Dirac, a British physicist, was the first physicist to predict the existence of a magnetic monopole. He first predicted the existence of positrons in 1930 after establishing the famous Dirac equation. Two years later, C.D. Anderson discovered positrons in his experiments. Based on his equations, Dirac also predicted two other elementary particles-magnetic monopoles with only the south pole or only the north pole.
These are two kinds of illusory particles, because they are completely calculated on paper, at least people know the existence of electrons before positrons are predicted. But since charge can be divided into independent positive and negative, it seems that magnetism should also be divided into South Pole and North Pole. For physicists, this is "symmetry".
Later, in the 1980s, when physicists tried to unify the weak-current interaction with the strong-current interaction, so as to finally complete the so-called "grand unified theory", some theories also predicted the existence of magnetic monopoles.
Physicists have had many unexpected stories in the process of studying magnetic monopoles.
In 1970s, American physicist Alan Guth studied the generation of magnetic monopoles in the early universe with his collaborators during his postdoctoral research at Cornell University. This research did not make him make a breakthrough in magnetic monopole, but made him make an important contribution to cosmology.
1979 65438+On February 7th, Gus, who has been working in the Linear Accelerator Center of Stanford, wrote "amazing insight" on the draft paper. The calculation the night before convinced him that there would be too many magnetic monopoles in the early universe, inferred from the particle physics and cosmological assumptions at that time. The solution to this contradiction is that the early universe experienced a "skyrocketing" stage. Gus became the founder of inflation theory.
Also in the 1970s, the physicist Brass Cabreira of Stanford University built an instrument with wires to detect magnetic monopoles in cosmic rays. If a magnetic monopole passes through the instrument, the instrument will get the signals of eight magnetons (the magnetons are constant). He did receive some signals, but only one or two magnetons, never more than three magnetons. 1982 Valentine's Day, Cabreira didn't work in the laboratory. When he returned to the office again, he was surprised to find that the instrument recorded an 8-magneton signal on Valentine's Day. Since then, Cabreira has built a bigger detector, trying to find more such signals, but never found them. The famous physicist Steven Weinberg also wrote a poem for Cabreira on Valentine's Day in 1983: "Roses are red, violets are blue, it's time to find a monopole, the second one!" But until today, no one has found a magnetic monopole. Cabreira's discovery was therefore suspicious in those days. Physicists have tried to find it in the collision experiment between lunar material samples and particle accelerators, but nothing has been found.
In the September 4, 2009 issue of Science, researchers at the Federal Research Center in Helmholtz, Germany, reported that they had observed a "magnetic monopole" in a special crystal. The process of these magnetic monopoles appearing in practical materials is also introduced. It marks the first time that people have observed the separation of magnetic monopoles in three-dimensional space.
However, their "magnetic monopole" is quite different from that predicted by Dirac. When scientists can find the real magnetic monopole, or even whether the real magnetic monopole exists is still a question mark.