On March 29th, Professor Giorgio Parisi, Nobel laureate in physics and Italian theoretical physicist, delivered a wonderful lecture titled Cross-scale “complex system”: Explore the simplest scientific laws in the world. More than 400 teachers and students from HUST attended the lecture.

Giorgio Parisi (born August 4th, 1948) is an Italian theoretical physicist, winner of the 2021 Nobel Prize in Physics, academician of the Accademia Nazionale dei Lincei, foreign academician of the French Academy of Sciences and academician of the US National Academy of Sciences. He was awarded the 2021 Nobel Prize in Physics for his contributions to “the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales”. In addition to the Nobel Prize, Giorgio Parisi has won the Dirac Medal, the Enrico Fermi Award, the Dannie Heineman Prize for Mathematical Physics, the Wolf Prize and many other awards.

Parisi’s most distinguished work was the discovery of hidden symmetry breaking in disordered spin glasses, and thus the development of a theory of ordered and random phenomena involving many different complex systems, which became the benchmark of complex systems. This has influenced not only physics research, but also research areas such as mathematics, biology, neuroscience and machine learning.

At the beginning of the lecture, Parisi reviewed his unique research journey, from elementary particles and quantum field theory to statistical physics, condensed matter and complex systems. He believes that research across different fields can help discover connections between physical phenomena in systems at different scales, which in turn may provide inspiration and lead to important discoveries. After that, he briefly introduced the significance and possible impact of the study of complex systems.

In the main part of the lecture, Parisi detailed his team’s research on the behavior of starling flocks. The team noticed that a flock of hundreds of starlings quickly adjusted the shape of the flock to avoid attack by falcons and reduce losses when attacked by an eagle falcon. During this process, each starling actually only communicates information with the starlings in its vicinity. How this local exchange of information affects the behavior of entire flocks at breakneck speed became an interesting problem for complex systems. Scientists hoped to answer this question and be able to simulate the collective behavior of flocks of birds and similar groups of animals on computers.

Parisi designed an ingenious experiment to photograph the position of starlings in flocks and obtained quantitative experimental results on the collective behavior of starlings. He shared the team’s research process of establishing numerical models and showed the cross-section of the flock movement obtained by the team, presenting how thousands of birds can form a borderline whole through local mutual information exchange. From these results, it can be seen that the collective behavior of flocks emerges from the process of interaction between individuals.

Ma Yiqiu, Professor of the School of Physics, said that Professor Parisi’s wonderful lecture opened a new window for students of the School of Physics. He believes that phenomena such as the movements of birds in daily life contain profound physical laws and theoretical physics is a powerful tool for explaining them.

Wang Chuming, Graduate of the School of Physics, said he was deeply inspired by Professor Parisi’s explanation of the basic laws in the complex scientific world via the simplest example: flocks of birds. He also said that questions raised by the teachers and students after the lecture were also very profound and refreshing.

Li Xiangbei, Graduate of the School of Physics, said that he became interested in “starling flocks” after listening to the lecture and this new perspective has greatly inspired him.

Wang Yushu, Undergraduate of the School of Optical and Electronic Information, said that the experimental details such as observations of bird behavior highlighted by Professor Parisi were eye-opening and that the question session had also broadened his horizons.

In order to create a rich academic atmosphere and stimulate students’ interest in physics, the School of Physics opened a polymath lecture hall in 2008 and a lattice forum in 2016. The regular reports given by the masters of physics introduce cutting-edge progress in the field of physics, discuss key disciplinary issues and explore future research directions.

From left: Nobel laureates in physics, Anthony Leggett, Steven Chu, Heinrich Rohrer, Murray Gell-Mann, Klaus von Klitzing, all of whom have lectured at HUST.

On June 27, 2019, the 2003 Nobel Prize winner in Physics Anthony Leggett gave a special lecture to teachers and students at HUST. On November 3, 2016, Steven Chu, winner of the 1997 Nobel Prize in Physics, was a guest at the Polymath Lecture Hall. On March 15, 2012, Heinrich Rohrer, winner of the 1986 Nobel Prize in Physics, visited HUST. On May 13, 2010, Murray Gell-Mann, the “father of quarks” and winner of the 1969 Nobel Prize in Physics, was a guest at the Polymath Lecture Hall of the School of Physics. On September 25, 2006, Klaus von Klitzing, winner of the 1985 Nobel Prize in Physics and discoverer of the quantum Hall effect, gave a lecture on “Scientific spirit and practice”, and then was invited to visit HUST for the third time on May 6, 2013.

Welcome to HUST, engage in dialogue with Nobel Prize winners and start a journey of world-class scientific research!

Written by: Cheng Yifang

Edited by: Shi Can, Chang Wen, Peng Yumeng