Dark matter. Dark matter in astronomy, cosmology and philosophy - interesting facts
Sooner or later our world will cease to exist. Just as it once emerged from a single particle smaller than an atom. Scientists have long had no doubt about this. However, if previously the dominant theory was that the death of the Universe would occur as a result of its rapidly accelerating expansion and, as a consequence, inevitable “thermal death,” then with the discovery of dark matter this opinion changed.
DARK FORCES OF THE UNIVERSE
Experts say that the entire vast cosmos may perish as a result of its collapse, being sucked into some giant black hole, which is part of the mysterious “dark matter”.
In the cold depths of space, two irreconcilable forces have been at war since the creation of the world - dark energy and dark matter. If the first ensures the expansion of the Universe, then the second, on the contrary, strives to pull it inside itself, to compress it into oblivion. This confrontation is going on with varying degrees of success. The victory of one of the forces over the other, the disruption of cosmic balance, is equally disastrous for all things.
Einstein also suggested that there is much more matter in space than we can see. In the history of science, there have been situations when the movement celestial bodies did not obey the laws of celestial mechanics. As a rule, this mysterious deviation from the trajectory was explained in the existence of an unknown material body(or several bodies). This is how the planet Neptune and the star Sirius B were discovered.
SPACE CLAMPS
In 1922, astronomers James Jime and Jacobus Kapteyn studied the motion of stars in our Galaxy and concluded that most of the matter in the Galaxy is invisible; In these works, the term “dark matter” first appeared, but it does not quite correspond to the current meaning of this concept.
Astronomers have long been aware of the phenomenon of the accelerating expansion of the Universe. By observing the distance of galaxies from each other, they found that this speed is increasing. The energy that pushes space in all directions, like air in a balloon, has been called “dark.” This energy pushes galaxies away from each other, it acts against the force of gravity.
But, as it turned out, her powers are not limitless. There is also a kind of cosmic “glue” that keeps galaxies from spreading apart. And the mass of this “glue” significantly exceeds the mass of the visible Universe. This enormous force of unknown origin was called dark matter. Despite the threatening name, the latter is not an absolute evil. It's all about the fragile balance of cosmic forces on which the existence of our seemingly unshakable world rests.
Conclusion of existence mysterious matter, which is not visible, is not recorded by any of the instruments, but whose existence can be considered proven, was made on the basis of a violation of the gravitational laws of the Universe. At least as we know them. It was noticed that stars in spiral galaxies like ours have a fairly high speed of rotation and, according to all laws, with such fast movement they should simply fly out into intergalactic space under the influence of centrifugal force, but they do not do this. They are held by some very strong gravitational force, which is not registered or captured by any known modern science ways. This got scientists thinking.
ETERNAL STRUGGLE
If these elusive dark “braces”, but superior in gravitational force to all visible cosmic objects, did not exist, then after some long time the rate of expansion of the Universe under the influence of dark energy would approach the limit at which a break in the space-time continuum would occur. Space will annihilate and the Universe will cease to exist. However, this is not happening yet.
Astrophysicists have found that about 7 billion years ago, gravity (dominated by dark matter) and dark energy were in balance. But the Universe expanded, density decreased, and the strength of dark energy increased. Since then it has dominated our Universe. Now scientists are trying to understand whether this process will ever end.
Today it is already known that the Universe consists of only 4.9% of ordinary matter - baryonic matter, which makes up our world. Most (74%) of the entire universe is made up of mysterious dark energy, and 26.8% of the mass in the universe is made up of physics-defying, hard-to-detect particles called dark matter.
So far, in the irreconcilable eternal struggle between dark matter and dark energy, the latter is winning. They look like two wrestlers in different weight classes. But this does not mean that the fight is a foregone conclusion. Galaxies will continue to disperse. But how long will this process take? According to the latest hypothesis, dark matter is just one manifestation of the physics of black holes.
BLACK HOLES ARE LOTS OF DARK MATTER?
Black holes are the most massive and powerful objects in the known Universe. They bend space-time so strongly that even light cannot escape their boundaries. Therefore, just like dark matter, we cannot see them. Black holes are a kind of centers of gravity for vast expanses of space. It can be assumed that this is structured dark matter. A striking example These are the supermassive black holes that live at the center of galaxies. Looking at the center of our Galaxy, for example, we see how the stars around it accelerate.
Anne Martin of Cornell University notes that the only thing that would explain this acceleration is a supermassive black hole. We can judge the existence of dark matter, as well as black holes, only on the basis of their interaction with surrounding objects. Therefore, we observe its effects in the movement of galaxies and stars, but we do not see it directly; it neither emits nor absorbs light. It is logical to assume that black holes are just clumps of dark matter.
Could one of the giant black holes, which will eventually swallow not only the surrounding space, but also its less powerful “holey” relatives, swallow the entire Universe? The question about this remains open. According to scientists, if this happens, it will not be earlier than in 22 billion years. So that's enough for our lifetime. In the meantime the world around us continues its voyage between the Scylla of dark energy and the Charybdis of dark matter. The fate of the Universe will depend on the outcome of the struggle between these two dominant forces in space.
TESLA'S PROPHECY
There is, however, also alternative view on the problem of dark matter. Certain parallels can be found between the mysterious substance and Nikola Tesla’s theory of the universal ether. According to Einstein, the ether is not a real category, but exists as a result of erroneous scientific views. For Tesla, the ether is reality.
Several years ago, at a street sale in New York, an antiques lover bought himself a fireman's helmet, worn out by time. Inside it, under the lining, lay an old notebook. The notebook was thin, with a burnt cover, and it smelled of mold. The sheets, yellowed with time, were covered with ink that had faded with time. As it turned out, the manuscript belonged to the famous inventor Nikola Tesla, who lived and worked in the USA. The recording explains the theory of the ether, in which one can find unmistakable indications of the discovery of the elusive dark matter decades after his death.
“What is ether, and why is it so difficult to detect? - the inventor writes in the manuscript. - I thought about this question for a long time and came to the following conclusions. It is known that the denser the substance, the higher the speed of propagation of waves in it. Comparing the speed of sound in air with the speed of light, I came to the conclusion that the density of the ether is several thousand times greater than the density of air. But the ether is electrically neutral and therefore it interacts very weakly with our material world, and besides, the density of the substance material world is insignificant compared to the density of the ether."
According to the scientist, it is not the ether that is ethereal - it is our material world that is ethereal for the ether. Thus, he offers a much more positive view of dark matter, seeing in it some kind of primordial substance, the cradle of the Universe. But not only that. According to Tesla, with a skillful approach, it is possible to obtain inexhaustible sources of energy from the dark matter of the ether, to penetrate parallel worlds and even establish contacts with intelligent inhabitants of other galaxies. “I think that the stars, planets and our entire world arose from the ether when, for some reason, part of it became less dense. Compressing our world from all sides, the ether tries to return to its original state, and the internal electric charge in the substance of the material world prevents this. Over time, having lost its internal electrical charge, our world will be compressed by the ether and turn into ether. The ether has left the ether and will leave,” Tesla asserted.
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The term “dark matter” (or hidden mass) is used in various fields of science: cosmology, astronomy, physics. It's about about a hypothetical object - a form of space and time content that directly interacts with electromagnetic radiation and does not allow it to pass through itself.
Dark matter – what is it?
Since time immemorial, people have been concerned about the origin of the Universe and the processes that shape it. In the age of technology were made important discoveries, and the theoretical basis has been significantly expanded. In 1922 British physicist James Jeans and Dutch astronomer Jacobus Kapteyn discovered that most of the galactic matter is invisible. Then the term dark matter was first used - this is a substance that cannot be seen by any of the methods known to mankind. The presence of a mysterious substance is revealed indirect signs– gravitational field, gravity.
Dark matter in astronomy and cosmology
By assuming that all objects and parts in the Universe are attracted to each other, astronomers were able to find the mass visible space. But a discrepancy was discovered in the actual and predicted weights. And scientists have found out that there is an invisible mass, which accounts for up to 95% of all unknown essence in the Universe. Dark matter in space has the following characteristics:
- subject to gravity;
- influences other space objects,
- weakly interacts with the real world.
Dark matter - philosophy
Dark matter occupies a special place in philosophy. This science deals with the study of the world order, the foundations of existence, the system of visible and invisible worlds. A certain substance determined by space, time, and surrounding factors was taken as the fundamental principle. The mysterious dark matter of space, discovered much later, changed the understanding of the world, its structure and evolution. In a philosophical sense, an unknown substance, like a clot of energy of space and time, is present in each of us, therefore people are mortal, because they consist of time, which has an end.
Why is dark matter needed?
Only a small part space objects(planets, stars, etc.) – visible matter. By the standards of various scientists, dark energy and dark matter occupy almost all the space in Space. The first accounts for 21-24%, while energy takes up 72%. Every substance is unclear physical nature has its own functions:
- Black energy, which neither absorbs nor emits light, pushes objects away, causing the universe to expand.
- Galaxies are built on the basis of hidden mass, its force attracts objects into outer space, keeps them in place. That is, it slows down the expansion of the Universe.
What is dark matter made of?
Dark matter in solar system– this is something that cannot be touched, examined and studied thoroughly. Therefore, several hypotheses are put forward regarding its nature and composition:
- Particles unknown to science that participate in gravity are a component of this substance. It is impossible to detect them with a telescope.
- The phenomenon is a cluster of small black holes (no larger than the Moon).
It is possible to distinguish two types of hidden mass depending on the speed of its constituent particles and the density of their accumulation.
- Hot. It is not enough to form galaxies.
- Cold. Consists of slow, massive clots. These components can be axions and bosons known to science.
Does dark matter exist?
All attempts to measure objects of an unexplored physical nature have not brought success. In 2012, the movement of 400 stars around the Sun was studied, but the presence of hidden matter in large volumes was not proven. Even if dark matter does not exist in reality, it exists in theory. With its help, the location of objects in the Universe in their places is explained. Some scientists are finding evidence of hidden cosmic mass. Its presence in the Universe explains the fact that galaxy clusters do not fly apart into different sides and stick together.
Dark matter - interesting facts
The nature of the hidden mass remains a mystery, but it continues to interest scientific minds around the world. Experiments are regularly carried out with the help of which they try to study the substance itself and its side effects. And the facts about her continue to multiply. For example:
- The acclaimed Large Hadron Collider, the world's most powerful particle accelerator, is firing on all cylinders to reveal the existence of invisible matter in space. The world community is awaiting the results with interest.
- Japanese scientists create the world's first map of hidden mass in space. It is planned to be completed by 2019.
- Recently, theoretical physicist Lisa Randall suggested that dark matter and dinosaurs are connected. This substance sent a comet to Earth, which destroyed life on the planet.
The components of our galaxy and the entire Universe are light and dark matter, that is, visible and invisible objects. If with the study of the first modern technology copes, methods are constantly being improved, then exploring hidden substances is very problematic. Humanity has not yet come to understand this phenomenon. Invisible, intangible, but omnipresent dark matter has been and remains one of the main mysteries of the Universe.
It is known that dark matter interacts with “luminous” (baryonic) matter, at least in a gravitational manner, and represents a medium with an average cosmological density several times higher than the density of baryons. The latter are captured in gravitational holes of dark matter concentrations. Therefore, although dark matter particles do not interact with light, light is emitted from where the dark matter is. This remarkable property of gravitational instability has made it possible to study the amount, state and distribution of dark matter using observational data from radio to X-rays.
Direct study of the distribution of dark matter in galaxy clusters became possible after highly detailed images were obtained in the 1990s. In this case, images of more distant galaxies projected onto the cluster turn out to be distorted or even split due to the effect of gravitational lensing. Based on the nature of these distortions, it becomes possible to reconstruct the distribution and magnitude of mass within the cluster, regardless of observations of the galaxies in the cluster itself. Thus, the presence of hidden mass and dark matter in galaxy clusters is confirmed by a direct method.
A study published in 2012 of the motions of more than 400 stars located at distances of up to 13,000 light-years from the Sun found no evidence of dark matter in the large volume of space around the Sun. According to theoretical predictions, the average amount of dark matter in the vicinity of the Sun should have been approximately 0.5 kg in the volume of the globe. However, measurements gave a value of 0.00±0.06 kg of dark matter in this volume. This means that attempts to detect dark matter on Earth, for example through rare interactions of dark matter particles with “ordinary” matter, are unlikely to be successful.
Dark matter candidates
Baryonic dark matter
The most natural assumption seems to be that dark matter consists of ordinary, baryonic matter, which for some reason weakly interacts electromagnetically and is therefore undetectable when studying, for example, emission and absorption lines. Included dark matter may include many already discovered space objects, such as: dark galactic halos, brown dwarfs and massive planets, compact objects on final stages evolution: white dwarfs, neutron stars, black holes. In addition, hypothetical objects such as quark stars, Q stars and preon stars may also be part of baryonic dark matter.
The problems with this approach are manifested in Big Bang cosmology: if all dark matter is represented by baryons, then the ratio of concentrations of light elements after primary nucleosynthesis, observed in the oldest astronomical objects, should be different, sharply different from what is observed. In addition, experiments to search for gravitational lensing of the light of stars in our Galaxy show that a sufficient concentration of large gravitating objects such as planets or black holes is not observed to explain the mass of the halo of our Galaxy, and small objects of sufficient concentration should absorb star light too strongly.
Nonbaryonic dark matter
Theoretical models provide large selection possible candidates for the role of nonbaryonic invisible matter. Let's list some of them.
Light neutrinos
Unlike other candidates, neutrinos have a clear advantage: they are known to exist. Since the number of neutrinos in the Universe is comparable to the number of photons, then, even having a small mass, neutrinos may well determine the dynamics of the Universe. To achieve , where is the so-called critical density, neutrino masses of the order of eV are required, where denotes the number of types of light neutrinos. Experiments carried out to date provide estimates of neutrino masses on the order of eV. Thus, light neutrinos are practically excluded as a candidate for the dominant fraction of dark matter.
Heavy neutrinos
From the data on the Z-boson decay width it follows that the number of generations of weakly interacting particles (including neutrinos) is equal to 3. Thus, heavy neutrinos (at least with a mass less than 45 GeV) are necessarily the so-called. “sterile”, that is, particles that do not interact weakly. Theoretical models predict mass in very wide range values (depending on the nature of this neutrino). From the phenomenology for follows a mass range of approximately eV, sterile neutrinos may well constitute a significant part of dark matter.
Supersymmetric particles
In supersymmetric (SUSY) theories, there is at least one stable particle that is a new candidate for dark matter. It is assumed that this particle (LSP) does not participate in electromagnetic and strong interactions. LSP particles can be photino, gravitino, higgsino (superpartners of the photon, graviton and Higgs boson, respectively), as well as sneutrino, wine, and zino. In most theories, an LSP particle is a combination of the above SUSY particles with a mass of the order of 10 GeV.
Cosmions
Cosmions were introduced into physics to solve the problem of solar neutrinos, which consists in a significant difference in the flux of neutrinos detected on Earth from the value predicted by the standard model of the Sun. However, this problem has been resolved within the framework of the theory of neutrino oscillations and the Mikheev-Smirnov-Wolfenstein effect, so cosmions are apparently excluded from candidates for the role of dark matter.
Topological defects of space-time
According to modern cosmological concepts, the vacuum energy is determined by a certain locally homogeneous and isotropic scalar field. This field is necessary to describe the so-called vacuum phase transitions during the expansion of the Universe, during which a consistent violation of symmetry occurred, leading to the separation of fundamental interactions. A phase transition is a jump in the energy of a vacuum field tending to its ground state (the state with minimum energy at a given temperature). Various areas spaces could experience such a transition independently, as a result of which areas with a certain “arrangement” of the scalar field were formed, which, expanding, could come into contact with each other. At the meeting points of regions with different orientations, stable topological defects of various configurations could form: point-like particles (in particular, magnetic monopoles), linear extended objects (cosmic strings), two-dimensional membranes (domain walls), three-dimensional defects (textures). All these objects, as a rule, have colossal mass and could make a dominant contribution to dark matter. At the moment (2012), such objects have not been discovered in the Universe.
Classification of dark matter
Depending on the speeds of the particles that presumably make up dark matter, it can be divided into several classes.
Hot dark matter
Composed of particles moving at close to the speed of light—probably neutrinos. These particles have a very small mass, but still not zero, and taking into account huge amount neutrinos in the Universe (300 particles per 1 cm³), this gives a huge mass. In some models, neutrinos account for 10% of dark matter.
Due to its enormous speed, this matter cannot form stable structures, but it can influence ordinary matter and other types of dark matter.
Warm dark matter
Matter moving at relativistic speeds, but lower than hot dark matter, is called “warm.” The speeds of its particles can range from 0.1c to 0.95c. Some evidence, particularly temperature variations in background microwave radiation, suggests that this form of matter may exist.
There are no candidates yet for the role of components of warm dark matter, but it is possible that sterile neutrinos, which should move slower than the usual three flavors of neutrinos, could be one of them.
Cold dark matter
Dark matter that moves at classical speeds is called “cold.” This type of matter is of the greatest interest, since, unlike warm and hot dark matter, cold matter can form stable formations, and even entire dark galaxies.
While particles suitable for the role components cold dark matter has not been detected. Candidates for the role of cold dark matter are weakly interacting massive particles - WIMPs, such as axions and supersymmetric fermion partners of light bosons - photinos, gravitinos and others.
Mixed dark matter
In popular culture
- In the Mass Effect series of games, dark matter and dark energy in the form of the so-called “Element Zero” are necessary for movement at superluminal speeds. Some people, biotics, using dark energy, can control mass effect fields.
- In the animated series Futurama, dark matter is used as fuel for the Planet Express spacecraft. Matter is born in the form of feces of the alien race “Zubastilons” and is extremely dense in density.
See also
Notes
Literature
- Modern Cosmology website, which also contains a selection of materials on dark matter.
- G.W.Klapdor-Kleingrothaus, A.Staudt Non-accelerator physics elementary particles. M.: Nauka, Fizmatlit, 1997.
Links
- S. M. Bilenky, Neutrino masses, mixing and oscillations, UFN 173 1171-1186 (2003)
- V. N. Lukash, E. V. Mikheeva, Dark matter: from initial conditions to the formation of the structure of the Universe, UFN 177 1023-1028 (2007)
- DI. Kazakov "Dark Matter", from a series of lectures in the PostScience project (video)
- Anatoly Cherepashchuk. “New forms of matter in the Universe, part 1” - Dark mass and dark energy, from the lecture series “ACADEMIA” (video)
Wikimedia Foundation. 2010.
See what “Dark Matter” is in other dictionaries:
DARK MATTER- (TM) unusual matter of our Universe, consisting not of (see), i.e. not of protons, neutrons, mesons, etc., and discovered by the strongest gravitational effect on cosmic objects of ordinary baryonic nature (stars, galaxies, black … …
Dark Matter The Outer Limits: Dark Matters Genre science fiction ... Wikipedia
This term has other meanings, see Dark Star. A dark star is a theoretically predicted type of star that could exist on early stage formation of the Universe, even before they could... ... Wikipedia
MATTER - objective reality, existing outside and independently of human consciousness and displayed by it (for example, living and non-living M.). The unity of the world is in its materiality. In physics M. all types of existence (see), which can be in different... ... Big Polytechnic Encyclopedia
MOSCOW, December 12 - RIA Novosti. The amount of dark matter in the Universe has decreased by about 2-5%, which may explain discrepancies in the values of some important cosmological parameters during the Big Bang and today, Russian cosmologists say in a paper published in the journal Physical Review D.
“Let’s imagine that dark matter consists of several components, like ordinary matter. And one component consists of unstable particles, whose lifetime is quite long: in the era of hydrogen formation, hundreds of thousands of years after the Big Bang, they are still in the Universe, but today they have already disappeared, decaying into neutrinos or hypothetical relativistic particles. Then the amount of dark matter in the past and today will be different,” said Dmitry Gorbunov from the Moscow Institute of Physics and Technology, whose words are quoted by the university’s press service.
Dark matter is a hypothetical substance that manifests itself exclusively through gravitational interaction with galaxies, introducing distortions into their motion. Dark matter particles do not interact with any species electromagnetic radiation, and therefore cannot be recorded during direct observations. Dark matter accounts for about 26% of the universe's mass, while "ordinary" matter makes up only about 4.8% of its mass—the rest is the equally mysterious dark energy.
Observations of the distribution of dark matter across the nearest and farthest corners of the universe, carried out using ground-based telescopes and the Planck probe, have recently revealed strange thing- it turned out that the expansion rate of the Universe and some properties of the “echo” of the Big Bang in the distant past and today are noticeably different. For example, today galaxies are flying apart from each other much faster than it follows from the results of the analysis of the cosmic microwave background radiation.
Gorbunov and his colleagues found possible reason this.
A year ago, one of the authors of the article, academician Igor Tkachev from the Institute of Nuclear Physics of the Russian Academy of Sciences in Moscow, formulated a theory of so-called decaying dark matter (DDM), in which, unlike the generally accepted theory of “cold dark matter” (CDM), part or all of it particles are unstable. These particles, as suggested by Tkachev and his associates, should decay quite rarely, but in noticeable quantities, in order to give rise to deviations between the young and modern Universe.
In his new job Tkachev, Gorbunov and their colleague Anton Chudaikin tried to calculate how much dark matter must have decayed, using data collected by Planck and other observatories that studied the cosmic microwave background radiation and the first galaxies of the Universe.
As their calculations showed, the decay of dark matter may indeed explain why the results of observations of this substance using Planck do not correspond to observations of galaxy clusters closest to us.
Interestingly, this requires decay relatively small quantity dark matter - from 2.5 to 5% of its total mass, whose amount almost does not depend on what fundamental properties the Universe should have. Now, as scientists explain, all this matter has decayed, and the rest of the dark matter, stable in nature, behaves as described by the CDM theory. On the other hand, it is also possible that it continues to decay.
“This means that in today’s Universe there is 5% less dark matter than there was in the era of the formation of the first molecules of hydrogen and helium after the birth of the Universe. We cannot now say how quickly this unstable part decayed, it is possible that dark matter continues to decay and now, although this is a different, much more complex model,” concludes Tkachev.
A theoretical construct in physics called the Standard Model describes the interactions of all known to science elementary particles. But this is only 5% of the matter existing in the Universe, the remaining 95% is of a completely unknown nature. What is this hypothetical dark matter and how are scientists trying to detect it? Hayk Hakobyan, a MIPT student and employee of the Department of Physics and Astrophysics, talks about this as part of a special project.
The Standard Model of elementary particles, finally confirmed after the discovery of the Higgs boson, describes fundamental interactions(electroweak and strong) ordinary particles known to us: leptons, quarks and interaction carriers (bosons and gluons). However, it turns out that all this huge complex theory describes only about 5–6% of all matter, while the rest does not fit into this model. Observations of the earliest moments of our Universe show us that approximately 95% of the matter that surrounds us is of a completely unknown nature. In other words, we indirectly see the presence of this hidden matter due to its gravitational influence, but we have not yet been able to capture it directly. This hidden mass phenomenon is codenamed “dark matter.”
Modern science, especially cosmology, works according to the deductive method of Sherlock Holmes
Currently, the main candidate from the WISP group is the axion, which arises in theory strong interaction and having very low mass. Such a particle is capable of transforming into a photon-photon pair in high magnetic fields, which gives hints on how one might try to detect it. The ADMX experiment uses large chambers that create a magnetic field of 80,000 gauss (that's 100,000 times more magnetic field Earth). In theory, such a field should stimulate the decay of an axion into a photon-photon pair, which detectors should catch. Despite numerous attempts, it has not yet been possible to detect WIMPs, axions or sterile neutrinos.
Thus, we have traveled through a huge number of different hypotheses seeking to explain the strange presence of the hidden mass, and, having rejected all the impossibilities with the help of observations, we have arrived at several possible hypotheses with which we can already work.
A negative result in science is also a result, since it gives restrictions on various parameters of particles, for example, it eliminates the range of possible masses. From year to year, more and more new observations and experiments in accelerators provide new, more stringent restrictions on the mass and other parameters of dark matter particles. Thus, by throwing out all the impossible options and narrowing the circle of searches, day by day we are becoming closer to understanding what 95% of the matter in our Universe consists of.
