Magic field that is ubiquitous

The following article comes from WeChat public account: principle, author Greenwald

When we look at the deep space, all the celestial fields of our eyes are embedded in the magnetic field. This is not only near the stars and planets, but also the same in the deep space between galaxies and galaxies. These magnetic fields are very weak, usually weaker than the magnets posted on the refrigerator, but they are particularly important because they have a profound impact on the dynamics of the universe.

Although scientists have conducted decades of research on this, the origin of these cosmic magnetic fields is still one of the most profound mysteries in cosmic science.

In previous studies, scientists realized the turbulence, that is, the stirring movement commonly shared by all types of fluids, and how to amplify the pre -existing magnetic field through a generator process. But this amazing discovery pushed this mystery to a deeper layer, that is, if the effect of turbulent generator can only enlarge the existing magnetic field, where did the "seed" magnetic field come from?

To get a complete and self -consistent answer to the origin of the physical magnetic field of the celestial body, we must explore the initial origin of these magnetic fields.

Recently, a group of new studies conducted by a group of scientists provided an answer that showed the basic process of the universe's magnetic field, from a state of completely unknown to the magnetic field to enough to make the generator mechanism take over and amplify to what we observed. degree.

The magnetic field is everywhere

The natural field that appears naturally can be seen everywhere in the universe.

As early as thousands of years ago, people had known their existence through the interaction of magnetic fields and magnetized minerals (such as natural magnets). Even before our ancestors understand their nature or origin, the magnetic field has been used in navigation and other aspects.

The magnetism of the sun was discovered in the early 20th century because it affects the solar spectrum. Since then, a stronger telescope has been found in the depths of space that these magnetic fields are actually everywhere.

Although scientists have long learned how to make and use magnets and electromagnets, they already have various practical applications on the earth, the natural origin of the magnetic field in the universe is still a mystery.

Generator effect

Scientists start thinking about this problem by considering the way to generate electric and magnetic fields in the laboratory. When a conductor such as copper wire moves in the magnetic field, the electric field will be generated. This field, or voltage can drive current. This is how we use the electricity we use every day. It is through this induction process that the generator can convert mechanical energy into electromagnetic energy to provide energy for our families and offices.

One of the key features of the generator is that they need magnetic fields to work. But there is no obvious "wire" or a huge steel structure in the universe. How should the magnetic field produce?

The progress of this problem began about a century ago, when scientists were thinking about the source of the Earth's magnetic field. Research on the spread of earthquake waves shows that under the surface layer with relatively low temperature of the mantle, most of the earth is actually liquid, and there is a core of melting nickel and iron. Researchers speculate that the flowing movement of this hot conductive liquid, combined with the rotation of the earth in some way, produced the magnetic field of the earth.

Star generator effect diagram. The ancient moon is painted in the picture. (Figure / Hernán Cañellas, MIT)

In the end, some models show how the current can enlarge the existing magnetic field. This is a self -organized example, that is, a feature that is often seen in complex dynamic systems. Large -scale structures grow spontaneously from small -scale dynamics. But like in the power plant, you need a magnetic field to make a magnetic field.

A similar process spreads throughout the universe. However, in the space between stars and galaxies, and the space between them, the conductive liquid is not a melting metal, but a plasma, which is a material state that exists at high temperature. Essence In this medium, the generator effect can enlarge the existing magnetic field, as long as it starts at a minimum level.

Make the first magnetic field

So the question is, where did the original "seed field" come from?

In this new study, scientists have developed a basic theory and made numerical simulation on powerful supercomputers, showing how the seed field produces and what basic processes existing.

An important feature of a plasma that exists between stars and galaxies is that it is very scattered and usually only about one particle per cubic meter. This is very different from the internal situation of the star, where the particle density there is 30 magnitude higher. Very low density means that the particles in the universe plasma never collide, which has an important impact on their behavior.

The team's computing tracks dynamics in these plasma. They develop from orderly waves, but as the amplitude increases, when interactions become extremely non -linear, they also become turbulent.

The study through detailed exploration of small -scale plasma dynamics on the physical process of the macro celestial body, and finally proves that the initial magnetic field can be spontaneously generated by universal motion like a shear flow. Like examples on the earth, mechanical energy can be converted into magnetic energy.

The first principle is the visual image of the wire -shaped seed magnetic field generated by the unskimped plasma in the numerical simulation. (Figure / mit)

An important output they calculated is the amplitude of the magnetic field expected to be spontaneous. This shows that the amplitude of the magnetic field can rise from zero to the level of "magnetization" by plasma, that is, the plasma dynamics has been strongly affected by the existence of fields. From this moment, the traditional generator mechanism can start to work and improve the field to the observed level. Therefore, this research represents a self -consistent model that generates a magnetic field on the cosmic scale.

Understand the first step in the occurrence of cosmic magnetic

Researchers said that although significant progress has been made in cosmology for decades, the origin of the magnetic field in the universe is still unknown. Seeing the most advanced plasma physical theory and numerical simulation is used to solve this basic problem, it is a very wonderful feeling.

The team will continue to improve their models and study the generation from the seed field to the "transfer" of the amplification phase of the generator. One important part of their future research is to determine whether this process can work on the time scale consistent with astronomical observation.

Researchers believe that this work provides the first step for establishing a new paradigm in understanding the magnetic occurrence in the universe.

#Groupe OD creation:

Original Author: Martin Greenwald (Mit Plasma Science and Fusion Center)

Compilation: takeko

Capture: Wenwen

#Reference source:

https://news.mit.edu/2022/how-diverse-sive-in ITS-Magnetic-field-0525

#Image Source:

Cover Map & First Figure: MIT

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This article is authorized to reprint from WeChat public account: Principle Author: Greenwald

Reprinted content only represents the author's point of view

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It does not represent the high energy office of the Chinese Academy of Sciences

Edit: Matthalin pig

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