Read simulating physics with computers

 

Reading "simulating physics with computers" today took a day to read "simulating physics with computers" by Feynman. Some of them were in the fog, and they couldn't help playing CS several times, so the content is really hard to understand. But he finally understood what he was about to describe-"quantum computers ". Like everyone else, Mr. Feynman came up with a computer to simulate the world. The reason for this is that he does not want to use a classic Turing Machine to simulate the world, and he proves that it cannot be implemented using a Turing machine. It seems that the computing workload is too large, similar to the meaning of NP problems. I believe many people have thought about this problem and come to the conclusion that they cannot use the classic Turing Machine to simulate the world. But Mr. feeman did not stop talking about it, but further considered this question: Since the Turing machine is not working, can other computing models be used to simulate the world? He used some elements and methods in quantum mechanics for computation, but encountered a difficult problem, that is, the question of Negative Probability (these are mostly quantum mechanics, which I did not understand ), nothing left. Think about it. It may be a waste of time on your own day. You should study such a classic article well. Looking at the world using traditional physics methods, he believes that there is such a problem, that is, it is impossible to use a farther future and the past to calculate a relatively near future, because we must calculate this relatively near future to calculate that far future. I have never understood this question: why should we use a distant future to calculate a near future?

Another problem he mentioned may be more important, that is, the continuity of time. In traditional physics, the time used in computing is actually discrete, and the minimum unit is about 10 to 38 power. If we want to simulate the real world, we need to calculate it in this time unit. From the perspective of quantum mechanics, because quantum theory is related to probabilities, "computers" must be able to express and calculate probabilities. The computer here is quoted because it is not a Turing machine. I don't know why quantum theory is probability, but I have heard of it. In addition, this article is a classical reading course for computer science at ucberkeley University. Their undergraduates are reading this course. The instructor will host these articles in class. I really envy them. If they are guided by people who can discuss them, half a day will be more effective than my desperate day. Appendix: I uploaded this article to csdn. It can be downloaded from csdn in pdf format. It can also be publicly downloaded.