Into Unscientific Chapter 709

 That's right.

 I only see this moment.

 Yang Zhenning and Li Zhengdao pushed it to the note in the center of the table, and three identical words were written in Chinese:

 Gravitons.

 The moment I saw this word.

 Huang Kun's mind instantly went blank, as if everything in his brain had been formatted.

If Yang Zhenning hadn't supported him in time, Huang Kun almost fell to the ground in public.

But this can't be blamed on Huang Kun's poor mental quality.

Looking at the entire world of physics, even top luminaries such as Einstein and Dirac. No, even future time travelers like Xu Yun cannot calm down when they hear gravitons.

 In a sense.

 The concept of gravitons can basically be understood as a mythical legend.

 It is well known.

 While no one can fully describe quantum mechanics, the formal system of modern quantum mechanics consists of five axioms:

  1. The states of isolated physical systems can be related to vectors in a Hilbert space.

  2. The observable quantity of the physical system corresponds to a Hermitian operator. If the system is in a state Φ, measuring the physical quantity A will obtain the eigenvalue a of A with probability p.

  3. If the system is in a state Φ, after measuring the physical quantity A to obtain the eigenvalue a, the system will instantly collapse to the subspace corresponding to a.

  4. The evolution of the system over time follows the Schrödinger equation

  5. The wave function of an identical particle is symmetric (boson) or antisymmetric (fermion).

Based on these five axioms, the physics community has optimized the force field renormalization method.

  That means reorganizing several basic forces and finding the corresponding mechanism.

 When the renormalization theory was first proposed, only electromagnetic force could be renormalized.

Later, with the efforts of a large number of outstanding physicists, methods for renormalizing weak interactions and strong interactions were also found, and the particles predicted by these theories were found.

For example, the basic particle of electromagnetic interaction is photon. When we shoot a laser beam from the "electromagnetic ray gun", we are actually opening a torrent of photons, which is the smallest beam of electromagnetic force. Two electrons exchange Photons transmit electromagnetic force.

 The strong interaction is gluons. For example, protons with positive charges repel each other. The reason why the atomic nucleus is not dismantled by protons is because of the existence of strong force. Two quarks transfer strong force by exchanging gluons.

The weak interaction forces are W and Z bosons, which can turn one quark into another kind of quark - for example, there are three quarks in a neutron. If one of the down quarks is turned into an up quark through the weak force, the other will If the two remain unchanged, then the neutron will become a proton.

So according to this logic, gravity should also have a transfer particle, which is a graviton, right?

  But unfortunately.

From the day the concept of gravitons was proposed to the time when Huang Kun and the others were chatting, there was still no sign of it being discovered. On the contrary, there were many theories that refuted the existence of gravitons.

This is actually a very inconsistent phenomenon:

The eldest child is called Da Mao, the second child is called Er Mao, the third child is called San Mao, and the fourth child, Si Mao, is called Golden Jasmine.

to be honest.

If this kind of particle is simply not found, then it is actually not a big deal.

Just like the fact that the fourth child is called golden jasmine is not a big problem, it's just a matter of name.

 But the problem is that this golden Jasmine is bald, has ED, and has athlete's foot, which is outrageous.

 As for gravitons, this is exactly the situation:

 Gravitons are inconsistent with general relativity.

 In Einstein's classic theory of relativity, gravity is the curvature of space-time and does not require gravitons to transmit it.

 The general phase is also one of the most successful theories of gravity in describing gravity so far.

  But in addition to the broad phase, another part based on quantum mechanics, the Standard Model, which takes elementary particles as the research object, has also been developed, and it is the basic theory that has changed human life the most in modern times.

 Gravitons are allowed to exist in the standard model, and it has been mathematically proven that the universal phase and the standard model are incompatible.

 So at least one of these two theories is wrong or incomplete.

Of course.

The above sentences are not as simple as they seem. They actually involve the category of metrics:

 The curvature of space-time is mathematically described by the geometry of space-time by a non-straight metric gw, and the gravitational effect is directly determined by this metric.

Metric is equivalent to a tensor field. From the perspective of field theory, this tensor field can be regarded as a gravitational field - this is the meaning of gravity = space-time curvature.

  And in quantum mechanics.

Considering that the gravitational field also has quantum effects, there will be quantum perturbations in the metric. If the perturbation is not too strong, the metric can be regarded as a classical background + perturbation on the background.

This perturbation is also a tensor field, and it can be quantized using the method of quantum field theory.

 Then, just like other quantum fields, the excited state in which the energy and momentum values ​​are separated after quantization is the graviton.

 Very simple and easy to understand.

  And once the graviton is discovered

That would be great fun.

Then Huang Kun took a deep breath and asked Yang Zhenning solemnly:

“Lao Yang, how sure are you of this inference? How did you discover its existence?”

　　　　　　　　　　　　　　　　　　　 institutions

Yang Zhenning raised his eyelids and glanced away from Li Zhengdao, thinking carefully and said:

“Compared with the existence of dark matter, the certainty of graviton is definitely not that high, otherwise I wouldn't write the numbers in parentheses.”

“Furthermore, my derivation is mainly based on the mathematical aspect of this methadron model. Whether it can be found in the physical aspects is another matter.”

 Hear this.

Li Zhengdao also nodded calmly.

Although he and Yang Zhenning have many conflicts, he still agrees with this statement.

  After all, he and Yang Zhenning are not masters of collider machines. They can discover new particles in physical phenomena without doing any experiments. No matter how powerful they are, they can only make some mathematical deductions.

That is.

 Reform or quantize gravity within the framework of perturbation space.

Then Yang Zhenning picked up the pen again, turned to one of the pages of the paper, and said:

“The biggest controversy, or problem, and confusion about the quantization of gravity in the theoretical physics community currently lies in why the operators describing gravitational interactions are irrelevant at low energies.”

 Huang Kun hummed, this was also his question.

At this time, Yang Zhenning had just returned to China from across the sea, and his speaking habits had not yet completely changed, so it was inevitable that there would still be English expressions when referring to certain professional terms. This approach is two different situations from that of later generations of fake foreign devils who would just say "This is not fashionable enough" after just two sentences. It is a problem that must be adapted to and adjusted.

The irrelevant operator refers to the irrelevant operator. According to the definition of the renormalization group, when the corresponding low energy scale is very different from the natural cutoff, the irrelevant operator should tend to disappear.

Then Yang Zhenning smiled and explained to Huang Kun:

“Lao Huang, there are many speculations on this issue. My personal explanation is that the irrelevant operator is suppressed by the Planck energy scale.”

 “Planck energy scale?”

Huang Kun was slightly startled when he heard this, and asked subconsciously:

 “How does it have anything to do with it? Can you provide other evidence?”

Yang Zhenning decisively snapped his fingers:

"Of course - Lao Huang, have you heard of the Fermi theory proposed by Fermi five years ago?"

 “Fermi theory.”

 Huang Kun was stunned again for a few seconds, but this time, the confusion in his eyes was gradually replaced by thoughts.

 A few seconds passed.

 He ​​suddenly thought of something, took the journal in front of him, turned to a certain page, and read it carefully.

 Five or six minutes later.

 Huang Kun just suddenly raised his head and said to Yang Zhenning:

“Old Yang, do you mean that the reason why the irrelevant operator appears in the Fermi interaction is because the mass of the intermediate boson is not heavy enough?”

“Because if it were heavy enough, the Fermi coupling constant would be driven down to zero?”

Yang Zhenning nodded heavily.

 Fermi theory, also known as Fermi liquid theory in the future.

The proposer of this theory was not Fermi, but Landau, who had rated many big names, and it was proposed five years ago.

 There is also an irrelevant operator in this model, which logically cannot be expanded beyond the path integral.

 But it is very reasonable in explaining physical phenomena. Even though its name contains the word "liquid", its actual application scenarios have long been expanded beyond liquids.

So the physics community is like the programmers of later generations, cursing the code for bugs in its writing, while reaping the dividends by running the code.

With the advent of the methadron model and Yang Zhenning's suggestion, Huang Kun suddenly discovered.

Under the non-perturbative quantization degree of freedom of the metahadron model, this bug in Fermi theory can actually be explained.

Looking at Huang Kun who was a bit belated, Li Zhengdao also sighed softly.

Perhaps this is the information gap caused by the current situation. You know, as early as a month ago, researchers on the Fermi liquid theory across the sea had already started to party.

 Then he picked up the pen again and returned his mind to the original discussion content:

“Similar to the Fermi liquid theory, if the influence of the Planck energy scale is taken into account, the existence of the irrelevant operator is actually reasonable.”

“I think the degree of freedom directly represented by gravity is not the basic degree of freedom, so the essence of quantization of gravity is to explain the existence of low-energy gravity theory.”

“And to do this, we must identify the true degrees of freedom of gravity.”

 Speaking of which.

Yang Zhenning paused intentionally, and after Huang Kun understood his thoughts, he continued:

“Based on the Fermi liquid theory, the existence of the negative mass dimension of general relativity should also be due to the fact that we were deceived by the low-energy theory—the coupling constant is not static, but may be dynamic.”

“In other words, if there is still some kind of very heavy intermediate particle, then this intermediate particle should also be caused by some kind of spontaneous breaking of symmetry.”

“In this way, three-dimensional quantum gravity becomes a topic with limited degrees of freedom, and equivalence can be achieved.”

Huang Kun's pupils suddenly shrank.

 Mentioned earlier.

 Although his major lies in solid-state physics, he actually has profound attainments in theoretical physics.

 Because the strong interaction had not been discovered while he was alive, the gravity studied by Einstein was only renormalizable in 2 dimensions.

 But if the concept of gravity is to be truly reconstructed, it must start at least in four dimensions, and in essence, it must be discussed to 5 or higher dimensions.

The 5 dimensions here are not the high-dimensional concepts of 5-dimensional civilizations in science fiction novels, but a purely mathematical category of path integrals—someone these days always likes to link dimensions with the so-called [world] or [civilization]. But in fact this is just a pure mathematical concept, and it is very serious.

For example, there is a Calabi-Yau space, which has six dimensions. It sounds very popular, right?

But actually its full name is Calabi-Qiu Chengtong Space. It doesn't matter if you think of the one in the front as a Calabimon, as long as you recognize the one in the back.

This space is even recognized as Yau's greatest achievement. He won the Fields Medal for proving Calabi's conjecture.

 The same is true for the quantization of gravity.

 It is difficult for the physics community to imagine what a four-dimensional world looks like, but mathematics can already push it to twelve dimensions under extreme circumstances that are not civilian science.

Then Yang Zhenning picked up the water glass and took a sip of water, and continued:

“Based on the above ideas, we will deduce that the Planck length has Lorentz invariance in this case, and the calculation equation also satisfies Lorentz symmetry.”

“So I spent a lot of time doing calculations and finally came up with an equation.”

 Say it.

Yang Zhenning picked up the pen and wrote an expression in front of Li Zhengdao:

 Wγ[A]=Pexp{∫γ0γ1dsγ˙aAai(γ(s))Ti}.

Huang Kun leaned over and looked carefully for a while, and quickly frowned:

 “What a chicken, I can't understand.”

Yang Chenning and Li Zhengdao:

Then Yang Zhenning took a deep breath and slowly explained:

“That's right, Lao Huang, you are not engaged in theoretical physics after all. Simply put, this is a quantized loop integral of space on the Planck scale.”

“It reproduces 4-dimensional space-time on a large scale, while space-time on a small scale, that is, near the Planck energy scale, appears as 2-dimensional. It can also calculate the distance between two points more accurately.”

“Of course, as I said before, it's all mathematical derivation.”

“It is estimated that it will be very difficult to find gravitons in physical phenomena, but at least the energy level is lower than what everyone originally thought.”

 Huang Kun raised his brows. He knew that the so-called original energy level obviously referred to the Planck scale:

 “Lao Yang, what's the energy level you calculated?”

Yang Zhenning thought for a while and explained:

“According to the parameter four-Fermi interaction I calculated based on the methadron model, it will probably fail at an energy level of tens of GeV, and will be replaced by the electroweak interaction theory with spontaneous symmetry breaking.”

“If this phenomenon can be verified successfully, then it may not need to reach the Planck scale, which is about 10^-18th power.”

  “10^-18th power”

Huang Kun frowned when he heard this:

“That's unlikely—at least in the short term.”

"really."

Yang Zhenning nodded calmly, but then changed the subject:

“But there is another way, maybe there is a chance to take a shortcut.”

Chapter end