Yang Zhenning is a world-renowned master of physics, but he has also experienced many failures in his studies and research. Interestingly, a person aspiring to a career in science has the most to learn from his failures.
In 1946, Yang went to the University of Chicago in the United States to study for a doctorate with Enrico Fermi (1901-1954), especially in the field of experiments. However, at that time, Fermi's laboratory was kept secret and Yang Zhenning could not enter, so Fermi recommended that he first theorize with another professor, Edward Teller (1908-2003).
The first topic that Teller gave to Yang Zhenning was the probability of annihilation of k-electrons between be and beo. After Yang Zhenning's preliminary calculations came out, Teller arranged for him to give a report, which was the first time Yang Zhenning gave an academic report in the United States. The teachers in the department responded very well to the report, and Teller asked Yang Zhenning to write this into an article. However, Yang Zhenning wrote for a week and never wrote well, because he used several different approximation methods in the calculation, and he was not sure about the reliability of the results. Teller didn't care, and gave him another topic of nuclear physics.
In the fall of 1946, Fermi introduced Yang to another professor, Samuel King Allison (1900-1965). Allison was a nuclear experimental physicist who was building a 400-kilovolt cockcroft-walton accelerator. Yang Zhenning finally got the opportunity to do experiments, but his experimental career was very miserable. In his own words:
At that time, I was a very well-known graduate student in the physics department of the University of Chicago, because the basic theoretical physics I learned at Southwest Associated University had reached the most cutting-edge standards at that time, but my hands-on ability was very lame. My classmates admired my theoretical knowledge and often asked me to help them solve theoretical exercises, but everyone laughed at me for being clumsy in the lab. “where there is bang, there is yang!(There is **, there is Yang Zhenning!) ）
I've heard this quote for a long time!
At the same time, Yang Zhenning was constantly looking for topics in theory, and he found as many as four. The first three were not of interest at the University of Chicago at the time, and he studied them alone in the library, each of which took weeks of hard work, and the result was nothing. Only the fourth topic was of great interest to Teller, and Yang spent several weeks analyzing the meaning of "the laws of physics do not change under the rotation of space" using group theory, and came up with several beautiful theorems, which he wrote into a short essay. Teller loved the article.
In the spring of 1948, all the teachers and students of the department knew that Yang Zhenning's work in Allison's laboratory was unsuccessful, so Teller took the initiative to come to him and asked, "Is your experiment not very successful?" Yang Zhenning said: "Yes." Teller said, "You don't have to insist on writing an experiment." You've written the theory, so use the theory for your graduation. I can be your mentor. "Yang Zhenning was very disappointed when he heard it, because he really wanted to write an experiment wholeheartedly. So he said to Teller that he needed to think about it.
After thinking about it for two days, Yang Zhenning decided to accept Teller's suggestion. That's why Yang didn't become an experimental physicist. Yang Zhenning himself said: Some friends say that this is probably the luck of experimental physics. I laughed when I saw this, and I would say that this is also the luck of theoretical physics.
However, the real turning point is that Yang Zhenning asked himself: Is my more than a year of experimental experience in vain? No. I learned that the values of experimentalists are different from theorists, and this has influenced many of my later work.
Let me comment on it. There is a very vivid story about the difference between the values of experimenters and theorists, from Murray Gell-Mann's (1929-2019) popular science book "Quarks and Jaguars". Quarks are elementary particles proposed by Gell-Mann, and both protons and neutrons are made up of three quarks, for which Gell-Mann was awarded the Nobel Prize in Physics in 1969.
When Gell-Mann was a Ph.D. student at MIT, he attended a seminar. Once, a speaker introduced his Ph.D.**, which used a plausible approximation to calculate that the spin angular momentum of the lowest energy state of the b-10 nucleus should be 1. When he finished, Gell-Mann wondered what the brilliant theoretical physicists sitting in the front row had to say about it. However, the first to speak was not a theoretical physicist at all, but a small man with a full beard who seemed to have just crawled out of a basement.
He said, "Hey, it's not 1 but 3 in its spin angular momentum. I measured! Suddenly, Gell-Men understood that the main goal of a theoretical physicist was not to convince the professors in the front row, but to conform to the observations. Of course, experimenters can also be wrong. But in this case, the guy who seems to have crawled out of the basement is right.
Let's go back to the story of Yang Zhenning. Between 1954 and 1956, experiments discovered many new particles, two of which were very strange as and . Their mass, lifetime, etc., are exactly the same, and it looks like they should be the same kind of particles. But it decays into two particles, it decays into three particles, and that creates a huge amount of confusion. Because there is a golden rule in physics called the conservation of universal symmetry, which means that the laws of physics should not change under the left and right transformations. Every particle has a cosmic symmetry, odd or even, i.e., -1 or +1. The cosmic symmetry of the particle is odd, which means that the cosmic symmetry of is even, because the square of -1 is equal to 1, and the cosmology of is odd because the cubic of -1 is equal to -1. So, is it the same particle as it?!
This problem is called the riddle and is the most troubling problem in fundamental physics at that time. The key here is that fundamental interactions fall into four categories: gravitational forces, electromagnetic forces, strong interactions, and weak interactions. In the first three interactions, the conservation of cosmic symmetry has a solid experimental basis. But in the weak interaction, the conservation of the universe has not been rigorously tested, and it is considered to be conserved only because it is "natural", which is a kind of inertia of thinking. and the decay of , which comes from weak interactions.
In the summer of 1956, Yang Chen-ning and Lee Tsung-dao carefully examined the past five types of experiments that proved the conservation of cosmic symmetry in weak interactions, and found that none of them actually proved the conservation of cosmic symmetry. They pointed this out, pointed out the possibility that the symmetry is not conserved in weak interactions, and suggested several classes of experiments that can detect whether the symmetry is conserved in weak interactions.
They sent ** to many peers, and soon received a unanimous response: Yucheng will never be non-conserved, and the experiments you suggest are a waste of time and resources! Only Chien-shiung Wu has a discerning eye, and although she does not believe that the universe is not conserved, she thinks it is worth testing. Even if the conservation of cosmic symmetry is not overturned, it is still valuable to test it in the case of weak interactions that have not been tested before.
After six months of hard work, Wu Chien-shiung announced in early 1957 that the universe is not conserved in weak interactions, and it is extremely non-conserved. This shocked the entire physics community, and Yang Zhenning and Lee Tsung-dao immediately won the Nobel Prize that year. However, why is nature cosmic and conserved in all three interactions, and only in weak interactions? It was not clear until now.
These stories of ups and downs tell us that we should never take the so-called "self-evident" law for granted. And Yang Zhenning's previous failures have also made the necessary paving for success. Being able to learn from failure is the style of a master. If you can learn from the failures of others, you can succeed faster.