Whether the magnetic single pole exists

Take a metal stick and lead all the electrons to one end. Now cut the metal rod into two halves, we will get a pair of charge: half is negative charge, the other half is positive charge, and these two charges have electric fields that directly radiate outward.

Now take another metal rod and magnetize it with magnets. We will get a puppet mi magnetic field that is very similar to the puppet pole electrical field. But if we divide this metal rod into two halves, the end of each half is still the Arctic and Antarctic, and there will still be a Polar field. According to the classic electromagnetic, no matter how many times the metal rod is cut, we will never get an isolated magnetic, that is, the magnetic single.

As early as 1269, French scholar Petrus Peregrinus de Marincourt performed this magnetic section experiment for the first time, which was before we know the principle of the magnetic production. Today, we know where magneticism comes from, and we are not surprised to produce two smaller magnets that are halved. In the iron magnet, the magnetic field is the sum of countless tiny electronic puppets in the magnetic atom. Another popular method for generating the Polar Magnetic field is electromagnetic. According to the classic electrical, mobile charge is the source of the magnetic field.

Classic theory

There is no existence of magnetic single poles into mathematics that is incorporated into classic electric power, especially the Gaussian Magnetic Law (one of the four equations of Maxwell), which shows that the scattered degree of the magnetic field is zero. Sanity is a mathematical term. It describes whether a point in the vector field is source or remittance. The scattered degree means that there is no source or no remittance. According to this law, we know that there is no magnetic single pole.

On the other hand, the Gaussian law of the electric field tells us that the dispersing of the electric field is not zero, and it is proportional to the charge density. This charge is where the electric field line can end -it forms their source or exchange, so there are things such as isolation of charge. If we quickly browse Maxwell's equations, we will find that electricity and magnetic are not symmetrical. If we add such things to the equation, we can also have symmetry between these equations.

Physicist Murry Gelman said: "All that is not prohibited is compulsory." This means that if the mathematics of physics theory allows it to exist, it exists in nature. Nothing in Maxwell's equation really shows that the magnetic single pole does not exist. Except for Maxwell set the magnet to zero, because he does not believe it exists. But in principle, the magnetic single pole can exist, at least according to the classic theory.

Quantum theory

What about quantum mechanics? By explaining by quantum fields instead of charge and force, we have completely changed our understanding of electromagnetics. Great physicist Paul Dirac has a habit to stare at mathematics and find particles. As we discussed in our previous article, he predicted the existence of anti -substances in 1928. But in 1931, before his anti -material was verified, Dirac made another prediction -the existence of magnetic single poles.

His argument is this: starting with the magnetic field of the Polar Polar, you can approximate the single poles by separating both ends and disappearing the connection in some way. There is a way to do this. A thread tube of the same electricity will get an even pole field, and its connection field is limited to the coil. So the width of the coil is far less than the length, and it looks like two isolated magnetic. This structure is called "Dirac String". Dirac's argument is that if the strings of the Dirac Strings cannot be detected fundamentally, the magnetic single pole can exist.

The second part of the argument is that the string cannot be detected under what conditions. The magnetic field will affect the charged particles. In quantum mechanics, this is achieved by changing the phase of the particle wave function. Imagine a charged particle passing through Dirak string, such as an electron. To draw this trajectory, all possible paths of the electrons need to be added, including the path to the left and right on the string. The existence of the string and its magnetic field should introduce different phase shifts according to which side of the electrons through the string, which will actually have a significant impact on the path of the electron. In other words, the string will be detected.

But there is a situation that the string can never be detected: the amount of phase shift is proportional to the charge. For the value of the charge, the phase shift caused by the different sides of the string is just a wave cycle. This means that there is no difference in observing, so it is irresistible for Dirac String, and the final charge can only exist at an integer multiple of basic charge. On the other hand, this is considered to be a prediction of charge quantization. As long as there is at least one magnetic polar child in the entire universe, the charge must be discrete. Of course, we know that the charge is indeed quantized. It can only be an integer multiple of electronic charge.

However, instead of using it as a quantitative prediction, we can also flip it: if the charge is quantified, the existence of magnetic single poles is possible. The charge is proved to be quantum, so quantum mechanics does not actually stop monocular sub -children.

Unified theory

Let's get fast to 40 years. In the early 1970s, physicists managed to explain weakness and unified them with electromagnetic science. After solving this problem, physicists are trying to force them to be strongly incorporated into it through the so -called great unity theory, which involve complex symmetrical destruction. It turns out that the magnetic single pole is inevitable in all the unified theories.

In the theory of electricity weakness, the Higgs field is a scalar field. It has two complex values ​​everywhere. The interaction of these two "degrees of freedom" gives the quality of Higgs particles. In the simplest unity theory, Higgs has three degrees of freedom instead of two. This means that the field can be a bit like a vector, even if it is really not a vector. It can have an internal arrow in a specific direction -not to the physical space, but to the three freedoms. In 1974, Gerard T'HOOFT and Alexander Polyakov also proposed that some points of Higgs can form some knots -the direction of the arrows is away from that point. Remove point. It turns out that in the theory of unity, these knots in Higgs are manifested as a particle with magnetic -magnetic single poles. They should be very large and should form spontaneously in a very high -energy environment to form spontaneous formation. For example, in a very early universe.

These theories predict that there are magnetic single poles, but there are indeed problems. Because these theories predict that in the early universe, there should be a large number of magnetic poles, which are as many as protons and electrons. So where are they now? And they should also be very large, which is trillions of proton quality, so they should quickly collapse the universe.

experiment

As early as 1982, physicist Blas Cabrera Navarro established a superconducting coil in his Stanford Lab and managed to detect the magnetic single pole of Dirac's prediction, but failed to succeed. There are also several different experiments on the large strong collision, and the magnetic single pole is not found. The energy that a large strong -tinner collision machine can achieve is about 100 billion times lower than the energy required by the unified theory prediction. People are also looking for magnetic single poles from space, but they have no convincing evidence.

Reprinted content only represents the author's point of view

Does not represent the position of the Institute of Physics of the Chinese Academy of Sciences

If you need to reprint, please contact the original public account

Source: Vientiane experience

Edit: Lezi Superman

- END -