What exactly is dark matter made of?

dark material

jeremiah p.Decades ago, dark matter was first proposed as a theory, but now we know that dark matter has become an important part of the universe. The total mass of dark matter is 6 times that of ordinary matter, accounting for 1 4 of the energy density of the universe, and more importantly, dark matter dominates the formation of the structure of the universe.

The nature of dark matter is still a mystery, but if it is assumed to be a weakly interacting subatomic particle, then the resulting large-scale structure of the universe is consistent with observations. However, recent analyses of the structure of galaxies and subgalaxies have shown discrepancies between this assumption and observations, which provide a variety of possible theories of dark matter. Through the study of the density, distribution, evolution and environment of small-scale structures, these potential dark matter models can be distinguished, bringing new dawn to the study of the nature of dark matter.

About 65 years ago, the first evidence of the existence of dark matter was discovered. At that time, Fritz Zwicky discovered that galaxies in large clusters of galaxies have extremely high velocities, and unless the mass of the cluster is more than 100 times the value calculated from the number of stars in it, the cluster simply cannot bind these galaxies. This was confirmed by observational analysis over the next few decades.

Although the nature of dark matter is still unknown, by the 80s, dark matter, which accounts for about 20% of the energy density of the universe, was widely accepted.

Dark matter is an invisible substance that may exist in the universe as a theoretical proposal, which may be the main component of the matter in the universe, but does not belong to any known matter that constitutes a visible celestial body.

Modern astronomy has shown that dark matter may exist in galaxies, star clusters and the universe in large quantities, and its mass is much greater than the sum of the masses of all visible celestial bodies in the universe through observations such as the motion of celestial bodies, the phenomenon of Newton's gravitational attrition, the gravitational lensing effect, the formation of large-scale structures in the universe, and the microwave background radiation.

Combined with the observation of the anisotropy of microwave background radiation in the universe and the standard cosmological model (CDM model), it can be determined that dark matter in the universe accounts for 85% of the total mass of all matter and the total mass energy of the universe. It is widely accepted that dark matter is composed of "weaklyinteractingmass particles" (WIMPs).

The first to suggest the possibility of "dark matter" was the astronomer Jacobuskapteyn, who proposed in 1922 that the possible presence of invisible matter around a star could be indirectly inferred from the movement of a star system. In 1932, astronomer Janoort conducted a study of dark matter on the movement of stars near the solar system. However, no conclusive conclusion has been drawn about the existence of dark matter.

In 1933, astrophysicist Fridzzwicky measured the velocity of individual galaxies in the Comae Cluster relative to the cluster using spectral redshifts.

Dark matter refers to substances that do not emit light and do not interact with light or electromagnetic waves, so we cannot find them directly through observation.

The essential properties of dark matter remain a mystery, but we can infer their existence from its gravitational effect. Dark matter is of great importance in cosmological research because they provide an additional amount of matter in the observable universe.

Regarding the conditions for the formation of dark matter, scientists have put forward some doula theories. One theory is that dark matter may have formed shortly after the universe was large, and that they took up a portion of the original matter and energy in the universe.

Another theory is that dark matter may have been transformed by ordinary matter in the universe under certain conditions. These theories need further observations and studies to confirm.

Scientists currently believe that dark matter may have the following properties: dark matter is not distributed in the same way as visible matter, and it may be more dense in some galaxies and galaxy clusters. Dark matter may have a certain temperature, because of the fact that they have a certain speed of motion in the universe.

Dark matter may be made up of microscopic particles that have yet to be discovered.

Known dark matter properties

1) Dark matter participates in gravitational interactions, so it should have mass, but the mass of individual dark matter particles cannot be determined.

2) Dark matter should be highly stable, since there is evidence of dark matter at different stages of the formation of the structure of the universe, dark matter should be stable on the time scale of the age of the universe (10 billion years).

3) Dark matter basically does not participate in electromagnetic interactions, and the interaction between dark matter and photons must be very weak, so that dark matter basically does not emit light; Dark matter is also largely not involved in strong interactions, otherwise the process of primitive nucleosynthesis will be disturbed, and the abundance of light elements will be altered, which will lead to inconsistencies with current observations.

4) Through computer simulation of the formation of large-scale structures in the universe, it is known that the speed of dark matter should be much lower than the speed of light, that is, "cold dark matter", otherwise our universe will not be able to form the observed large-scale structures under the action of gravity.

The above content reference: Encyclopedia - Dark Matter.

"Dark matter" is a hypothetical substance due to the existence of phenomena that cannot be explained by existing theories, a substance smaller than electrons and photons, has no electric charge, does not interfere with electrons, can pass through electromagnetic waves and gravitational fields, and is an important part of the universe.

The earliest evidence for the existence of dark matter** is the observation of the rotational velocity of dwarf ellipsoid galaxies.

Dark matter - dark energy is the "two dark clouds" that affect today's quantum particle physics + astrophysics, the density of dark matter is very small, but the quantity is huge, so its total mass is very large, they represent 96% of the material content in the universe, of which the human visible only accounts for less than 5% of the total material in the universe (approx.