What is dark matter?
An astrophysicist researching discovered that in the vast cosmic space, the masses of light-emitting celestial bodies (including X-ray objects, Y-rays belonging to electromagnetic currents) is only one small part of the total mass of matter in this space. There is also a very large mass component due to something, which we have not yet clarified, is carrying. That real thing does not see but exists, it’s called “dark matter.”
Scientists’ perception of dark matter can look back in time to the early 30s of the twentieth century. In 1933, the Swiss astronomer, Zweig, used two different types of methods: the luminosity method and the dynamic method when estimating the total mass of the Hau Phat system. As a result, the mass calculated using the kinetic method is 400 times greater than the luminosity method! Such a large error could only have one explanation: the mass of the glowing celestial objects was only a fraction of the whole system’s mass; there was a very large part of the mass that did not know-how. He called it “missing mass.”
At that time, this discovery was not of much importance. Until 1978, some radio astronomers, when systematically measuring the vortex system’s motion curves, found that objects at different distances from the center of the system had the same long speeds. These observations are in stark contrast to the situation of the solar system one is familiar with. In the Solar System, the farther away the planet is from the Sun, the lower the long velocity. That is what the famous Kepler’s law tells us. The movement of objects around the system, affected by the same universal force of gravity, must also obey Kepler’s law!
Regarding this, a scientist has pointed out; it is only hypothesized that dark matter exists around the system, then the movement of the observed sperm will match with the calculation results of Kepler’s law. Therefore, outside of the system’s light-emitting object, there is certainly an amount of invisible dark matter. This concept was gradually absorbed and along that way, scientists discovered much evidence of dark matter. For example, in 1983, the R15 star was discovered 200 thousand light-years away from the Milky Way center. The speed in the direction of view reached 465 m/s. To generate such a great rate, the total mass of the Milky Way system must be at least ten times the mass of the light-emitting region.
Besides, in the theoretical study of the origin of the Universe, scientists also really felt the need for the existence of dark matter to make their theories round.
So what is dark matter? In this regard, scientists have many speculations. Some people say the dark matter is the gas radiating throughout the Universe space, some say it is dust in the Universe, others guess it is “a dead star” that has darkened, maybe even a black hole. These speculations are all reasonable but lack convincing evidence and can not receive the academic community’s approval.
Among the numerous candidates for dark matter, neutrinos are the most noticed and valued. Because it is a known particle that exists in the Universe, besides, the number is extremely numerous. Especially in 1980, after the Soviet Institute for the Study of Theoretical and Experimental Physics announced that the resting mass of neutrinos might not be zero, it gave scientists a rich imaginary space of the relationship between neutrinos and dark matter. Since the number of neutrinos is extremely large, their total mass is still quite considerable even though its resting mass is very small. The vast majority of neutrinos do not glow, have only very weak electronic effects, etc. These properties make it very similar to dark matter.
Of course, particle physicists also predict a series of new candidates for dark matter, such as neutrinos, axions, supersymmetric particles, etc. Unfortunately, those new hypothetical particles have not been found to date. It seems that wanting to clarify the true face of dark matter is still a difficult problem.