However, there was a time when this simple state was explored by nature. At that time, the universe had not been born in the big bang for a second. At that time, the temperature was as high as 1027 degrees, which was just the energy needed to explore the original state. Physicists in this period called it the era of great unity, because physics at that time was dominated by the process of great unity of fundamental forces. The crucial non-equilibrium we mentioned in the third chapter was established at that time. With that kind of non-equilibrium, matter is a little more than antimatter. Later, with the cooling of the universe, the original unified force was divided into three different forces-electromagnetic force, weak force and strong force. These forces are what we see in the relatively cool universe.
Today's complex physics is formed by the simple physical cooling of the original big bang flame. The scenery is wonderful and attractive. The ultimate principle of nature, that is, Wheeler's "central mechanism of flash", is difficult for us to see because of the lack of energy. If people trace back to those periods before the Great Unity era and catch up with places closer to the beginning of time and higher temperature, they can find supergravity. Supergravity represents the beginning of existence, where time and space are integrated with basic forces. Most physicists believe that the concept of space-time cannot be used in the era of supergravity. In fact, there are signs that time and space should also be regarded as two kinds of fields, which are themselves "cooled" by the original soup composed of geometric elements. Therefore, in this super-gravity era, the four forces of nature are chaotic and integrated, and time and space have not yet become an image. At that time, the universe was just a pile of ultra-simple components, which were used by some gods to create time, space and matter.
This chapter describes the latest progress in the study of fundamental forces in physics. These advances make people look at nature from a new angle. The influence of this view is rapidly expanding among physicists and astronomers. Now, people have begun to regard the universe as a complex thing produced by the cooling of simple things, rather than an invisible ocean frozen into ice floes with different postures. Scientists have a feeling that the research theme of cosmology and people's study of fundamental forces in matter are providing a unified description of the universe. In this description, the microstructure of matter is closely related to the overall structure of the universe, and both structures affect each other's development in subtle and complicated ways.
A series of successes in physics described in this chapter undoubtedly represent a victory of modern physics thought based on reductionism. Physicists try to simplify matter into its final components-leptons, quarks, messenger particles-so that they can understand this basic law. It is that basic law that controls the forces that form material structure and behavior and can explain many basic characteristics of the universe.
However, it is not enough to pursue some ultimate truth felt in this way. As we have seen in the previous chapters, reductionism cannot explain many obvious phenomena with holistic characteristics. For example, we can't use quarks to understand inanimate systems such as consciousness, living cells and even tornadoes. Otherwise there will be jokes.
So far, the language used in this chapter has largely failed to convey the concept of material structure in the minds of physicists. When a physicist says that protons are made up of quarks, he doesn't mean that. For example, when we say that an animal is made up of cells, or a library is made up of books, we mean that we can take out a cell or a book, or anything from that larger system for isolated research. But quarks are not like this. As far as we know, it is impossible to really take apart protons and take out quarks.
However, disassembly has a glorious history. Disassembling atoms is now commonplace; It is difficult to crack the nucleus, but it will also split under the impact of high energy. This may mean that bombarding protons or neutrons with high-speed particles will crush them into quarks. However, this is not the case. A tiny high-speed electron will pass through the proton and violently rebound one of the quarks, thus making us sure that there is a quark somewhere inside the proton. However, if it is not a small electron but a sledgehammer, that is, another proton, then we will not see quarks in the fragments of protons, but only more hadrons (protons, mesons, etc.). ). In other words, quarks never appear in isolation. Nature seems to only allow quarks to appear as a group, always two or three together.
So when a physicist says that protons are made up of quarks, he doesn't mean that these mysterious quarks can appear alone. He only refers to a descriptive level, which is more basic than the proton level. The mathematical laws governing quarks are simpler and more basic than those governing protons. In a sense, protons are synthetic, not basic; But synthesizing protons from quarks is different from synthesizing books in the library.
When we take quantum factors into account, as we saw in chapter 8, it is more difficult to understand the basic structure of matter. This is because no subatomic particle (whether quarks or other elementary particles) is a real particle. In fact, subatomic particles may not even be "things". This makes us realize once again that the so-called description of matter as a collection of particles must actually be regarded as a description level determined by mathematics. Physicists can accurately describe the structure of matter only through abstract advanced mathematics, and only when people realize this background can they understand the true meaning of reductionism.
One aspect of Heisenberg's uncertainty principle well illustrates the difficulties brought by quantum factors to the study of "what is made of what". But this duality is not between waves and particles, nor between motion and position, but between energy and time. The two concepts of energy and time are mysterious and antagonistic: you know one but you don't know the other. Therefore, even if a system is observed in a short time, its energy may fluctuate greatly. In daily life, energy is always conserved. Conservation of energy is the cornerstone of classical physics. But in the quantum micro-world, energy may come out of nowhere or disappear in a spontaneous and unpredictable way.
When Einstein's famous formula E=mc2 is considered, the fluctuation of quantum energy becomes a complex structure. Einstein's formula says that energy and mass are equal, or that energy can create matter. This has been discussed in previous chapters. However, the energy mentioned in those chapters comes from the outside. Here, we want to discuss how to create matter particles from the fluctuation of quantum energy without external energy input. Heisenberg's principle is much like an energy bank. Energy can be borrowed for a short time, as long as it is returned quickly. The shorter the loan period, the larger the loanable amount.
For example, in the microscopic world, a sudden energy fluctuation may make a pair of positive and negative electrons appear and disappear in a short time. The short-lived existence of the pair of positive and negative electrons was maintained by Heisenberg-style borrowing. Its existence time never exceeds11021sec. But the cumulative effect of countless such flickering ghost particles gives the empty space a certain transformed texture, although it is a vague and unreal texture. Subatomic particles must swim in this constantly moving ocean. Not only electrons and positrons, but also protons and antiprotons, neutrons and antiparticles, mesons and antiparticles. In short, all the particles in nature are so turbulent.
From a quantum point of view, electrons are not just electrons. The pattern of energy change flashes around it, and I don't know when it suddenly leads to the appearance of photons, protons, mesons and even other electrons. In short, everything in the subatomic world is attached to electrons, for example, electrons are covered with an invisible coat, or a group of bees buzz around the middle hive like ghosts, forming the cover of the hive. When two electrons are close to each other, their covering layers are also entangled, so interaction occurs. The so-called cover is just a quantized expression that was previously considered as a force field.
We can never separate electrons from the ghost particles they carry. When someone asks "what is an electron", we can't say that an electron is such a small particle; We must say that electrons are an inseparable whole string of things, including ghost particles that generate force with them. When it comes to hadrons with internal structures, it is even more vague and difficult to distinguish. A proton somehow always carries quarks, which are connected by gluons. There is also a strange circle here: force is generated by particles, and the generated force generates force.
For particles like photons, this strange circle means that photons can show many different faces. By borrowing energy, it can temporarily become an electron-positron pair or a proton-proton pair. Experiments have been carried out to observe how photons become positive-negative electron pairs or positive-negative proton pairs. However, people once again found that it is impossible to separate "pure" photons from this complex change.
We will see that the essence of matter has a strong holistic flavor in its quantum theory: the descriptions of different levels of matter are interrelated, and everything is composed of everything else, but at the same time everything shows the hierarchical order of structure. It is in this all-encompassing integrity that physicists pursue the ultimate composition of matter and the ultimate unified force.