Any of us at least once heard about "dark matter", but not everyone is able to correctly explain what it is. Perhaps there will be no need for these explanations, because the latest research calls into question the existence of "dark matter" as such.
GALACTIC ANOMALY
The “dark matter” hypothesis emerged in an attempt to understand the nature of the anomaly observed by astronomers.
In 1922, the Dutchman Jacobus Kaptein, studying the motion of stars, came to the conclusion that a significant part of the matter in the Galaxy is invisible - in his work, probably, the term "Dark Matter" was first used. Ten years later, the hypothesis was supported by radio astronomer Jan Oort, but it became widespread a year later, when the Swiss astrophysicist Fritz Zwicky calculated the radial velocities of eight galaxies located on the edge of the Coma cluster (Coma constellation), and compared the obtained data with similar, but calculated with using the apparent brightness of the cluster. He found that in order to maintain stability, the total mass of the cluster must be four hundred times greater than the mass of its stars. Based on this, Zwicky suggested that there is a significant supply of matter in the cluster, which remains invisible to us,but has the strongest gravitational effect on galaxies. Zwicky made a mistake in the calculations by an order of magnitude, but more careful measurements confirmed: the mass of the Coma cluster, if calculated in two different ways, does not converge in the result significantly!
However, before making generalizations, it was required to prove that such an effect is widespread in the foreseeable space. In 1939, the American astronomer Hores Babok, studying the nearest galaxy M 31 (the Andromeda Nebula), found that the speed of rotation of stars around its center does not decrease, as predicted by celestial mechanics, inversely proportional to the square of the distance, but remains almost constant. This means that the galaxy along its entire length contains a significant mass of invisible matter. Babok, however, did not associate the anomaly with an incomprehensible "dark matter", but suggested that in the outer part of M 31 some processes are taking place that change its dynamics.
DARKER DARK
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Astronomers returned to the hypothesis of "dark matter" in the 1960s, when new precise instruments for studying the Universe appeared. And in 1975, Vera Rubin and Kent Ford spoke at a conference of the American Astronomical Society, who said that they had managed to obtain reliable data indicating a significant mismatch between the theory of mass distribution in galaxies and the observed reality. Scientists used the most modern spectrograph, which made it possible to determine the speed of rotation of the branches of spiral galaxies even "when viewed from the edge." And they found that the vast majority of stars in galaxies move in their orbits with the same angular velocity, confirming the incredible assumption: the mass density in galaxies is evenly distributed. After another three years, the observations were independently confirmed.and in 1980 the astronomical community finally acknowledged the validity of the conclusions. At the same time, Rubin established that for the theory to be consistent with practice, galaxies must contain an amount of invisible matter six times greater than that which we can see through telescopes.
At the same time, other evidence began to arrive. First, the study of motion in systems of double galaxies revealed the colossal influence of "dark matter", clearly violating the classical laws of celestial mechanics. Second, without the presence of "dark matter" elliptical galaxies would quickly lose their hot gas, which is not observed. Thirdly, “dark matter” itself bends light, which is revealed in the effect of gravitational lensing.
Today it is generally accepted that the share of "dark matter" is 84.5% of all matter contained in the universe.
SEARCHING FOR THE UNKNOWN
The idea of "dark matter" turned out to be in demand by cosmologists when they could not detect the inhomogeneity in the relict radiation (cosmic microwave background) predicted by the theory of the origin of the Universe and explain the appearance of galactic structures through this. The introduction of some particles into the model, which almost do not interact with ordinary matter, but are very heavy, made it possible to bypass the difficulty. However, in the early 1990s, the inhomogeneity of the relict radiation was nevertheless revealed using the orbital observatory COBE. It seemed that the question was closed, but "dark matter" has already fascinated the scientists so much that they did not abandon it, but, on the contrary, started looking for a "carrier" at the subatomic level.
The problem is that "dark matter" does not interact with electromagnetic radiation (including visible light), so it cannot be detected by traditional methods. Worse, the study of the motion of four hundred stars located within a radius of 13,000 light years from the Sun did not show any influence of "dark matter", and scientists had to conclude that it is negligible in our region of space (about 500 grams on the volume of the globe), that is, registering a particle of such a substance is incredibly difficult, if not impossible. Physicists tried to solve the problem theoretically, by defining the parameters of a hypothetical substance based on the Standard Model of elementary particles. Neutrinos (but they are too light) and such hypothetical particles as axions, cosmons, gravitons, geijinos, wimps, were considered as candidates.magnetic monopoles, etc. The observed distribution of “dark matter” in space also raises questions: after all, if it interacts with ordinary matter through gravity, then it should be drawn to the centers of galaxies in the same way as ordinary matter, but this does not happen.
It is clear that the strangeness in the behavior of "dark matter" arouses instinctive protest from a number of physicists, so they refuse to recognize its existence, explaining the anomalies in the distribution of galactic masses in other ways. For example, the aforementioned Vera Rubin believes that it is wiser to refine classical theories than to introduce a fundamentally new class of subatomic particles into the model. She is a supporter of Modified Newtonian Dynamics (MOND), proposed by Mordechai Milgrom in 1983 and still marginal.
However, the latest research, it seems, will soon force the scientific world to reconsider its attitude to "dark matter". A group of physicists from the University of Case Western Reserve (Cleveland, Ohio) published an article on September 19, 2016, which analyzes the results of observations of 153 galaxies using the Spitzer infrared telescope, and both spiral galaxies like ours and galaxies of irregular shape fell into the field of view, and giant galaxies and dwarf ones. The study was carried out in order to clarify the degree of influence of "dark matter" on the rotation of stars. And suddenly it turned out that there was no influence at all, and the known anomalies were perfectly explained by the distribution of normal matter.
The authors of the discovery suggest that their results are fundamentally at odds with previous ones, because for the first time, images in the infrared range were used to estimate the mass of distant astronomical objects, and not in visible light. Many of these objects look very faint, which probably led to errors in calculating their real mass.
If the data are confirmed, then the cosmological model, which is based on the hypothesis of the existence of "dark matter", can be safely rejected, and even without resorting to revising classical physics.
Anton Pervushin