📬 🚕 🕝 Dark Universe. Part 2 🤷 👶🏽 🤸🏾

And again, good day! This article is a continuation of a previously published article about our “dark” Universe. In this part, we will continue to consider various interesting features in cosmology, which many scientists are struggling to explain.

In general, I tried to make the parts independent of each other, so if you did not read the first part, then some understanding problems should not arise.

Negative mass

After the publication of the first part, many questions arose about such a characteristic of “dark liquid” as negative mass . Therefore, I decided to dwell on this topic in more detail.

A. Einstein spoke for the first time about negative mass. In 1918, commenting on the introduction of the cosmological constant in GR, he said:

modification of the theory is required so that the "empty space" takes on the role of negative masses that are distributed throughout the interstellar space

At the moment, science does not know particles that would have a negative mass. But from theoretical studies conducted by scientists, it is quite possible to learn about some of the expected properties of such particles. For example, that a body of negative mass will have negative inertia. That is, the body under the action of an external force will accelerate opposite to the action of the force. The gravitational interaction of particles with opposite masses as a whole will be as follows:

A positive mass attracts both other positive masses and negative masses.
A negative mass repels both other negative masses and positive masses.

With the positive masses, in principle, everything is clear - they will be attracted. Two negative masses will repel. But for the masses with different signs, there is an interesting paradox: on the one hand, the positive mass is repelled from the negative mass, and on the other, the negative mass is attracted to the positive. Therefore, two objects of equal and opposite mass will cause a constant acceleration of the system to an object of positive mass - the effect of the so-called “runaway motion”.

Such a pair of objects will accelerate without restrictions (except relativistic), although the total mass, momentum and energy of the system will remain equal to zero. This behavior is completely incompatible with our idea of the “ordinary universe”, and with the known interaction of the positive masses, but scientists have shown that in itself it is completely mathematically consistent and consistent.

In addition to the skepticism due to the extreme unusualness of the effect, the more significant fact is that if we consider our Universe as a Riemannian manifold with a single metric, then such an effect becomes impossible in it. But mathematicians fully admit that there may be more than one metric, and at the moment bimetric theories of the Universe have already been proposed, in which an additional metric is introduced, and in which particles with different sign masses repel each other. This resolves the runaway paradox, and makes the existence of negative mass completely legal.

Summing up, from the point of view of modern science, the existence of a negative mass seems theoretically possible, but there is currently no experimental evidence of its existence. Research in this direction is underway - in 2017 wasA post on Habré with the news that scientists allegedly created a substance with the properties of a negative mass, but later this news was disproved.

Dipole repulsive

But back to the general narrative vector, in the last part of the article we settled on such a concept as a dipole repulsor .

In the 1970s, when studying relict radiation, data were obtained that showed that our galaxy and its neighbors, making up the so-called “local supercluster of galaxies” (also known as the Virgo supercluster), move at a speed of about 600 km / s direction of the constellation Hydra. Scientists have hypothesized that there is a huge accumulation of matter located at a distance of about 60 Mpc, and responsible for this gravitational effect. This hypothetical accumulation of matter was called the Great Attractor .

At the same time, a direct study of the area in which the Great Attractor was supposed to be found is complicated by the fact that it is located in the so-called “avoidance zone” - closed from observation by the Milky Way plane with a large number of stars and interstellar dust - and therefore not accessible to direct observations. However, during radio observations of X-ray sources, the accumulation of matter was clearly visible.

Only by the end of the 1990s, scientists were able to detect about 600 galaxies in this direction. According to the study, the center of the Great Attractor is in the constellation of the Gon. It has a mass of the order of 10 ¹⁵ Mʘ, or about 10,000 masses of our Galaxy.

In areas adjacent to the attractor, massive large-scale motion of galaxies in its direction is detected. Although, compared with the large-scale structure of the Universe, these are all local, local phenomena, and their existence does not contradict the validity of the cosmological principle on a large scale.

At that time, scientists decided that the problem was solved, but in 2005, when calculating the masses, it was found that the Great Attractor has only 1/10 of the mass that was originally assumed, which is not enough to explain such a powerful gravitational force acting on our supercluster.

Later, scientists found that our supercluster is also attracted by the Perseus-Pisces supercluster , and much more massive, compared to the already voiced, Shapley supercluster. But their total gravitational impact was not enough to fully explain the movement of the Milky Way.

And in 2017, scientists put forward a hypothesis about the so-called “dipole repulsor”. Its location is assumed in the neighboring void (an area with a relatively small stellar and galactic density), which literally pushes our supercluster towards the Shapley supercluster.

By virtue of only a recent discovery, there is no reliable information about the nature of the dipole repulsor, as well as experimental evidence of its existence, for example, through the effect on individual nearby galaxies. Although, as I have already indicated in the last part of the article, both dark energy and dark liquid have a repulsive effect, perhaps somewhere there lies the key to this phenomenon.

Dark stream

In addition to the movement of our supercluster to the area of the Great Attractor, evidence of a much more global current of the local Universe is recorded. It was discovered when analyzing the nature of displacements of the order of 1400 clusters. However, this is only part of the stream, stretching over 3 billion light-years. This current has received the name " dark stream ".

The existence of such a global movement is not consistent with the cosmological principle, according to which the movement of groups of galaxies on a large scale should be random and chaotic.

At the moment, scientists cannot look further than about 380,000 years after the Big Bang, when the Universe became transparent. This corresponds to a distance of about 46 billion light years. However, studies have shown that the force that causes movement in this direction is outside this range, and possibly beyond our universe.

According to scientists, a possible cause of the dark flow is the effect of the mass, which is currently outside the visible part of the Universe. However, this explanation stumbles on the already mentioned cosmological principle, according to which the Universe must also be homogeneous and isotropic on a large scale. And the Big Bang theory does not allow the formation of such large masses in such a short time.

In addition, there are more exotic explanations, for example, that the flow is initiated by the presence of a parallel universe, with which at the time of the Big Bang ours was linked at the quantum level. But so far, these explanations and even the very existence of the “dark stream” have not received unanimous recognition, and they, at the moment, are more a subject for scientific discussion.

Great walls

As already mentioned, according to the cosmological principle , on a very large scale of observations, the Universe should be homogeneous and isotropic, that is, the differences in the mass and structure of matter between different regions of the Universe should be very small. The main evidence for this is the observation of relict radiation, which is generally uniform and the statistical fluctuations in it are minimal.

According to modern concepts, the scale at which uniformity should manifest itself is 250-300 million light-years. And no heterogeneous structures of larger sizes should exist. This hypothesis is known as the “ end of greatness ."

At the beginning of the 20th century, it was known that stars are grouped into star clusters, which, in turn, form galaxies. Clusters of galaxies and superclusters of galaxies were later found. However, the size of superclusters is very different.

In 2003, scientists discovered the Great Wall of Sloan , which has a size of 1.37 billion light-years, which is 4.5 times the predicted scale of the uniformity of the Universe. Next, a huge group of quasars with a size of 4 billion light-years was discovered , which is 13.5 times larger. And in 2013, the Hercules-Northern Crown wall was discovered - a heterogeneous structure measuring more than 30 times the size of the predicted scale. The existence of such large-scale structures casts doubt on the cosmological principle itself.

The Wall of Hercules-Northern Crown is located at a distance of about 10 billion light-years from us. Which means that we are observing it as it was 10 billion years ago, or only 3.79 billion years after the Big Bang. As already mentioned at the moment, there are no generally accepted hypotheses about how such a large structure could have formed in such a relatively short time.

Scientists are trying to explain the relatively small superclusters by the effect of dark matter, which attracts baryonic matter, which we later observe in the form of superclusters or galactic filaments. But about the huge group of quasars or the wall of the Hercules-Northern Crown, scientists only shrug their hands and suggest that perhaps these are not real structures, but only “apparent” ones, due to the limited technology used.

Although some scholars are seriously considering the assumption that the age of our Universe is perhaps much more than 13.79 billion years now accepted. In this case, it becomes possible not only to explain the formation of such large walls, but also to make the hypothesis about the nature of dark matter more robust, suggesting that it is due to the large number of black dwarfs that form from white dwarfs when they cool, lasting tens of billions of years.

Axis of evil

Another rather controversial phenomenon, when different groups of scientists, analyzing the same data, come to the opposite conclusions. This phenomenon directly relates to relic radiation.

Relic radiation is thermal radiation, which, according to the theory of the Big Bang, originated in the era when our Universe was just a bunch of plasma. The latter, being very hot, emitted a large number of energy photons, which should have been uniformly emitted in all directions.

Due to this, microwave radiation filling the Universe has a high degree of isotropy (uniformity) with an accuracy of 0.01%. Areas with a temperature deviation from the mean are called fluctuation regions.

Studying relic radiation, in the early 2000s, scientists drew attention to some anomaly in the distribution of microwave radiation in the Universe. It turned out that its fluctuations are located in the Universe not randomly, as the Big Bang theory claims, but along a certain extended region, the scale of which is significant in comparison with the Universe. Further development of this hypothesis led scientists to the fact that, probably, the entire structure of the Universe is built around this very line, which was called the " axis of evil ."

This name was not given by chance, the fact is that its presence contradicts both the Big Bang theory and the principle of Copernicus, according to which neither the Earth, nor the Sun, nor any other object occupy any special position in the Universe.

An example of this anomaly is the “relict cold spot” in the constellation Eridanus, a region of space whose microwave radiation is much lower than what scientists predict based on the properties of relict radiation.

If the existence of the axis of evil is confirmed, it is likely that this will entail a revision of most known theories, because today they do not allow the existence of such axes in principle.

Cosmic strings

If before that we mainly dwelled on cases that do not agree or do not agree well with existing theories, then with cosmic strings the opposite is true - both quantum field theory and string theory predict their presence.

A cosmic string is a one-dimensional fold of time space, a topological defect, when two neighboring structures or spaces somehow "do not coincide" with each other, which makes a smooth transition between them impossible. In other words, the circle around the outside of the string will make up a total angle of less than 360 °.

The diameter of cosmic strings is much smaller than the size of atomic nuclei (of the order of ^10–29 centimeters), the length is at least tens of parsec, and the specific gravity is of the order of 10 ²²g / cm, that is, only a thousand kilometers of string has a mass of the Earth, which indicates their extremely high density.

From the theory of cosmic strings it follows that they arose shortly after the Big Bang and were either closed or endless. They can bend, overlap and tear. The dangling ends of the strings are immediately connected, forming closed pieces. Both the strings themselves and their individual fragments fly through the Universe at a speed close to the speed of light.

GTR predicts that a direct cosmic string has no gravitational effect. The only gravitational effect of a direct cosmic string is the relative deviation of the substance (or light) passing through the string from opposite sides. In this case, a closed cosmic string has the usual gravitational effect.

During the expansion of the Universe, cosmic strings formed a network of loops, and it was previously believed that their gravity could be the cause of the initial accumulation of matter in galactic superclusters. But at present, it is estimated that their contribution to the formation of the structure in the universe is less than 10%, which excludes their noticeable influence in the formation of the large-scale structure of the Universe.

It is impossible to see the cosmic string, but it, like any very massive object, creates a “gravitational lens”: the light from the sources located behind it must bend around it. And although publications in the scientific world periodically appear with indirect evidence of experimental confirmation of their existence, at the moment, none of them has been confirmed.

The experimental discovery of cosmic strings will have important consequences, including for string theory - at the moment, a wide range of models of cosmic strings built on its basis have already been proposed, and with the opening of cosmic strings, it will be possible to advance to the side of their first experimental confirmation.

From the author

Initially, I wanted to show the connections between the well-known theories of physics and cosmology, and how they increased our knowledge of the Universe. But at the moment, as you can see, a situation has formed in science when there are much more questions on the agenda than there are answers to them. Many connections are more speculative, and often are not supported by observations, and observations often contradict theories.

New theories often add much more questions than they cover white spots - at the moment, dozens of theories of gravity, quantum gravity, theories of everything have been proposed - someone will say that these are powerless attempts to explain without a real result, someone will say that this is the development and creation of new theories is a confirmation of the fact that science does not stand still.

We can definitely say that over time, many of our ideas will surely change - some problems will be resolved, and new ones will replace them, but the knowledge and understanding of our Universe will gradually increase. Thank you all, I hope this article was interesting to you.

Dark Universe. Part 2