At the first meeting with Ramsey, Chen Muwu once asked an interesting question in front of the apostles of the Cambridge Apostolic Society.

Six random people from all over the world were selected, and at least three of them knew each other or didn't know each other.

This is actually a corollary of Ramsey's theorem, which some people would call the friend and stranger theorem.

In addition, there is another interesting one: in a group of no less than three people, if you choose any two people, and they both happen to have only one person in common, then there is always one person in the group who is known to everyone.

As for the Ramsey theorem itself, according to the statement that I just knew or didn't know, it can be expressed as:

For any positive integers k and l, if the number of n people in a party is large enough, then k people must know each other, or l people do not know each other, regardless of the acquaintance relationship.

If two positive integers k and l are given, the minimum n value of the foregoing conclusion is guaranteed, which is called the Ramsey number R(k,l).

Of course, it is also possible to turn the relationship between people who know each other and those who don't know each other into a dyeing problem in graph theory, and then use the terminology discussed to express Ramsey's theorem.

From Ramsey's theorem, a Ramsey theory can be derived, which is used to find the inevitable substructures with overlapping order in large and non-overlapping structures.

Grind said that Ramsey theory is a branch of combinatorics.

It was on the basis of this theory that he himself came up with the "Grey Constant Number", which was once regarded as the largest number ever appeared in a formal mathematical proof, and was included in the Guinness Book of World Records in 1980.

LATER, OF COURSE, THE GREY CONSTANT NUMBER WAS OVERTAKEN BY TREE(3), THUS LOSING ITS POSITION AS THE LARGEST NUMBER IN THE WORLD.

Although Ge Liheng is an authentic Chinese name, Ge Liheng is not Chinese, but a native American.

His surname Graham, literally translated as Graham, is translated as Graham, but the reason why it is translated as Graham is because he later married a Chinese wife who was also a mathematician.

Ramsey, who was born in 1903, is only 23 years old this year.

In the original history, four years later, he would have come up with the Ramsey theorem named after him.

At that time, he was only a twenty-seven-year-old young man, and it stands to reason that Ramsey would have a bright future in the field of mathematics.

But unfortunately, he also died of illness in the same year.

The reason for his death was not an accident or a sudden illness.

Rather, Ramsey had a chronic liver disease, developed jaundice after an operation, and then died.

Now, in a conversation with Chen Muwu, Ramsey came up with the Chen-Ramsey theorem four years ahead of the original time and space, and maybe he can go further in the study of this problem.

Seeing that Chen Muwu agreed to his request, Ramsey was in a good mood.

After agreeing with Chen Muwu on a time and place to meet each week to discuss papers, he picked up the wine glass on the table and drank it down, then put the glass back in and stood up.

Before leaving, Ramsey talked to Chen Muwu about another matter.

"Brother Chen, summer is coming soon, find a chance, let's go swimming in the Kang River together? I've wanted to compete with you as an Olympic champion for a long time!

"By the way, I also asked someone to help make a pair of swim trunks you invented, although it is a little revealing on the body, but in the water, it is indeed much less resistant to swim than that one-piece swimsuit."

There is also an unconfirmed theory about the cause of Ramsey's death.

He said that he was an avid swimmer and died when he was swimming in the River Cam when he contracted undiagnosed leptospirosis.

Although this statement is most likely a rumor, Chen Muwu still feels a little afraid.

Although the water of the River Cam looks clear far from the industrial area, there may still be a lot of dirt in it that you can't see.

He felt that if he wanted to swim again in the future, it would be better to go to that kind of special swimming pool, and he must not joke about his body anymore.

"I'm sorry, Ramsey brothers, but I'd love to swim with you, but I have a full schedule this summer and I don't necessarily have time to spare.

"And the water in the River Cam doesn't feel as clean as it seems, so if you want to swim, it's better to go to a more professional pool."

Ramsey smiled and said goodbye to Chen Muwu, but took the latter's words as a deaf ear.

His father swam in the River Cam when he was in school, and he never had any problems since he was a child.

This Dr. Chen, he is really a little rare and weird.

After the meeting of the Apostolic Society, others went to the church to worship on Sunday, and Chen Muwu also rested for a day.

On Monday, after breakfast, he had just left the door of Trinity College, just as Oppenheimer had returned from the United States, and was stopped by someone who had come to his way.

This time, it was Dirac who stopped him.

In the eyes of unfamiliar people, compared with the one who first entered Cambridge two years ago, a country man from Bristol, Dirac is even more shy now.

It is reasonable to suspect that although he learned a lot of knowledge at Cambridge University, he may have learned more than that, and he may have learned how to be autistic.

But the truth of the matter is that Dirac suffered a major blow in his life at the turn of last spring and summer.

At the time, his brother, who had remained with his parents, disappeared in Bristol, and then a few days later, the police who came to the door told the old Dirac couple the bad news that the body of their eldest son had been found, and it was basically determined that it was a suicide.

Dirac was so reticent because of the influence of his family of origin.

His father is a very typical paternalistic style, abusing his wife and scolding his children at every turn, and the head of the family is majestic.

Most of the care Dirac received from his parents came from his mother, and because the younger brother was more intelligent than the elder brother, Mrs. Dirac favored the younger son.

However, Dirac's withdrawn personality and excessive maternal love were also a burden for him.

On the contrary, he felt a little envious of the enthusiastic and cheerful brother, and he got closer to his brother.

His brother's suicide was a devastating blow to Dirac, and after dealing with the funeral, he returned to Cambridge from Bristol to be in a state of confusion every day, and finally found a way to explain himself, which was to forget everything and devote himself to his studies.

It was at that time that Dirac's skills in mathematical physics advanced by leaps and bounds.

When Dirac was depressed, Chen Muwu happened to be doing his low-temperature physics experiment in London, and he couldn't stay with his good friend to comfort him.

Fortunately, however, there is also a Capitsa at Cambridge University.

As one of Cambridgeshire's most interesting Russians, Kapitsa has also experienced the loss of a loved one, so he knows how to comfort people.

It was precisely because of Capitsa's presence that Dirac would not sink deeper and deeper into his grief.

"Paul, long time no see!"

"Chen."

"Is there something you have to do today? Why did you come to me so early. ”

"I went to the Cavendish lab last week to look for you, but was told you weren't there.

"That's why I thought about trying my luck at Trinity College today, but I didn't expect to meet you."

"I'm sorry, Paul, I've had some trouble lately, so I haven't been to the lab."

Some time ago, Chen Muwu has been writing a paper on the imperfection theorem at Trinity College.

After writing it, he ran to the particle accelerator under development every day, and it was indeed a long time since he went to the Cavendish laboratory to order it.

"That's right, Chen, I'm going to graduate with a PhD this summer. St. John's has sent me an invitation to stay at the college as a researcher after graduation. ”

"That's a good thing, congratulations!"

"Thank you, and I would like to congratulate you on publishing such a great mathematical paper. Have you always studied mathematics before? ”

"No, it was at the beginning of this year that I suddenly became interested in this matter."

"I really envy you, you can do experiments well, and you can come up with so many new theories, and you are not limited to physics, astronomy and mathematics. For me, math alone is very difficult to learn. Take my graduation thesis as an example, it tortured me for almost a year. ”

"Then have you finished writing, you should have finished writing, right?"

Dirac nodded, "The dissertation is finished, but Professor Fowler has arranged another matter for me."

"This fall, or maybe next year, he's going to start a course on Quantum Mechanics at Cambridge University, so he's hoping I'll write a handout for the course.

"After receiving this task, I immediately thought of you. Have you been busy lately? Do you want to study math or physics? If you're not busy, can you write this book with me? After all, you are the founder of quantum mechanics. ”

Okay, well, I know that I haven't had anything to do lately, so I'm here to find you, right?

Fowler was going to give a lecture on quantum mechanics at Cambridge University, and Chen Muwu was not surprised.

In the original space-time, after the birth of the new quantum theory, Bohr of Copenhagen, Denmark, and Bohn of the University of Göttingen, Germany, competed against each other.

The University of Cambridge, thanks to the Cavendish Laboratory under the leadership of Rutherford, is still in a leading position in the world in experiments.

But in theory, Fowler was the only one left to support him.

Fowler, like Eddington, also came from a secondary school mathematics background at Trinity College.

But he often provided some theoretical support to Rutherford, and later became the latter's son-in-law, so he also knew a lot about cutting-edge physics.

It was he who snatched Dirac from Eddington, and instead of making him an astronomer, he led him to the study of theoretical physics.

It's a pity that after his good students graduated, they did not stay at Cambridge University to act as their right-hand man, but went to Göttingen and Copenhagen, two holy places of quantum mechanics, to visit, and finally joined the Copenhagen School.

When Chen Muwu was teaching linear algebra last year, he asked Oppenheimer to prepare a lesson plan for himself.

Fowler also asked Dirac to write lecture notes on quantum mechanics this time.

Unbeknownst to Dirac, the "Quantum Mechanics" he was about to write was famous.

But, Chen Muwu knows.

He didn't expect that he would be able to get a piece of the pie again this time, so he agreed to Dirac's request without hesitation.

That's right, quantum mechanics.

He remembered that a few months earlier in Rutherford's office, he had promised Bohr that after writing a mathematical paper, he would publish another paper on quantum mechanics.

If there was no reminder from Dirac today, Chen Muwu would definitely forget about it.

On Zhao Zhongyao and Cockcroft's side, the progress of the particle accelerator is not going well.

After experiencing various blows, the two of them have also become a little less confident from the initial vows.

In Cockroft's idea, Chen Muwu has already built a model of the starting motor, so it only needs to be enlarged in equal proportions, and then consider the breakdown electric field and tip discharge and other possible problems, and modify the drawings, you can easily create a physical starting motor that meets the requirements, and use the high potential difference created by the starting motor to accelerate the particles.

The drawings were drawn very smoothly, but the drawings could be converted into real objects, and the two experienced all kinds of difficulties.

First of all, Chen Muwu pointed out the insulation problem of the experimental environment.

As a result of this incident, they had to stop all processes and use the purchased asphalt and mica flakes to finally remove this potentially life-threatening safety hazard.

And then, again, there was a problem with the silk that transported the charge.

Chen Muwu's entire model of the hoisting motor is the size of a canned food box, so the ribbons he uses in it are very short and narrow, and they can be seen everywhere.

However, the hoister designed by Zhao Zhongyao has a spherical electrode more than two meters high from the ground, but a conveyor belt that transports the charge, and it forms a ring back and forth, which means that at least five meters of silk is needed to meet the requirements of the hoisting motor.

Cockcroft basically ran all the Chinatowns in England, but could not find this kind of silk that met the requirements.

He also asked the shopkeeper how long it would take if he sent an order to China.

The time given by the shopkeeper is not optimistic, and if it is transported by ship or train from the country, there are too many variables.

But he couldn't find any better way, so he could only order one from the silk merchants in China through the boss's channel.

In fact, Chen Muwu has a better solution to this problem.

But Cowcroft was embarrassed to tell Chen Muwu about it, he just said that there was a problem with some parts, and the manufacturing process of the motor had to slow down, which may take several months to half a year.

Chen Muwu was concentrating on writing mathematical papers at that time, and he didn't ask specific questions, what he thought was that anyway, with Zhao Zhongyao and Cockcroft, things must not be done wrong.

So he planned to take advantage of these few months of free time to write papers with Ramsey and books with Dirac.

But before these two things, we have to get out the paper on quantum mechanics that I have promised Bohr.

He thought that after writing his mathematical paper, he would ask Russell or Ramsey to help him rigorously prove that matrix mechanics and wave dynamics are mathematically equivalent.

But now that Dirac has asked him to write a book with him, it is okay to ask Dirac for help.

After Einstein and Hilbert, another invisible race unfolded between Chen Muwu and von Neumann.

It's just that they don't know each other, and there is another opponent.

(End of chapter)