1900: A physics genius wandering around Europe

Chapter 546 Quantum Tunneling Effect! Mysterious "Through the Wall"! Proving Probability Wave and Uncertainty Principle at the Same Time!
1924 was destined to be the most extraordinary year in the history of physics.

The achievements produced in this year may not be the most important in physics. After all, with the general physics in the past, it is difficult to surpass them.

But this year is definitely the most exciting year. The entire physics community is crazy about quantum mechanics.

It has extremely rich connotations and its physical explanation is mysterious.

Many geniuses, even if they only do a small amount of work, are enough to go down in history.

University of Göttingen, Germany.

As usual, Hong Te came to the laboratory early.

It's just that he seemed a little excited today.

Because he discovered a very interesting phenomenon some time ago.

He plans to study hard today.

After graduating with a doctorate the year before last, Hund became a teaching assistant to his mentor Born, who also found him a lecturer job at the University of Göttingen.

So, he could attend classes while continuing to do research with Born, just like Wilson did in the past.

As the originator of Hund's rule, he should not be considered an unknown figure in the physics community.

But Hundt was a very low-key person. He didn't like to attend meetings everywhere. He only liked to immerse himself in research, so he published a lot of papers.

In real history, he published more than 250 papers in total, making him an absolutely prolific physicist.

With the rise of quantum mechanics, Hund, as a student of Born, certainly would not miss it.

His latest research topic is the study of molecular spectra using quantum mechanics.

Both the old quantum theory and quantum mechanics have produced particularly good results in the study of single atoms and can explain almost all problems.

But once you get into molecules, even the simplest diatomic molecules, things get very, very complicated.

Quantum mechanics will encounter various problems, and thus many theories in different fields have been born.

Molecular spectroscopy is one of them.

During his experiment, Hund discovered a very incredible phenomenon.

Molecules can actually cross the barrier from one potential well to another, and then cross back again.

What does that mean?

Let me give you a vivid example.

Suppose the molecule is a small ball with a small slope in front of it.

Now, the molecule wants to cross the obstacle of the small hill and reach the other side.

So what is the conventional approach?

Apply energy to the molecular ball so that its energy exceeds the potential energy required for the height of the small soil slope.

For example, you can push the molecular ball, or pull the molecular ball over a small slope.

This is easy to understand and fits the picture of classical physics.

But Hund discovered that molecules actually had another way.

This method is extremely bizarre.

That is: the molecular ball seemed not to see the small slope and went straight through it.

It's like walking through a wall, there's no reason for it.

This overturned Hunt's three views.

He is here today to solve this problem.

Soon, he repeated the experiment and the result was beyond doubt.

Miraculously, the molecule passes right through the barrier again.

He couldn't help but exclaim.

“This is so bizarre!”

At this time, a young man was attracted by Hunt's voice.

He came over, his face full of curiosity, and asked with a smile:

"Brother Hong, have you made any breakthrough in your experiment?"

When he saw the visitor, Hunt seemed very enthusiastic and excited.

"Fermi, I think I have discovered something remarkable."

"You are a genius recognized by Professor Bruce. How about you help me analyze it?"

Fermi quickly said modestly:
"Brother Hong, please stop making fun of me."

"I just graduated and I don't know anything. I need to learn from you."

After graduating with a doctorate, Fermi went to study in Germany with the support of a special scholarship from the Italian government.

By chance, he came to the University of Göttingen and conducted research under the guidance of Born.

So he became good friends with Hunt. They were of similar age and naturally had many common topics.

As the hope of the Italian physics community, Fermi carries everyone's expectations.

In real history, after Fermi spent some time under Born, he went to Leiden University in the Netherlands and stayed there for more than a year.

After finishing his studies abroad, he returned to the University of Rome and served directly as a professor of physics.

And at that time, he was only 25 years old.

Immediately afterwards, at the age of 28, he was elected as a member of the Italian Academy of Sciences.

The level of genius is evident from this.

Upon hearing this, Hong Te laughed.

He knew that the little brother in front of him was an absolute genius.

So, he seriously wanted to seek the other party's opinion.

So he described the strange molecular phenomena he had discovered.

After listening to this, Fermi became very interested.

"Wow!"

“This phenomenon is very interesting!”

"In classical mechanics, this is impossible."

"How can the ball go directly over the obstacle?"

The two of them started a heated discussion.

At this time, Fermi said:
"I think this phenomenon can be explained by probability waves."

“The molecule is on one side of the barrier, but its essence is a probability wave.”

"That is to say, there is a certain probability that the molecule will appear on the other side."

Hunt frowned, thought for a while, and said:

“Before, I also thought of using probability waves to explain it.”

“But there’s a problem with that.”

"The molecules will appear directly on the other side of the barrier though because of the probability wave."

“But what does this [emergence process] look like?”

"What is the mechanism by which it overcomes the obstacle?"

"Electrons can appear anywhere inside an atom because the inside of an atom is empty and there are no obstacles."

"But if you put an obstacle inside the atom, will the electrons be blocked?"

Fermi was a genius after all, and he understood Hund's meaning instantly.

What the other party said does make sense.

Whether it can appear and how it appears are not the same thing.

If there were no such barrier, it would be easy to explain why the molecules appeared on the other side.

But with barriers in place, we need to explain how molecules get through them.

For a moment, the two racked their brains but could not come up with any clues.

This phenomenon is so weird.

At this time, Fermi proposed:

"Brother Hong, let's go ask Professor Born."

"Quantum mechanics. He has more experience than us."

Hong Te smiled and said, "That's exactly what I meant!"

So the two of them went to Born's office together.

Boom boom boom!
"Please come in!"

A deep voice sounded.

Born didn't even raise his head; he was replying to his good friend von Karman.

More than ten years ago, the two began to collaborate on publishing papers and developed a deep friendship.

Now, von Karman has gone to the United States.

At Millikan's invitation, he helped Caltech set up an aeronautical laboratory and built a wind tunnel.

Von Karman was at the University of Göttingen at the time, and his main research areas were fluid mechanics and aerodynamics.

These two areas are definitely the hard nuts to crack in mechanics.

Von Karman has made many achievements and is recognized as a mechanics expert in the industry.

As for the real historical story between him and Qian Xuesen, there is probably no need to say more.

This time, von Karman wrote to Born to discuss the "First World Congress of Mechanics" that was being prepared.

As a recognized leader in the field of mechanics, von Karman wanted to hold his own Bruce Conference for mechanics.

This is the so-called First World Congress of Mechanics, a conference specifically established to discuss the theory of pure mechanics.

Although mechanics is the oldest science in the field of physics, it has been enduring and its impact on the world has not diminished over time.

In later universities, mechanics was even a subject on the same level as physics, rather than a branch.

This shows its position in physics.

As a big boss, von Karman raised his hand and people from all directions gathered.

Mechanics scientists around the world were extremely excited.

It was finally decided that the first World Congress of Mechanics will be held in Delft, the Netherlands in August this year.

Von Karman wrote this letter hoping that his old friend Born could mobilize his connections to promote him.

Born readily agreed.

Although he himself would not attend this mechanics conference, it was a big event in the field of physics after all, and he was happy to help.

He planned to inform Professor Bruce and other bigwigs of the news.

Maybe someone is interested in mechanics.

At this time, Hund and Fermi walked in.

The two saw Professor Born busy and stood quietly aside.

Born looked up and saw that they were together. He smiled and asked:

"what happened?"

Hundt said:

"Professor, I encountered a problem when studying molecular spectroscopy."

"I have come to ask you for advice after discussing this with Fermi to no avail."

Born became interested after hearing this.

In his heart, Hundt was a low-key genius who was no less than Fermi.

Since the two of them came here at the same time, it means that this problem must be not simple.

"Oh?"

"You two sit down and tell me what's going on."

Hund then elaborated on the problem of molecules crossing obstacles.

After hearing this, Born's expression became more and more surprised.

This phenomenon is so interesting.

Maybe we can prove the existence of probability waves!
It is well known in the circle that Professor Bruce found the inspiration for probability waves in his published paper.

Born also regarded this paper as his greatest achievement.

More than once, he shook his head and sighed.

"Oh, if I had thought a little more, maybe I would have proposed the probability wave."

“Just a little bit more”

But even so, no one in the physics community dares to underestimate him.

After all, not everyone has the qualifications and ability to enlighten Professor Bruce.

After the quantum mechanics conference, Born repeated his previous experiments several times, proving that the direction of particle scattering is related to probability.

But this is far from enough.

The probability wave was originally summarized from his experimental results.

Unless he can discover new experimental phenomena to further prove the probability wave.

And now, he saw hope in Hunt's discovery.

However, he also agreed with the other party's point of view.

"Indeed, probability waves alone cannot explain this strange wall-penetration behavior of molecules."

Born fell into deep thought.

Suddenly, he exclaimed and asked subconsciously:

"What if the moment a molecule crosses a barrier, its energy suddenly changes, exceeding the barrier's energy barrier?"

“Once it passes through, the energy returns to its original state.”

"So, overall, the energy of the molecule itself doesn't change, but it passes through the barrier."

hiss!
Hunt and Fermi were both shocked when they heard this.

Yup!

This is a way to go!

The two people's eyes became brighter and brighter!
But the question arises, how can the energy of a molecule suddenly increase and then decrease?

This is unreasonable!
Suddenly, Born laughed.

"Ha ha!"

"I see!"

“It’s the uncertainty principle!”

boom!
It was as if thunder was exploding in the minds of Hundt and Fermi!
Mouth open!

They were not stupid and understood it immediately.

Hong Te couldn't help but sigh:

"Oh, God!"

“This is so clever!”

“I discovered this amazing phenomenon right after Professor Bruce published the uncertainty principle.”

Hunt had never been happier.

Even the publication of the Hunt Rules did not make him so excited.

Like Dr. Davidson, he accidentally proved a shocking theory.

According to the uncertainty principle, the position and momentum of a molecule are uncertain.

If the molecule's position were suddenly very precise at the moment it crossed the barrier, its momentum would have to change dramatically.

When momentum changes, kinetic energy naturally changes, so molecules have the possibility to cross the barrier.

Even if it is only a moment too short to be measured, it is enough for the molecular scale.

Once the molecule passes the obstacle, its position becomes imprecise again, and the momentum returns to its original position and becomes precise.

The logic is perfect!

Of course, this requires rigorous mathematical proof.

But Hundt was not afraid at all, because Professor Born in front of him was an expert in matrices.

With him around, everything is worry-free!

Hong Te couldn't help but flatter:

"Professor Born, you are so strong!"

Fermi was shocked!

It is true that one should not underestimate the heroes of the world.

Before coming to the University of Göttingen, he knew the name of Born, but he did not admire him too much.

For the young people of their generation, there is only one person to admire: Professor Bruce.

As for the others, they are all people that Fermi wants to surpass.

And now, Fermi realized that perhaps his future achievements would surpass Born.

But at this moment, there is still a lot for him to learn from the other party.

Born smiled and said:

"Hunter, your discovery is extremely important."

"As I understand it, it should be regarded as proving both the probability wave and the uncertainty principle at the same time."

"Probability waves provide the possibility for molecules to travel, while the uncertainty principle provides the method for molecules to travel."

"The two complement each other and have led to this magical quantum phenomenon."

Hundt and Fermi both nodded.

Femi was also genuinely happy for his brother Hong.

The other party is usually very low-key, but he made a big move without making any noise.

It has a sense of strength due to lack of desire.

He smiled and said:

"Brother Hong, why don't you give this phenomenon a name?"

"For example, the Hund effect?"

Upon hearing this, Hong Te laughed so hard that he couldn't close his mouth, and then waved his hands quickly.

"No, that won't work. It's too high-profile."

Then he turned to Born and said:
"Professor, how about you name it?"

Born smiled and said:

"You young people just like to waste your time on this, call it what you want."

"Since this is a quantum phenomenon, it's like the molecule is opening a tunnel in front of the obstacle and passing through it."

“Why not just call it: quantum tunneling effect.”

(End of this chapter)