Into Unscientific Chapter 710

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

 On the deck.

Hearing Yang Zhenning's words, Huang Kun subconsciously clenched the edge of the table:

 “What method? Is it related to donkeys?”

Yang Zhenning was about to answer, but when he heard the word donkey, he couldn't help but was startled and stopped talking:

“Donkey? What does this have to do with donkeys?”

Only then did Huang Kun realize that he seemed to have made a subconscious reaction, so he coughed slightly awkwardly:

“Oh, it's nothing, it's nothing, I just got distracted, Lao Yang, keep going, keep going.”

Yang Zhenning glanced at Huang Kun strangely, thinking that this old classmate must have been kicked by a donkey before boarding the boat.

Then he quickly took a deep breath and brought his attention and topic back to the original place at the same time:

“Lao Huang, the method I mentioned is not useful to you. It may be a relatively unfamiliar field to the country.”

“Actually, if this paper by Lao Zhao and others hadn't brought me some inspiration, I might not have thought of this aspect myself.”

 After giving Huang Kun a vaccination.

Yang Zhenning paused and continued:

“Old Huang, how much do you know about AdS space and time?”

 “AdS space and time?”

 Huang Kun raised his eyebrows slightly and quickly replied:

“Old Yang, are you talking about Anti-deSitter, which is anti-deSitter space-time?”

Yang Zhenning nodded slightly.

 Mentioned earlier.

  At present, the most perfect theory that describes gravity is the general theory of relativity. This framework is called "theory", but in fact its theoretical core is a system of equations.

 That is, Einstein's gravitational field equation.

This is a highly complex set of nonlinear partial differential equations. The unknown function to be solved includes both the metric component gμν and the component Tμν of the energy momentum tensor.

 It is well known.

 The straight Min space-time metric is: ηαβ= (1, 1, 1, 1) and the sign difference is ±2.

So the spatial geometric diagonal element of the gravitational field is: ds2=(1+2)dt2+(12)(dx2+dy2+dz2)

The static gravitational potential of the gravitational field is: h00=2, and the Newtonian gravitational field potential is: ▽2=4πGp

 It can be statically normalized under a nearly quasi-weak field. Comparing the two equations, we get: h00=4

 Substituting Newton's gravitational potential, we can easily get: ▽2h00=16πp; (G=1)

 Add a four-dimensional operator D'Alembert □ to the left side of the equal sign to represent spatial fluctuations: □h00=16πp

 Assuming that the change of the field is only due to the fluctuation of the field source, it may be related to:

　　=▽2+0（v2▽2）

 And because the stress energy tensor is T00=p, □h00=16πT, this is the "linear Einstein field equation".

From this expression, it is not difficult to see that hαβ is treated linearly in this equation, as if a three-dimensional thing was flattened for you to see.

 So naturally, the gravitational field equation of the particle system is: h00=8πT

 Introducing the Einstein tensor to represent the static field quantity in curved space-time is:

ˆGαβ=8πTαβ.

At the same time, assuming that space-time matter is distributed along the curvature of the space-time surface, just like the contents of a bag are distributed in the bag, the index-free simplified expression is:

  G+Λ=±KT This is the basic form of Einstein's field equation.

Λ is the cosmological constant. Einstein thought that he had done the wrong project, so for now, just treat it as 0.

˜According to the field quantity, it is obvious that the coefficient K=8π, the one on the left is the Riemann curvature Rαβ, and according to the Bianchi identity, the transfer can be completed, so it is: Rac12Rgac=8πGTαβ

If it is in an electromagnetic field, according to Maxwell's equations, the square of the vacuum light speed in space is the product of the vacuum permittivity and the vacuum permeability, that is:

ˆˆC2=με

 Hence Rac12Rgac=8πGμεTαβ, and because Tαβ is a second-order tensor field tangent using the geometric unit system C≡1 and unifying the dimensions, we get:

  Rac12Rgac=8πGC4Tαβ

 This is Einstein's field equation under electromagnetic action. (Some readers have been curious about how the field equations came about before, so I wrote them down when I had the opportunity. I typed the whole process from memory. It should be right. This is probably the first book from Qidian that writes out the detailed derivation process of field equations? Probably .)

 Even until 2023 in later generations.

Einstein's field equations still have no analytical solutions, only some special solutions.

 One of the most famous special solutions is obviously the Schwarzschild solution, also known as the Schwarzschild metric - as mentioned earlier, the metric is a way of saying the solution.

 Among these few special solutions, there is one solution that is the most special.

 It is.

 AdS, which is the anti-de Sitter metric.

 It is the maximum symmetric vacuum solution of Einstein's field equations when the cosmological constant is negative, and is often called "space within a point".

This special solution appeared very early. After all, William de Sitter was one of the first scholars to study the structure of space-time with Einstein. Both the anti-de Sitter metric and the de Sitter metric are named after him.

but

Although this special solution has existed for a long time, it has not had much research value in physics.

But now it seems that Yang Zhenning has discovered something in this regard?

Then Yang Zhenning pondered for a while and continued:

“Old Huang, you should know that in anti-De Sitter space-time, space-time does not tend to be flat asymptotically.”

“That is to say, at a distance from the central celestial body, space-time still has curvature, and it is not a general flat space.”

“So I'm thinking, if we can use AdS as a theoretical basis to integrate a model that can describe gravitons, and then look for signs of it in the universe.”

“In this way, is it possible to discover the existence of gravitons without reaching the Planck energy level?”

Huang Kun was startled when he heard this.

But soon, he digested Yang Zhenning's ideas.

· AdS is a mathematically problem-free special solution to field equations. It is completely different from folk science or unfounded conjectures. When many people mention space and time, they subconsciously think of it as a concept in science fiction.

 But in fact, many of these science fiction concepts appear because they already have physical or mathematical models.

The original curvature engine was the Alcubierre metric. It has been mentioned several times. Here is another example.

  In 1916.

Austrian physicist Ludwig Frahm proposed the concept of wormholes.

  1935.

Einstein and Nathan Rosen improved the wormhole theory. They symmetricalized the metric of the wormhole, introduced the radial component grr and the radial coordinate r0 of the wormhole throat, and made a mathematical model called Einstein Rosen Bridge.

This thing is the wormhole that spaceships will travel through in almost all science fiction novels of later generations - this thing is really a mathematical model

This is not over yet.

 Develop according to the original history.

 In a year from now, Robert Fuller and John Wheeler will publish a paper proving that:

If a wormhole connects two places in the same universe, then this type of wormhole is unstable.

 That's right, it's a proof, not a conjecture.

 Hence, space-time is not a very mysterious concept in the world of physics or mathematics - what is really mysterious is not [space-time], but [civilization].

The same is true for Einstein Rosenbridge, and the same is true for Yang Zhenning at this time.

 Yang Zhenning introduced the AdS theory with a very formal or serious attitude. This theory maintains symmetry due to the limitations of the field equations, that is, maintaining the basic framework of the theory.

But at the same time.

He also abandoned the concept of "field" in general relativity, which does not support the existence of gravitons, and instead looked for a suitable fulcrum as a partner in metahadrons, that is, the standard particle model.

 Then use this new combination theory to search for possible gravitons.

  In other words.

 This should be a model specially adapted for gravitons. Think of this.

 Huang Kun couldn't help but look at Yang Zhenning and asked:

“Lao Yang, apart from AdS, what is your other fulcrum theory?”

 Yang Zhenning did not answer him directly this time, but looked at Li Zhengdao, who had been silent:

"What do you think?"

Li Zhengdao raised his eyelids and gave Yang Zhenning a meaningful look.

Yang Zhenning's words are not implying that Li Zhengdao only listens but does not speak, nor does he want to make Li Zhengdao embarrassed, but he wants to give Li Zhengdao a chance to show his ability.

After all, Huang Kun is now a member of the academic department of Hua Xia. In addition to welcoming Yang Zhenning and others, his trip also has the responsibility of preliminary observation of a few people.

Perhaps he himself is unable to understand some theories in real time due to professional issues, but as long as he goes back and repeats the news, there will naturally be people in the country who understand to make judgments.

Li Zhengdao was silent for a few seconds and then slowly said his answer:

“I think quantum system equations can be used as an entry point, because it can not introduce the concept of gravity in certain situations.”

 It is well known.

There are four key equations in quantum mechanics:

 Schrödinger equation, Heisenberg equation, Dirac equation and density matrix equation.

However, the quantum system equation mentioned by Li Zhengdao is not any of the above, but an equation involving pure states.

 Quantum systems are generally represented by state vectors, which describe the system properties of orthogonal states.

 Then Li Zhengdao wrote an expression that was somewhat complicated and inconvenient to display, and brought it together with Yang Zhenning's previous AdS metric.

 Yang Zhenning did not express any refutation throughout the whole process, which means that Li Zhengdao's thinking is consistent with his.

Huang Kun moved the two pieces of paper in front of him and began to combine them.

This kind of combination process involving a lot of mathematics is easier for him to understand than some theoretical concepts - after all, many of the parameters are interoperable with solid-state physics.

 “Adapt the derivative operator, that is, if agbc=0 is satisfied, then aζb+bζa=0”

“The maximum symmetric space-time must have the largest Killing vector field, and the definition of Riemann curvature tensor abζcbaζc=Rabcdζd is brought in.”

 “Equate this tensor in coordinates.”

  “12345678abcdefg”

A few minutes later.

 Huang Kun raised his head in confusion and asked Yang Zhenning hesitantly:

“Lao Yang, are you going to start with the dual situation?”

Yang Zhenning nodded slightly:

 “That's right.”

 Huang Kun was silent for a moment.

how to say

This model that Yang Zhenning and Li Zhengdao came up with is indeed interesting in a sense:

  The two fulcrums of the model come from different theories, and the associated scenarios are also different, and even the space-time dimensions are different.

but

 After the introduction of the concept of duality, it suddenly underwent some changes.

 The so-called duality means that if a physical system has two different but equivalent ways of describing it, then these two ways of describing it are dual.

 The more well-known examples include the self-dual of the classic two-dimensional Ising model and the particle vortex dual of the two-dimensional xy model.

 There is also the Boseization of the one-dimensional interacting fermion system, which in principle can also be regarded as a type of duality.

 In this dual model made by Yang Zhenning and Li Zhengdao.

 When one theory is strongly coupled, the other theory is weakly coupled.

 The two combine something from general relativity and quantum mechanics in a very subtle way.

 Based on the simple calculation Huang Kun just made.

The quantized loop integral previously derived by Yang Zhenning is established under this model, but that's all.

If you replace it with any other particle, whether it is an electron, a proton, or a neutrino, they all fail under the model—at least mathematically.

 For example, a proton.

If calculated based on this duality, the mass of a proton will eventually show more than 300 grams, and the mass of a neutrino is even negative

However, this situation has long been expected by Huang Kun. After all, Yang Zhenning said from the beginning that this is a model specially made for gravitons.

 Then Huang Kun put down the pen in his hand and asked Yang Zhenning:

“Lao Yang, this framework has been developed. So what about the technical applications?”

“How are you going to use this framework to catch the big fish of gravitons?”

 Mentioned earlier.

The theoretical energy level of gravitons is close to the Planck scale. This scale, let alone now, will probably be a bit difficult in a hundred years.

Although Huang Kun is not desperate enough to find gravitons now, he is not so broad that he can wait for more than a hundred years - by then, the Chinese football team will probably win the World Cup, right?

 The timeline he can accept is around 20-30 years, and no later than forty years.

 After all, forty years later, almost all of them are close to death or have passed away.

And if you want to determine the specific time, the specific project application is very critical.

 The difficulty and reasonableness of the project are directly related to the time it takes to produce results—at least in theory.

Then looking at Huang Kun with burning eyes, Yang Zhenning was silent for a few seconds:

“Old Yang, do you still remember what I said to you before?”

“—Using AdS as the theoretical basis, integrate a model that can describe gravitons, and then look for its signs in the universe.”

 “If you think about it carefully, what is the point of this sentence?”

 “The point?”

 Huang Kun repeated Yang Zhenning's words, and immediately his breath stagnated:

 “Lao Yang, are you talking about the signs in the universe?”

Yang Zhenning nodded slightly and looked up at the sky deeply:

“Yes, the universe, to be precise”

 “Primordial gravitational waves.”

Note:

 The recovery period from the surgery took much longer than I expected. I missed all my attendance this month, ugh.

Chapter end