Indeed, the impression of Dirac's phenomenal discovery was still fresh, and there were years of silence that were gently bypassed by physicists of the Dirac equation, when the American scientist Anderson first saw the trace of a positively charged electron, born in Wilson's chamber when a space particle passed through it. His path was curved by a magnetic field in the opposite direction to the path of an ordinary electron. All other signs coincided.
Undoubtedly, it was the same positron that Dirac brilliantly predicted to exist. It was in 1932. The appearance of the positron became a world sensation, the nail of the fourth decade of our century. The doors to the anti-world were open. Physicists rushed to discover new "lands". They were eagerly looking for other particles and antiparticles.
Wilson's camera decided, apparently, to play the role of the horn of plenty. And after the first sensation gave birth to the second, then the third, fourth ... a whole cascade of new elementary particles and antiparticles.
Hunters for space particles even lower bent over their installations. They began to look even more closely at the photos, covered with thick and thin, barely visible and distinct lines - the traces of flashing space particles and fragments of broken atoms. Physicists showed miracles of observation, digging into the confusion of nothing but them, non-verbal traces. And finally, in 1936, Anderson and Neddermeyer saw another, unseen particle by nobody. It was moving faster than a proton, but more solid than an electron. It was lighter than the first, but heavier than the second. That's what they called it - "meson", which means "intermediate" in Greek.
The fate of this particle is very similar to that of the Dirakovsky positron. The meson was also introduced into science with the pen of theoretical physicist. Japanese scientist Yukawa in 1935, when developing the theory of the nucleus was forced to introduce a special field of nuclear forces, the quanta of which, according to his calculations, should be special particles whose mass is about 200 masses of the electron, that is, was about 10 times less than the mass of the proton.
It has long been no longer a secret that we share not only the atom itself, but also its nucleus, that when a cosmic particle breaks the nucleus directly, it is scattered into shards - the nuclei of lighter atoms and single protons and neutrons. Protons were not of much interest to anyone. These were long known nuclei of hydrogen atoms, from which nature sculpts the nuclei of heavier elements. Neutrons, these neutral, uncharged particles, were also familiar to scientists. But what was really a mystery behind the seven seals was the question of how protons and neutrons could weave into such a solid ball as an atomic nucleus. It is not a house where bricks are bound with lime; it is not a tree permeated with fibers; it is not a living organism of cells. What is this - an atomic nucleus? What connects it to the whole? In short, what is the nature of nuclear forces, overcoming the electrical forces of repulsion of positively charged protons?
And Yukawa answered that question simply and ingeniously. He said... However, imagine this picture. There are two people walking along the road. They don't stop, they throw the ball to each other all the time. Because of this, they cannot move away from each other beyond a certain distance. If you look at these people from afar, you can't see the ball, and you might think that these two are just talking to each other in a friendly way, going next to each other in a friendly way, and that they are being held by some kind of gravitational force.
- Protons and neutrons in the atomic nucleus experience these gravitational forces," said Yukawa. - They can "play ball" without rest for billions of centuries, throwing mesons until a projectile, like a space particle, breaks this pleasant occupation. Then, after dropping the ball, protons and neutrons will splash out of the nucleus, and it will die. In this case, you can find and mesons.
This dramatic situation and scientists have managed to adjust and trap in their devices. They witnessed a performance that took place behind the scenes of the microworld, and were able to see its actors without masks. This is how they got to know the mezzanine.