Shing-Tung Yau is a busy man indeed. Not only is he the William Caspar Graustein Professor of Mathematics at Harvard University in Cambridge, Massachusetts, he is also director of six mathematical institutes in China. Yau is known for his work in geometry, general relativity, and string theory; the Calabi–Yau manifold, used in superstring theory to describe extra dimensions of spacetime, is partially named in his honor.
Yau is the winner of several prestigious awards, including the Fields Medal, the National Medal of Science, the Crafoord Prize, the Veblen Prize, the Wolf Prize, and a MacArthur Fellowship. He has written and edited more than 20 books and is the editor-in-chief of three mathematics journals.
Image credit: Susan Gilbert.
His most recent book describes plans to build a 100 TeV multinational particle-accelerator research facility in China; it would consist of a circular electron–positron collider (CEPC) and a super proton–proton collider (SPPC). Written with science journalist Steve Nadis, From the Great Wall to the Great Collider: China and the Quest to Uncover the Inner Workings of the Universe (International Press of Boston, 2015) starts off with an overview of particle physics, moves next to China’s historical and anticipated role in the field, and ends with a chapter on the societal benefits of high-energy physics experiments.
The CEPC–SPPC concept is still just that, a concept. But if funded, it “is expected to involve thousands of scientists and engineers from all over the world,” writes astronomer Lifan Wang in his book review for the April issue of Physics Today. “From that point of view,” he continues, “the proposal is a quantum leap to a future in which China will help lead international efforts to understand the universe.”
Physics Today recently caught up with Yau to discuss his new book.
PT: What inspired you and Steve Nadis to write about this project now—before rather than near or after its completion?
YAU: It’s true this project is still in the design phase without formal government backing. The principal motivation for our book was to help make the scientific case for an endeavor of this sort—whether it occurs in China or elsewhere, although I am partial to China, having been born there.
I’ve spent my career in math and physics, often working at the boundary between those fields—an exciting place to be. Although my mathematical work is mostly “pure” rather than applied, I often derive inspiration from theoretical physics, which in turn depends on experimental input.
The quest to uncover the forces of nature and the structure of matter has been under way for thousands of years. I cannot believe that this glorious pursuit will end with [CERN’s] Large Hadron Collider (LHC). We will eventually need a successor to that marvelous instrument, and the time to start planning is now. Many of my physics friends—including David Gross, Edward Witten, and Nima Arkani-Hamed—believe that China offers our best hope for a 100 TeV collider. But if this “Great Collider” is actually built, it will not be a Chinese machine. Physicists from all over the world will participate in experiments there, united in the drive to better understand our universe.
PT: Can you describe your connection to the collider project in China and what role that played in convincing you to write about it?
YAU: I travel to Asia often. I helped establish six mathematics institutes (two in Beijing, one in Hangzhou, one in Hong Kong, and two in Taiwan), which I currently direct. I also started high school competitions in math and physics—perhaps soon to be followed by competitions in biology—all with the purpose of building up science throughout the region. When I heard about early plans for a new collider about five years ago, I naturally offered to help, talking up the idea with scientists I knew in China, the United States, and Europe. I also helped get proposals into the hands of influential decision makers in China.
This book with Steve is somewhat of an outgrowth of that early involvement, which really just piqued my interest. The subject of particle physics and the incredible developments in the 20th century are fascinating in themselves, and that, more than anything else, is what persuaded us to write this book. We felt that we were describing one of the greatest intellectual adventures in human history. It was a thrilling topic to take on, and one that I hope we did justice to.
PT: Politically and financially, what do you think makes this project more like the LHC and less like the canceled Superconducting Super Collider project?
YAU: In matters of money and politics, no one can predict the future with absolute certainty. Yet I’m still confident that this project will go forward. Money should not be a huge obstacle. In its initial phase, the collider will run as an electron–positron device, which is expected to cost about $6 billion—a sum China can easily afford. In fact, the country will probably spend more on the 2022 Winter Olympics, which lasts just a couple of weeks. I have nothing against the Winter Olympics, but China can get a far greater return from the Great Collider—in terms of building its capacity in science and high technology and boosting its international reputation.
Chinese leaders like big projects. A big peaceful project like this, involving countries from all over the world, is a good way to show that China favors peace and the advancement of basic research. China has a lot to gain from this project and little to lose. I have talked with people all over the country and have not encountered a single, high-level official against it. The only opposition I’ve seen, ironically, is from a handful of physicists in other areas who’d rather see their own projects funded.
PT: When it is completed, what types of results are expected that may not be achieved at existing facilities?
YAU: You never know what you’re going to see when you turn on a machine that’s roughly an order of magnitude more powerful than anything built before. But history tells us that we’re bound to see something new and likely astounding. While the LHC confirmed the existence of the Higgs boson, a higher-energy accelerator like the Great Collider can tell us much more about this particle, which is unlike any we’ve seen before. The Higgs was the final piece of the standard model, but we know theoretical particle physics cannot end there. Gravity, for instance, is not incorporated in the standard model, which only applies to the strong, weak, and electromagnetic forces. Many physicists are not satisfied with having two mutually incompatible theories—one describing gravity and another describing the other known forces.
Eighty-five percent of all matter, according to current doctrine, is of the “dark” (invisible) variety. Dark-matter particles may be detected at a 100 TeV collider. Supersymmetric partners to the known bosons and fermions might also be lurking, just beyond our current view. We’ll never know what’s out there until we take a good look. The notion that we’ll soon end the search, and look no further, is something I cannot accept.
PT: What does a project like this mean for the Chinese research community and for international relations with it?
YAU: This project would provide a tremendous boost to the Chinese physics community, which would have to grow rapidly to provide enough trained people to support an operation of this scale. If it were built, the Great Collider would put China at the center of high-energy physics research for decades. But, as I mentioned before, this will be an international undertaking and already is, to some extent. Three hundred scientists from nine different countries worked on the 600-page Preliminary Conceptual Design Report, which was completed in 2015 for the proposed Chinese collider. Many of these scientists take part in the continued effort to advance this project.
International collaborations in physics and other areas of science are good for China—exposing its researchers to new ideas—and good for the rest of the world too. China has hosted successful collaborations in the Daya Bay Reactor Neutrino Experiment and at the Beijing Electron Solenoid (BES-III) Experiment. Friendships sparked by those scientific interactions can only serve to enhance world relations. The Great Collider would involve international cooperation on a scale unprecedented in China—and one that the nation’s particle physics community actively welcomes.
PT: What books are you currently reading?
YAU: I always have several books going. Right now I’m reading Topics in Complex Function Theory (Wiley, 1988) by Carl Siegel for a course I’m teaching this term at Harvard. As chief editor of three math journals and editor for half a dozen others, I always see a large volume of technical papers, but I like to take a break from math sometimes.
I’m enjoying Visionary Journeys (Harvard University Asia Center, 2012) by the Harvard scholar Xiaofei Tian. Her book describes a fascinating period of Chinese history, from around AD 300–500, when the country produced an outpouring of work in poetry, literature, philosophy, science, and mathematics that was comparable to the European Renaissance. No Chinese mathematicians had proved theorems until that time, and I’m trying to understand how that kind of thinking arose.
I’m also looking at some ancient Chinese texts about the Han Dynasty (from around 200 BC to AD 200), which is when communications between China and the Western World first came about. I’d like to see how those communications developed over time. It seems relevant today, as the Great Collider would lead to scientific collaborations between the East and West on scales never witnessed before.
