As early as before, whether it was the East or the West, mankind was in a relatively backward feudal society, science and technology had not yet developed, and the system of theoretical knowledge had not yet been established, so human beings only knew the gods, not science and truth.
Unlike the ancient Chinese royal family, which always flaunted itself as the Son of Heaven, the imperial power is providence, and the development of religion trembling under the imperial power, the religious forces in the West are growing day by day, and even control the change of royal power, and are deeply involved in royal disputes.
In order to better promote religious ideas, "geocentric theory" has become the mainstream Western worldview, that is, the earth where human beings live is the center of the universe, which has a great similarity with the claim propagated by religion that God created human beings and put human beings at the center of the universe.
At this time, Copernicus proposed the "heliocentric theory" according to the views of his predecessors, and completely overturned the so-called "world system" under the inherent concept, believing that the sun was the center of all planets, and the earth was only one of the planets revolving around the sun.
In fact, with the invention of the later astronomical telescope and the development of technology in the space field since the 60s of the last century, human beings have now deeply understood the smallness of the earth, the infinity of the universe, and even the sun is only one of the hundreds of billions of stars in the milky way, like the gravel in a desert.
There are also many secrets of the universe, and the dark matter in it has not been directly observed by humans even so far, and its existence can only be speculated through indirect means.
In fact, when Einstein made the great discovery of general relativity in 1915, he derived the gravitational equation from it, deriving the average density of cosmic matter, arguing that they must meet the mass of 5×10^-30 grams per cubic centimeter in order for the universe to operate stably.
In fact, his gravitational equation showed the expansion of the universe at the beginning, but Einstein was not satisfied at the time, because he believed that the universe should be constant, so he added the cosmic constant. However, another scientist then discovered that the universe was indeed expanding at an accelerating rate, and that Einstein's initial gravitational equation was not wrong.
Later, through observational data, the density of cosmic matter was 100 times smaller than the average density value obtained by Einstein, so in 1932 he and William Desit jointly published a related paper, arguing that there is an "invisible non-luminous matter" in the universe.
But they were not the first to suggest the possibility of the existence of "dark matter," but a scientist named Kaptan, who in 1922 suggested that there might well be a lot of matter near the stars that humans could not see.
In 1932, Dutch scientist Jan Ault studied the celestial bodies of the solar system and said that the Milky Way may have a lot of dark matter.
The following year, Zwicky observed the changes in the speed of the Posterior cluster in the universe through spectral redshifting, and found that the visible body velocity of the cluster was very high, and according to the mass of the galaxy it observed at the time, the gravitational pull of the Posterior cluster was actually difficult to retain the inner galaxy, and even the mass of visible matter accounted for only a small part of the star cluster.
In other words, there will be some clusters of galaxies that are too fast to exceed the constraints of the galaxy cluster's own gravitational pull, and can rush out of the galaxy cluster, which is like a human making a spaceship, which needs to rely on the impact of the rocket, so that the rocket has the speed to collide with the earth's gravity, so that it can go out of the earth and come to the solar system.
But some of the constellation cluster's star velocities have far exceeded the cluster's escape velocity and are still trapped in it.
Therefore, scientist Zwicky believes that the Posterior Cluster is likely to be due to the presence of a large amount of dark matter, even far more than 100 times the mass of the galaxies that humans already have.
In 1970, scientists used the spectral measurement technology of the time to study and analyze the Andromeda Nebula and found that the speed of the stars on the outer periphery of the galaxy remained constant in the original universe.
It should be known that scientists originally thought that through the rotation curve of the galaxy, the mass and distance from the center of the visible celestial body, coupled with gravitational force, the farther away the celestial body was from the center of the galaxy, the slower the rotation speed was naturally.
However, the above conclusions are not consistent with the actual situation, which also shows that the dark matter of the universe may not only exist in the core region of the galaxy, but is distributed in various places, and the mass of dark matter is far greater than the combined weight of the stars visible to humans.
Although humans still cannot directly find the "real body" of dark matter, scientists have found a lot of evidence that dark matter does exist. In addition to the above methods, scientists can also deduce the existence of dark matter through cosmic microwave background radiation, cosmic large-scale structure, etc.
Some people may want to ask, what exactly is dark matter? It is actually a kind of matter that may exist in the universe, and human beings are only speculating about dark matter, and it is only a theory.
Some people think that dark matter may be a kind of "weakly interacting mass particles", but others say that dark matter is composed of other particles, the former is actually one of the possibilities of dark matter that many people discuss widely, and many scientists believe that this particle has a greater possibility of being dark matter.
Although one of the elementary particles in the universe, neutrinos, meet the conditions of weak interaction, is called the "invisible man" of the universe, and it took scientists more than 20 years to find it, such properties seem to be almost very similar to dark matter, but it itself is moving at high speed, and even the speed is close to the speed of light, rather than saying that it is "dark matter", it is better to say that neutrinos are "hot dark matter", which is not quite consistent with dark matter.
However, among all the particles currently discovered by humans, there is no particle that satisfies both weak interactions and the conditions for possessing a certain mass, so it may be a new type of particle that has not yet been discovered by humans.
Therefore, what exactly dark matter really is, because there is no definite discovery, we cannot give an accurate answer, and no one can know the components of dark matter.
For now, what humans can be sure of is that dark matter accounts for almost 26.8% of the universe's matter, may be moving much slower than the speed of light, and that the components of dark matter should be an electrically neutral particle.
According to speculation, scientists believe that the properties of dark matter should have 4 points, one of which is the weak interaction, which is also because dark matter cannot be observed by humans, so it should neither participate in electromagnetic interactions, but also "stay away" from photons, which makes the main means of observation at this stage of human beings - light and electromagnetic signals can not obtain the signal of dark matter.
The second reason is that dark matter itself can also participate in gravitational interactions, such as the galaxy cluster we said earlier, the mass of human observations is far from being able to support such a vast galaxy cluster gravitational structure.
But with the support of dark matter, the stars rotate steadily precisely because of the gravitational influence of dark matter and celestial bodies. So we can conclude that dark matter actually has mass, but we can't confirm how much weight a dark matter really weighs.
The third is that dark matter is very stable matter, because whether it is galaxies, galaxy clusters, galaxy groups, superclusters, etc., all the way to the largest structural unit in the universe - the universe's large-scale network structure complex, these cosmic structures have dark matter.
This also means that dark matter may have existed since the birth of the universe and has been stable for such a long time.
Fourth, it is also because of the large-scale structure of the universe, if dark matter wants to form the "skeleton" of the "cosmic network", then it must be "cold dark matter", that is to say, the speed of movement of dark matter needs to be much lower than the speed of light, in order to have enough gravity to structure the large-scale framework of the universe.
Although human beings have not yet achieved the task of discovering dark matter, scientists are still constantly observing the universe and conducting related experiments to take the lead in opening up the "true face" of dark matter.
Because the visible matter in the universe actually occupies only a very small part of the entire vast universe, more dark matter and dark energy are still hidden behind the "veil".
If we can find the existence of dark matter, then we can study dark matter to find out what the origin of the universe looks like, and we can also find out how the structure of the universe is formed, and maybe even make dark matter used by humans to become a more efficient and powerful energy.
Therefore, human beings mainly use three ways to observe dark matter for the properties of dark matter.
The first is that according to the dark matter itself is a particle, then even if the interaction of dark matter is weak, there is a certain possibility that it may be detected and observed by the instrument, and there will be a large number of cosmic particles passing through the earth at any time, then there must be dark matter particles.
Because dark matter is difficult to find, scientists have built dark matter detectors underground in order to maximize the protection of other cosmic particles, and set up multiple barriers to avoid cosmic ray interference as much as possible.
If there is a dark matter particle to the center of the barrier detector, other cosmic particles are blocked out of various "walls", when it hits the detector's atomic nucleus, scientists can monitor the existence of dark matter, but until now, these experiments have not directly found conclusive evidence of the existence of dark matter.
The second is a probe built using satellites or space stations to collect particles from the universe and find the elementary particles formed after the annihilation or decay of dark matter.
The third way is to monitor the existence of dark matter by using human technology to produce dark matter particles in the laboratory through the high-energy particle collider.
Human scientific and technological development is actually not very advanced, perhaps we still need to wait for decades, or even hundreds of years, one day we will find dark matter.