Introduction: Recently, Associate Researcher of of the University of Science and Technology of China and President of the Fengyun Society, Yuan Lanfeng was interviewed by Observer.com , and discussed his "Quantum Information Brief Introduction" and shared his views on topics such as climate change, "troll" phenomenon, "Chinese materials and great use" phenomenon, knowledge philosophy, logical thinking and worldview. This article is the second half of the interview.
[Interview/Observer Network Li Zexi]
Observer Network: As a theoretical science, quantum mechanics explores the essence of the universe and is at the forefront of scientific cognition. Therefore, other fields, such as chemistry and physics, can answer the question of "why", but quantum mechanics sometimes cannot answer "why". Does this bother you?
Yuan Lanfeng: In fact, if you ask about physics major, he would say that quantum mechanics is part of physics. It is not outside of physics, but it is one of the two most essential basic theories in the entire physics, and there is also a theory with the same foundation as it is called relativity. How come there are two basic theories? If you have two basic theories, it means that they are not basic enough; there should be only one basic theory, which is at the bottom, and then the other theories are derived from it. There are many people who are working hard to unify the two basic theories.
The "Quantum Information Brief Introduction" I wrote also gave an example at the end, saying that some Australian scientists proposed a theory called event form, and wanted to integrate quantum science with general relativity . Pan Jianwei and Peng Chengzhi used this Mozi quantum satellite to conduct an experiment, but the result was that this phenomenon was not observed. So the initial version of their theory has been denied, but Australian scientists would not go die so easily: Our theory can be changed, right? We can modify the parameters and give another wave of predictions to explain why we cannot see the existing experimental conditions, and what conditions can be seen. In the future, our country will launch higher-orbit quantum satellites, and then re-explore the improved theories under a new experimental condition, and then iterate them one after another. This is the basis for truly promoting scientific progress.
But for your most basic problems, some theories can be explained by other theories, while some theories cannot. Regarding this, my book actually talks about the part about quantum entanglement. The principle of quantum entanglement is the superposition principle and the measurement principle of quantum mechanics. What are the principles behind these two principles? I said we don't know at the moment, we can only say that we think these two are correct, because all the predictions they give are consistent with the experiment, so we have strong confidence in them. Ultimately, we are confident in any scientific theory because the predictions they make are consistent with the experiments. In fact, science has always been like this. The direction of scientific efforts is to explain as many phenomena as possible using as few principles as possible. Our continuous progress is reflected in the fact that there are fewer principles and more and more phenomena that can be explained. But at any moment, there is always a basic principle under it. What is behind the most basic principle we think is currently? We can only answer honestly but don’t know. This is a truly honest attitude. This is a scientific attitude.
What science does specifically do, there is a very interesting metaphor, from Richard Feynman . There is a section at the beginning of his physics lecture notes explaining what science does, and there is a very interesting metaphor. He said that science is like watching people play chess, just like there are many gods in this world who play chess without doing anything, and then you are watching chess here without saying anything. You can't let God tell you directly what kind of chess they played. The only thing you can do is watch this chessboard, see how they move, and then you guess what the rules of this chess are. For example, you are watching chess.After observing for a while, you understand one thing, which is sometimes black and sometimes white, but the black and white will always stop in the black. It cannot suddenly walk to the white, and the white and white will always stop in the white. Then after looking at this rule for a period of time, you find this rule. The black and white nature of the image will never change. You think this is a natural rule.
Richard Feynman used chess to compare science
But the most interesting thing in observation is when some of the rules you have originally summarized are broken. For example, one day you suddenly find that an elephant appears where it shouldn't have appeared, and the black grid turns white grid.
This is because a pawn rushed to the bottom line and the ascension became an image. So when the original rules are broken and some phenomena that are originally incomprehensible occur, it is a great thing for scientists. What they are most excited about is that when this unconventional phenomenon occurs, it means that you have to discover a new law. Fehman also gave some examples, for example, you originally had a rule that kings can only walk one square at a time, but once you suddenly found that a king jumped to a place far away from it. Why is this? The answer is Wangche’s position. The example
illustrates the essence of science. The only thing you can do is observe how the world runs, and then summarize these laws in operation. These laws are broken from time to time. Of course, this break is a good thing, which means that some new laws can be discovered, and then your understanding will deepen. How long can this game last? Is there a deepest rule behind this? Actually, we don't know. The only thing we can do in is to keep playing.
Observer Network: For example, in many phenomena in economics, others can explain them, and people can logically "get" to the point. However, in quantum mechanics, people cannot "get" the point in it. When thinking about these problems, people can only say that this is what science and evidence tell me. How do you understand this difference?
Yuan Lanfeng: Quantum mechanics is indeed a very counter-intuitive science. It talks about a lot of effects, such as the tunneling effect. It says that a particle can tunnel through a barrier with a higher energy than it, just like a person who goes through a wall, you will definitely not be able to pass through it in the macro world. But the quantum world tells you that there is a certain chance of it, although the chance is very small. This is a very interesting effect, and this effect has been confirmed. People even invented a new microscope called scanning tunneling microscope based on the tunneling effect.
Quantum mechanics has this feature, that is, it is very unintuitive. But on the other hand, from the pedagogical point of view, what is intuitive? In fact, it depends a lot on the education you receive.
A phenomenon I discovered during the popular science process is that at the beginning I tried very hard to explain special relativity . The most basic thing about special relativity is called Lorentz transformation . That is to say, the superposition of two velocities is not directly added, but a relatively complex formula: for example, you have a reference system, whose speed of motion relative to the ground is u, and an object's speed of motion relative to the reference system is v, so what is the speed of movement of this object relative to the ground? Instead of u adding v, u adding v is divided into the following denominator. This denominator is 1 plus u multiplied by v and then divided by c. c is the speed of light, which is called the Lorentz transformation. This formula is much more complicated.
I will explain to you why the Lorentz transformation is correct, and Galileo transformation is wrong. The Galileo transformation is what we think in daily life, u plus v, the simplest speed superposition, which is actually wrong, but is actually just an approximation. When your u and v are very small, the Lorentz transformation is almost the same as the Galilean transformation, and there is no difference in measurement.
Lorentz Transformation: The half-light speed train is heading in another half-light speed train, and the speed should be 0.8 light speed instead of the speed of light obtained by directly adding
. But when I went to tell others about this, I was very shocked to find that there was a large number of people who could not even accept the Galileo transformation.
Many people have replied, "You said I was running forward on the fire, but I was faster than the train?" This is nonsense, how can a person run faster than a train? This shocked me. You want to explain the second floor to him, but many people don’t even know the first floor, and they can’t even understand the first floor. This is because they have so poor education that they may not have learned it at all.
So this reminds me of one thing, that is, you think that is intuitive or not, it actually depends on your educational background. So I have heard such suggestions, saying that if you let primary school students learn quantum mechanics from elementary school, they will also think that quantum mechanics is natural. This is what Feynman wants to do in the Physics Lecture Notes: He encourages us to use the simplest descriptions that can make people feel that the facts should be like this, and it would be strange if they are not.
Now we think Newton's three laws and the law of universal gravitation seem very easy, and we also think they are natural. In fact, this is because you have learned this since you were a child and received this education. You are constantly receiving feedback and can be used in daily life, and then you feel that this thing is very real and within reach. However, for those who have not learned it, they still can't even get over this basic concept, and they can't even understand Galileo's relativeity.
Observer Network: You mentioned education and the book also mentioned the key elements of popular science. I believe it is also more useful for scientists in other fields. For example, scientists of climate change often say that they cannot explain their fields to non-professionals. Until today, many people question the fact that greenhouse effect causes climate change. What specific suggestions do you have for these scientists?
Yuan Lanfeng: I am of course very concerned about climate change, but I only know a little bit. The most basic problem of
is that scientists’ propaganda to the media is really not enough, so until now you still see people coming out to question this matter from time to time. Their doubts are divided into many categories. Some people first question whether the entire climate change exists. The second level of doubts is questioning whether climate change is caused by humans. So I think these people questioned each other, what effect do you want to achieve? Is your ultimate goal to say that we don’t have to do anything, which is a waste of time? I think that's the motivation of these people.
But you have to respond to these people’s questions scientifically. Even if these questions are actually nonsense, you still use scientific responses. The standard response of scientists may be: look at the report of IPCC (Intergovernmental Panel on Climate Change), because every few years, the United Nations will organize a group of experts to write a report on climate change; then look at the process of changing the change, and you will find that these two confidences are getting stronger and stronger about the existence and anthropogenic nature of climate change; early reports said that it might be like this, and then there is a great possibility that it is like this, and now we are very sure that it is like this. This matter does not have a unified caliber from the beginning, but in the past 30 years, our understanding of it has deepened a lot, so it must have a lot of scientific evidence.
Last year's Nobel Prize in Physics was given to three people, two of which were model predictions of climate change. The importance of this study lies in their proposal of a complete set of models to predict the Earth's climate, and then based on this model, we can calculate how much climate change in recent centuries is caused by human activities and how much nature is caused. You can deduct this part of nature, and most of the rest are human. The academic community believes that this research is solid enough to win the Nobel Prize for , but ordinary people don’t know it. Most people have never heard of the names of these Nobel Prize winners.So there should be a huge "gap" (cognitive gap). Scientists who specialize in climate change should make greater efforts to communicate with the public and explain the truth to everyone.
If you just repeatedly tell everyone this conclusion, saying that first there is climate change, and then climate change is largely caused by human activities, many people still don’t believe it. Because no matter what you tell him, he will have a conspiracy theory, whether it is climate change or quantum information. quantum information will be considered a conspiracy. For example, some people think it is completely fake, some people think that this is the United States deliberately released the wind, hoping that you will do this. There will be any strange logic. What can I do? You can only explain the scientific principles to everyone.
, I believe there is a lot to do. First of all, they have to understand the literature in their professional field very clearly and then extract it. What is the most valuable information to the public? If a person questions this matter, or does not understand at all, then you should tell him what he should first, and then tell him what he should set up a big picture as soon as possible. I think this is what they should do. Of course, if I have time, or if the country and society think it is necessary to let me do this, I will bite the bullet and learn about climate change, and then carefully think about how to spread this matter to everyone.
Yuan Lanfeng: Climate change scientists should first sort out the literature and extract the most valuable information to the public
Observer Network: In "A Brief Talk on Quantum Information", you mentioned many principles of pursuing truth, which can be summarized as, don't use your amateur to challenge other people's majors. However, in this split world, it seems that inappropriate "troll" means that you may be destined to be unknown. You obviously have thought deeply about these knowledge and philosophy issues. How do you think we can solve this social phenomenon today?
Yuan Lanfeng: Thank you very much for this question. I have read a lot of books like Russell "History of Western Philosophy", so the question you asked made me feel very friendly. In fact, there is a lot of content in my book. I think a person who has never read philosophy would not think so at all.
I often think from a philosophical perspective. For example, if Russell faces such a question, how would he answer? Think from this perspective. So I wrote many discussions that ordinary people may see, and you have noticed them.
There will be such a problem in this world. If you don’t speak astonishingly, will you never stop until you die, right? If he is not out of line, few people will come to listen to him. But as far as we are concerned, as far as we do scientific communication is concerned, our goal is to spread as much as possible while ensuring correctness, and the premise of correctness is the most important. I am definitely not like an entertainment star, or like a person who makes a living by relying solely on self-media. The first thing I consider is traffic and do everything for traffic. I was on the premise of spreading the correct information and then found a way to increase its traffic. Whether the traffic is large or not is actually not that important to me. actually determines that my approach is different from many so-called popular science self-media. For the sake of publicity, all methods are made.
For example, a few days ago, a friend sent me a video about the so-called double-slit interference experiment on TikTok. Many of the likes are hundreds of thousands and millions of playbacks are played, but the content is all wrong because they are called alarmist. Double-slit interference is a very basic experiment in quantum mechanics. Everyone has been studying it for decades. The textbook has already made it clear. These people have to interpret it as it collapses our worldview. This world is determined by consciousness. The conclusion is that idealism is better. The people don’t understand this, and after reading it, they were shocked and mysterious, and then they liked it. Many people asked me about this kind of thing. We admit that this approach is easy to catch the eye, but this is the approach we are going to oppose. So what I often do is to pour cold water on many eye-catching things.
Today, my dad also sent me an article saying that someone "suddenly posted a message", "The United States was shocked", or who "silenced", etc. I said that such titles are obvious title parties, and many of them do not need to click to know that they are "nonsense".
We can't stop the trend. Many people write such articles for their livelihood, or maybe a robot is automatically generating documents. But ourselves, such people with a sense of social responsibility, or those with this ability, should stick to their original purpose. We are here to spread science and spread the right things, and some people are willing to listen to these things. society is always like this. Some people are willing to absorb that kind of effective information, and they love to learn. There are also many people who don’t like to study. You can’t do anything about people who don’t like to study because they have no motivation. But for those who love to learn, we provide them with the right information, and I believe this is a good thing to do for society.
Yuan Lanfeng: Scholars should ensure that the information is correct and must not use everything like celebrities or self-media for traffic
Observer Network: But we cannot ignore the existence of these people who do not like to learn, because they still have an impact on society. How can we make them love to learn as much as possible, or even if they insist on not learning, how can we at least minimize the social impact of their "not love to learn"?
Yuan Lanfeng: I feel like this. In fact, we can’t directly change these people, but we can benefit those who love to learn. I found that there is a group of people who love learning, that is, those who invest, because they are playing there with their own money all day long. What they think about all day is how to spend their money, whether they go to stock trading or buy funds, they have to use their real money to practice. So they just learn all kinds of things all day long. For example, if you want to buy an electric car, you have to learn about electric car . So these people are very enthusiastic about learning. They discuss all day long how to learn and how to improve themselves. They also invent a lot of words, such as iterating , breaking the circle, etc. So it is also very interesting to talk to these people. You may feel that ordinary people don’t like to study, and this group of people love to study too much.
I think if people who love learning can benefit, they will have a strong motivation to maintain this state. We can only use this attraction instead of exclusion, and you cannot sanction those who do not like to study; allows people who love to study to get corresponding benefits in society through the natural selection of society, and more and more people will go in this direction.
Observer Network: In some of your published articles, the phenomenon of "Chinese materials and materials" in China is often mentioned. Can you briefly explain your understanding of the constitutive factors here and how we can overcome this problem specifically? Why does this phenomenon seem to exist in quantum mechanics?
Yuan Lanfeng: Researcher at the Institute of Natural Sciences, Chinese Academy of Sciences Researcher at Liu Yidong Teacher often says "Chinese materials are of great use". I think this question is very valuable, so I often spread these views of him. There is a common historical reason for "Chinese Materials to Be Useful". Our country is actually doing scientific research after reform and opening up. There were many twists and turns in the process, because the Cultural Revolution was delayed for so long, and then after the reform and opening up, many of them hurriedly sent abroad, many of whom did not come back. When they came back, they found that the domestic material conditions were still so poor at that time, and the investment in scientific research was far inferior to that of foreign countries, so the conditions were very difficult.
I don’t have any complaints about my predecessors, because it’s very difficult for everyone, but due to such historical reasons, this effect will be formed: some people are far from being a top scholar in the world, but they have become vested interests in China. He monopolized the high position in this field and his level was not high, but he was very afraid that others would surpass it, just like Wu Dalang opening a store.So Teacher Liu Yidong used a very interesting word in his article, called "Defensive jealousy and jealousy" , which means that he knew that his level was not high, so they formed a gang to suppress people with real high levels, stuck to the entire field, and could only be limited to their level, which formed such a harm. These people with low levels will naturally realize that their core competitiveness does not lie in science, but in interpersonal relationships, and they will work harder to maintain the situation.
As for how to break this situation, Teacher Liu Yidong’s article talks a lot, and I will promote good things to him. For example, he has a so-called sword idea, about how you evaluate a scholar. What is the current way? Now it is more about looking at the hat, how many titles a person has, whether he is an academician, whether he is an outstanding young man, whether he is an Yangtze River scholar, whether he is a thousand young people, and a lot of titles like this. : Each unit says how powerful we are, it often becomes a competition of hats. To count how many academicians our unit has, it makes people laugh. even asked me seriously what indicators should be used to illustrate the rise in the technological level of our country over the years. Can the increase in the number of academicians be used?
I said, isn’t this funny? Because academicians are evaluated by the country. No matter how weak a country is, if they are willing to evaluate academicians, they can evaluate as much as they want. Do you think their technological strength is stronger? Of course, this is completely uncountable. What is really useful is the international comparison of your country: what fields are you ahead of the international community, who are internationally renowned scholars, and what achievements they have proposed, which is really valuable. You said that your country's internal reviews, and after review, what's the use of this?
"Judging the price by hat" (Photo source: "Intellectuals" website)
Liu Yidong's swordism means that we should let a scholar take out his representative achievements. How do you know that a person is an amazing scholar? In fact, it depends on his achievements in the final analysis. For example, when you mention Einstein , you first think of the theory of relativity, and when you mention Darwin , you think of evolution theory . This is what shows that a person is truly amazing. If there is any scholar who can list his achievements openly and say that I made this thing, and when I see it, I will think of me. Other things that can be considered are what the comparison between this achievement at home and abroad, what the foundation was before, what problems were solved, what was cited at home and abroad, and how was invited to give a report? Post this up and the person's status in the academic world will be clearly visible. Then everyone flocked to him, whether they were consulting him or working with him, there were everywhere. If a person cannot list a representative achievement and just says how many articles he has published and where he posted it, then it is clear that this person is flooding. Whether a person has real materials or not is very obvious. So I think this is a very good method proposed by Teacher Liu Yidong, but I don’t know how much resistance there is to implement it, but no matter what, let’s try our best to promote it.
Then your last question, why does the field of quantum information seem to be an exception? It is strange that China is actually ahead of the world in this field? One of the reasons why our country has been relatively successful in the field of quantum information may be because this is an emerging field. In fact, there is a common phenomenon. The more emerging the field, the better our country performs, because there is no historical precipitation. Historical precipitation often becomes a historical burden. The more it requires deep accumulation, the worse our country performs, such as chips and engines. This effect can be seen from the inside and from the outside.
Observer Network: In 1970, Zambia nun Mary Jucunda wrote to NASA (NASA), asking them why they don’t use this money and this energy to solve real problems of famine and poverty when they invest billions of dollars a year in pioneering unknown space? I am now referring to her question, why do the government and society spend money and energy to support the research and development of quantum mechanics instead of solving various other problems?
Yuan Lanfeng: The deputy director of NASA wrote her a reply letter at that time, a very classic document. The basic spirit of that answer is still applicable now, that is, we cannot just look at the things in front of us, we must also look up at the stars. Because looking up at the starry sky can open up a new realm for you, and it can solve some problems you can't imagine.
The photo attached to the reply from the deputy director of NASA
In his reply, he gave an example in his reply. There was an earl in Germany. On the one hand, he helped the poor, and on the other hand, he wanted to fund a person who polished his lenses. Many people have said, you spent so much money to fund the grinding of lenses. What are the benefits of this grinding of lenses for us? He said I don’t know what the benefits are, but I think what he did is quite interesting, maybe when it will be useful. As a result, this man later invented a microscope and discovered many pathogens, which solved many medical problems. Of course, this was an unexpected development.
However, the practical prospects of quantum information are very clear. Quantum confidential communication is now in use and is gradually being promoted. In the past, it was mainly government and financial departments, but now individual users are gradually starting to use it.
Quantum computing 's business prospects are very clear. After it came out, many problems that were originally thought to be unsolvable can now be solved, so the industry is investing huge funds in research and development.
Observer.com: I'll ask a little more theoretical question. You said that quantum information has very specific applications, so for research that there are no specific applications, or we don’t know what we will find, is it worth it, or how much investment should be made?
Yuan Lanfeng: Your question is very good. I just saw an example like this yesterday. My dad transferred me an article, which criticized the Chinese science and technology community, saying that you write papers all day long and ignore the national economy and people's livelihood. When you are really bored, you realize that our chips are not good, lithography machine is not good, and the engine is not good, and you university professors are all "fooling". This article is biased overall.
We should understand that basic scientific research and applied technology are different, or science and technology are different, and many people can’t even understand the most basic one. The purpose of the essence of science is not for practical purposes. The purpose of the essence of science is to understand how the world works and to understand the laws of this world; its research is to satisfy human curiosity. Technology must have a practical purpose, so although we often use the practical use of technology to defend science, practicality is not necessary for science.
If we think about this issue seriously, we should understand that some sciences do not have practical effects. For example, cosmology, what practicality is like for you, at least you can't see at the moment; of course, maybe we know the fate of the universe, whether it expands infinitely or turns into contraction, what dark energy, , dark matter, , may be useful in the future, but that is a relatively distant future. If you must find usefulness for cosmology now, the answer will be useless.
But we should tell you very clearly that this uselessness itself is a great use because it satisfies human curiosity. We should think that understanding the nature of this world is a very valuable thing in itself, and we should invest something in it. Of course, you cannot account for most of the national economy and people's livelihood, but it is still very valuable to allocate some of the money from it to do this.You can't just keep your penis and do everything practical, then your country is too hopeless and has no future, too short-sighted.
Many people criticized that university teachers only publish papers and do not solve practical problems. I said that this criticism is completely wrong, and this is not what they should do. Everyone has their own duties, and college teachers should publish papers. Distributing papers is a good thing in itself, and you should not say that publishing papers is bad. Then the engineers in the company should be the ones who really solve the front-line technical problems and study professional technology. It would be a good thing for university teachers to cooperate with them, but you should not mix the responsibilities of both parties together.
For example, Chen Jingrun to study Goldbach conjecture , 1+1 (any even number ≥6 can be represented as the sum of two odd prime numbers). What's the use? No use so far. But everyone should consider this an amazing achievement, because it is a purely intellectual achievement, and we humans are now able to prove some theorems about the decomposition of an even number into two prime numbers. Although Goldbach's conjecture Chen Jingrun did not prove it, he proved that 1+2, which is an even number that can be decomposed into a prime number plus a number whose prime factor has no more than 2 (that is, it is a prime number or the product of two prime numbers); this is a very amazing intellectual achievement, and we should be proud of it, right?
We cannot just look at what is in front of us, we must also look up at the starry sky
There are different values in this world, and those non-practical values are also worth investing in. Although you don’t need to invest so much, if you don’t give up, you’re a short-sighted view. We should tell you honestly that not everything should be measured by practical value, and there are some value beyond practicality in the world.
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