When he received Einstein's letter, Chen Muwu was working with three of his students in the laboratory to imitate the vacuum pump purchased from General Electric in the United States.
After Rutherford's birthday, Chen Muwu, who had intensively proposed many physical theories some time ago, finally shifted the focus of his work from theory back to experiment, and began to develop an electron microscope.
Although he had the patent certificate in hand, the patent only contained a few principles. After actual hands-on operation, Chen Muwu finally realized how difficult it was to build such a big machine in the laboratory.
The electron source and electron lens are both trivial matters. The key is to create an electron microscope with a magnification much higher than that of an optical microscope, and the requirements for a vacuum environment are also very high.
Unlike a glass tube with a length of less than fifty centimeters, an electron diffraction experiment can be completed.
The length of the vacuum chamber in an electron microscope must be at least two meters.
If we only relied on the previous General Electric vacuum pump to extract vacuum, the efficiency would be too low.
Therefore, the first step in making an electron microscope is to try to see if we can increase the speed of vacuum degree and speed it up a little.
Although he had always resisted letting Oppenheimer get involved in specific experiments, because of the lack of manpower, he decided to let Oppenheimer, Zhao Zhongyao and Shi Ruwei all come to the laboratory. help.
Zhao Zhongyao and Shi Ruwei finally passed the entrance examination without any danger, entered Trinity College of Cambridge University, and became alumni with Chen Muwu.
The relationship he had established with Ramsay, the son of the dean of Magdalen College in the Apostolic Society, was of no use after all.
How to reduce the vacuum degree in the vacuum chamber of an electron microscope is one problem, and how to make the electron wave finally image after several amplifications is another problem.
The electron microscope that Chen Muwu used in the laboratory in his previous life was an image formed after being connected to a computer through a CCD photosensitive element. But obviously in this era, it is very unrealistic to produce these two things.
So what Chen Muwu thought was, either, just like the electron diffraction experiment, using photographic film to create the image.
Or simply use a fluorescent screen to allow the electronic signal to interact with the fluorescent material on the screen to create an image.
It’s just that no matter which one of these two methods is chosen, it is not very convenient and efficient, and can only be used reluctantly.
Chen Muwu felt that he had taken it for granted at the beginning, thinking that since he had mastered the principles and had a lot of funds, he would only need a month or two to develop an electron microscope.
But the various difficulties now facing everyone directly shattered the ideas in his brain.
Chen Muwu felt that it would take at least a year and a half to build this electron microscope.
Although this progress has stalled, making Chen Muwu feel a little depressed, Oppenheimer has always maintained a high spirit.
He even gave his teacher a shot in the arm: "Teacher Chen, I don't think you should be discouraged because of such a small setback.
"As far as I know, Mr. Edison, the 'King of Inventions', made more than a thousand attempts and tested countless materials and designs before he finally invented the light bulb. Finally, he used carbon filament to successfully create the first bulb. Bulb……"
Why can I still hear such poisonous chicken soup for the soul even though I have traveled a hundred years ago?
Chen Muwu was dumbfounded. Oppenheimer should not stay in the laboratory, but should be sent to Penguin Publishing House to write various chicken soups for the soul for that magazine to nourish the indifference of people in this era. And a dry heart.
However, Oppenheimer's performance in the laboratory surprised Chen Muwu. Although he was not as hardworking as the two Chinese compatriots, he also had a strong execution ability and did not cause sabotage or make any mistakes in the laboratory. What happened?
Perhaps Blackett did not read Oppenheimer's instructions and sent him to do a lot of simple and repetitive work instead of creative experiments, which led to his dissatisfaction.
Einstein's letter was brought to the Cavendish Laboratory by Kapitsa from Trinity College to Chen Muwu.
"Chen, there's your letter again!"
"Thank you Peter, why are you so diligent today?"
In Chen Muwu's memory, this should be the first letter Kapitsa brought him. Before that, it was all Blackett's work.
"Actually, I don't want to bring it to you. After all, you receive so many letters every time. But I just happened to see that the sender of this letter is Dr. Einstein. I was afraid of delaying your affairs, so I gave it to you. Brought it here. Take a look, what is written in this letter?"
The arrival of this letter, especially Kapitsa's mention of Einstein's name, finally temporarily boosted the somewhat low morale in the laboratory.
Whether it is Zhao Zhongyao and Shi Ruwei from China, or Oppenheimer from the United States, everyone knows Einstein's name, but no one knows the relationship between Chen Muwu and Einstein.
Although Oppenheimer was studying the vacuum pump on the side, he would always glance at Chen Muwu from the corner of his eye from time to time, and was very curious about what the most famous scientist in the world would write to his teacher in a letter.
"Dear Chen:
“I haven’t written to you for a long time, nor have I heard from you.
“First of all, congratulations on your four gold medals at the Paris Olympics that just passed.
“I’m a little lucky now that I met you in Shanghai and discovered a talent like you in the physics community.
“I think if we had not met at that lecture, maybe the world of physics would have lost a genius and your country would have gained a dedicated swimmer.”
After reading this, Chen Muwu felt that Einstein was a little pretentious.
Although he still respects and is grateful to Einstein in his heart, if Chen Muwu would not be where he is today without Einstein, he does not really agree with it.
Even without Einstein's lecture visit to China, Chen Muwu still had other ways to participate in the changes in physics in the 1920s.
He could have gone north to Tsinghua University to obtain the 1923 Gengzi Scholarship for Studying in the United States, and then, together with Xie Wanying, Liang Shiqiu, Wu Wenzao, Sun Liren and others, board the steamer York Sun on the Sihai Sea and sail to the other side of the Pacific. Study in the United States.
If you don't want to go to that free country full of discrimination, it won't be a problem for Chen Muwu to study in Germany with only the Chen family's property.
As long as he holds oceans or U.S. dollars tightly in his hands and does not exchange them for German marks unless absolutely necessary, he can spend a wonderful 1923 comfortably in Germany.
Chen Muwu didn't want to waste too much time on Einstein's compliments, so he continued to read the letter in his hand.
“I have read several papers on the laws of motion in the microscopic world that you published this summer in the Annals of Physics and the British journal Nature. To be honest, these papers of yours confuse me.
"You pointed out in your paper "On Quantum Mechanics" that you used the same Mach philosophical principles on the issue of electron orbits as I did when I proposed the theory of relativity.
"But what I want to say is that there are still some differences between the two. I use the principle of observability to deny some artificially added concepts to explain real phenomena, such as ether, absolute time, absolute Space and simultaneity.
"But in your paper, you mentioned that because it cannot be observed, you believe that electron orbits do not exist, which is a somewhat radical view. I really find it difficult to agree with it.
"Mach's philosophical view of doubting everything cannot create anything alive, and may only destroy harmful insects.
"Even his own view that 'because atoms cannot be observed, therefore atoms do not exist' has been confirmed by the experiments of Sir Thomson and Sir Rusev in recent years. This is simply a fallacy.
"One thing I must advise you is that there is an objective reality whether we can observe it or not. The belief in an external world that does not depend on human observation is the basis of all science.
"As for the explanation of probability waves that you proposed to explain what the wave function is, I think this is even more nonsense.
"The ultimate goal of physics is to discover strictly certain laws of cause and effect. It is impossible for electrons to exist here and there, and to be distributed throughout the entire space at the same time, as you stated."
For Einstein to write such words in his letter was exactly what Chen Muwu expected.
His philosophical views made him no longer as radical as he was when he was young, and he gradually transformed from a physics dictator to a defender.
"Frankly speaking, I am not a staunch atheist. Although I do not believe in a personal God who will govern everything in the world, I have always believed that the elegant laws that govern the universe and yet to be discovered reflect a divine the design of.
“When I’m not sure whether a theory is correct, I often ask myself, if I were God, would I design the world this way?
“I imagine that a good God would not create wonderful and subtle rules that determine most of what happens in the universe, leaving a few things entirely to chance and probability.
“If he really did that, I think we wouldn’t have to look for the so-called laws at all.
"Although the quantum mechanics you proposed is amazing, there is always a voice in my brain telling me that it is not real. You said a lot in the theory, but it did not bring us closer at all.' The old man's secret.
"Anyway, I'm sure there's no mahjong in heaven, and He's not playing dice.
"Albert Einstein in Berlin"
After much anticipation, Chen Muwu finally found this sentence at the end of the letter.
The famous quote that would have appeared in the letter to Born was now in his hands.
Chen Muwu made a mental decision to collect this letter and donate it to a museum in the future, or put it in a museum named after himself.
To completely convince Einstein on quantum mechanics is something that many physicists have failed to accomplish after decades.
If you try to convince him with various examples, you will never get approval, but a more fierce counterattack from Einstein.
Therefore, Chen Muwu did not intend to do such useless work and hit the south wall of this building named Einstein.
Since this old German man is so against probability and chance, he might as well make his opposition louder.
The electron microscope being developed in the laboratory at the moment brought him inspiration, so Chen Muwu loaded the typing paper into the typewriter and typed a reply to Einstein.
"Hello Mr. Einstein!
"Your letter from the past few days has been received. Thank you for your congratulations and your concern for my progress in physics.
"Now I will introduce to you what I am currently working on..."
Anyway, the paper and ink ribbon were not drawn with his own money, so Chen Muwu typed out a lot of nonsense without restraint, starting with his proof that electrons are a kind of wave, and then talking about his plan to use the wavelength of electron waves to be larger than visible light waves. This feature of being shorter can create a microscope with higher resolution.
After talking about electron microscopy, this letter finally got to the point.
"Doctor, the reason why I choose to use electrons instead of electromagnetic waves with shorter wavelengths, which we call gamma rays, to develop a microscope with higher resolution is because the materials of the current optical components are far from meeting the requirements. This will cause gamma rays to produce a strong scattering phenomenon during the refraction process, and ultimately cannot be focused, making it impossible to meet the requirements of microscopy.
"But if one day, we humans can really build a high-resolution gamma ray microscope, maybe then we will be able to observe many things that cannot be observed under a visible light microscope, for example, the position of an electron.
"The shorter the wavelength of the gamma ray, the more precisely the electron's position can be measured.
"However, we will face a more serious problem at this time. The wavelength of gamma rays is inversely proportional to the energy. The shorter the wavelength, the higher the energy. High-energy gamma rays will inevitably interact with electrons called ' Chen scattering' collision, which will cause the electron to suddenly receive a large momentum,
"This means that it is not possible to obtain the accurate speed of an electron while accurately determining the electron's position. At this time, the electron's orbit is still undetermined."
"On the contrary, if you want to avoid large momentum disturbances to the electrons, you must use photons with the lowest possible energy to detect the electrons. However, in this way, there is no way to accurately measure the position of the electrons, and it is also impossible to determine the electron's orbit.
"Of course, it is still unknown whether humans can create a gamma ray microscope. The experiment mentioned above is just a thought experiment that exists in the brain.
“But I think this does not prevent us from conducting a qualitative and semi-quantitative error estimate for this experiment.
"According to Abbe's formula, which can obtain the resolving power of a microscope, assuming that the wavelength of the incident light is λ and the opening angle of the electron to the radius of the lens system is θ, then the observation error in the position of the electron is x~λ/sinθ.
"Based on the law of conservation of momentum in Chen scattering, and assuming that after scattering is completed, the photon's momentum p=h/λ remains unchanged and only changes direction, then the momentum error brought by the photon to the electron is Δp~h/λsinθ.
“Multiplying the position error and momentum error, you can get ΔxΔp~h.
"This means that it is impossible to accurately measure the electron's position while also accurately measuring the electron's momentum. Let me temporarily name this uncertain relationship the uncertainty principle.
“If the electron is replaced by another microscopic particle, I think this uncertainty principle will still exist.
"Time is limited, so I can only briefly introduce my thoughts to you in this letter with such a thought experiment.
“Another point I want to make clear is that as a Chinese, I am not a believer in God.
"But, here, I want to tell you something else. More than two thousand years ago, there was a great philosopher in China named Confucius. He once said, 'A gentleman has three fears.' Among them, the first The most important thing is to fear destiny.
"Whether it is God or destiny, I think we should not use our mortal bodies to tell God what he should do."
"As for the rigorous derivation process of this uncertainty principle, I will compile it into a paper and publish it in the "Annals of Physics" or "Nature" journals in the future, so please pay attention.
"As for whether this principle is correct or not, please give me your advice.
“Finally, I wish you success in your work, good health, and a smile.
"Your student, Chen Muwu."
How humble Chen Muwu wrote this letter, the content he mentioned in it was so explosive.
The uncertainty principle appeared in this world for the first time in this reply.
Professor Wien, who was in charge of the doctoral graduation experimental examination at the University of Göttingen, almost failed to let the conceited German obtain a doctorate because Heisenberg could not answer how to calculate the resolution of an optical system.
But Heisenberg was also a blessing in disguise. He firmly remembered how to calculate the resolution, and one day he was inspired to derive the uncertainty principle from this formula.
Now that this killer weapon was thrown out, Chen Muwu had to hurry up and write a paper to theoretically verify the correctness of this principle.
This is because Heisenberg's thought experiment he threw out in his reply to Einstein. Of course there is nothing wrong with bluffing people in the letter, but as long as you think about it carefully, you will know that it is not rigorous in fact and still faces many problems. difficulty.
The first is that in the thought experiment, it is assumed that the electron has a certain position and momentum before measurement. This itself violates the uncertainty principle, and there is no way to verify it experimentally.
Secondly, the error x calculation method used in this experiment is actually a statistical average result.
And this kind of statistical average, at least here, is not applicable.
Although Chen Muwu has advanced knowledge reserves, Einstein, who is known as having the smartest brain in human history, is certainly not a vegetarian.
If he was left with this kind of clue in the letter without finally solving it, then these loopholes would become a powerful weapon for Einstein in his counterattack.
So as soon as he typed the last punctuation mark on the letter on the typewriter keyboard, Chen Muwu began to think about how to write this paper well.
He took off the last piece of printing paper from the typewriter and read the letter from beginning to end. After confirming that there were no spelling, grammatical and content logic errors, he took out an envelope from his desk and folded the letter paper. Put it in.
After sealing the envelope, Chen Muwu put two one-penny and one-half-penny stamps on it, planning to find a postbox after get off work and post the letter.
He looked up and found that Kapitsa was still sitting on the sofa in his laboratory, with no intention of leaving.
"Is there anything else you want, Peter?"
"Actually, it's not a big deal. It's just that this is the first time I see the Chinese compatriots you keep talking about. I just want you to introduce them to me and say hello to them by the way."
Of course there is no problem, Chen Muwu immediately introduced each other to the three of them.
But during the introduction, he discovered that something was wrong. It took at least half an hour to write his reply letter, and he, Kapitsa, stayed here all the time. It was obviously not as simple as an introduction.
"Peter, if you have anything else to do, just tell me!"
Kapitsa was not shy at all when he was exposed: "I would also like to ask Mr. Zhao and Mr. Shi, do you know how to cook Chinese food? Since George left Cambridge University, I haven't had the taste of the East for a long time. .”
"Go, go! They came all the way to England, not to cook for you! If you really want to eat, I will take you to London if you have a chance."
Chen Muwu drove Kapitsa out with a smile, knowing that he had no good intentions.
Ye Gongchao can do the cooking, but these two will never cook for you!
And seeing that his teacher had not only read Einstein's letter, but had even written a reply to him, Oppenheimer couldn't help but join in.
After getting along with him for more than half a month, Oppenheimer has learned that his teacher is not as serious as when he first met, but a very elegant and easy-going person.
That's why he could boldly ask now: "Teacher Chen, are you familiar with Professor Einstein?
"Because I am very curious about Professor Einstein, I have been quietly observing you just now, and I found that your expression is sometimes relaxed, and sometimes you are frowning. I don't know what happened?"
Zhao Zhongyao and Shi Ruwei on the other side of the laboratory also quietly pricked up their ears.
"What happened? Of course he didn't understand some of the papers I wrote recently, so he wrote to me to ask some questions.
"Although I have already given the answer in my reply, I guess he will not agree with my point of view even if he is stubborn.
"Robert, in comparison, you, as a student, make me worry more."
Chen Muwu relied on this joking way to tell the truth.
Oppenheimer smiled on the surface, but what he was thinking in his heart was that his teacher was indeed elegant and easy-going, but his only shortcoming was that he sometimes bragged too much!
But just now he actually praised me as being better than Einstein. It seems that I really did not follow the wrong mentor, and I must continue to work well under him.
(End of chapter)
