Fall 2020 > IAS Scholars

IAS Junior Fellow and Research Assistant Professor of Social Science

Dr. LIU Tong

Once a physicist, always a physicist?

It is not uncommon for physicists to end up working in fields other than physics, such as business and finance. The Dutch economist Prof. Jan TINBERGEN, the 1969 Nobel Memorial Prize laureate in Economic Sciences, is once such renowned physicist-turned-economist. IAS Junior Fellow Dr. LIU Tong, however, did not have to leave physics to take up economics. He completed a dual undergraduate degree in both subjects at Peking University and continued his education with a PhD in Environmental Science, Policy and Management at HKUST. Here, Liu tells us how his mathematical physics background and analytical skills have helped him excel in academia.

What did you find so fascinating about economics? How different is it from physics?

Science has always been where my passion lies. I enjoyed studying many subjects, including mathematical physics, theoretical and statistical mechanics, and lab experiments at the School of Physics at Peking University. Based on my internship in a solar energy company, my bachelor’s thesis applied atmospheric modeling to estimate the energy efficiencies of various solar panels. Prof. LI Chengcai, who is an outstanding scientist and a great mentor at Peking University, supervised me and encouraged me to learn more about atmospheric science, which became one of my research interests.

In terms of economics, I didn’t actually have a chance to study it formally until university. I was inspired by many great scholars at the China Center for Economic Research at Peking University, including Profs. Justin LIN Yifu, ZHOU Qiren, YAO Yang and ZHANG Fan, among others. There, I had the opportunity to explore a variety of topics in economics, such as development and environment, institutions, and the Chinese economy. I am particularly interested in economic and environmental disparities in urban and rural China.

I like both economics and physics, and have found many similarities between them. For example, some scholars have used the theory of entropy to probe the economic system. Economics and physics follow similar research paradigms to discover causality with critical thinking, rigorous modeling, experiments, and data analysis. As a student of both disciplines, I pay attention to economic phenomena and apply mathematical tools to the understanding of human behavior. Some human behaviors and activities can be irrational or suboptimal, and it can be challenging to tackle their externalities, which calls for more empirical evidence to support theory development and evidence-based policymaking.

Why did you pick environmental economics for your graduate studies? What did you intend to achieve?

Environmental issues have been very close to my heart. As you know, air pollution is a pressing issue in China. I grew up in a rural resource-dependent county in Northwest China and got used to the smoke from coal burning. In college, I served as a volunteer for the 2008 Beijing Olympic Games and Paralympic Games and witnessed the bluest skies I had ever seen, which made me wonder about the relationship between the environment and economic and social development, and prompted me to think about ways to improve the air quality in China.

Besides pollution, farmers in my hometown used to cut down large numbers of trees for farming and grazing, which exacerbates soil erosion and sandstorms. During my final year of undergraduate studies, I joined the Global Social Venture Competition in China and co-founded an entrepreneurial team to look into the balance between farmland and forests in Northwest China. We designed a social business model to help struggling farmers and the environment by growing Caragana, an eco-friendly crop with good economic value. In my graduate studies, I further investigated how agricultural straw burning, a common practice adopted by farmers to clear the fields for cultivation in agrarian regions worldwide, affects air quality and human capital — including physical health, mental health and cognitive performance — in China. There was also a sharp decline in straw burning when the government started to subsidize straw recycling beyond command-and-control regulations. The findings of my study serve as evidence of the social costs of air pollution and support policymaking to reduce the costs.

Looking backwards to connect the dots in my life, I consider myself lucky to have found my research interest in environmental economics and to have been able to pursue it with support from many people including my supervisors, collaborators and colleagues. I hope my research can facilitate the sustainable development of our society.

What part does interdisciplinary research at HKUST play in your graduate studies? What is special about it?

HKUST is a young university with great potential and an excellent research environment. Working with two excellent scholars, Prof. Alexis LAU Kai-Hon, Chair Professor of Environment and Sustainability, and Prof. HE Guojun, Assistant Professor of Economics, is a true privilege and means that I get the best of both worlds. The interdisciplinary approach to research helps students like me to think outside of the box, to be exposed to alternative perspectives, and to carry out cross-disciplinary collaborations.

For instance, Prof. LAU offered me rich opportunities for data exploration and training in atmospheric science. I worked with him and Prof. Jimmy FUNG Chi-Hung, Head and Professor of the Division of Environment and Sustainability, on air quality forecasting in Hong Kong, combining numerical modeling with statistical methods. The study was published in the Journal of Geophysical Research: Atmospheres, a top journal in atmospheric science. During the process, I also had the chance to advise two visiting international students on related research projects.

Prof. He inspired me with his great research enthusiasm, creative ideas and solid analysis in applied microeconomics. Thanks to his introduction, I also met Prof. Joshua GRAFF ZIVIN, Professor of Economics and of Global Policy and Strategy at the University of California, San Diego, who later hosted me as a visiting scholar for the last year of my PhD studies. It was an invaluable experience — I attended many seminars, gave talks and met many outstanding scholars with whom I later developed collaborations.

Do you have any suggestions for students who plan to follow in your footsteps and pursue an interdisciplinary degree?

The first and foremost thing is research interest — you have to ask yourself whether what you are working on is really going to keep you up at night. Second, you need an open mind to engage with people from different disciplines using their own academic languages. Third, it is important to have a clear-eyed understanding of your research purpose, seeing things critically with strong analytical skills. Having a steely commitment to becoming a researcher who stays motivated to find the frontiers of research topics is crucial. After all, it takes just as much time to do research on a bad topic as on a good one.

You finished your PhD without an MPhil in just four years. What’s the secret of your success?

As the saying goes, “Work hard, be kind, and amazing things will happen.” I was fortunate to have teachers and peers who taught me to stay focused on my studies and other important things in life. I have had opportunities to work with and learn from the best in the research field. I could not have done much without wholehearted support from them and my family. I will always follow their example and commit myself to research and teaching.

What do you aim to achieve with your research?

Environmental economics may seem like a small sub-field of economics, but, in fact, it encompasses many topics that are worth exploring in depth. My current research focuses on the causes and consequences of environmental issues in Mainland China and Hong Kong, covering a variety of topics on human capital accumulation, industrial production, technologies and institutions. I hope that my research can reduce the environmental and economic disparities between urban and rural contexts, help those who are disadvantaged or left behind, and improve social welfare.