The discussion between Junxin and Horowitz did not last long, and the two only had some in-depth exchanges about the content published in Physical Review Letters. Then, Professor Candela walked in with Professor Strominger. Less than five minutes after the two of them sat down, Professor Witten, the initiator of the seminar, also came to the conference room.

"Jun, have you read the contents of Physical Review Letters?" After the greetings, Professor Witten asked unceremoniously.

"Well, this issue of Physical Review Letters has published a total of four articles on superstring theory, one of which is one of mine, one of which is signed by the five of us and Professor Schwartz, and one paper that I have co-authored with Professor Witten, and one paper that Professor Candela has collaborated with Horowitz and Professor Witten. In addition, in the first draft of the paper in the next issue, Horowitz's paper on the six-dimensional structural space has been sent to me by the editorial office of Physical Review Letters, and a paper on the supersymmetric properties of superstring theory that I collaborated with Professor Strominger has also been submitted to the journal "Annals of Physics", and it is estimated that if nothing goes wrong, it will be published in the next issue. ”

Professor Witten nodded and said, "What we have achieved so far is very good, which proves that our research has achieved certain results, and this is a very good start for us." However, this also fully shows that there will be more important things to be done in the coming period. ”

Hearing Professor Witten say this, Junxin, Horowitz and the other two professors also agreed. As Professor Witten said, although it seems that they have made some achievements in discussing superstring theory, it is precisely because of these achievements that it will be subject to the most widespread skepticism in the physics community in the coming period.

No matter how correct the superstring theory is, no matter how correct the theory is, in the final analysis, this theory is just a theory, or even a theory that cannot be verified in a short period of time. Even this theory is just a simple mathematical model that cannot be used to verify its correctness.

"What do you want to do?" Candela asked.

Professor Witten shook his head and said, "I don't know what to do next, but I want to continue to find and build models for other superstring theories that satisfy the Yang-Mills equation in the next few years." The mathematical model of the E8 topology in Lie algebra that I found in collaboration with Jun satisfies the Yang-Mills equation perfectly, but it seems that there are other models that can be used to solve this problem as well. ”

"You want to go ahead and sift through all the right types of mathematical models, which isn't going to be easy!" Jun Xin raised his eyebrows and said in surprise.

"It's a big project!" Horowitz agrees, "According to my calculations, even if all the theoretical physicists around the world were to work on the grand unified theory, it would take at least one to two years to build the various models." ”

"It's not very difficult to build a model, it's hard to sift through it, because these theories are generally based on quantum mechanics, so there's a lot of computation to be done on each model, and it's a question of whether they're a Yang-Mills gauge field." Professor Strominger also nodded.

Professor Witten said disapprehantly: "Indeed, the construction of the model requires a good mathematical foundation, but for most theoretical physicists at least an amateur mathematician, this is enough, if you want to filter out an accurate model, it may not work, but it is very simple to screen out a relatively early model, which saves us a lot of time spent on screening, and this is the most important point." ”

"I think what Professor Witten said is very reasonable, after using string theory to build the foundation of basic quantum mechanics and relativity, it is not so difficult to establish a basic model of physics that is not very rigorous, it is nothing more than a question of correctness, which is a very easy thing to solve."

"However, there is a problem that we need to imagine in advance, according to the current superstring theory to build a model, there are already two known laws that conform to the basic mechanics and the motion of matter, so can it be said that in the future, physicists will find other models that are relatively accurate and conform to the principles of basic mechanics and kinematics?"

"There is no doubt about it, and if the open-string model you built is the only model that fully conforms to the Yang-Mills equation, I might think that it is a model of the only nature, but in fact, Professor Witten has found a correct model for closing the strings, so I am not sure that there is no other model that is correct. Perhaps other correct models will be found in the future boom of superstring theory. Professor Candela said calmly, in fact he was close to finding one of them, which was probably only known to Professors Junxin and Witten, and others such as Horowitz knew that he was working on other models, but they didn't know how far they were going.

"Why are there so many models?" Junxin didn't think so much, but raised such a question.

Professor Witten and several others did not know how to answer this question, in fact, it was not that they were not aware of the problem, but that they did not discuss the problem in depth. Because they will not easily start the next problem without completely ending the problem of the string theory model. However, since Junxin raised this question at this time, they could only start thinking about this question in advance.

"What do you think, Jun?" Professor Witten asked, since this is the question raised by Junxin, it means that Junxin has made some thoughts, or he thinks that it is time to think about this problem and has a certain amount of thinking about this issue, so it is very necessary to listen to Junxin's opinion.

In fact, Jun Xin knows the answer to this question very clearly, but he has a very different feeling when he thinks about this question from the perspective of the parties. That's why Junxin raised this somewhat "far-sighted" question at this time.