Chih-Kung Jen
Encyclopedia
Chih-Kung Jen (August 15 or October 2, 1906-November 19, 1995) was a Chinese physicist who emigrated to the U.S. and participated in some of the 20th century's major scientific, political and social developments in both the United States and China.

Born in a mud house in a remote and largely illiterate village in China, he was awarded a scholarship funded as a result of the Boxer Rebellion
Boxer Rebellion Indemnity Scholarship Program
The Boxer Indemnity Scholarship Program was a scholarship program funded by Boxer Rebellion indemnity money paid to the United States that provided for Chinese students to study in the U.S...

 of the late 19th century to attend Beijing's prestigious Tsinghua University
Tsinghua University
Tsinghua University , colloquially known in Chinese as Qinghua, is a university in Beijing, China. The school is one of the nine universities of the C9 League. It was established in 1911 under the name "Tsinghua Xuetang" or "Tsinghua College" and was renamed the "Tsinghua School" one year later...

. As part of that scholarship, he came to the U.S. in 1926 to study electrical engineering and physics at MIT. He completed his graduate studies first at the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...

, and then in physics at Harvard University
Harvard University
Harvard University is a private Ivy League university located in Cambridge, Massachusetts, United States, established in 1636 by the Massachusetts legislature. Harvard is the oldest institution of higher learning in the United States and the first corporation chartered in the country...

. Jen was among the first to provide experimental proof of the existence of the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

. In addition, he obtained the first theoretically calculated value for the electron affinity
Electron affinity
The Electron affinity of an atom or molecule is defined as the amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion....

 spectrum of the hydrogen atom, a problem of fundamental significance in quantum mechanics
Quantum mechanics
Quantum mechanics, also known as quantum physics or quantum theory, is a branch of physics providing a mathematical description of much of the dual particle-like and wave-like behavior and interactions of energy and matter. It departs from classical mechanics primarily at the atomic and subatomic...

 and astrophysics
Astrophysics
Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties of celestial objects, as well as their interactions and behavior...

.

In 1937, Jen returned to China, and subsequently joined in the "Academic Long March" to set up a wartime refugee university (the National Southwestern Associated University
National Southwestern Associated University
When the Second Sino-Japanese War broke out between China and Japan in 1937, Peking University, Tsinghua University and Nankai University, merged to form Changsha Temporary University in Changsha, and later National Southwestern Associated University in Kunming...

) in Kunming
Kunming
' is the capital and largest city of Yunnan Province in Southwest China. It was known as Yunnan-Fou until the 1920s. A prefecture-level city, it is the political, economic, communications and cultural centre of Yunnan, and is the seat of the provincial government...

. His wartime teaching and research contributed to the training of what would become the nucleus of the present-day Chinese scientific intelligentsia.

After the war, Jen returned to the Physics Department at Harvard, and eventually settled at the Applied Physics Laboratory at Johns Hopkins University
Johns Hopkins University
The Johns Hopkins University, commonly referred to as Johns Hopkins, JHU, or simply Hopkins, is a private research university based in Baltimore, Maryland, United States...

 to carry on pioneering research in trapping free radicals and other topics in microwave spectroscopy.

In 1972, following Richard Nixon
Richard Nixon
Richard Milhous Nixon was the 37th President of the United States, serving from 1969 to 1974. The only president to resign the office, Nixon had previously served as a US representative and senator from California and as the 36th Vice President of the United States from 1953 to 1961 under...

's visit to China, Jen led a ground-breaking delegation of Chinese American
Chinese American
Chinese Americans represent Americans of Chinese descent. Chinese Americans constitute one group of overseas Chinese and also a subgroup of East Asian Americans, which is further a subgroup of Asian Americans...

 scientists to that country. The delegation conferred with Premier Zhou Enlai
Zhou Enlai
Zhou Enlai was the first Premier of the People's Republic of China, serving from October 1949 until his death in January 1976...

, and initiated what was to become a steady stream of scientific exchanges between the U.S. and China. Jen subsequently made numerous visits to China. He continued to work on strengthening U.S.-China scientific relations, and in addition was a leader in improving scientific education in Chinese universities.

Biography

C K Jen was born on October 2, 1906 in Hexi Village on the west bank of the Qin River in Shanxi
Shanxi
' is a province in Northern China. Its one-character abbreviation is "晋" , after the state of Jin that existed here during the Spring and Autumn Period....

 Province in northern China. Shanxi Province is part of the Yellow River Valley which served as the "cradle of Chinese civilization," but by the time of Jen's birth, was a largely arid region populated by poor farmers struggling with overworked soil and periodic flooding. Jen was the second son in a family with five children. He began his elementary school education at age 11 and two years later entered middle school. At age 15, he was admitted to the prestigious Tsinghua University
Tsinghua University
Tsinghua University , colloquially known in Chinese as Qinghua, is a university in Beijing, China. The school is one of the nine universities of the C9 League. It was established in 1911 under the name "Tsinghua Xuetang" or "Tsinghua College" and was renamed the "Tsinghua School" one year later...

 in Beijing, China. The students at Tsinghua were chosen from each province on the basis of that province's indemnity payment for the Boxer Uprising of 1900. While at Tsinghua, Jen participated in the May Fourth Movement
May Fourth Movement
The May Fourth Movement was an anti-imperialist, cultural, and political movement growing out of student demonstrations in Beijing on May 4, 1919, protesting the Chinese government's weak response to the Treaty of Versailles, especially the Shandong Problem...

, the first expression of what was to be a lifelong opposition to imperialism and colonialism throughout the world.

In 1926 he came to the US to study at MIT, where his mentors included Norbert Wiener
Norbert Wiener
Norbert Wiener was an American mathematician.A famous child prodigy, Wiener later became an early researcher in stochastic and noise processes, contributing work relevant to electronic engineering, electronic communication, and control systems.Wiener is regarded as the originator of cybernetics, a...

, Vannevar Bush
Vannevar Bush
Vannevar Bush was an American engineer and science administrator known for his work on analog computing, his political role in the development of the atomic bomb as a primary organizer of the Manhattan Project, the founding of Raytheon, and the idea of the memex, an adjustable microfilm viewer...

, and others. He received a graduate fellowship to the University of Pennsylvania in 1928, where he published with G. W. Kendrick two papers on the experimental proof of the existence of the ionosphere
Ionosphere
The ionosphere is a part of the upper atmosphere, comprising portions of the mesosphere, thermosphere and exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere...

. The following year he entered Harvard and in 1933 received his PhD in physics. While there, he derived the first theoretically calculated value for the electron affinity of the hydrogen atom
Hydrogen atom
A hydrogen atom is an atom of the chemical element hydrogen. The electrically neutral atom contains a single positively-charged proton and a single negatively-charged electron bound to the nucleus by the Coulomb force...

 (six years later to be improved by HSW Massey).

He returned to Tsinghua in 1934 and continued his research in numerous areas of experimental physics, including the effects of microwave radiation on animate objects, anticipating the microwave oven by some thirty years. His scientific research however inevitably became entwined with the political events of the time. After occupying Manchuria in the early 1930s, Japan invaded Beijing on July 27, 1937 (as luck would have it, the exact day Jen was to wed his wife :pl:Paocheng Tao Jen). Subsequent to the Japanese invasion, Jen joined many of the remaining faculty and students of the three leading North China universities—Peking University, Tsinghua University, and Nankai University—in what became known as the "Academic Long March." The refugees fled first to Changsha in Hunan Province and then to Kunming
Kunming
' is the capital and largest city of Yunnan Province in Southwest China. It was known as Yunnan-Fou until the 1920s. A prefecture-level city, it is the political, economic, communications and cultural centre of Yunnan, and is the seat of the provincial government...

 in Yunnan Province, a distance of some 3000 km. In Kunming the 800-some faculty and student established the National Southwestern Associated University
National Southwestern Associated University
When the Second Sino-Japanese War broke out between China and Japan in 1937, Peking University, Tsinghua University and Nankai University, merged to form Changsha Temporary University in Changsha, and later National Southwestern Associated University in Kunming...

. Over the next eight years of bombing, deprivation and hardship, Jen persisted in his theoretical and experimental radio research as well as in his physics teaching responsibilities. His students during this period included future Nobel Prize winners C. N. Yang and T. D. Lee
Tsung-Dao Lee
Tsung-Dao Lee is a Chinese born-American physicist, well known for his work on parity violation, the Lee Model, particle physics, relativistic heavy ion physics, nontopological solitons and soliton stars....

, and other distinguished researchers such as Chen-To Tai.

At the end of World War II, he returned to the United States on sabbatical leave at Harvard and turned his research focus to microwave spectroscopy. His work in this area was influenced by senior colleagues at Harvard including John Van Vleck, Charles Townes, Edward Purcell
Edward Mills Purcell
Edward Mills Purcell was an American physicist who shared the 1952 Nobel Prize for Physics for his independent discovery of nuclear magnetic resonance in liquids and in solids. Nuclear magnetic resonance has become widely used to study the molecular structure of pure materials and the...

 and others. In 1950, he became a senior physicist at the Johns Hopkins University Applied Physics Lab (APL), where he continued his research on microwave spectroscopy, and, together with collaborators including Samuel Foner, Edward Cochran, and others, carried out pioneering research on trapping of free radicals. Their paper on electron spin resonance (1958) proved to be one of the most frequently cited APL publications into the 21st century (Berl 1996). As stated in Physics Today (Moorjani 2001), the study led by Jen on the trapping of hydrogen atoms in a solid hydrogen matrix at liquid helium temperatures "allowed Norman Ramsey to infer the lifetime of hydrogen atoms bouncing around in the maser chamber and to conclude that the system will not be too lossy. Ramsey could therefore confidently proceed with the building of the hydrogen maser." Jen was the author of numerous entries on microwave physics in the McGraw-Hill Encyclopedia of Science and Technology
McGraw-Hill Encyclopedia of Science and Technology
The McGraw-Hill Encyclopedia of Science & Technology isan English-language multivolume encyclopedia, specifically focused on scientific and technical subjects, and published by McGraw-Hill. The most recent edition in print is the tenth edition, copyright 2007 , comprising twenty volumes...

and in the Encyclopedia of Physics.

Through the 1960s and 1970s, Jen became an outspoken political activist and participated in numerous anti-Vietnam War demonstrations. Following President Nixon's successful trip to China in February, 1972, he decided to organize a group of scholars to visit China as well. Overcoming numerous obstacles and objections, he led the first trip by a group of Chinese-American scientists to the People's Republic of China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...

 since World War II. The group was received by Premier Chou En-Lai. At the reception, Chou spoke for the first time in public on the fate of Lin Piao and arrangements were made for Jen's youngest daughter, Erica, to become the first American student to study in China since 1949.

Jen made eight more visits to China. He devoted the latter part of his life to improving relations between the U.S. and China, and to the modernization of education, especially in physics, in China. He presented a series of lectures on recent advances in physics, including the Hall effect and nonlinear dynamics, to university students throughout China, and also lectured in the U.S. and Canada on developments in China since 1949. In 1981 his contributions were recognized by Deng Xiaoping
Deng Xiaoping
Deng Xiaoping was a Chinese politician, statesman, and diplomat. As leader of the Communist Party of China, Deng was a reformer who led China towards a market economy...

, who gave a reception in his honor. He was granted honorary professorships by Tsinghua and four other universities.

Abbreviated list of publications

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