1900: A physics genius wandering around Europe

Chapter 552: Three levels of explanation for vacuum! There is also a fourth level! Vacuum is not empty! Shocking the audience!
In the lecture hall of Berlin University.

As soon as Li Qiwei asked the question, everyone was confused.

"What is a vacuum?"

What everyone is confused about is not that the questions are too difficult, but that they are too simple.

A vacuum is a vacuum.

Take the air out of space and what remains is a vacuum.

There is nothing in a vacuum.

But what kind of person is Professor Bruce?
When he says 1+1=3, I'm afraid many people will not object at first, but will think about it first.

The many bigwigs in the front row seemed to be thinking about something.

They were thinking, what is the connection between vacuum and the uncertainty principle?

Since the topic of the speech was the uncertainty principle, Professor Bruce would certainly not mention the vacuum for no reason.

Li Chengdao looked excited.

He was finally able to hear his father's speech in person.

As word of mouth had proven, my father always liked to start his speeches with a simple question.

Most people thought the answer was simple, and then my father came up with an incredible theory.

Shocked the whole audience!

This is the Bruce-style speech that everyone talks about.

At this time, someone stood up and said:

"Hello, Professor Bruce. I am Rabbi, Professor Sommerfeld's postdoctoral fellow."

"I want to try to answer your question."

Everyone was shocked!
Wow, it’s the postdoctoral fellow who takes action right away!
Is it necessary to make such a fuss over a small vacuum problem?

Sommerfeld smiled.

He liked Rabi, a young man from the United States, who was lively, cheerful and very innovative.

The other party's current research topic is the interaction between magnetic fields and atomic nuclei.

When Li Qiwei heard the name, he understood.

In real history, Rabi was the inventor of nuclear magnetic resonance and was known as the "Father of Nuclear Magnetic Resonance", for which he won the 1944 Nobel Prize in Physics.

The principle of NMR is simple.

When an atomic nucleus is placed in a magnetic field, its spin direction will be aligned parallel to the magnetic field in a positive or negative direction.

At this time, electromagnetic waves are emitted to the atomic nucleus, and the atomic nucleus changes its spin direction because it absorbs the electromagnetic waves.

Using this principle, we can create a nuclear magnetic resonance imaging device that can image the human body.

Because different tissues in the human body have different water contents, the hydrogen nuclei in the water absorb different amounts of electromagnetic waves.

After using a nuclear magnetic resonance imaging device to irradiate the human body, different tissues on the film have different degrees of brightness and darkness.

If there is a lesion somewhere, it can be seen from the film.

Unlike X-ray-based CT, which is suitable for imaging hard tissues such as bones, MRI is mainly suitable for detecting soft tissues and is more precise.

Therefore, the price of MRI is much higher than that of CT.

Nuclear magnetic resonance imaging plays an extremely important role in the fields of physics and medicine.

In addition, Rabi was the originator of the concept of the atomic clock.

The so-called atomic clock uses electromagnetic waves absorbed or released by atoms to measure time. These electromagnetic waves are very stable.

Common atoms include rubidium, cesium, hydrogen, etc.

The watches used by ordinary people will have an error of about one minute every year.

The accuracy of an atomic clock can reach one second every 20 million years.

Therefore, atomic clocks are used for timekeeping in ultra-high-end fields such as satellites and aviation.

Interestingly, it was during his research on atomic clocks that Rabi accidentally discovered the phenomenon of magnetic resonance.

This guy has a lot of personality.

Rabi returned to the United States as a professor of physics at Columbia University.

The president of Columbia University at that time was the famous Eisenhower, who had just retired from the military.

Once, the school invited a rabbi to give a speech.

In his opening remarks, Eisenhower said:
“The school is proud that you, among so many employees, have received such an important award.”

As a result, the rabbi did not give Eisenhower any face and replied directly:

"Dear President, I am a professor at this school and you are the employee."

This is the pride of the rabbi.

In the United States at that time, university presidents had great power.

But in the eyes of a great professor like Rabi, the president, like other administrative and logistical staff, serves students and professors.

This may also be one of the reasons for the prosperity of American academia.

What’s funny is that the rabbi later personally accepted a student at Columbia University who had a stronger personality than him.

That is the famous Schwinger.

He, Feynman and Shin'ichirō Tomonaga won the 1965 Nobel Prize in Physics for their creation of quantum electrodynamics.

Schwinger had an even more amazing student named Glashow.

Glashow is known as the father of the "Standard Model of Particle Physics" and won the 1979 Nobel Prize in Physics.

Glashow had a PhD named Yao Qizhi, who switched from physics to computer science and later became a superstar in my country's computer field.

It was he who founded the awesome Huaqing "Yao Class".

At this moment, after digesting this information, Li Qiwei felt deeply moved as he looked at the 26-year-old rabbi.

His disciples and followers have made tremendous contributions to the future development of quantum field theory and particle physics.

Li Qiwei smiled slightly and replied:

"Of course, Dr. Rabbi."

The rabbi gathered his thoughts and said:
“Even before the birth of the scientific system, people realized that there was air in space.”

"Space is not empty as we see it, it is filled with matter."

"Later, Lavoisier proved through experiments that air is composed of nitrogen and oxygen."

"It was not until 1892 that Lord Rayleigh and Professor Ramsay discovered a noble gas in the air: argon."

“Physicists have a better understanding of the composition of air.”

“And the study of the properties of air is another line.”

"In 1643, Italian physicist and Galileo's student, Torricelli, proved the existence of atmospheric pressure in the air through mercury experiments."

"But many people did not believe Torricelli's experimental results at that time."

“So, in 1654, the mayor of Magdeburg, Germany, Glick, conducted the famous Magdeburg Hemisphere Experiment in front of countless people.”

"He filled the two brass hemispheres with water and put them together, then pumped all the water out of the spheres and finally screwed the valve shut."

"Under the influence of atmospheric pressure, the two hemispheres are tightly pressed together."

"Then, Glick used eight powerful horses, but he couldn't pull the two brass hemispheres apart."

"You have to know that the diameter of the hemisphere is only 37 centimeters, which is equivalent to the size of a basketball."

"But the forces generated between them are terrifyingly large."

"This experiment strongly proves the existence of atmospheric pressure."

"Later, with the discovery of atoms, physicists gained a deeper understanding of air."

"Air is made up of nothing but atoms."

"So, Professor Bruce asked what a vacuum is."

“I think there are several levels to answer this question.”

"First, in the eyes of ordinary people, the inside of the copper ball in the Magdeburg hemisphere experiment is a vacuum."

"Because all the air inside has been sucked out, there's nothing left."

"But in the eyes of good engineers, the copper sphere is not a true vacuum."

"Because even with current technology, it is impossible to extract all the gas molecules in the copper ball."

"Even if we do that, after a long time, molecules in the air will get in through the gaps again."

"For engineers, as long as there are few enough molecules and atoms left that they do not interfere with the experiments they need to conduct, then it can be called a vacuum."

"Therefore, the current industrial definition of vacuum is: a gas state below a certain atmospheric pressure in a given space."

“It’s a vacuum of second meaning.”

"And the third layer of vacuum is what physicists see as vacuum."

“That is, the space state where there is no atom inside the copper ball.”

"Not only does no matter exist, but even electromagnetic waves do not exist inside the copper ball." "At this moment, the space is truly empty, a true vacuum."

"That's my answer."

Wow!
After the rabbi finished speaking, there was an exclamation in the hall.

Everyone listened with great interest.

"As expected of a postdoctoral fellow, his level is top notch."

"If it were me who answered, I could only say one sentence at most."

“There’s something about the Yankees.”

The rabbi explained the concepts of air and vacuum from the simplest to the most complex.

He also added his own thoughts and divided the vacuum into three layers according to different cognitions.

The third level of the concept of vacuum is absolute vacuum in the physical sense.

In a piece of space, there are no particles such as atoms or electrons, nor are there photons such as X-rays and gamma rays. Nothing exists.

Everyone nodded, and everyone agreed with the rabbi's point of view.

The meaning of the third layer is the meaning of vacuum, there is no doubt about it.

At this time, Li Qiwei smiled and said:

"Dr. Rabbi, that's a very good explanation."

"As expected of Professor Sommerfeld's postdoctoral fellow, his thinking logic is very clear."

The rabbi was very excited when he heard this.

He was praised by his idol himself.

However, what he didn't expect was that Li Qiwei suddenly said:
"Heisenberg, do you think the rabbi is right?"

Heisenberg, who was chatting with Pauli below, looked confused.

He didn't expect Professor Bruce to ask him this.

Is the rabbi right?

Of course!

Even this answer shows that the other party has a deep foundation in physics and is not the kind of student who only knows how to study.

But Heisenberg was so smart.

He knew that since Professor Bruce asked this, there must be a deeper meaning.

The other party is likely to deny the rabbi!

But here is the problem.

Heisenberg did not think there was anything wrong with the rabbi's answer.

He couldn't figure out how Professor Bruce would refute it.

So, after struggling for a while, he answered honestly:
"Professor, I think Dr. Rabi's explanation of the vacuum is correct."

Li Qiwei smiled and nodded, but did not reply.

This reaction made Heisenberg even more confused.

Not only him, but the rabbi himself was also confused.

He was very happy just now.

After all, Professor Bruce praised him.

But it was obvious that Professor Bruce was just praising his answer but did not really agree with it.

These two are not the same.

Otherwise, the other party would not have asked Heisenberg for his opinion again.

The rabbi thought, there is nothing wrong with my answer, it even takes electromagnetic waves into consideration.

Is there anything else in space besides particles and waves?

impossible!

Is it the soul? Or is it the will?

But this is a philosophical realm.

The rabbi smiled and shook his head. He felt that given Professor Bruce's status and position, it was impossible for him to be so mysterious.

It must exist in the physical sense.

So, he was extremely confused.

"How can a vacuum be empty?"

At this moment, Planck, Einstein, Schrödinger and others all frowned slightly.

Given what they knew about Bruce, the rabbi’s answer was certainly not perfect.

But the problem is that in their opinion, the rabbi's answer is indeed correct.

Einstein thought of the uncertainty principle again.

This is the topic of the speech, Bruce shouldn't go off topic.

But there is not even a single atom in the third layer of vacuum, so how can there be any uncertainty?

These two concepts are totally unrelated.

Einstein was puzzled.

Among the crowd, Li Chengdao showed great interest in his father's question.

This problem does not require calculation with paper and pen, just think with your brain.

But precisely because of this, it seems particularly difficult.

At least he had no clue.

In Li Chengdao's opinion, the doctor named Rabi was already very strong, and his answer was perfect.

He felt that Europe was indeed a place where hidden dragons and crouching tigers were everywhere, and anyone in it could be so awesome.

If Li Qiwei told him about the rabbi's future, he might not think so.

At this time, Li Chengdao pushed Li Chengde's arm and asked:

"Second brother, what do you think?"

Li Chengde is looking around to see if there are any beautiful women.

From the disappointed look on his face, you can tell that studying physics will lead to loneliness.

Although there were a few that looked good, none of them were his cup of tea.

Well! I'd better listen to my father's speech.

Without hesitation, he said coolly:

"The rabbi must be wrong."

"He just said that there are no more atoms and photons in a vacuum."

"But these are all matter. There is also energy in the universe."

"In the rabbi's third level of vacuum, the existence of energy is not considered."

ha?
Li Chengdao didn't know whether to laugh or cry.

He didn't know whether he should praise his brother for his wild imagination or criticize him for his ignorance and stupidity.

Energy also needs matter as a carrier!

Kinetic energy, potential energy, and electromagnetic energy all depend on the existence of matter.

Even from the perspective of special relativity, matter and energy are two sides of the same coin.

Now there is no matter in the vacuum, so where does the energy come from?

"There's something wrong with my brain. I actually thought of asking my second brother about such a high-end physics academic topic."

Li Chengdao laughed at himself and didn't think about it any more.

Let's wait for my father to reveal the answer.

He couldn't wait to find out.

At this moment, everyone, like Li Chengdao, was curious about Professor Bruce's questions.

Under everyone's expectation, Li Qiwei said:
"Yes, just as you suspected."

"I think the third layer of vacuum Dr. Rabi just mentioned is not a real vacuum!"

"Even if there are no atoms, electrons, photons or other particles in this space, there will still be something there."

"Based on the rabbinic foundation, I have a fourth level of interpretation of the vacuum."

"The vacuum is not empty!"

“And all of this comes from the inference of the uncertainty principle.”

boom!
The whole audience was shocked!

Does the vacuum really have a fourth explanation?
(End of this chapter)