Wolfgang Kroll (March 21, 1906 – February 28, 1992) was a German physicist who received his doctorate in physics from the University of Breslau in 1930. He spent the next few years in Leipzig conducting postdoctoral research with Werner Heisenberg.
Due to the power of the Nazi Party, Kroll left Germany in 1937 to teach in Hokkaido, Japan, and then arrived in the Japanese colony of Taipei in 1941, where he taught at the Preparatory Department of the Taihoku Imperial University. After the war, Kroll was invited to transfer to the as the university was renamed as National Taiwan University. He was promoted to associate professor and then to professor. He was the first full-time professor in Taiwan to hold a doctorate in theoretical physics after the war. Afterward, he was invited to teach in the Department of Physics of Tunghai University.
In August 1976, Kroll retired from the Department of Physics at National Taiwan University and became an honorary professor along with the following year. After his retirement, Kroll also taught part-time at the Chinese Culture University and other places. In the late 1970s, as Taiwan's economy began to take off, prices rose and Kroll's pension became relatively meagre, leaving him in a difficult position. On February 28, 1992, Kroll died of emphysema at National Taiwan University Hospital at the age of 87.
Life
Early years
Wolfgang Kröll was born on March 21, 1906, in Greifswald in the northern part of the German Empire.張幸真. 台灣知識社群的轉變－以台北帝國大學物理講座到台灣大學物理系為例: 20. 2003-07-31 [2012-06-11]. (Original content archived on 2015-06-28)林夏玉. 終生奉獻台灣物理教育的克洛爾教授 . 臺大校友雙月刊. 2006-03-01, (44) [2016-06-27]. (the original content is archived on 2016-03-04. When he was a child, Kroll experienced the First World War, when Germany was short of supplies and the elephants in the zoo were shot and killed, leading Kroll to eat their flesh.張秀蓉. 我們在做拼圖 -「克洛爾教授百年紀念歷史影像文物展」策畫始末. 臺大校友雙月刊.2006-11-01, (48) [2016-06-27]. (Original content archived on 2016-06-27) In the late 1920s, Kroll entered the University of BreslauCurrently the University of Wroclaw in Poland. where he studied theoretical physics and received his Ph.D. in physics from the university in 1930 with a thesis on Dirac's electron theory.張幸真. 克洛爾與台大物理系：一位德國教授在台灣. 古今論衡 (中央研究院歷史語言研究所).December 2003, : 101-128. issn 1561-0594Beiträge zur Quantenmeehanik der Dispersion und Magnetorotation in Diracs Theorie des Elektrons. Zeitschrift für Physik. 1930, (66): 69–108. In the same year, he received a fellowship from the German Science Aid Organization and went to Leipzig University to do postdoctoral research under Werner HeisenbergWinner of the 1933 Nobel Prize in Physics. for seven years.許仲平. 嗨！克洛爾教授.... 科學月刊 (科學月刊雜誌社).November 1993, 24 : 829-832. ISSN 0250-331X During this period, he also met Edward Teller, who would become the father of the hydrogen bomb. Between 1930 and 1937, Kroll published eight papers on quantum mechanics, magnetisation spectra, and thermoelectric effects, laying the foundation for his future independent research. After the Nazis gained power, Kroll often criticised current affairs. Although he was not Jewish, he was in danger because he was disliked by those in power. Therefore, with the help of his father and the university, Kroll began a solo exile to Japan in 1937.Jerome F. Keating. The Kroll connection. Taipei Times. 2016-01-28 [2016-06-27]. (Original content archived on 2016-01-28) Kroll stated that he chose to go to Japan to see the "fascinating East" and that he and his father had many friends in Japan.P. Hsu; G. Leung. JingShin Physics Symposium in Memory of Professor Wolfgang Kroll. World Scientific. 1996-11-18. ISBN 981-02-3126-1. The original content is archived on 2016-06-28).
There are two accounts of the way Kroll left Germany. According to Xu Zhongping, Kroll exchanged with Shin'ichirō TomonagaJapan's second Nobel Laureate in Physics. in Japan, while another theory suggests that Kroll's journey to Japan was arranged by his father. Kroll first went to London and then to Japan via Shanghai, finally arriving in Hokkaido.
Travel to Japan
After arriving in Hokkaido, Kroll went to Hokkaido University,It was originally the Sapporo Agricultural School established in 1886, and it was changed to this name in 1918 where he was a lecturer for five years beginning in 1937. At that time, he published three papers in five years with Tomonaga Shin'ichiro, who had just graduated from the physics department of Kyoto Imperial University, and also co-organized a course on quantum theory with Tomonaga. In 1937, with the support of Yoshio Nishina, Kroll published a paper on the theory of thermal conduction,Wolfgang Kroll. Zur Theorie der Wärmeleitung. Scientific Papers of the institute of Physical and Chemical Research. December 1937. and in 1941, he published a paper on the behaviour of free electrons in monovalent metals and their relation to specific heat.Tomiyuki Toya; Wolfgang Kroll; Kwai Umeda. Zur Wärmeleitung einwertiger Metalle. Scientific Papers of the institute of Physical and Chemical Research. August 1941. However, since the salary at the Hokkaido Imperial University was not high, Kroll took a part-time job as a teacher of German at a nearby commercial school. After the outbreak of World War II, Kroll left Hokkaido University to teach at the Institute of Physical and Chemical Research in Tokyo, and soon after left Japan to teach at Taipei Imperial University. At the end of 1941, Kroll arrived in Taiwan to teach at the Imperial University of Taipei. His salary was increased by 60%. However, the lecture system at that time did not allow Kroll to hold a lecture in physics, but only to teach German courses in the preparation and higher schools in Taipei. It was not until the end of the war that he began to teach physics. From April 20, 1945, all prep teachers and students, including Kroll, were engaged in position construction between Tamsui and Xinzhuang from that month onwards and were disbanded and reinstated after the war. He published a paper on mathematical physics in 1944 through the Proceedings of the Faculty of Science of the Imperial University of Taipei.
Post-war period
After the war, the Nationalist government took over Taiwan. Lo Tsung-lo, who was in charge of receiving the Taipei Imperial University, became the first acting president of NTU after the war, and invited Kroll to stay at NTU; Kroll was promoted from lecturer to associate professor and transferred to the Department of Physics to teach physics and German. However, after Lo left office, there were rumours that Kroll would be demoted because he was a national of a defeated country. After Fu Sinian became the president of National Taiwan University, he was encouraged to stay in the office again, and his salary was raised at the same time. Kroll was also invited to participate in the May 24, 1951 discussion of the freshman curriculum setting program, and Kroll was the only foreign faculty member at that meeting.
In 1948, a paper by Kroll on the study of the electron radius was published in the Japanese Journal of Arts and Sciences, which became the first paper published in an international scientific journal by a faculty member of the Department of Physics at NTU. In 1950, Kroll completed his research on the specific heat of solids alone. His research paper on this topic was published in 1952 in Developments in Theoretical Physics published in Kyoto, Japan, and he was promoted to full professor in 1954.鄭以禎; 張秀蓉; 林秀美. 1970年前台灣物理系所的發展. 中華民國物理學會. 2006. ISBN 9868137039 During this period, Kroll mentored assistant professor in his research on the specific heat of solids and frequency spectra. He also completed a revision of the Houston method in 1955, using interpolation to determine the ISO-frequency spectral map, avoiding the singularity problem of the original Houston method at the high-frequency end. He also wrote a paper on his research results and published it in Physical Review that year, which became the first paper by a Taiwanese scholar in this journal.A. A. Maradudin; E. W. Montroll; G. H. Weiss. Theory of lattice dynamics in the harmonic approximation. New York: Academic Press. 1963 [2016-04-23].(Original content archived on 2016-04-23)
Since then, almost all the theoretical physics courses in the Department of Physics at NTU had been taught by Kroll, including courses in theoretical physics, quantum mechanics, relativity, statistical mechanics, physical mathematics, electronics, and other theoretical courses.
His theoretical physics courses were mainly based on the textbooks written by the German physicist Arnold Sommerfeld, whose contents were compiled into a notebook for use as a textbook. Kroll would print handouts for his students, but left the formulae blank and asked them to fill them in during the class.鄭旭峰. 我所認識的Kroll. 物理會訊 (台大物理系學會).April 1992.
Before the 1970s, Kroll was the only full-time professor in Taiwan with a PhD in theoretical physics. However, because of the priority given to experimental physics in the early years of the Department of Physics at NTU, theoretical physics was relatively unappreciated, and Kroll did not have any research labs in the department, or even a dedicated desk. Because Kroll found Chinese difficult to learn and did not know Taiwanese Hokkien or Taiwanese Mandarin, he taught in English with a German accent. He would ask students to "stand and salute" and then sit down before starting the lesson. Kroll did not smile in class and hardly mentioned his research, preferring to teach in hunting clothes or European tuxedos and copying equations all over the blackboard, which students had to copy. However, Kroll preferred Japanese to English when talking to students.
The early physics students had more contact with Kroll because they had studied Japanese, but the later students had less contact. In the early postwar period, many professors who came to Taiwan with the Nationalist government used the Shanghai dialect or to teach their classes. Taiwanese students could not understand them, so they asked Kroll for advice in Japanese during their spare time. Sometimes teachers and students would drink together. When a student drifted out of the window during Kroll's lecture, Kroll threw chalk at him and angrily exclaimed, "Is the blackboard outside the window?" If a student dozed off during class or was late and left early, Kroll would throw chalk at them, and if a student talked privately during class, he would pound his face on the table and reprimand them. Kroll always graded students in whole multiples of ten (e.g., 60, 80) and never gave grades such as 56 or 85, similar to the future grading system. This is because he believed that the difference of a few points was not meaningful, so the scores should not be divided.