Dirac's equation behaved like a disobedient genie, carelessly released from a bottle. What the scientists read in this equation seemed to them, to put it mildly, a misunderstanding. They did not want to offend the author with a stronger word. On an equal footing with a negatively charged electron, a positive electron took its rightful place in it! "Isn't it a paradox? - thought the involuntary culprit of this strange discovery. Dirac was not looking for this particle at all. He didn't even know it existed.
No one had ever seen such particles in nature. If an ordinary electron is repulsed by a negatively charged body, a new, diraclean electron should be attracted to it. If in a magnetic field the "old" electron would run in one direction, the "new" one would turn to the other. From the equation looked an unprecedented, amazing, positive electron.
When the scientist created a formula for not yet known phenomenon, he did not even have in mind a hint of such a strange particle. It is not surprising that several years passed, and the scientist still could not explain anything to his colleagues. As one physicist said: "For several years there was a conspiracy of silence about these unpleasant decisions of the relativistic equation of Dirac.
But soon Dirac himself resolved the doubts. He suddenly remembered a problem he had solved during his student days.
Whether it's just a legend or a reality, physicists love to tell how Dirac surprised everyone at the annual Christmas contest organized by the Cambridge Student Mathematical Society. The contestants seemed to have a simple task. Perhaps it would have been forgotten long ago by the contestants and Dirac himself, if it hadn't been the indirect reason for the discovery of the anti-world. This is the task. Three fishermen were fishing on a dark, rainy night.
Together with the catch, they stayed on a desert island to wait until morning. In the middle of the night, the storm subsided, and one of the fishermen decided to leave the island, taking with him his third of the catch. He did not want to wake the others. He divided the catch into three equal parts, but one fish remained superfluous. Throwing it into the sea and taking his third, he left the sleeping. Shortly afterwards, a second fisherman woke up, who did not suspect that one of his comrades had already left, and began sharing the catch again. Like the first fisherman, he divided the whole fish into three equal parts, and he also had one extra fish. Throwing this extra fish into the sea, he took his part of the catch and sailed away. The same was done by the third fisherman, who woke up a few hours later: he again divided the remaining fish into three equal parts, and again he had an extra one.
The contestants were required to find the number of fish that would satisfy the conditions of this task.
What was the surprise of the jury when it read the answer of the student Dirac. By his decision, the fishermen caught minus two fish! But this absurd answer satisfied all the conditions of the problem!
Perhaps Dirac remembered these negative fish when the inexorable laws of nature slipped him an unprecedented particle. That's when Dirac presented his strange find to the scientific world and confidently stated that electrons with negative energy are as real as electrons with positive energy. But these are not ordinary electrons, but positrons - particles similar in every respect to electrons, but carrying a positive charge.
Moreover, the scientist has disappointed his colleagues with the assumption that all the particles in nature exist in pairs, that each charged particle corresponds to its own anti-particle with the same mass, but with the charge of the opposite sign. Dirac rightly decided that if there is a pair for the electron - a positron (so called the anti-electron), then there must be a pair for the proton. If there are hydrogen atoms, there must be hydrogen atoms. That is, in nature, along with the substance should exist on an equal footing with the antimatter.
So, as the famous Swiss physicist Paulie said, "a subtle natural instinct of physics has helped Dirac to begin his reasoning, not knowing that they will lead to a theory that has an exact symmetry in relation to the sign of charge, in which the energy is always positive and which predicts the birth and annihilation of pairs.
Dirac's equation pushed scientists to the path of amazing discoveries.