Over two and a half weeks, 27 professors and 49 students from home and abroad gathered at the PEBBLE BioFusion Camp to consider a question raised by Erwin Schrödinger 80 years ago: What is life?

Prof. Chao Tang, academician of the Chinese Academy of Sciences and Westlake University chair professor and director of the Center for Interdisciplinary Sciences, used this question to kick off the summer camp.

Prof. Chao Tang

Schrödinger published his book "What is Life" in 1944, a time before the discovery of DNA. Schrödinger believed that life, a natural phenomenon like the sunrise, must follow the basic laws of physics. Looking at heredity and mutation from the perspective of quantum mechanics and statistical physics, he concluded that it is likely to involve other yet unknown laws of physics, and the code of life should be preserved in a nonperiodic pattern that is neither repetitive nor random.

This hypothesis inspired generations of scientists to challenge the underlying logic of the life sciences. The rest was history: the DNA double helix structure was discovered, molecular biology flourished, and the intersection of math, computer science and biology led to the development of genomics.

Eighty years after "What is Life?" was published, interdisciplinary research involving materials science, information, engineering and biology continues to thrive and raise more questions about life. Scientists want to understand "the physics of life," just like electrodynamics for communications, and quantum mechanics for computer science. They want to know how the interactions between microscopic components give rise to the macroscopic functions of life, and how living systems represent and process information.

Such questions require highly specialized interdisciplinary research, which was rarely done in the past. "Biology is an extremely dynamic field. It is so high-dimensional, and many of the phenomena are beyond our current tools and methods. However, the research is far from enough," said Prof. Leihan Tang, chair professor of physics at the Center for Interdisciplinary Studies in the Westlake University School of Science.

Prof. Leihan Tang

The Center for Interdisciplinary Studies hopes to further consolidate frontier sciences and promote research on complex life systems.

The challenge for the PEBBLE BioFusion Camp was how to present the grand topic of "What Is Life?" to the 49 participants.

The faculty offered classes and presentations in the interdisciplinary areas of physics, biology, math and AI, as well as hands-on experiences in research.

The second day of the summer camp introduced the students to six topics: soft/active matter and morphogenesis, molecular circuits, cell biology, pattern formation, microbial communities/ecology, and self-organization. Students chose an area of interest and then worked with relevant principal investigators and teaching assistants to form a team and develop a research topic. The program set aside time each day for literature review, discussion and experiments. This arrangement allowed the students the opportunity to work on actual research questions and deepen their understanding, while refining their analytical skills and problem-solving abilities.

On Aug. 15, the students presented their projects.

"Evolution: The Driving Forces of Diversity in Resource Competition" was the title of the project that involved Tairan Li, a student at Peking University.

"We chose to work on dilution because it is a viable and fun project. At first, we thought about investigating the influence dilution interval had on microorganism strategy. It came up in the discussion that the current model lacked mutations, and we wanted to incorporate mutations into the model.

"Our research proved the validity of existing studies: In the absence of mutations, if the convex hull formed by the enzyme strategies of all species in the strategy space does not cover the nutrient supply point, then at most only (n-1) species can coexist, where n is the type of nutrition. And we also discovered something new: In the presence of mutations, the number of species that can coexist increases significantly, and complex dynamics such as separation of timescale and oscillation will occur during species evolution.

"There is still a long way to go between our model and reality, but even such a simple model can produce such complex phenomena, so we can expect that if we take more realistic factors into account, the real evolution of species will be more complex and interesting."

Hainuo Huang, a student at the University of Chinese Academy of Sciences, presented a project titled "Active Gel Model for Cell Migration," noting that the work is crucial for understanding the migration of cells on a substrate. "We followed the framework introduced by Drozdowski et al. in 2021, simplifying the model to focus on the purely viscous case. The study reduces the problem to solving a bulk PDE (or ODE in the viscous case) with appropriate boundary conditions."

The project "Diffusion in Cells: Simulation of Inhomogeneous Diffusion Coefficients" was introduced by a group of students: "Studies (Nat. Comm. 10,1038) showed that the diffusion of substances within cells was related to the morphology of the cells, reflected in the different diffusion coefficients in different areas of the cells. This is closely related to the migration behavior of cells, because the lamellipodium, the main part of the cell required for its migration, requires faster material transport within the cell to complete its migration. We hope to explore the experimental phenomena through simulation and theoretical analysis. Specifically, we want to simulate the migration of cells by making reasonable assumptions about the spatial form of the diffusion coefficient D(x) and compare them with the experiments."

The summer camp left a positive impression on participants. Diya Shaji, a student at Delhi University in India, valued the connections she made. "We were able to build genuine friendships with people who are willing to care and share in such a competitive community, coexisting while embracing our diversity."

Peking University student Renyu Wang said, "The summer camp really opened my eyes to many new subjects, and I was happy to discover things that interested me. We had the chance build models to quantitatively study biological phenomena, and observe logical, elegant work. I've always been curious about gel and active matters, but never had the chance to explore them before this program. It was a great opportunity to talk more in depth with researchers in the field."

According to Peking University student Shengyao Luo, "PEBBLE opened my eyes to the world. Prior to this, my understanding of research was quite shallow – I'd read papers and attended meetings. But here, the theories I had read about in books came to life in the lectures by Prof. Prost and Prof. Jülicher. I was greatly inspired."

For Hainuo Huang, the most memorable moments were subtle. "I was heading to the dining hall with my roommate after the lecture on the first day, and we were talking about the Fibonacci sequence. Was it a coincidence that many structures seem to favor the Fibonacci sequence, or does it confer certain advantages? We ended up having a deep conversation on a sofa in the Academic Ring. It was wonderful that we could engage in such a profound conversation with people at the summer camp."