Feynman's lecture record

Feynman's lecture record -- A Nobel Prize winner in Physics sees the society

Mr. John Danz asked me to give a lecture on the impact of science on other areas of human thought. In the first lecture, I will discuss the nature of science and focus on the doubts and anxieties about the existence of science, and in the second, I will discuss the implications of scientific thinking on political and religious issues; in the third lecture, I will describe what society looks like to me, that is, what society is like for a scientist, And what kind of social problems may be brought about by future scientific discoveries. Of course, this is just my personal opinion.

How much do I know about religion and society? "We never know you have a strong interest in these areas, and now listen to what you can say," The University of Washington and several other university physics friends laughed. "Of course, what they mean is that I'm interested in these issues, but I'm not afraid to talk about them.

When it comes to the impact of one field of thought on another, it is always considered self-deceiving. Because in today's increasingly specialized disciplines, few people can have a deep understanding of the two different areas of human knowledge, and can do not deceive themselves or fool others.

However, I am talking about some thoughts of the ancients in the past. What I'm talking about tonight is hardly a problem for me, but it's not easy for the philosophers of the 17th century to say that. Why are we repeating this? Because there are many new generations of people born every day, great ideas abound in the history of mankind, and they cannot continue unless they are consciously passed on to one another.

Many of the Ancients ' ideas have now become a consensus that people don't need to discuss or explain them anymore. Many people now agree with this view, especially in universities, where most people agree. But, according to my observations, some of the ideas related to scientific development are not universally agreed. So it seems to me that you may have come to the wrong place today to listen to my speech.

When it comes to the question of the influence of an area of thought on other areas, I will start with the conclusion I have reached. I do understand science, know the scientific way of thinking, the attitude of scientific treatment of knowledge, the source of scientific progress and scientific thinking training. So, in this first lecture, I will discuss the science I know, and leave many of my more ridiculous arguments to the following two words. According to the general situation, I guess the audience will be much less than the present when the two speak.

What is science? I don't think it's necessary to give it a strict definition because the definition is too strict and accurate to be better understood. The term "science" usually refers to one of the following three meanings or a mixture of the three: sometimes people talk about science, which means the concrete method that leads to scientific discovery, and in other cases, the science refers to the knowledge that originates from scientific discovery, and third, science can also mean, When you have some scientific discoveries you can do new things or actually do new things, this aspect is often called technology. But if you look at the science section of time, you will find that about 50% of the content is a new discovery in Guan Gan Science, and about 50% is about what will be the next new discovery and what is being done in the new research. Therefore, the general definition of science also refers to a certain degree of technology.

I will discuss these three aspects of science in a reverse order. First of all, let me talk about the new attempts and new applications that people can do because of scientific discoveries, namely application technology. The most obvious characteristic of science is its application. In fact, as a result of science, technology refers to the ability of a person to do something new. However, the effect of this ability is seldom noticed. Without the development of science, the whole industrial revolution was almost impossible to succeed. Today, thanks to advances in scientific development and production, it is possible to produce medicines that feed so many people and control diseases, suggesting that humanity is no longer a slave to the production of the necessities of life.

Now, no guide book can tell people how to use the power of good science, to the benefit of human society. The product of scientific power is either beneficial or harmful, and depends mainly on how humans use it. We are willing to improve production technology, but there are still many problems in automation application. On the one hand, we are pleased with the new achievements and developments in the field of medicine, because they eliminate diseases, prolong life expectancy and reduce mortality, on the other hand, because of the high birth rate and low mortality, the rapid growth of the population causes us to worry. In addition, there are hidden labs in the community where some people are trying to nurture new germs that others will not be able to find to treat their methods. We are pleased with the development of the air transport industry, which has facilitated our travels, but should also be aware of the horrors of air combat. We are pleased with the growing mutual exchanges and cooperation between nations, but on the other hand we are concerned that our actions and plans can be easily stolen by spies. We are excited to be able to enter space, cough! There is no doubt that there are disadvantages to which we will meet. Of all the advantages and disadvantages of these projects, the most notable is the development of nuclear energy and the obvious problems posed by nuclear weapons.

Is Science worth it?

Science can make people do things they can not do, I think this power of science is valuable. No matter how it is used, the result is good or bad, but the power itself is a value.

Once, in Hawaii, I was dragged by someone to visit a Buddhist temple. One of the people in that Temple said, "I'm going to tell you something you'll never forget." Then he said, "for everyone who comes here, he gets the key to the gate of heaven, but the same key can open the gates of hell." ”

The same is true for science. On the one hand, people can make science for the benefit of mankind, it is the key to the door of heaven, on the other hand, people can also use science to endanger society, the same key also opened the gate of Hell. As for which is the door to heaven, which is the gateway to hell, there is no guiding information for us to judge. Should we throw away this key so that we no longer have a way into heaven? Or should we try to find the best way to use the key correctly? Of course, this is a very serious question. But, I think, we should not deny the value of this key that opens the door to heaven.

All the major problems of science and social relations lie in this respect. When scientists are cautioned that they must be responsible for the social impact of scientific discoveries, it is also a hint of scientific application. If you study the use of atomic energy, you must also recognize that atomic energy can also be used to kill. However, I do not want to discuss this further in detail. Because it is an exaggeration to say that these are the problems of science itself, they are merely questions that the humanitarian people are talking about. In fact, the mechanism of how this power is produced is clear, but we do not yet know how to control it. This is not a problem that science should solve or can solve, and scientists do not know much about these aspects.

Let me explain why I don't want to talk about this kind of problem. It was in 1949 or 1950 that I had been to Brazil to teach physics. At the time, it was an exciting four-point plan, and everyone was willing to help the backward countries.

In Brazil, I live in Rio, the city is surrounded by mountains, and there are many wooden huts on the mountain. The people there are very poor, they have no sewing machine, not even tap water. In order to get the necessary water for life, they went down the mountain with a broken oil barrel, to a construction site where there was water for the preparation of concrete. People filled the barrels with water and carried them to the mountains. And then you will see that the water is turned into a sewage stream down the hill. It's so pathetic! On the right side of the mountain is the charming complex of Capacabana beach, the beautiful apartments and so on.

I said to a friend who joined the project: "Is this a question they don't know about technology?" Don't they know how to lay a pipe down the hill to the top of the mountain, or at least go along this pipe and move the buckets full of water to the mountains and move the empty barrels down the hill? ”

This is obviously not a technical question about how to do it, as there are various types of pipes in the nearby apartment building, and there are also pumps. Now we realize that this is an economic aid problem. Laying a pipe and building a water station how much it will take to get the water to the mountain is not in the scope of the question I am discussing.

Although I do not know how to solve this problem, I would like to point out that we have tried to do two things, technically know how to do and financial support. Neither of these measures is so encouraging, and we are trying other ways. I think it is a way to solve all the problems by continuing to try new measures. In this way, the new measures to solve the problem become the practical application of science, so that people can do things that could not be done before. They are so obvious that we do not need to discuss them further in detail.

Another aspect of science is the content of science, the theories and laws that have been discovered. This is what scientists do after scientific research and is the highest reward they can get. Doing this kind of work is not for application, but for causing exciting discoveries. Perhaps most of you understand that. But to those of you who do not understand this, it is impossible to comprehend this important aspect of scientific research through one of my speeches, and this exciting part is the real reason why scientists work in scientific research. However, if you do not understand this, you will not understand my whole point of view. Unless you understand and appreciate the great adventures of our time, you cannot understand the relationship between science and its application and other things. Unless you realize that science is a great adventure, something exciting and exciting, you can't live in your time.

Do you think the problem is boring? I hope not. It is very difficult to make this very clear, but perhaps I can talk about some of my ideas casually.

For example, the ancients believed that a sea turtle was adrift amid beige on the boundless, unfathomable sea, and an elephant was standing on the back of the turtle, and the land on which we lived was the elephant's spine. Of course, what supports the sea is another problem. They also don't know the answer to the question.

This cosmic outlook of the ancients is the result of imagination. It is a poetic, beautiful and vivid worldview. Let's take a look at what people today think about the universe. The earth is a rotating sphere, human beings live on its surface, when we head upward, some people are head-down. We rotate like a string of meat on a fire as the Earth rotates, and the Earth revolves around the sun. This looks more romantic and more exciting. So, what is the power that makes us not be thrown into space? Gravity. Not only does it work on Earth's objects, but it also keeps the earth in a spherical shape as it was originally formed, keeping the solar system as a whole, and making us orbit around the sun as our Earth tries to keep away from the sun. This gravitational attraction exists not only on earth and on the sun but also in the stars, which hold stars in different distances and in different directions in the Galaxy to form galaxies.

But suppose that nature's imagination goes far beyond human imagination, and to those who are unaware of it, it is impossible to imagine that nature is so magical by observation.

Let's talk about Earth and time. At first, there was no life on Earth. For more than billions of years, the sphere has been spinning with sunrise and sunset, tide and tide, without any vitality to appreciate it. Can you imagine what the universe means when there is no life in this world? Although there is no life on earth for most of the Earth's evolution, we are so accustomed to seeing the world from the human point of view that we cannot understand what the universe means when there is no life. In addition, most places in today's universe are likely to have no life.

Let's talk about life itself. The internal mechanism and chemical composition of the living body embody perfection and harmony. It shows that all life is connected to other life. As an important compound in the process of plant assimilation-chlorophyll, a part of which has a planar structure, it is a beautiful ring called benzene. Farther away from plants are animals like ours, and in our blood and hemoglobin there is this equally interesting and peculiar plane structure of the benzene ring. The elements in these ring centers are iron rather than magnesium, although they have the same ring structure, but are not green but red.

The protein of bacteria is the same as human protein. In fact, it has recently been discovered that the mechanism of protein production in bacteria depends on the order of raw materials in the production process from red blood cells to red blood cells. So, different forms of life are closely linked. The universality of the chemical process within the body of life is indeed a wonderful idea. For a long time, we humans have been too arrogant and even able to correctly recognize our connection with animals.

Let's talk about atoms again. In the crystal, a small ball next to each other is arranged in a certain way to form a beautiful pattern. A cup of water covered with a lid for several days seemed to be stationary. In fact, the inside of the molecule, the atom has been constantly moving, some atoms are leaving the surface, some atoms because of the glass wall is being bounced back, some atoms moving back and forth. Although many objects seem to us to be stationary in our eyes, in fact the movement at the microscopic level is quite active and quite intense.

Moreover, scientific discoveries show that the whole universe is made up of the same atoms. The elements that make up celestial bodies are the same as the elements that make up our human beings. Then there is the question of where the material that makes up our human being comes from. Ask not only where life comes from, where the earth comes from, but also where the material that makes up the life and the Earth comes from. Like some stars are still exploding, it seems that the materials that make up life and the Earth seem to come from the dust of a star's Big bang. So, after 4.5 billion years of gathering and evolution, the dust is now a strange animal standing here, giving a speech to a group of strange animals. What a magical universe!

Let's take a look at the human physiology system, which is no different from what I said above. If you look closely at everything around you, you will understand that there is nothing more exciting than a scientist finding truth through hard work. From a physiological point of view, when you see a young girl who is doing the intense rope skipping movement, she will associate the heart rate to the speed. What happened to the little girl's body? The heartbeat is linked to the nervous system, which quickly feeds back into the brain, as if saying, "Now that I have touched the ground, I have to increase my muscle tension so that my heel does not get hurt." As the little girl beats up and down, another part of the muscle feeds back to the other nerves saying, "one, two or three, one, two or three." When she was jumping, the professor of physiology, who might be smiling and watching her, would be affected by her cheerful emotions.

Let me talk a little more about electricity. There is a strong attraction between positive and negative charges, and objects with different charges are attracted to each other, but within the normal material, all positive and negative negatives cancel each other out. In addition to the occasional chance of rubbing amber and finding it appealing to confetti, no one noticed the electrical phenomenon for a long time. However, we found today that there are a lot of objects in the intrinsic mechanism is based on the principle of design, they have brought great convenience and fun to people's lives. However, science is not fully appreciated by people.

To find some suitable examples, I read Faraday's history of the chemistry of candles. The book collects six Christmas speeches made by Faraday for children. If you read this book carefully, you will find that Faraday's view in these speeches is that, no matter what you think, you are closely related to the whole universe. Therefore, under the guidance of the belief that there is a universal connection between things, Faraday studies the physical properties and chemical laws of the combustion phenomena by observing the characteristics of the candles in various aspects. But when it comes to Faraday's life and his scientific discoveries, the editor of the book explains in his preface that Faraday has discovered the law of electrolysis, that is, the amount of electricity required for an electrolytic compound is proportional to the valence of the separated atom in the compound. The preamble further explains that Faraday's law, discovered today, is widely used in industry for the electroplating and anodic dyeing of metals and many other aspects. I don't like this kind of expression. Here's what Faraday has to say about his discoveries: "The atoms of matter have the ability to live in a certain way or have a property associated with a charged capability, and the most remarkable property of the atom is the power of this charge, which has a mutual chemical affinity." "He found that determining the root cause of how atoms are combined, or determining how iron atoms bind to oxygen atoms to form iron oxides, is due to the positive nature of iron atoms and the negative charge of oxygen atoms in the compound of iron oxides, which attract each other and bind together in a definite proportion." He also found that electricity in atoms is expressed in the form of an integral multiple of the basic unit. Both are important scientific discoveries and one of the rare scientific achievements in the history of science, which marks the combination and unification of the two fields of physics and chemistry. He suddenly discovered that two distinctly different things were different aspects of the same thing. So he studied both electricity and chemistry. In this way, electricity and chemistry are the two different disciplines that study the same thing, and chemical change is the result of the interaction between the charges. However, such important scientific discoveries are understood in the way described above, and it is inexcusable to note that these principles can be used for electroplating.

As you know, newspapers have a basic standard for each of today's findings in the field of physiology: "The findings say the findings can be used to treat cancer." "But those who find themselves cannot explain the value of their discoveries."

Trying to understand the laws of nature is the most severe test of human rational ability. In order to avoid making mistakes in predicting certain events, one must rule out all kinds of false deception and establish their own theories on the basis of strict logic. The ideas of quantum mechanics and relativity are examples of this.

The third aspect of science refers to the method used for scientific discovery. The scientific approach is based on the principle that observational experimentation is the criterion for judging whether a scientific discovery is confirmed. When we learn that observing experiments is the only and final criterion for examining the correctness of a theory, we really understand all the other aspects of science and the nature of science. But here, the true meaning of the word "vouch for" is "inspection". In the same way, 100 evidences show that a liquid is alcohol, and it only shows the results of an experimental test of a liquid called alcohol. For today's people, the real meaning should be understood as "exceptional circumstances to test judgment". Or, in other words, "exceptional circumstances to justify a judgment is wrong". This is the principle of the falsification of science. For any theory, if there is a counter-example, and it is possible to observe the experiment to prove that the counter-example does exist, the theory is wrong.

For any inverse of the theory, the most interesting is the inverse of the example itself. Because they reveal to us the mistakes of the old theories, then we can find out what the right theory is, and this is the most exciting thing. Scientists will use the conditions that produce these similar results to institute anomalies, and will try to find more counter-examples and determine the nature of these counter-examples. With the deepening of research, a process that inspires him to continue his research is unfolding. Instead of trying hard to avoid examples of the mistakes that have been made in the past, he will try to find evidence of falsified old theories and be excited about his discoveries. It is even desirable to prove that what you have discovered is wrong as quickly as possible, leading to the discovery of updates.

Of course, judging whether the theory is correct by observing the experiment, this standard has strict restriction. This evaluation criterion is limited to questions raised in this way, such as "If I do this, what will happen" such problems can be examined by observation experiments. Questions such as "Should I do this" and "what is the value of this matter" do not belong to scientific questions that can be examined by observing experiments.

However, if a proposition is not a proposition of science, and it is not able to accept the test of observation, it does not mean that it is a meaningless proposition, a wrong proposition or a foolish proposition. We are not trying to explain why science and other things are not good, and what scientists are dealing with and trying to solve is the problems that can be analyzed by observing experiments. However, there are still some omissions, as this approach is not effective for those problems. This does not mean that these problems are unimportant, and on the contrary, they are, in many cases, the most important. There are always things like "what to do" before you make any decisions and take action, and what you have to think about. Such questions cannot be found only in questions such as "If I do this, what will happen". Of course, you would say, "Sure, you realize what's going to happen, and then you decide whether you want it to happen." "But that's a step that scientists can't take. You can tell what's going to happen and then you have to decide if you want it to happen.

In science, there are many technical results that are based on observational experiments as criteria for judging standards. However, in observation can not be careless, must be very careful. If there is a little stain on the lens of the instrument, it will lead to a change in color, which you did not anticipate. And you have to check the results very carefully, re-examine them, be sure you know everything, and not misinterpret your observations.

Interestingly, this thoughtful consideration is often misunderstood as a virtue. When someone says that he has studied a phenomenon scientifically, he often means that he has thoroughly studied the phenomenon. I have heard people talk about the "scientific" extinction of the German Jews, in fact, there is no scientific element, but the total extinction. There is no doubt that in order to determine something, we must first observe it and then verify it. According to this understanding, there were also "scientific" extinctions of people in Roman times, although science did not develop to today's level and people did not attach much importance to the observation. In these examples, one should say "complete" or "thorough" rather than "scientific".

To cite a small example of daily life, there is a famous joke about a person complaining to his friend about a strange phenomenon. On his farm, the White horse eats much more than the black horse. He was worried about it and did not understand the phenomenon. Later, his friend suggested that he might need to raise more black horses and less white horse. This joke looks ridiculous, but think about how many times similar errors have occurred in a variety of judgments. In life, it is sometimes said, "My sister had a cold for two weeks the other day ..." If you think of the joke above, which has a "more white horse" argument, this is one of the examples of error judgments. Scientific reasoning requires some training, and we should try to teach people to learn this way of reasoning, because even at the lowest level, such errors are not uncommon today.

Another important feature of science is its objectivity. It is necessary to treat the results objectively, because the experimenter is likely to favor a certain result. As a result of accidental factors, such as dust fell on the instrument lens, you conducted several experiments, each time you get different results, you can not control all the factors in the experiment. You want to get a definite result, the result of this experiment is the same as you hoped. You would say, "Look, this is what I want." "Next time you do this experiment, the results are different." Perhaps in the last experiment, a speck of dust landed on the lens of the observation instrument, but you didn't notice it.

These situations appear to be apparent, but they are not given sufficient attention when deciding on scientific issues or the periphery of science. Of course, there is a certain sense factor, for example, because what the president says or does not say, you infer that the stock price rises or falls.

Another very important technical point is that the more specific a statement is, the more interest it will attract. The more clearly defined statements, the more it can cause people to test its interest by observing experiments. If someone tries to suggest that the planets revolve around the sun because all the material that makes up the planet has a movement, that is, motion, which we call an "instinct", this theory can also explain many other phenomena. Isn't that a good theory? It really is not. It cannot be compared with such a view that the planet revolves around the sun in a centripetal force, the magnitude of which is inversely proportional to the square of the planet's distance to the sun. The second theory is better than the first, because it is more specific and clearly less of an accidental result; Its statement is so clear that it is correct to use the most obvious error in the course of the movement, as the planet swings around its orbit, and according to the first theory, you say, "Oh, That's a funny expression of instinct. "

Therefore, the more specific and detailed a theory, the more convincing it is, easy to directly face the abnormal situation, it can also arouse people to test its interest. And the more valuable it is to test its work.

Some of the words are meaningless. If this kind of word, like the above example of the "instinct", can not be derived from the strict conclusions, the use of such words to express the point of view is almost meaningless. Because you can almost explain anything by using the idea that there is a movement trend in things. Philosophers have done a lot of work in this regard, and they believe that it is important to define the meaning of the concept very precisely. In fact, I disagree with that view in a way. I think it is often not worthwhile to give a concept a very strict definition. In fact, it's impossible in most cases, but I'm not going to discuss it in depth here.

As for science, philosophers talk most about how to ensure that scientific methods are effective, and I wonder whether these views remain valid in areas that cannot be judged by observational experiments. I am not prepared to say that any problem must be studied in the same way when some methods are used that are different from observation. Perhaps in different fields, a clear definition of the meaning of the concept is not so important, perhaps there, the law, the content of the theorem does not need to be very specific and so on.

In summary, there are some very important things I did not take into account. I have said that observation is the criterion for examining the truth of a theoretical point of view. The rapid development and progress of science requires humans to invent something to test the correctness of knowledge.

It is thought that the medieval people simply carried out many specific observations, which in themselves hint at the law behind the phenomenon. But that is not the case in fact. To some extent, their observations are more of a result of imagination than from observation. So, next I have to talk about how the ideas that have been confirmed by observation are coming. We have a way to test whether a theory is correct, but we are not aware of where this approach comes from. We are just comparing with the observation to judge whether a theory is correct or not. So, in the scientific community, we are not interested in how an idea is obtained.

No authority can decide which opinion is superior to other ideas. To find out whether a point is correct or not, we don't have to resort to any authority. We can read the works of an authoritative person and listen to his advice, but we must examine whether his point of view is justified and whether his ideas are correct. If his views are wrong and more serious, these "authorities" will lose their "authority".

As is the case with most people, at first there was a debate between the scientists. In the early days of physics, for example, there was a heated debate. But in today's physics world, the relationship between scientists is very good. As both sides of the debate are constantly designing new experiments and betting their bets on possible outcomes, a scientific debate is likely to leave a lot of jokes on both sides and create uncertainty about the outcome of both sides. In physics, physicists have hardly taken into account the fact that a large number of observational experimental facts have long been accumulated and a fairly mature theory has been established, and if a new idea differs from all existing ideas and is incompatible with all the theories proven in the observed experiments. So whether you learn a new idea from anyone or anywhere, you may be willing to accept it, but you have no reason to think other people will accept it.

However, many disciplines do not develop to this height of physics. In these disciplines, the relationship between scientists is similar to that in early physics. At that time, because there was not so much to observe the facts, nor was it universally accepted theory. As a result, there is a heated debate among the various viewpoints and the scientists ' opinions. I have raised this point because there must be an independent, objective way to test the truth and the debate between people can be solved.

Most people find it strange that no one in the scientific community is interested in the personal background or motives of scientists who put forward scientific ideas or theories. Please note that an opinion or an idea seems worth checking, and it is different from being able to test it. Moreover, some of these views may not seem worth validating in the past, but with the advent of new theories or facts of relevance, these ideas can become more interesting and more worthwhile to examine. You don't have to worry about how long these scientists have spent studying these issues, or why they want you to believe these ideas. In this sense, it is no different to us where these ideas come from. Their true origins are unknown, and we call it the imagination in the human brain, the creative imagination that people say.

Surprisingly, people don't think science is imaginative. Unlike the artist's imagination, imagination in science is a very interesting imagination. What is very hard to do is that you are trying to imagine something that you have never seen, that is very consistent with what you have already seen in all respects, and that it is different from what is commonly thought to be, in particular, that the imagination in science must be clear and definite, not just a vague hypothesis. It is indeed difficult to do so.

By the way, the fact that there is a law that can be proved right in nature is a miracle in itself. Like the law of gravity, which finds the inverse of the square, one can see that these laws are also miracles. People cannot fully understand this, but these laws lead to the possibility of prophecy-that they will tell you what to expect before they do not experiment.

Interesting and absolutely necessary is that the laws of science are compatible. Since the observation of the experimental results are all the same, one law cannot give a prophecy, and the other law gives another prophecy. In this way, science is not a personal matter for researchers. It excludes the individual influence of the researcher and has a universally applicable nature. I talk about electrons in astronomy, electricity, and chemistry, and they are universal and must be consistent on different occasions. You can't find any new things that aren't made up of atoms.

Interestingly, in the process of trying to discover the laws of science, logical reasoning plays an important role. At the very least, the laws of physics are simplified by logical reasoning. For example, some of the laws of chemistry and electricity have been simplified into laws that apply to two disciplines, and there are numerous examples of these.

The laws of nature seem to be expressed in mathematical language. This is not because the observation experiment is the criterion of judging the truth of theory, nor is it because the law of mathematical form is the necessary characteristic of science. It simply means that you can express the law in mathematical form, at least in physics, which facilitates the making of life-rich prophecies. As to why the law of nature is mathematically, it is still a mystery.

In this way, we have another important issue. The old law may be wrong, and observing how can it go wrong? If the result of observation has been carefully checked, how can it be wrong? First of all, the answer to this question is that the old laws are not based on observing the facts, and secondly, the observation experiment invariably has an error. In addition, the law is always obtained by guessing and extrapolation, not just the accumulation of observations and experimental results. They are only a screened, and at the time considered to be the best guess. Later results proved that the sieve used now was smaller than the sieve hole of the past, ruled out some mistakes in the past, and discovered new laws. Therefore, the laws and theorems in science are speculative, and they are pushed from known to unknown. You don't know what will happen in the future, but you have to choose a guess as the law.

In the past, for example, it was generally thought that exercise did not affect the quality of an object, that is, if the mass of a spinning gyro is weighed, and then it is stopped and weighed again, the result of two measurements is the same. This is an experimental result. However, you cannot call the quality of very, very small objects, for example, 1 billion grams of something. Now we know that the spinning top is about less than one-zero bigger than it is at rest. If the gyro spins fast enough that its edge is close to 300 000 km/s, its mass will increase significantly. However, if this speed is not reached, this quality difference is difficult to measure. In the initial experiment, the gyro spins at a much lower speed than 300 000 km/s. The quality of the spinning gyro and the non-rotating gyro seems to be exactly the same, so it is assumed that the mass will never change with the speed of the object moving.

What a foolish mistake it is! How foolish people are! The quality of the same is only a speculative conclusion, but a extrapolation of experimental results. Why do scientists who come to this conclusion do such unscientific things? In fact, the scientist did the experiment is blameless, his practice is no unscientific place. It's just that his results are uncertain. You know, if scientists make guesses, they risk making unscientific mistakes. But, on the other hand, science requires scientists to speculate on the unknown by known, because this extrapolation is the only thing that counts. In certain situations, it is not very valuable if you can guess what will happen before you do something. If all that you tell me is what happened yesterday, what is the true value of such knowledge, though deterministic? If you do something, even if it's not something you can't do, but just for fun, it's important to say what's going to happen tomorrow. But, again, you will risk making mistakes.

Every scientific law, every scientific principle, and every statement of observation is a generalization of omitting a certain detail, because nothing can be described in a completely precise manner. The scientist just forgot to add a control condition, he should describe that principle as "when the speed is not very large, the quality of the object has not changed significantly." "The rule of this game in science is to come up with a clear idea and see if it will stand the test." So the result of the scientist's speculation is that no matter how fast the object changes, its quality will not change. Of course, it does not prevent people from proving that the conclusion is wrong. It is only uncertain, and is not a hazard of uncertainty. It's better to talk about something, even if it gives you an uncertain conclusion than nothing.

There is no doubt that all the things we say and all the conclusions in science are uncertain. Because they're just inferences. They're guesses about what's going to happen, but you don't know what's going to happen in the future because you haven't exhausted all the experiments.

Curiously, the effect of rotation on the quality of the gyro is so small that you might say, "Oh, the rotation doesn't make much difference to the quality of the object." "But in order to get a correct law, or at least a law that is constantly tested and validated for more observational experiments, the researcher needs to have a wisdom and a rich imagination to break our existing ideas and understanding of time and space." Here, I'm talking about relativity. This fact shows that the weak effects found in the experiment must require the greatest courage and the most revolutionary improvement in thought and concept.

As a result, scientists often deal with problems and uncertainties. All scientific knowledge is uncertain. This experience of dealing with problems and uncertainties is important. I think it has great value, even far beyond the subject field. I think that in order to solve a problem that has never been solved before, you have to leave the unknown, and you must allow the uncertainty to exist because you have not exhausted all the observational experiments to ensure that your conclusions are absolutely correct. Otherwise, if you are always afraid that your conclusions are uncertain, you will not be able to solve the problems you are studying.

When a scientist tells you that he doesn't know the answer to the question, you think he's an ignorant person. When he tells you that he has a general idea of how to carry out a job, he is not sure about the problems to be studied. When he knows exactly how to carry out his work, he will tell you, "That's the way to study the problem, I bet," but he still has some problems to solve. In order to make scientific progress, it is very important that we recognize these unknowns and problems. Because we have doubts, we will look for new solutions from a fresh perspective. The speed of scientific development not only refers to how many observation experiments have been conducted, how much experimental data have been obtained, but more importantly, how many new ideas and new ideas have been put forward for people to test.

If we cannot or do not want to look at things from a new angle, if we have no doubts or are unaware of our ignorance, there will be no fresh ideas. Because if you know everything is right, there is nothing to test. So what we call scientific knowledge today is a collection of different degrees of deterministic representation. Some of them are difficult to determine whether they are correct, some are almost certainly correct, but no certainty is absolutely correct. The scientists are used to the situation. We know that there is no contradiction between being able to survive and what is unknown. Some people will say, "How can you live with so many unknown things?" "I don't understand what they mean, but I always live in the midst of ignorance around the world.

I believe that the freedom of exploration and suspicion is very important both in the scientific field and in other fields. It is an innate pursuit of humanity, a struggle for human rights to be questioned and explored, to overcome uncertainty. I don't want us to forget the importance of this quest and take the default way to make it go away. As a scientist, I feel a duty, and I know the great value of acknowledging our ignorant thoughts. I think it is this concept that makes the progress of science and human society possible, and that these advances are the fruits of freedom of thought. It is my duty to appeal to the value of free exploration, to teach people not to be afraid of problems, but to welcome them as a new potential possibility for the development of human society. If you have something that you are not sure about, you may be able to try to change the situation. I am willing to call for this freedom for our descendants.

Obviously, in science, suspicion is important. Whether it is equally important in other areas is a question that has no definite answer and cannot be asserted. In the next lecture, I intend to discuss this issue and try to explain the importance of skepticism. My point is that suspicion is not only not scary, but also something of great value.

Feynman's lecture record