor like him who had made such a great discovery. Their relationship has never reached its full potential, and even their interaction in class seems to have become unnecessarily complex. In an oft-mentioned story, Ellen Fester won Boltzmann's favor because he quoted Boltzmann's work in particular detail to the rest of the class. Boltzmann jokingly replied, "if only I knew so much about my work!" But people remember that Ellen Fester also frustrated his mentor. In another class exchange, Boltzmann accused the young man of treating him like a lemon that could drain the juice. Apparently Ellen Fester just wanted the professor to clear up some confusion. But his irrepressible desire to communicate-personality traits that turned out to be crucial to Ellenfester's success-may have alienated him from the elder.

Boltzmann, Photo Source: Wikipedia, but in the end, it may not matter. Boltzmann committed suicide just two years after receiving his doctorate from Ellen Fester. Although it seems inappropriate to find anything positive in a person's suicide, in retrospect, Boltzmann's death clearly created an opportunity for Ellenfester, an opportunity in the form of unfulfilled obligations. Shortly before his death, Boltzmann agreed to write an article for the prestigious Encyclopedia of Mathematical Science (Encyclopedia of Mathematical Sciences) on the statistical basis of the second law. When the unfinished article suddenly lost its original author, Felix Klein, the editor of the Encyclopedia, needed a replacement, which prompted him to turn to Ellenfester for help. Klein met Ellen Fester at a math seminar, where the newly awarded doctorate made an unusually clear statement on the notoriously thorny issue of the second law. In that speech, Ellen Fester introduced a simple model that clarified many of the more controversial aspects of Boltzmann's work. The model does not rely on overly complex mathematical calculations, but only on a thought experiment in which balls are randomly selected to move back and forth between two jars, or in a more humorous version, fleas jump around on two dogs, commonly known as the dog-flea model (dog-flea model). Whether it's a ball in a jar or a flea in a dog, it shows how particles are distributed in space and how this distribution evolves over time. The model embodies the characteristics of Ellenfester's method and reveals his fundamental talent as a scientist. He is the most important teacher of his generation.

The mathematics seminar led to the article in the Encyclopedia. The article in the Encyclopedia contributed to the professorship of Ellenfester. The professorship also contributed to those friendships and cooperation, which made him widely known. However, true greatness means a heritage, a historical need. Is Ellen Fester really that kind of scientist? What kind of talent does a teacher have to be recognized as great?

Think of Arnold Sommerfeld's comments-he nurtured Nobel laureates Werner Heisenberg and Wolfgang Pauli-"he lectured like a master," Sommerfeld wrote in a letter of recommendation for Ellenfester's application for the Leiden position. " I have never heard a person speak so charming, so talented. He knows how to make the most difficult things concrete and express them visually. The mathematical argument was transformed by him into an easy-to-understand image. "

Ellen Fester's methods outside the classroom are also noteworthy, especially his tenacity in training graduate students. George Uhlenbeck, a former student of Ellenfester, describes his educational experience at Leiden: "he basically works with only one student, and every afternoon of the week. He discusses with the students either the problem he is studying or the most recent paper in the literature he wants to know in detail. The discussion went on quickly." Urenbeck added, "by the end of the afternoon, the students were exhausted to death. Oddly enough, after a while, the tiredness disappeared, and a year later, both sides worked almost equally."

When the outstanding scientists of the 20th century work together to lay the foundation for modern physics, they want Ellen Fester to be there.

In Urenbeck's case, he not only survived his apprenticeship, but also made a fundamental discovery with his classmate Samuel Goudsmit-the nature of electron spin. Admittedly, he might not have made such a discovery if he had not first put up with Ellen Fester's stringent demands. Instructively, Ullenbeck's discovery gave him the honor he deserved. A scientist inferior to Ellenfester may distort the student's work into his own and steal the honor of the student's future. But it is clear that Ellen Fester is not only a great scientist, he is also a good man.

For this good man, there may be no more convincing character witness than his friend and colleague Albert Einstein. In his book Out of My Later Years, Einstein described Ellenfester as a man "passionate about the development and fate of mankind, especially his students." Understand others, gain their friendship and trust, help anyone involved in an external or internal struggle, and encourage talented young people-all of which are real elements of him, almost more important than immersion in scientific problems. " Einstein further pointed out that Ellenfester "always brings clarity and sharpness to discussion. He opposes vagueness and beating around the bush, using his wit, even downright rudeness, if necessary."

When the outstanding scientists of the 20th century worked together to lay the foundation for modern physics, they wanted Ellen Fester to be there. His peers realized that the scientific revolution needed not only revolutionary ideas, but also sharp thinkers to organize emerging stories. Ellen Fester is clearly a model of the latter category. His biographer, Martin Klein, describes his role in this way: "No one is more committed to creating the concepts of physics in the 20th century than he is, and no one is more committed to maintaining clarity and understandability in the torrent of revolution. His efforts have been recognized by his peers and are therefore privately known as the conscience of physics."

Unfortunately, Ellen Fester is not content to be merely a conscience of physics. He aspires to play a very different role and win a place among revolutionaries-a difference that seems increasingly impossible as he grows older. The younger generation (the generation he helped cultivate) is changing the nature of physics in a way that seems to reduce the value of his skills. For Ellen Fester, physics has always been a figurative thing. It gives way to concrete examples. It is not just a set of self-consistent mathematical propositions. (physics) meaning and understanding are contained in mathematics. But the younger generation has succeeded by turning to increasingly esoteric methods. So when physics began to slide irrevocably towards abstraction, Ellen Fester seemed to be left behind.

Bohr and Einstein debated quantum theory at their home in Leiden Ellenfester (December 1925). Source: Wikipedia made no secret of his confusion and shame. However, his shame is groundless and contradicts his daily experience. He has been highly regarded by the physics community; his colleagues still seek his advice. However, he felt excluded from communication, and a sense of lack of confidence that had been floating on the surface began to grow. In a letter to several former students, he wrote: "every issue of Zeitschrift f ü r Physik or Physical Review puts me in a blind panic. Kids, I really don't know anything." The students assured their mentor that he actually knew too many things. He found that the most puzzling problems-those related to emerging quantum theory-were major obstacles facing the physics community as a whole. (editor's note: Ellenfester's work on blackbody radiation can be seen in many derivations of blackbody radiation formulas and their significance in modern physical construction (3). They encouraged him to talk more openly about the challenges posed by quantum theory. He did it, but after some stimulation. He finally published an article in the Journal of Physics, one of the magazines that blindly panicked him. This article is entitled "some Inquiry questions about Quantum Mechanics" (Einige die Quantenmechanik betreffende Erkundigungsfragen). The response to this article confirms that Ellen Fester's "exploring the problem" is not a simple confusion, let alone a burden on anyone. His question actually points the way forward. As a result, Ellen Fester, in his own way, once again emphasized the need for clarity as an indispensable guide.

But in the end, it cost him the price and made the physics community lose its most important teacher. Ellen Fester followed Boltzmann's path to a tragic end. However, he will not make a hasty decision. The letter, which is often quoted as his suicide note, was actually written (but never mailed) a year before he committed suicide. In the letter he wrote [2]:

"my dear friends: Bohr, Einstein, Frank, Hergroz, Joffe, Kohnstamm and Tolman! In the next few months, I really don't know how to continue to bear the burden of life that has become unbearable. I'm gonna kill myself. If that day really comes, then I would like to know that I have written to you calmly and unhurriedly, and that your friendship has played such an important role in my life. In recent years, it has become increasingly difficult for me to understand the development of [physics]. After trying hard, I became more and more weak and miserable, and finally gave up in despair. Apart from suicide, I have no other "practical" possibilities. Forgive me. "

A year later, his opinion did not improve. In the end, it's not just a matter of physics. A failed marriage, the rise of Nazis in neighboring Germany, and the subsequent emigration of his old friend Einstein to the United States could all lead to the tragedy of September 25, 1933. Ellen Fester went to Amsterdam that morning, where he first met a former student. Although he plans to commit suicide later in the day, he clearly needs to play the role of mentor for the last time. After the meeting, he went to the Institute for suffering Children (Institute for Afflicted Children), where his 15-year-old son, Vasik, works. Vasik, who suffers from Down syndrome, was recently transferred to Amsterdam from a German clinic. The Nazis seized power earlier that year. After arriving at the institute, Ellen Fester met his son in the waiting room. He shot his son in the head with a pistol and committed suicide. It was an indescribable ending-an incredible act that betrayed his meaningful life. Ellen Fester is a great scientist, but not a keen judge of his life.

A brief introduction to the author

Eric Johnson is the dean and associate professor of chemistry at Mount St. Joseph University in Cincinnati University in Cincinnati. He is the author of anxiety and equations: understanding Boltzmann Entropy (Anxiety and the Equation: Understanding Boltzmann's Entropy).

Annotation

[1] the articles the Ellenfesters wrote for the Encyclopedia attracted widespread attention in academic circles at the time, along with other factors that led H.A.Lorentz of Leiden University to appoint Ellenfester as his successor to take over the professorship there.

[2] the original text is as follows: "My dear friends: Bohr, Einstein, Franck, Herglotz, Joff é, Kohnstamm, and Tolman! I absolutely do not know any more how to carry further during the next few months the burden of my life which has become unbearable... It is as good as certain that I shall kill myself. And if that will happen some time then I should like to know that I have written, calmly and without rush, to you whose friendship has played such a great role in my life. ... In recent years it has become ever more difficult for me to follow the developments [in physics] with understanding. After trying, ever more enervated and torn, I have finally given up in DESPERATION. ... I have no other 'practical' possibility than suicide... Forgive me. "

This article is translated from The Perils of Being Paul Ehrenfest, a Forgotten Physicist and Peerless Mentor (The Perils of Being Paul Ehrenfest, a Forgotten Physicist and Peerless Mentor | The MIT Press Reader). The translation made a slight change to the original topic.

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