1900: A physics genius wandering around Europe

Chapter 468 The end of the old quantum theory! In the name of Bruce Lee! I announce the arrival of quantum mechanics!

Li Qiwei's statement that "electron spin is indescribable" shocked everyone present.

No matter whether they are geniuses or bigwigs, they cannot imagine what that state is like.

As physics develops to the end, is it true that the ultimate result is unknowable?

That's a bit too cruel for physicists.

In real history, the introduction of the concept of electron spin was an important watershed in quantum mechanics.

Before it, it was called [Old Quantum Theory];
After it comes the real quantum mechanics.

The reason why the old quantum theory has the word "old" in it is because it still uses the concepts of classical physics to understand the quantum world.

From Planck's proposal of the quantum concept, to Bohr's proposal of quantized orbit, to the final appearance of the four major quantum numbers.

You will find that classical physics is everywhere.

For example, Bohr believed that the movement of electrons around the nucleus is in the form of orbits, which is a concept in classical physics.

The spin in electron spin is also a concept in classical physics.

It can be said that everything in the old quantum theory is based on classical physics.

We cannot use mathematics to deduce the various behaviors of electrons based on the most basic principles or assumptions.

In other words, the old quantum theory has no theoretical basis.

That's why various problems arise.

For example, the paradox of electron spin.

and many more.

The above problems eventually led to the birth of quantum mechanics.

Its importance to modern physics is no less than that of Newtonian mechanics to classical physics.

No words can describe its greatness enough.

Li Qiwei stood in front of the crowd, and the magnificent history of quantum mechanics flashed through his mind.

For every physics student of later generations, that was a fascinating era.

And Li Qiwei will soon even create this golden age with his own hands.

No one could understand the excitement in his heart.

But now, he had to explain the problem of electron spin to Pauli first.

This question is not easy to answer.

In real history, Heisenberg emerged and proposed the first version of quantum mechanics: matrix mechanics.

Through matrix mechanics, the first three quantum numbers of the electron (excluding spin) can be directly derived.

Shock the world!

But matrix mechanics has a disadvantage, which is that it is too obscure and difficult to understand.

Because the mathematical tool it used: matrix, was not familiar to many physicists at the time, let alone used.

Even a brilliant scientist like Pauli needed half a month to use matrix mechanics to derive the electronic model of the hydrogen atom.

You can imagine what happened to others.

Fortunately, however, it wasn't long before Heisenberg proposed matrix mechanics.

Immediately afterwards, Schrödinger had a burst of inspiration and proposed the second version of quantum mechanics: wave mechanics (Schrödinger equation).

(Schrödinger was able to propose wave mechanics because he was inspired by de Broglie's wave-particle duality.)
(This is another fascinating story, involving the struggle between matrix mechanics and wave mechanics, which I won’t spoil for now.)
Using wave mechanics, it is also straightforward to deduce that electrons have the first three quantum numbers.

But for physicists, wave mechanics is much friendlier than matrix mechanics.

Because knowledge of waves is the strong point of physicists, everyone can understand and calculate it well.

Therefore, as soon as wave mechanics appeared, it overwhelmed matrix mechanics and became the mainstream version of quantum mechanics.

At the same time, because of this, Heisenberg and Schrödinger disliked each other.

But after a period of time, everyone discovered that matrix mechanics and wave mechanics are actually mathematically equivalent.

(Note! They are not physically equivalent!)
Neither is wrong, they are just different aspects of the same theory.

But no matter which one, it is impossible to correctly derive the fourth quantum number: electron spin.

At this time, Dirac took action!
He creatively combined the special theory of relativity and wave mechanics, unifying the special theory of relativity and quantum mechanics.

He proposed the Dirac equation, which shocked the physics world.

In this equation, Dirac took into account the relativistic effects of electrons moving at high speeds.

Through it, we can directly deduce that electrons have spin and that the spin quantum number is 1/2, and we can also deduce the magnetic moment.

Later, particles with half-integer spin were called fermions, such as electrons.

Particles with integer spin are called bosons, such as photons, which have a spin quantum number of 1.

At this point, all the behaviors and properties of electrons have a solid theoretical foundation.

This is how the derivation of electron spin came about.

It can be said that it runs through the entire development process of quantum mechanics.

In this process, physicists' understanding of the quantum world has gradually deepened.

Only then did everyone realize that the mysterious electron spin is just the tip of the iceberg of quantum mechanics.

There are many incredible phenomena that are even more outrageous than electron spin.

For example: uncertainty principle, wave function collapse, quantum entanglement.
So, everyone stopped struggling and finally accepted the indescribability of electron spin.

Since we can’t figure it out, just treat it as an inherent property of electrons.

Other quantum properties are also accepted.

This is the weirdness of quantum mechanics.

The deeper they go, the more it seems like there is an invisible barrier preventing physicists from continuing their exploration.

In the quantum world, many things can only be accepted but not understood.

Don’t ask, I don’t know even if you ask.

At this moment, there was only one way for Li Qiwei to convince Pauli.

"Because, in the name of Bruce Lee!"

"Within five years, I will prove the correctness of electron spin!"

boom!
As soon as the words fell, the whole audience was shocked!
Everyone opened their mouths wide, their faces filled with disbelief.

No one expected that Professor Bruce would take the issue of electron spin so seriously.

He even swore on his own name.

What kind of spirit is this!
"Oh my God, I seem to remember the scene twenty-one years ago when Professor Bruce faced Lord Kelvin."

"It's just that the identities have been switched."

"Professor Bruce became Lord Kelvin, and Pauli became Professor Bruce."

"But even so, Professor Bruce's passion has never changed."

"His pursuit and passion for physics is even crazier than that of young people."

"Forty years old is the prime age in the field of physics!"

At this moment, many students present seemed to be given an injection of chicken blood and screamed.

Even someone as strong as Professor Bruce is still working so hard.

What qualifications do they have to not work hard?

Pauli's expression at this moment was extremely shocked.

He really didn't expect that Professor Bruce would think so highly of him.

Given the other party's status and position, this is completely unnecessary.

But the other party is just so serious.

This made Pauli's soul tremble.

He felt that Professor Bruce was the same type of person as him, and only cared about pure physics.

Pauli would not dare to question Professor Bruce just because he was a big shot.

Professor Bruce would not choose to be perfunctory just because Pauli is a rookie.

The two have certain qualities in common.

That's seriousness!
Treat any physics problem with extreme seriousness.

At this moment, Li Qiwei left an indelible impression in Pauli's heart.

As proud as Pauli was, he regarded Professor Bruce as an idol whom he respected throughout his life.

At this time, Li Qiwei smiled slightly and continued to say to everyone:
"Don't think that I'm using my status to pressure Pauli."

"I dare to say this because electron spin gives me hope."

Wow!
Everyone was shocked!
They immediately perked up and listened attentively, because they knew that the following content was absolutely the most important.

Li Qiwei glanced around and said:

"Last year, in a speech at the University of Berlin in Germany, I put forward an idea that many people found incredible."

"That is, I want to reconstruct the existing quantum theory."

There was an instant buzz in the room, and it was obvious that everyone present knew about this.

"At the time, many of my friends were not optimistic about this."

"For example, Professor Rutherford, Professor Einstein, etc."

"They have good reasons, because quantum theory can already solve the vast majority of problems."

“Why would you modify it at all?”

"It's like my tool is working perfectly fine, why should I melt it down and make a new one?"

“At the time, I couldn’t convince them.”

"Because I want to reconstruct quantum theory, it all comes from my strong intuition."

“For physicists, intuition is sometimes more important than anything else.”

"Until recently, I made some breakthroughs in my research."

"I am now convinced that the path I have chosen is not wrong."

boom!
Everyone was shocked!

No one expected that Professor Bruce actually made a breakthrough in quantum theory.

Oh my god!
Is he going to do the same as when he published the theory of general relativity?
The existing quantum theory is like the special theory of relativity, and Professor Bruce wants to make another breakthrough based on it.

What would it be?
No one dared to imagine it anymore.

But it is definitely earth-shattering.

Maybe it will change the history of physics again.

Everyone present had a sense of pride.

At this time, Li Qiwei suddenly said excitedly:

"And today, the emergence of electron spin is the final ray of light."

"It makes me absolutely certain that quantum theory must have a deeper essence!"

"Many concepts in existing quantum theory are based on classical physics."

"So it can't explain spin, a purely quantum property."

“We need to create a new paradigm that breaks away from the constraints of classical physics.”

"Using it, we can deduce everything about existing quantum theory."

“Let quantum theory truly become the pillar of modern physics.”

“This is destined to be a great undertaking.”

"It is absolutely impossible for me to complete it within five years by myself."

"so!"

"Gentlemen, let us work together to rebuild the Quantum Glory!"

boom!
The whole place was excited!
Shocked!
Everyone felt Professor Bruce's determination to overcome all odds.

What a passion!

How domineering!
How earth-shattering!
This scene left an eternal mark in the blood of everyone present.

Heisenberg suddenly felt his heart beating.

It was as if a vast force was about to burst out from within the body.

His soul trembled.

It seems like fate has come to us.

On Quantum Eve, Heidegger will appear!
Who can compete with the heroes of the world?
Heisenberg's heart was screaming wildly:
"I must reshape quantum theory and leave my name in physics!"

Schrödinger's expression changed from his usual romantic and dashing self to an extremely serious one.

He was deeply infected by Li Qiwei's aura.

An indescribable will surged in my body.

"Women have to stand aside when it comes to physics."

Of course, for him, this realization is only useful today.

As you get older, it’s okay to get excited occasionally, as long as the meaning is conveyed.

Dirac's sharp eyes seemed to pierce the sky.

At this moment he was no longer aloof and low-key.

The unparalleled momentum that dominates the world bursts out without reservation!
His ambition is higher than the sky and wider than the sea!
He not only wants to transcend quantum theory, he wants to transcend quantum theory.

Quantum field theory shocks the world!
Bohr looked at his mentor excitedly.

He felt the long-lost passion.

It was like going back to the time when I was a young doctor.

As the founder of quantum theory, he felt it more than anyone else.

At the same time, it is more passionate.

"I, Bohr, can continue to dance!"

Pauli was finally moved, his breathing became rapid and his face flushed.

His and Bohr's momentum rose at the same time.

at the same time.

Eight hundred miles away, in the center of Paris, France, a breath of air rose into the sky.

De Broglie's pair of noble eyes penetrated time and space.

"How can I be missing from this great event?"

One thousand five hundred miles away, at the University of Göttingen in Germany, the light of wisdom is shining.

Born murmured:

"Professor Bruce, twenty-one years ago, the first time I saw you, I was ruined for life!"

boom!
These two auras echo the more powerful aura from the direction of Britain.

At this moment, if anyone could look down at the whole of Europe from the sky, they would find a shocking scene.

One after another, the heart-pounding waves finally converged together to form a huge cloud.

It is dreamy, magnificent and breathtaking, and even the soul will be captivated by it at just one look.

And deep in the clouds, a domineering figure appeared vaguely.

It is the Tao, the principle, the singularity, and the dimension.

It is God coming to the world!
call!
After an unknown amount of time, the strange phenomenon disappeared and the room finally became quiet.

It was as if everything that just happened had never happened and no one saw it.

Pauli did not continue to ask because there was no need.

Electron spin, whether you admit it or deny it.

Its relationship with quantum theory can no longer be separated.

At least the vast majority of people present agreed with Professor Bruce's point of view.

Because it's incredible.

Between Professor Bruce and Pauli, everyone would of course choose the former.

At this point, the four major quantum numbers in quantum theory have returned to their places!

Pauli was not upset by this.

Because he has glimpsed the wider world.

Even Kronig and Gudschmidt had let go of their grudges with Pauli.

Their argument seemed so insignificant in Professor Bruce's vast quantum world.

Summer insects can't talk about ice.

In front of Professor Bruce, they were like summer insects.

At this moment, Li Qiwei's heart was filled with shock but his face was calm.

“Quantum mechanics, here I come!”

(End of this chapter)