1900: A physics genius wandering around Europe

Chapter 659 Electricity and Magnetism! The Beauty of Symmetry and Breaking! Magnetic Monopole! A Sensation in the Academic World! A Theoretical Frenzy!

University of Cambridge, UK.

After his speech, Dirac stayed in his office.

He had a completely new idea about quantum field theory.

On the way back from Singapore by boat, he had asked Bohr a very simple question:

"Professor Bohr, why is electric charge quantized?"

Electromagnetism has been developing for over 100 years, and it seems that no one has ever considered this question.

Even when the concept of quantum mechanics was born, the first thing was to quantize energy.

Because in everyone's experience, energy is continuous and can be infinitely divided.

Therefore, energy quantization has attracted special attention.

But the charges are different.

Since the discovery of the electron, the physics community has generally accepted that the charge carried by an electron is a basic unit of negative charge.

Later, as atomic science developed further, people discovered other particles such as protons and neutrons.

Coincidentally, the charge of a proton is also a basic unit of charge, and it is a positive charge.

Why isn't it a proton carrying 1.5 positive charges?
In this way, two protons and three electrons can maintain charge balance, and the atomic structure may still remain stable.

In other words: Why is the charge of all charged particles an integer multiple of the electron's charge, rather than a fractional multiple?
No one has ever thought about this question.

Perhaps some people have thought about it, but don't know how to explain it.

At the time, Bohr answered as follows:
"This is one of the fundamental rules of the universe."

"It's the same as why the speed of light is 30 kilometers per second."

"It is an axiom, and it cannot be derived using more basic concepts."

However, Dirac was not satisfied with this answer.

He then asked another strange question.

"From the perspective of symmetry, electricity and magnetism should be symmetrical to each other."

"Electric charges can be positive or negative, and magnetic fields have a south pole and a north pole."

"But why can electric charge exist alone, but magnetic charge cannot exist alone?"

Do magnetic monopoles exist in the universe?

Wow!
Bohr was deeply shocked!

Goodness, young people these days are always thinking about weird and strange things.

This can easily lead to getting stuck on a single point.

In physics, when opposite charges come together, they are called "dipoles".

When a single charge exists, it is called a "monopolar".

This concept has also been introduced into chemistry; anything where two poles are combined can be called a dipole.

It is clear that an electric charge can exist as a monopole on its own.

An electron can exist alone, and a proton can also exist alone; they each carry only one type of charge.

So here comes the question.

Do magnetic monopoles exist?
Bohr thought about it carefully, and it seemed that no one had ever raised this question before.

Or, even if it was raised, it would simply fizzle out and not generate any response.

Because the answer is obvious: it doesn't exist.

The best examples can be found in everyday life.

Breaking a magnet in two does not give you a separate North Pole and a separate South Pole.

Instead, it obtained four magnetic poles, and the two sections of the magnet each had their own north and south poles.

If you keep breaking it, you'll get 8 poles and 16 poles.
In short, it is impossible for a magnetic monopole to exist in isolation.

Bohr could only say:

"I don't think it exists."

But Dirac seemed to be talking to himself:
"But electricity and magnetism are clearly symmetrical phenomena."

"Electricity has an electric field, and magnetism has a magnetic field."

"Electricity generates magnetism, and magnetism generates electricity."

"But electricity has charge and electric monopoles; magnetism has no magnetic charge and no magnetic monopoles."

Why does it become asymmetrical here?

In other words, there is no such thing as "magnetic charge".

Just as magnetism does not have a smallest basic unit.

Bohr pondered for a long time. He knew that Dirac was a genius of unparalleled talent and would not speak without reason.

So he asked in a deep voice:

"Dirac, what are your thoughts?"

Upon hearing this, Dirac looked up at the sea with his deep eyes, as if countless secrets were hidden beneath the calm surface.

"When I was watching Professor Bruce derive quantum electrodynamics, a question came to mind."

"Quantum electrodynamics is the quantum field theory of electromagnetic interactions."

"In this theory, Professor Bruce assumes that electric charge is quantized."

"This point seems to require no proof, and he did indeed quote it directly without further explanation."

"But there's a problem."

"Quantum field theory is a theory of symmetry."

"If Professor Bruce believes that electric charge is quantized, then there must also be quantized magnetic charge."

"Otherwise, the theory will be asymmetrical."

"But Professor Bruce did not mention magnetic charge in quantum electrodynamics."

"I think he must have thought of this problem, but he couldn't solve it, so he ignored it."

"Even without magnetic charge, many phenomena can still be explained."

"But I believe this will always be a hidden danger."

hiss!
Bohr gasped.

This Dirac is just too fierce.

He was already able to identify problems when very few people in the world could understand the ideas of quantum field theory.

Moreover, it's such a profound and fundamental question.

Bohr did not think the other party was a hothead.

Once upon a time, he was also such an unparalleled genius.

At the time, everyone believed that Professor Bruce's atomic planetary model was correct.

However, he overturned the theory and proposed a quantum orbital model.

He was so full of vigor and ambition back then.

Now, he saw his own reflection in Dirac.

I was overwhelmed with emotion.

Bohr took the Dirac problem very seriously.

"So, you think there are imperfections in quantum electrodynamics?"

"That means it is necessary to add magnetic charge, or the presence of magnetic monopoles."

Dirac nodded.

"Yes."

"Moreover, I always felt that there was some kind of relationship between magnetic monopoles and the quantized nature of electric charge."

"I want to go back and study this issue carefully."

Bohr laughed:

"Then why don't you ask Professor Bruce?"

Dirac smiled wryly:

"I only thought of it after I boarded the ship."

After saying this, Bohr burst into laughter.

"You're deliberately making things harder for yourself."

"Don't worry, you will definitely succeed."

"The teacher's theories will surely be carried forward and developed!"

At that moment, Dirac recalled his conversation with Bohr, and inspiration flowed like a spring.

First, he boldly proposed the existence of "magnetic monopoles".

In this way, the contents of quantum electrodynamics regarding electricity and magnetism can be symmetrical.

Next, he needs to prove its existence theoretically.

Dirac wrote in his pen:

"Within the framework of quantum field theory, magnetic monopoles and the closed nature of magnetic field lines can coexist."

"The premise is that the magnetic charge must satisfy some kind of quantization condition."

If this statement were to get out, it would absolutely shock the physics community. The electric field lines of a point charge radiate in straight lines in all directions and do not form a closed loop.

Similarly, it is natural to think that the magnetic field lines emitted by a magnetic monopole should also be in this manner.

However, quantum electrodynamics indicates that magnetic field lines must be closed.

If Dirac wanted to introduce magnetic monopoles, a contradiction would arise.

He had to figure out how to make a magnetic monopole generate closed magnetic field lines.

This seems like an impossible task.

However, what can he do? He is Dirac.

"I can imagine that there is a string."

“Every magnetic north and south pole is connected by this string.”

"This string is an ideal solenoid with no cross-section, capable of guiding magnetic field lines from the South Pole to the North Pole."

"This maintains the closed nature of the magnetic field lines."

"if it is like this"

Dirac began to display his extraordinary mathematical talent.

Based on quantum electrodynamics, he proved the possibility of the existence of magnetic monopoles.

Moreover, through calculations, he discovered that the interaction force between two magnetic monopoles is 4700 times that between two electrons.

This demonstrates that the force between magnetic monopoles is extremely strong.

Furthermore, and most importantly, with the existence of magnetic monopoles, he could theoretically deduce that electric charge must be quantized.

This explains why the charge of all charged particles is an integer multiple of that of electrons.

This phenomenon, in turn, proves the possibility of the existence of magnetic monopoles.

At this moment, even Dirac, known for his aloofness, couldn't help but feel excited.

He knew that his achievement would shake the physics community.

Moreover, he was the first person to perfect quantum electrodynamics.

Finally, Dirac wrote:

"The existence of magnetic monopoles will rewrite Maxwell's equations."

"Electricity and magnetism are two phenomena that are absolutely symmetrical!"
-
1926 8 Month 20 Day.

Dirac's paper was published in the journal Nature.

The article caused a sensation in academic circles!

The concept of magnetic monopoles has completely shaken the worldview of all physicists.

"Oh, God!"

"Someone has actually theoretically proven the existence of magnetic monopoles?"

"Could such an unbelievable thing really exist?"

"."

Immediately, the experts began their research.

Heisenberg, Pauli, and others were immediately shocked when they saw the paper.

As some of the most brilliant theoretical physicists today, they are still deeply studying the ideas of quantum field theory.

However, Dirac, that taciturn fellow, had even begun to use quantum field theory to solve problems and put forward such astonishing conjectures.

Heisenberg said enviously:

"Dirac was present at the lecture."

"He must have heard some details that we don't know."

"Damn it! I wish I had been there."

However, little did he know that Dirac had not relied on anyone's help, but entirely on his own strength.

Pauli couldn't help but say:

"If magnetic monopoles really exist, the entire field of electromagnetism would have to be rebuilt from scratch."

Although Pauli was arrogant and talkative, he was always able to objectively evaluate the achievements of others.

When Bohr saw Dirac's paper at the institute, he smiled slightly.

“He succeeded.”

"The magnetic monopole conjecture is absolutely the most advanced physics conjecture."

When Ridgway saw Dirac's paper in Borneo, he smiled slightly.

He immediately issued a public statement:

"The magnetic monopole conjecture is an unsolved mystery at the level of fundamental physics."

"Its impact will certainly be significant and far-reaching."

"According to the Big Bang theory, electricity and magnetism may have been symmetrical in a high-energy state."

"But for some reason, this symmetry was broken, which caused the magnetic monopole to disappear."

"But its existence is crucial to quantum field theory."

The news once again shocked the physics community.

Everyone was filled with emotion:

"Professor Bruce is really awesome."

"The Big Bang theory encompasses everything!"

"Now even magnetic monopoles can be explained."

"So scary!"

In real history, the magnetic monopole caused a sensation as soon as it was proposed by Dirac.

Countless physicists are searching for its traces.

The most famous of these experiments was the magnetic monopole detector experiment conducted by Cabrera in the 1970s.

He used a long metal wire to make eight coils.

This allows for the measurement of the magnetic flux passing through the coil.

Moreover, the magnetic flux of a monopole and a dipole through a coil is easily distinguishable.

Initially, Cabrera could only detect two signals, indicating that both were magnetic dipoles.

He didn't see a magnetic monopole for several months, and became disheartened.

However, just when he was about to give up, he suddenly saw the signal of eight magnetic monopoles on the computer.

Cabrera was overjoyed.

He immediately published his findings as a paper, which caused a sensation throughout the academic community.

Many people began to replicate his experiment.

However, disappointingly, no one has seen any trace of magnetic monopoles since.

Therefore, everyone believed that there was some malfunction in Cabrera's experiment, which led him to mistakenly believe that he had discovered a magnetic monopole.

Some even joked:

"The only magnetic monopole in the universe happened to pass through Cabrera's detector."

Later, with the advent of the Large Hadron Collider, physicists attempted to create magnetic monopoles by colliding them.

No breakthrough was achieved even in later generations.

However, the idea of ​​perfect symmetry between electricity and magnetism has always attracted physicists to pursue it.

However, just as everyone was awestruck by the conjecture about magnetic monopoles...

Einstein, however, published an even more astonishing conjecture.

"There is no magnetism in the universe. Magnetic fields are just a phenomenon caused by the relativistic effects of electric field motion."

"In a current that generates a magnetic field, the motion of positive and negative charges is not the same."

"In the reference frame in which the charged particle resides, the charge distribution changes due to relativistic effects."

"This causes the particles to be subjected to force, and their state of motion changes. This is magnetism."

His article left everyone stunned and speechless.

"Oh, God!"

"Professor Einstein was insane!"

"This idea is even more groundbreaking than the magnetic monopole."

According to Einstein, magnetic fields are simply a relativistic effect of electric field motion.

Therefore, there is no such thing as a magnetic monopole, and even the magnetic field B is redundant.

Many leading figures in theoretical physics have joined the discussion.

Einstein's conjecture is of great research value.

It is another paradigm of the combination of quantum mechanics and special relativity.

Ligvii's proposal of quantum field theory, which was made shortly after its inception, inspired everyone.

This is the scene he wanted to see.

Theoretical physics is once again leading the future of physics.

At the same time, experimental physics also made significant breakthroughs.

(End of this chapter)