On December 4, Professor Lu Dexin, Academic Supervisor at Kuang Yaming Honors School and author of the textbook University Physics, gave a lecture to the students of Kuang Yaming Honors School and the Top-Ranking Class, and his title was “On Learning and Research.”

He outlined his lecture with one after-class exercise of University Physics and four stories, and he would focus on the relationship between study and research and the method by which students proceed from study to research.

The lecture went with a swing, and students listened attentively and responded positively to Professor Lu’s questions.

Lu talked about how he had compiled the textbook University Physics and said that the guiding idea for compiling the book was, on the one hand, to bring the university physics course in line with the international standards and, on the other hand, to write a textbook with Chinese educational characteristics so as to cultivate the interest of students in learning and research.

Professor Lu discussed the relationship between learning and research by saying that learning is to master existing knowledge and research is to discover and form new knowledge. Existing knowledge is the result of previous research, but there is no guarantee that it is complete, accurate or correct. It is possible to supplement, amend or even overturn the existing knowledge, so there is no insurmountable gap between learning and research. When we start to carry out a series of similar behaviors such as questioning, inquiring, correcting, and finding leaks in the existing knowledge, we start our research career.

Then, Professor Lu used an after-class exercise from University Physics to show how to do research: a model of a roll of strip with one fixed end rolling freely down a slope. Lu pointed out that research needed to start with questioning and must not be limited to standard answers. He gave three different ways of interpreting this exercise.

First, if the relationship between acceleration and angular acceleration is analyzed from the geometric relationship, the relationship between them is independent of thickness, and the nonlinear differential equation is used to find the velocity. Lu broke the conventional thinking by transforming a nonlinear equation into a linear equation, that is, a nonlinear problem in time space into a linear problem in phase space.

Lu inspired students to think whether a physical problem would be easier after being transformed from time space to phase space.

If we analyze the dynamic effect and derive the angular momentum, Lu continued, we will notice that the moment of inertia will change with time. In physics, we can expect that the moment of inertia is inversely proportional to the acceleration, and this would lead to a conclusion opposite to the geometric relationship.

Professor Lu then led students to a new conclusion considering the fact that the mass of the strip decreases in motion.

He also asked what other points were worth exploring, and the students responded with some new ideas: the existence of adhesion resistance during the unwinding of the strip; the deformation of the rope to produce tension; the possible discontinuous change of the radius with time; the change of energy during the motion; and the numerical simulation to investigate the stability of the differential equation.

Lu was very satisfied with students’ answers and added that relativistic effects need to be considered when the strip is long enough. He used this exercise to tell students that to conduct research, they need to do research outside of the original model and come up with new ideas.

It is worth mentioning that Lu asked students to read the literature and encouraged them by adapting what Deng Xiaoping said, “If you don’t read the literature for one day, you know it; if you don’t read the literature for two days, your colleagues know it; if you don’t read the literature for three days, everyone knows it.”

After that, Professor Lu continued to discuss learning and research with four short stories.

The first story was about a little trick to turn a complex integral into a derivative of an elliptic integral, thus turning a five-page paper into two lines. This impressed the audience.

The second story was about entertainment and physics. The professor pointed out that the Snooker Rotational Collision is still an unsolved problem, inspiring the students to explore the unknown field.

The third story was about culture and science. Lu recalled that when he was teaching at Tsinghua University and asked students to write course papers, some of them got high marks for their musical expertise by writing an acoustics paper on melody. The story inspired students to build on their strengths and avoid their weaknesses.

The fourth story went straight to the frontline research. Lu brought up the new MEMS inertial sensing technology by mentioning the problem that GPS signals could not penetrate the water 5cm deep during submarine navigation.

The lecture ended in warm applauses.