Hello everyone, today we have handed over to the printing house the book by Frank Wilczek
, exploring the background of the newest physical ideas about the mass, energy and nature of a vacuum. The author, the Nobel Prize winner in physics, sets out modern views on our incredible Universe and predicts a new golden age of fundamental physical science. The magnificent story of the unity of matter and energy, of elementary particles and their interactions is in this masterpiece of serious popular science literature.
Here we publish an excerpt from the book "Fermi Dragons"
From the very beginning it was clear that other new forces were ruling the nuclear world. The classical forces of pre-nuclear physics are gravity and electromagnetism. However, repulsive forces act in nuclei: the nucleus has a common positive charge, and like charges repel each other. Gravitational forces acting on a small amount of mass in any single nucleus are too weak to overcome electrical repulsion. (We’ll talk in more detail about the weakness of gravity in the second part of this book.) A new force was needed. She received the name of strong interaction. In order for the nuclei to remain tightly connected with each other, the strong interaction had to be more powerful than any of the previously known ones.
It took decades of experimenters 'efforts and theorists' sophistication to discover the fundamental equations describing what happens in atomic nuclei. It's amazing that people even managed to find them.
The obvious difficulty lies in the fact that observing these equations in action is hampered by the small size of the atomic nucleus. It is about 100,000 times smaller than the atom itself. This takes us a million times further beyond nanotechnology. Kernels belong to the field of micronanotechnologies. Trying to manipulate the nucleus with the help of macroscopic tools, such as weights or ordinary tweezers, we get worse result than a giant trying to lift a grain of sand with a pair of Eiffel towers. This is a difficult task. To study the nuclear world, it was necessary to develop completely new methods for conducting experiments and to create unusual types of tools. In the next chapter, we will visit an ultrastroboscopic nanomicroscope (known as the Stanford Linear Accelerator (SLAC)) and a creative destruction station (known as the Large Electron-Positron Collider (LEP; BEPC)) where discoveries were made
Another difficulty lay in the fact that the micronanocosm, as it turned out, follows laws that are completely different from what was previously studied. Before paying tribute to the strong interaction, physicists had to abandon the natural way of thinking for humans and replace it with strange new ideas. We will look at these ideas in more detail in the next few chapters. They are so strange that if I simply cite them as facts, they will not seem plausible to you *, however, they should not seem so. Some of the new ideas are completely different from everything known before. They may contradict - and probably actually contradict! - what you studied in school. (It depends on which school you went to and when.) In this short chapter I will explain what prompted us to revolution. This chapter serves to unify the traditional concept of nuclear physics, which is still given in most of the textbooks on physics for high school students and freshmen that I came across with our new understanding.
The discovery of a neutron by James Chadwick in 1932 was a landmark event. After the discovery of Chadwick, the path to understanding seemed simple. It seemed that the building blocks of nuclei were found. They are protons and neutrons, two kinds of particles that weigh about the same (the neutron is 0.2% heavier) and have similar strong interactions. The most obvious differences between protons and neutrons are that the proton has a positive electric charge, and the neutron is electrically neutral. In addition, an isolated neutron is unstable. The period of its existence is about 15 minutes, after which the neutron turns into a proton (and thus an electron and antineutrino also appear). By simply putting together protons and neutrons, you could create models of a nucleus with different charges and masses, which roughly correspond to similar parameters of known nuclei.
It seemed that understanding and refining these models was just a matter of measuring the forces acting on protons and neutrons. These forces would keep the nucleus from decay. The equations describing these forces would become a theory of strong interaction. Solving the equations of this theory, we could check it and make predictions. Thus, we would write a new laconic chapter called “nuclear physics”, the central idea of which would be “nuclear force”, described by a simple and elegant equation.
Such an action program inspired experimenters to study proton collisions with other protons (neutrons or other nuclei). We call such experiments, in the process of which the particles collide with others and study what happened, the experiment on scattering. The idea is that by studying the deviation of protons and neutrons, or, as we say, scattering, you can determine which forces act on them.
This simple strategy failed miserably. First, the power was very difficult. It was found that it has a complex dependence not only on the distance between the particles, but also on their speeds and the directions of their spins. It soon became clear that we would not be able to find a simple and beautiful law for this force, worthy of a place in line with the law of Newton or Coulomb's law for electricity.
Secondly, which was even worse, “force” was not force. When two energetic protons collide, not just their deflection occurs. Often, as a result, more than two particles are formed, which are not necessarily protons. In fact, in the course of high-energy scattering experiments conducted by physicists, many new types of particles were thus discovered. New particles, which were found dozens, unstable, so we usually do not observe them in nature. However, upon their detailed study, it turned out that their other properties, especially strong interactions and size, are similar to those of protons and neutrons.
After these discoveries, it became unnatural to consider protons and neutrons by themselves or to think that the main problem is to determine the forces causing their interaction. Instead, “nuclear physics” in the traditional sense has become part of a larger subject, including all new particles and obviously complex processes of their creation and decay. To describe the new "zoo" of elementary particles, this new kind of dragon, the name hadron was invented.
Experience in the field of chemistry suggested the possibility of explaining all these difficulties. Maybe protons, neutrons and other hadrons are not elementary particles. Perhaps they consist of simpler objects with simpler properties.
In fact, if you conduct the same experiments on atoms and molecules as on protons and neutrons, studying what remains after their collisions, you will also get difficult results. You could rearrange and decompose molecules to obtain their new species (or excited atoms, ions and radicals), in other words, to carry out chemical reactions. Only electrons and nuclei obey the simple law of interaction. Atoms and molecules consisting of many electrons and nuclei do not obey him. Could there be a similar pattern for protons, neutrons, and their recently discovered congeners? Can their obvious complexity be explained by the fact that they consist of smaller building blocks that obey much simpler laws?
Breaking something into pieces can be a rough way, but this method can also be the most reliable way to figure out what it consists of. If two atoms are pushed together strongly enough, they will disintegrate into their constituent electrons and nuclei. Thus, the building blocks of which they are composed are detected.
Nevertheless, the search for simpler building blocks inside protons and neutrons led to unusual difficulties. If you really strongly collide protons with each other, then as a result you will receive even more protons, sometimes accompanied by their hadron relatives. A typical result in the collision of two protons at high energy is the appearance of three protons, an antineutron, and several pi-mesons. The total mass of the resulting particles exceeds the mass of the original. We discussed this opportunity earlier, and here she again overtook us. Instead of opening smaller and lighter building blocks, switching to higher and higher energy and making more and more collisions, you simply find more of the same. The tendency to simplify is not observed. It is the same as if you pushed two apples of the same variety together and got three apples of the same variety, one apple of another variety, a melon, a dozen cherries and a couple of zucchini.
Fermi's Dragon turned into a nightmarish hydra from a myth. Cut off the hydra's head and several new ones will appear in its place.
More simple building blocks exist. However, their fundamental “simplicity” implies strange and paradoxical behavior, which makes them both revolutionary for the theory and elusive during experiments. In order to understand them or even perceive them, we will have to start from the beginning.
»More information about the book can be found on the publisher's website.
» Table of Contents
For readers of this blog 20% discount coupon - Wilczek