Yang Chen-Ning, Nobel Prize-winning physicist and supporter of NTU’s scientific programmes, dies at 103

BEIJING – Professor Yang Chen-Ning, a Nobel Prize-winning physicist who gave up his US citizenship to become a citizen of China in 2015 and helped persuade other scientists to do the same, has died. He was 103.

Prof Yang died of illness on Oct 18 in Beijing, according to a statement posted on Tsinghua University’s website.

Prof Yang had been a strong supporter of scientific programmes at Singapore’s Nanyang Technological University (NTU), according to the university’s website.

He was appointed external examiner for the Department of Physics at Nanyang University in 1971.

In July 2006, he launched NTU’s CN Yang Scholars Programme for undergraduate students with aspirations in fields of science and engineering. Prof Yang also delivered two lectures titled “Symmetry and Physics” and “My Life” for students and faculty at the university.

In 1986, Prof Yang personally advocated for and guided the establishment of the “Tan Kah Kee Young Inventors’ Award” in Singapore.

In a tribute to Prof Yang, the Tan Kah Kee Foundation said Prof Yang envisioned the award as a means to encourage young people to think critically, to embrace invention and creativity, and not to be confined by the pressures of examinations.

“For nearly four decades, this award has benefited countless youths, sowing seeds of scientific inquiry and sparking the flame of innovation. His passion for education and his visionary spirit will forever remain an inspiration,” the foundation said in a release on Oct 19.

The Nobel Prize Committee in 1957 recognised Prof Yang and fellow physicist Tsung-Dao Lee, both of whom were born in China and later became naturalised US citizens, for their work on the violation of the parity law in weak interactions. Up until the publication of the pair’s paper a year earlier, physicists had long assumed that particles would act the same when mirrored, a theory both of them showed to be misplaced.

Never before had someone of Chinese descent won a Nobel Prize.

“My most important contribution in life is helping change Chinese people’s psychology of feeling inferior to others,” Prof Yang is quoted as saying on the cover of a 2000 book collecting his various writings.

Prof Yang left China for the US in 1946 to attend the University of Chicago on a scholarship, earning his doctorate two years later.

Among the faculty who praised Prof Yang at Chicago was Nobel laureate Enrico Fermi, who recommended him to Dr Julius Robert Oppenheimer, the father of the atomic bomb, who was then the director of the Institute for Advanced Study at Princeton University.

At Dr Oppenheimer’s invitation, Prof Yang joined the institute and worked there for 17 years, crossing paths with scientists such as Albert Einstein and physicist Freeman Dyson.

Dr Oppenheimer later described Prof Yang’s work as demonstrating “great imaginativeness and basic conceptual simplicity, as well as considerable analytic power. It is also characterised by a good taste, restraint, and critical judgment, quite remarkable in so young a scientist”.

To facilitate his work in the US, Prof Yang became an American citizen in 1964. He said the decision was “painful” and one he came to regret, because his father, even on his deathbed, refused to forgive him.

Prof Yang reversed that decision in 2015, when he renounced his US citizenship and became a citizen of China.

“The US is a beautiful country and a country that gave me very good opportunities to conduct scientific research,” Prof Yang said of the choice. “I am grateful to the US.” 

He said the blood in his veins was his father’s and “belonged to the Chinese culture”. 

Professor’s son

Born on Sept 22, 1922, in the eastern city of Hefei, capital of Anhui province, Prof Yang spent most of his childhood on the campus of Tsinghua University in Beijing, where his University of Chicago-educated father Yang Ko Chuen was a professor of mathematics.

Prof Yang climbed every tree and studied every blade of grass on the university compound, he recalled in a 2005 speech.

After Japan invaded China in the 1930s, Prof Yang moved with his family almost 3,218km away to the south-western province of Yunnan. He earned a bachelor’s degree from National Southwestern Associated University in 1942 and a master’s from Tsinghua University in 1944, before his move to the US.

In 1954, Prof Yang and physicist Robert Mills formulated the Yang-Mills Non-Abelian Gauge Theory to explain interactions between nuclear particles. The model “synthesises the physical laws of nature and provides us with an understanding of the fundamental forces of the universe”, the Franklin Institute said in its citation when presenting Prof Yang the 1994 Bower Award and Prize for Achievement in Science. 

In 1971, Prof Yang was the first prominent Chinese American scholar to visit China after the US lifted a travel ban. When Chinese leader Deng Xiaoping visited the US in January 1979 to mark the start of official bilateral ties, Prof Yang delivered a speech at a welcoming banquet hosted by Chinese Americans. 

Special duty

In those remarks, Prof Yang said that Chinese Americans, rooted in two cultures, shouldered a special duty to enhance understanding between the countries, according to a documentary produced by the state-owned broadcaster China Central Television.

Prof Yang became more involved in bolstering China’s scientific capabilities in the years after that. 

In 1997, when Tsinghua University established its own Institute for Advanced Study, Prof Yang was named an honorary director.

He moved full-time back to China in 2003, taking on research work and teaching at Tsinghua. At the age of 82, Prof Yang taught general physics to four freshman classes, according to a 2017 article by Tsinghua physics professor Zhu Bangfen.

Prof Yang persuaded other scientists to follow his path. The most prominent of them was Professor Andrew Chi-Chih Yao, a top computer scientist and winner of the A.M. Turing Award, who became a professor at Tsinghua’s Institute for Advanced Study in 2004, thanks in part to a push from Prof Yang.

Prof Yao, who counts among his former students the founders of some of China’s most-promising artificial intelligence start-ups, later also gave up his US citizenship in 2015, according to a report in the journal Science.

But efforts to recruit US-educated scientists to China, such as with the Thousand Talents programme, also fuelled American suspicions that Beijing was attempting to appropriate cutting-edge technology.

In 2018, US President Donald Trump’s administration started the what it called the China Initiative, to investigate and prosecute Chinese and Chinese American researchers it said were stealing American secrets. That initiative would be ended in 2022 after coming under intense criticism for fanning discrimination.

While Prof Yang never publicly expressed his views on the rivalry between Washington and Beijing or its impact on scientific cooperation, he was conscious of the inherent tension even as a young man accepting the Nobel Prize some seven decades earlier. 

In his acceptance speech, Prof Yang described himself as feeling “in more than one sense a product of both the Chinese and Western cultures, in harmony and in conflict”. BLOOMBERG