The question of the origin of the Universe, its past and future has worried people since time immemorial. Over the centuries, theories have arisen and been refuted, offering a picture of the world based on known data. A major shock for scientific world became Einstein's theory of relativity. She also made a huge contribution to the understanding of the processes shaping the Universe. However, the theory of relativity could not claim to be the ultimate truth, not requiring any additions. Improved technologies have allowed astronomers to make previously unimaginable discoveries that required a new theoretical framework or a significant expansion of existing provisions. One such phenomenon is dark matter. But first things first.
Things from days gone by
To understand the term “dark matter,” let’s go back to the beginning of the last century. At that time, the dominant idea was that the Universe was a stationary structure. Meanwhile, the general theory of relativity (GTR) assumed that sooner or later it would lead to the “sticking together” of all objects in space into a single ball, the so-called gravitational collapse would occur. There are no repulsive forces between space objects. Mutual attraction is compensated centrifugal forces, creating constant movement stars, planets and other bodies. In this way, the balance of the system is maintained.
In order to prevent the theoretical collapse of the Universe, Einstein introduced a quantity that brings the system to the necessary stationary state, but at the same time it was actually invented and had no obvious basis.
Expanding Universe
The calculations and discoveries of Friedman and Hubble showed that there was no need to violate the harmonious equations of general relativity using a new constant. It has been proven, and today almost no one doubts this fact, that the Universe is expanding, it once had a beginning, and there can be no talk of stationarity. Further development of cosmology led to the emergence of the big bang theory. The main confirmation of the new assumptions is the observed increase in the distance between galaxies over time. It is precisely the measurement of the speed of removal of neighboring space systems and led to the formation of the hypothesis that dark matter and dark energy exist.
Data inconsistent with theory
Fritz Zwicky in 1931, and then Jan Oort in 1932 and in the 1960s, were engaged in calculating the mass of matter of galaxies in a distant cluster and its relationship with the speed of their removal from each other. Time after time, scientists came to the same conclusions: this amount of matter is not enough for the gravity it creates to hold together galaxies moving at such high speeds. Zwicky and Oort suggested that there is hidden mass, the dark matter of the Universe, which does not allow cosmic objects to fly apart into different sides.
However, the hypothesis received recognition from the scientific world only in the seventies, after the results of Vera Rubin’s work were announced.
She constructed rotation curves that clearly demonstrate the dependence of the speed of motion of the galactic matter on the distance that separates it from the center of the system. Contrary to theoretical assumptions, it turned out that the velocities of stars do not decrease as they move away from the galactic center, but increase. This behavior of the stars could only be explained by the presence of a halo in the galaxy, which is filled with dark matter. Astronomy was thus faced with a completely unexplored part of the universe.
Properties and composition
They call it dark because it cannot be seen by any means. using existing methods. Its presence is recognized by an indirect sign: dark matter creates a gravitational field, while not emitting electromagnetic waves at all.
The most important task facing scientists was to obtain an answer to the question of what this matter consists of. Astrophysicists tried to “fill” it with the usual baryonic matter (baryonic matter consists of more or less studied protons, neutrons and electrons). The dark halo of galaxies included compact weakly emitting stars of the type and huge planets close in mass to Jupiter. However, such assumptions did not stand up to scrutiny. Baryonic matter, familiar and familiar, thus cannot play a significant role in the hidden mass of galaxies.
Today, physics is engaged in the search for unknown components. Practical research of scientists is based on the theory of supersymmetry of the microworld, according to which for each known particle there is a supersymmetric pair. These are what make up dark matter. However, evidence of the existence similar particles So far we have not been able to obtain it, perhaps this is a matter of the near future.
Dark energy
The discovery of a new type of matter did not end the surprises that the Universe had prepared for scientists. In 1998, astrophysicists had another chance to compare theoretical data with facts. This year was marked by an explosion in a galaxy far from us.
Astronomers measured the distance to it and were extremely surprised by the data they received: the star flared up much further than it should have been according to the existing theory. It turned out that it is increasing over time: now it is much higher than it was 14 billion years ago, when the Big Bang supposedly happened.
As you know, in order to accelerate the movement of a body, it needs to transfer energy. The force that forces the Universe to expand faster has come to be called dark energy. This is no less mysterious part of space than dark matter. It is only known that it is characterized by a uniform distribution throughout the Universe, and its impact can be registered only at enormous cosmic distances.
And again the cosmological constant
Dark energy has shaken the big bang theory. Part of the scientific world is skeptical about the possibility of such a substance and the acceleration of expansion caused by it. Some astrophysicists are trying to revive Einstein’s forgotten cosmological constant, which can again go from being a major scientific mistake to a working hypothesis. Its presence in the equations creates antigravity, leading to acceleration of expansion. However, some consequences of the presence of a cosmological constant are not consistent with observational data.
Today, dark matter and dark energy, which make up most of the matter in the Universe, are mysteries for scientists. There is no clear answer to the question about their nature. Moreover, it may not be the last secret what space keeps from us. Dark matter and energy may be the threshold of new discoveries that could revolutionize our understanding of the structure of the Universe.
The term "dark matter" (or hidden mass) is used in different areas sciences: 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 galactic matter is not visible. Then the term dark matter was first coined - this is a substance that cannot be seen by any of the known to mankind ways. The presence of a mysterious substance is indicated by indirect signs - gravitational field, heaviness.
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 of visible space. But a discrepancy was discovered in the actual and predicted weights. And scientists have found 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 was taken as the fundamental principle, determined by space, time, and surrounding factors. The mysterious dark matter of space, discovered much later, changed the understanding of the world, its structure and evolution. IN 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 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%. Each substance of unknown 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 in outer space and holds them in their places. 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:
- Not known to science particles participating 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 has not been 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 in different directions 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 much-lauded 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.
In the articles of the series we examined the structure of the visible Universe. We talked about its structure and the particles that form this structure. About nucleons playing main role, since it is from them that all visible matter consists. About photons, electrons, neutrinos, and also about the supporting actors involved in the universal play that unfolds 14 billion years after the Big Bang. It would seem that there is nothing more to talk about. But that's not true. The fact is that the substance we see is only a small part of what our world consists of. Everything else is something we know almost nothing about. This mysterious “something” is called dark matter.
If the shadows of objects did not depend on the size of these latter,
and if they had their own arbitrary growth, then perhaps
soon there would be no left at all globe not a single bright place.
Kozma Prutkov
What will happen to our world?
After Edward Hubble's discovery of redshifts in the spectra of distant galaxies in 1929, it became clear that the Universe was expanding. One of the questions that arose in this regard was the following: how long will the expansion last and how will it end? The forces of gravitational attraction acting between individual parts of the Universe tend to slow down the retreat of these parts. What the braking will lead to depends on the total mass of the Universe. If it is large enough, gravitational forces will gradually stop the expansion and it will be replaced by compression. As a result, the Universe will eventually “collapse” again to the point from which it once began to expand. If the mass is less than a certain critical mass, then the expansion will continue forever. It is usually customary to talk not about mass, but about density, which is related to mass by a simple relationship, known from school course: Density is mass divided by volume.
The calculated value of the critical average density of the Universe is approximately 10 -29 grams per cubic centimeter, which corresponds to an average of five nucleons per cubic meter. It should be emphasized that we are talking about average density. The characteristic concentration of nucleons in water, earth and in you and me is about 10 30 per cubic meter. However, in the void that separates clusters of galaxies and occupies the lion's share of the volume of the Universe, the density is tens of orders of magnitude lower. The nucleon concentration averaged over the entire volume of the Universe was measured tens and hundreds of times, carefully calculating different methods number of stars and gas and dust clouds. The results of such measurements differ somewhat, but the qualitative conclusion is unchanged: the density of the Universe barely reaches a few percent of the critical value.
Therefore, until the 70s of the 20th century, the generally accepted forecast was the eternal expansion of our world, which should inevitably lead to the so-called heat death. Heat death is a state of a system when the substance in it is distributed evenly and its different parts have the same temperature. As a consequence, neither the transfer of energy from one part of the system to another, nor the redistribution of matter is possible. In such a system nothing happens and can never happen again. A clear analogy is water spilled on any surface. If the surface is uneven and there are even slight differences in elevation, water moves along it from higher to lower places and eventually collects in the lowlands, forming puddles. The movement stops. The only consolation left was that heat death would occur in tens and hundreds of billions of years. Consequently, you don’t have to think about this gloomy prospect for a very, very long time.
However, it gradually became clear that the true mass of the Universe is much greater than the visible mass contained in stars and gas and dust clouds and, most likely, is close to critical. Or perhaps exactly equal to it.
Evidence for dark matter
The first indication that something was wrong with the calculation of the mass of the Universe appeared in the mid-30s of the 20th century. Swiss astronomer Fritz Zwicky measured the speeds at which galaxies in the Coma cluster (one of the largest clusters known to us, it includes thousands of galaxies) move around a common center. The result was discouraging: the velocities of the galaxies turned out to be much greater than could be expected based on the observed total mass of the cluster. This meant that the true mass of the Coma cluster was much greater than the apparent mass. But the main amount of matter present in this region of the Universe remains, for some reason, invisible and inaccessible to direct observations, manifesting itself only gravitationally, that is, only as mass.
The presence of hidden mass in galaxy clusters is also evidenced by experiments on the so-called gravitational lensing. The explanation for this phenomenon follows from the theory of relativity. In accordance with it, any mass deforms space and, like a lens, distorts the rectilinear path of light rays. The distortion that galaxy clusters cause is so great that it is easy to notice. In particular, from the distortion of the image of the galaxy that lies behind the cluster, it is possible to calculate the distribution of matter in the lens cluster and thereby measure its total mass. And it turns out that it is always many times greater than the contribution of the visible matter of the cluster.
40 years after Zwicky’s work, in the 70s, American astronomer Vera Rubin studied the speed of rotation around the galactic center of matter located on the periphery of galaxies. In accordance with Kepler's laws (and they directly follow from the law universal gravity), when moving from the center of the galaxy to its periphery, the rotation speed of galactic objects should decrease in inverse proportion to square root from the distance to the center. Measurements have shown that for many galaxies this speed remains almost constant at a very significant distance from the center. These results can be interpreted only in one way: the density of matter in such galaxies does not decrease when moving from the center, but remains almost unchanged. Since the density of visible matter (contained in stars and interstellar gas) rapidly falls towards the periphery of the galaxy, the missing density must be supplied by something that for some reason we cannot see. To quantitatively explain the observed dependences of the rotation rate on the distance to the center of galaxies, it is required that this invisible “something” be approximately 10 times larger than ordinary visible matter. This “something” was called “dark matter” (in English “ dark matter") and still remains the most intriguing mystery in astrophysics.
Another important piece of evidence for the presence of dark matter in our world comes from calculations simulating the process of galaxy formation that began about 300,000 years after the Big Bang. These calculations show that the forces of gravitational attraction that acted between the flying fragments of the matter generated during the explosion could not compensate for the kinetic energy of the expansion. The matter simply should not have gathered into galaxies, which we nevertheless observe in modern era. This problem is called the galactic paradox, and for a long time it was considered a serious argument against the Big Bang theory. However, if we assume that particles of ordinary matter in early universe were mixed with particles of invisible dark matter, then in the calculations everything falls into place and the ends begin to meet - the formation of galaxies from stars, and then clusters of galaxies, becomes possible. At the same time, as calculations show, at first a huge number of dark matter particles accumulated in galaxies and only then, due to gravitational forces, elements of ordinary matter were collected on them, the total mass of which was only a few percent of the total mass of the Universe. It turns out that the familiar and seemingly studied in detail visible world, which we recently considered almost understood, is only a small addition to something that the Universe actually consists of. Planets, stars, galaxies and you and me are just a screen for a huge “something” about which we have not the slightest idea.
Photo fact
The galaxy cluster (at the lower left of the circled area) creates a gravitational lens. It distorts the shape of objects located behind the lens - stretching their images in one direction. By magnitude and direction of stretching international group Astronomers from the Southern European Observatory, led by scientists from the Paris Institute of Astrophysics, constructed the mass distribution, which is shown in the bottom image. As you can see, the cluster contains much more mass than can be seen through a telescope.
Hunting dark, massive objects is not a quick task, and the result does not look the most impressive in photographs. In 1995, the Hubble Telescope noticed that one of the stars in the Large Magellanic Cloud flashed brighter. This glow lasted for more than three months, but then the star returned to its natural state. And six years later, a barely luminous object appeared next to the star. It was a cold dwarf that, passing at a distance of 600 light years from the star, created a gravitational lens that amplified the light. Calculations have shown that the mass of this dwarf is only 5-10% of the mass of the Sun.
Finally, the general theory of relativity clearly connects the rate of expansion of the Universe with medium density substance contained in it. Under the assumption that the average curvature of space is equal to zero, that is, the geometry of Euclidean, and not Lobachevsky, operates in it (which is reliably verified, for example, in experiments with cosmic microwave background radiation), this density should be equal to 10 -29 grams per cubic centimeter. The density of visible matter is approximately 20 times less. The missing 95% of the mass of the Universe is dark matter. Note that the density value measured from the expansion rate of the Universe is equal to the critical value. Two values, independently calculated completely different ways, coincided! If in fact the density of the Universe is exactly equal to the critical density, this cannot be a coincidence, but is a consequence of some fundamental property of our world, which has yet to be understood and comprehended.
What is this?
What do we know today about dark matter, which makes up 95% of the mass of the Universe? Almost nothing. But we still know something. First of all, there is no doubt that dark matter exists - this is irrefutably evidenced by the facts given above. We also know for certain that dark matter exists in several forms. After to beginning of XXI centuries as a result of many years of observations in experiments SuperKamiokande(Japan) and SNO (Canada) it was established that neutrinos have mass, it became clear that from 0.3% to 3% of the 95% of the hidden mass lies in neutrinos that have long been familiar to us - even if their mass is extremely small, but their quantity is in The universe has about a billion times the number of nucleons: each cubic centimeter contains an average of 300 neutrinos. The remaining 92-95% consists of two parts - dark matter and dark energy. A small fraction of dark matter is ordinary baryonic matter, built from nucleons; the remainder is apparently accounted for by some unknown massive weakly interacting particles (the so-called cold dark matter). The energy balance in the modern Universe is presented in the table, and the story about its last three columns is below.
Baryonic dark matter
A small (4-5%) part of dark matter is ordinary matter that emits little or no radiation of its own and is therefore invisible. The existence of several classes of such objects can be considered experimentally confirmed. The most complex experiments, based on the same gravitational lensing, led to the discovery of so-called massive compact halo objects, that is, located on the periphery of galactic disks. This required monitoring millions of distant galaxies over several years. When a dark, massive body passes between an observer and a distant galaxy, its brightness is a short time decreases (or increases, since the dark body acts as a gravitational lens). As a result of painstaking searches, such events were identified. The nature of massive compact halo objects is not completely clear. Most likely, these are either cooled stars (brown dwarfs) or planet-like objects that are not associated with stars and travel around the galaxy on their own. Another representative of baryonic dark matter is hot gas recently discovered in galaxy clusters using X-ray astronomy methods, which does not glow in the visible range.
Nonbaryonic dark matter
The main candidates for nonbaryonic dark matter are the so-called WIMPs (short for Weakly Interactive Massive Particles- weakly interacting massive particles). The peculiarity of WIMPs is that they show almost no interaction with ordinary matter. This is why they are the real invisible dark matter, and why they are extremely difficult to detect. The mass of WIMP must be at least tens of times greater than the mass of a proton. The search for WIMPs has been carried out in many experiments over the past 20-30 years, but despite all efforts, they have not yet been detected.
One idea is that if such particles exist, then the Earth, as it orbits the Sun with the Sun around the galactic center, should be flying through a rain of WIMPs. Despite the fact that WIMP is an extremely weakly interacting particle, it still has a very small probability of interacting with an ordinary atom. At the same time, in special installations - very complex and expensive - a signal can be recorded. The number of such signals should change throughout the year because, as the Earth moves in orbit around the Sun, it changes its speed and direction relative to the wind, which consists of WIMPs. The DAMA experimental group, working at Italy's Gran Sasso underground laboratory, reports observed year-to-year variations in signal count rates. However, other groups have not yet confirmed these results, and the question essentially remains open.
Another method of searching for WIMPs is based on the assumption that during billions of years of their existence, various astronomical objects (Earth, Sun, the center of our Galaxy) should capture WIMPs, which accumulate in the center of these objects, and, annihilating each other, give rise to a neutrino stream . Attempts to detect excess neutrino flux from the center of the Earth towards the Sun and the center of the Galaxy were made on underground and underwater neutrino detectors MACRO, LVD (Gran Sasso Laboratory), NT-200 (Lake Baikal, Russia), SuperKamiokande, AMANDA (Scott Station -Amundsen, South Pole), but have not yet led to a positive result.
Experiments to search for WIMPs are also actively carried out at particle accelerators. In accordance with Einstein's famous equation E=mс 2, energy is equivalent to mass. Therefore, by accelerating a particle (for example, a proton) to very high energy and having collided it with another particle, we can expect the birth of pairs of other particles and antiparticles (including WIMP), the total mass of which is equal to the total energy of the colliding particles. But accelerator experiments have not yet led to a positive result.
Dark energy
At the beginning of the last century, Albert Einstein, wanting to provide cosmological model V general theory relativity independence of time, introduced into the equations of the theory the so-called cosmological constant, which he designated Greek letter"lambda" - Λ. This Λ was a purely formal constant, in which Einstein himself did not see any physical meaning. After the expansion of the Universe was discovered, the need for it disappeared. Einstein very much regretted his haste and called the cosmological constant Λ his greatest scientific error. However, decades later it turned out that the Hubble constant, which determines the rate of expansion of the Universe, changes with time, and its dependence on time can be explained by selecting the value of that very “erroneous” Einstein constant Λ, which contributes to the hidden density of the Universe. This part of the hidden mass came to be called “dark energy”.
Even less can be said about dark energy than about dark matter. First, it is evenly distributed throughout the Universe, unlike ordinary matter and other forms of dark matter. There is as much of it in galaxies and galaxy clusters as outside of them. Secondly, it has several very strange properties, which can only be understood by analyzing the equations of the theory of relativity and interpreting their solutions. For example, dark energy experiences antigravity: due to its presence, the rate of expansion of the Universe increases. Dark energy seems to push itself away, accelerating the scattering of ordinary matter collected in galaxies. Dark energy also has negative pressure, due to which a force arises in the substance that prevents it from stretching.
The main candidate for dark energy is vacuum. The vacuum energy density does not change as the Universe expands, which corresponds to negative pressure. Another candidate is a hypothetical super-weak field, called the quintessence. Hopes for clarifying the nature of dark energy are associated primarily with new astronomical observations. Progress in this direction will undoubtedly bring radically new knowledge to humanity, since in any case, dark energy must be a completely unusual substance, completely different from what physics has dealt with so far.
So, 95% of our world consists of something about which we know almost nothing. One can have different attitudes towards such a fact that is beyond any doubt. It can cause anxiety, which always accompanies a meeting with something unknown. Or disappointment, because such a long and complex path to constructing a physical theory that describes the properties of our world led to the statement: most of the Universe is hidden from us and unknown to us.
But most physicists are now feeling encouraged. Experience shows that all the riddles that nature posed to humanity were sooner or later resolved. Undoubtedly, the mystery of dark matter will also be resolved. And this will certainly bring completely new knowledge and concepts that we have no idea about yet. And perhaps we will meet new mysteries, which, in turn, will also be solved. But this will be a completely different story, which readers of “Chemistry and Life” will not be able to read until a few years later. Or maybe in a few decades.
Plays a decisive role in the development of the Universe. However, little is known about this strange substance yet. Professor Matthias Bartelmann - Heidelberg Institute for Theoretical Astrophysics - explains how dark matter research was carried out, answering a number of questions from journalists.
and how does it arise?
I have no idea! No one yet. It probably consists of heavy elementary particles. But no one knows if these are really particles. In any case, they are very different from everything we knew before.
Is it like discovering a whole new species of animal?
Yes, that's right, that's a good comparison.
Who discovered dark matter and when?
In 1933, Fritz Zwicky considered the motion of galaxies in galaxy clusters, which depends on the total mass of the cluster. The researcher noticed that the galaxies, given their calculated mass, move very quickly. This was the first hint of dark matter. No known matter could explain why stars in galaxies stick together: they must fly apart due to their high speed of rotation.
Gravitational lens Photo: Wissensschreiber
What other evidence is there?
A pretty good proof is the gravitational lens effect. Distant galaxies appear distorted to us because light rays are deflected from matter along their path. It's like looking through fluted glass. And the effect is stronger than it would be if only visible matter existed.
What does dark matter look like?
It cannot be seen, since there is no interaction between dark matter and electromagnetic radiation. This means that it does not reflect light and does not emit any radiation.
How do you study dark matter then? What instruments are needed for research?
We do not study dark matter specifically, but only its manifestations, for example, the gravitational lens effect. I'm a theorist. Actually, I just need my computer, a pen and a piece of paper. But I also use data from large telescopes in Hawaii and Chile.
Is it possible to depict dark matter?
Yes, you can create a kind of map of its distribution. Just like the elevation lines show on geographical map The contours of the mountain can be seen here by the density of the lines, where there is especially a lot of dark matter.
When did she appear?
Dark matter arose either directly at the Big Bang, or 10,000-100,000 years later. But we are still studying this.
How much dark matter exists?
No one can say this for sure. But based on latest research, we believe that there is approximately seven to eight times more dark matter in the Universe than visible matter.
Computer modeling shows the spread of dark matter in the form of a web, and we see its accumulation in the brightest areas
Photo: Volker Springel
Is there a relationship between dark energy and dark matter?
Probably not. Dark energy powers the accelerated expansion of the Universe, while dark matter holds galaxies together.
Where did she come from?
Dark matter is probably everywhere, but it is not distributed evenly - just like visible matter, it forms clumps.
What does dark matter mean for us and our worldview?
For Everyday life it doesn't matter. But in astrophysics it is very important, since it plays a decisive role in the development of the Universe.
What is our Universe made of? 4.9% - visible matter, 26.8% dark matter, 68.3% - dark energy Photo: Wissensschreiber
What will it cause in the future?
Probably nothing more. Previously, it was very important for the development of the Universe. Today it only continues to hold individual galaxies together. And as the Universe continues to expand, it becomes increasingly difficult for new dark matter structures to emerge.
Will it be possible in the future to directly image dark matter using instruments?
Yes it is possible. For example, it is possible to measure vibrations that occur when dark matter particles collide with atoms in a crystal. The same thing happens in a particle accelerator: if elementary particles, seemingly for no reason flying in an unexpected direction, then an unknown particle may be to blame. Then this would be further evidence of the existence of dark matter. Imagine: you are standing on a football field and there is a ball in front of you. He suddenly flies away without any apparent reason. Something invisible must have hit him.
What interests you most about your work?
I am attracted by the assumption that visible matter is only a small part of the whole, and we have no idea of the remainder.
Thank you for taking the time. We hope that you will learn even more about dark matter soon!
>What's happened dark matter and dark energy The Universe: structure of space with photos, volume in percentage, influence on objects, research, expansion of the Universe.
About 80% of the space is represented by material that is hidden from direct observation. This is about dark matter– a substance that does not produce energy or light. How did the researchers realize that it was dominant?
In the 1950s, scientists began to actively study other galaxies. During the analyses, they noticed that the Universe is filled with more material than can be caught by the “visible eye.” Proponents of dark matter emerged every day. Although there was no direct evidence of its existence, theories grew, as did workarounds for observation.
The material we see is called baryonic matter. It is represented by protons, neutrons and electrons. It is believed that dark matter is capable of combining baryonic and non-baryonic matter. For the Universe to remain in its usual integrity, dark matter must be present in an amount of 80%.
The elusive substance can be incredibly difficult to find if it contains baryonic matter. Among the candidates are brown and white dwarfs, as well as neutron stars. Supermassive black holes can also add to the difference. But they must have contributed more influence than what scientists saw. There are those who think that dark matter must consist of something more unusual and rare.
Hubble composite image of a ghostly ring of dark matter in the galaxy cluster Cl 0024+17
Most of the scientific world believes that the unknown substance is represented mainly by non-baryonic matter. The most popular candidate is WIMPS (weakly interacting massive particles), whose mass is 10-100 times greater than that of a proton. But their interaction with ordinary matter is too weak, making it more difficult to find.
Neutrinos, massive hypothetical particles that are larger in mass than neutrinos, but are characterized by their slowness, are now being examined very carefully. They haven't been found yet. A smaller neutral axiom and pristine photons are also considered as possible options.
Another possibility is that knowledge about gravity is outdated and needs to be updated.
Invisible dark matter and dark energy
But if we don’t see something, how can we prove that it exists? And why did we decide that dark matter and dark energy are something real?
The mass of large objects is calculated from their spatial movement. In the 1950s, researchers looking at spiral galaxies assumed that material close to the center would move much faster than material farther away. But it turned out that the stars were moving at the same speed, which meant there was much more mass than previously thought. The gas studied in elliptical types showed the same results. The same conclusion suggested itself: if you focus only on visible mass, then the galaxy clusters would have collapsed long ago.
Albert Einstein was able to prove that large universal objects are capable of bending and distorting light rays. This allowed them to be used as a natural magnifying lens. By studying this process, scientists were able to create a map of dark matter.
It turns out that most of our world is represented by a still elusive substance. You will learn more interesting things about dark matter if you watch the video.
Dark matter
Physicist Dmitry Kazakov about the overall energy balance of the Universe, the theory of hidden mass and dark matter particles:
If we talk about matter, then dark matter is certainly the leader in percentage. But overall it takes up only a quarter of everything. The universe abounds dark energy.
Since Big Bang the space began a process of expansion that continues today. The researchers believed that eventually the initial energy would run out and it would slow down. But distant supernovae demonstrate that space does not stop, but picks up speed. All this is only possible if the amount of energy is so huge that it overcomes the gravitational influence.
Dark matter and dark energy: a mystery explained
We know that the Universe is mostly dark energy. This is a mysterious force that causes space to increase the rate of expansion of the Universe. Another mysterious component is dark matter, which maintains contact with objects only through gravity.
Scientists can't see dark matter through direct observation, but the effects can be studied. They manage to capture light that is bent by the gravitational force of invisible objects (gravitational lensing). They also notice moments when the star rotates around the galaxy much faster than it should.
All this is explained by the presence huge amount an elusive substance that affects mass and speed. In fact, this substance is shrouded in mystery. It turns out that researchers can rather say not what is in front of them, but what “it” is not.
This collage shows images of six different galaxy clusters taken using space telescope NASA Hubble. The clusters were discovered during attempts to study the behavior of dark matter in galaxy clusters during their collision
Dark matter... dark. It does not produce light and is not observable in direct view. Therefore, we exclude stars and planets.
It does not act as a cloud of ordinary matter (such particles are called baryons). If baryons were present in dark matter, it would show up in direct observation.
We also exclude black holes, because they act as gravitational lenses that emit light. Scientists do not observe enough lensing events to calculate the amount of dark matter that must be present.
Although the Universe is a huge place, it all began with the smallest structures. It is believed that dark matter began to condense to create "building blocks" with normal matter, producing the first galaxies and clusters.
To find dark matter, scientists use various methods:
- The Large Hadron Collider.
- instruments like WNAP and the Planck space observatory.
- direct view experiments: ArDM, CDMS, Zeplin, XENON, WARP and ArDM.
- indirect detection: gamma ray detectors (Fermi), neutrino telescopes (IceCube), antimatter detectors (PAMELA), X-ray and radio sensors.
Methods for searching for dark matter
Physicist Anton Baushev on weak interactions between particles, radioactivity and the search for traces of annihilation:
Delving deeper into the mystery of dark matter and dark energy
Scientists have never been able to literally see dark matter, because it does not contact baryonic matter, which means it remains elusive to light and other types of electromagnetic radiation. But researchers are confident of its presence as they monitor the impact on galaxies and clusters.
Standard physics says that stars located at the edges of a spiral galaxy should slow down. But it turns out that stars appear whose speed does not obey the principle of location in relation to the center. This can only be explained by the fact that the stars feel the influence of invisible dark matter in the halo around the galaxy.
The presence of dark matter can also decipher some of the illusions observed in the depths of the universe. For example, the presence of strange rings and arcs of light in galaxies. That is, light from distant galaxies passes through the distortion and is amplified by an invisible layer of dark matter (gravitational lensing).
So far we have a few ideas about what dark matter is. the main idea- These are exotic particles that do not come into contact with ordinary matter and light, but have power in the gravitational sense. Now several groups (some using the Large Hadron Collider) are working on creating dark matter particles to study in the laboratory.
Others think the influence can be explained by a fundamental modification of gravitational theory. Then we get several forms of gravity, which differs significantly from the usual picture and the laws established by physics.
The Expanding Universe and Dark Energy
The situation with dark energy is even more confusing and the discovery itself became unpredictable in the 1990s. Physicists have always thought that the force of gravity works to slow down and one day may stop the process of universal expansion. Two teams took on the task of measuring the speed and both, to their surprise, detected acceleration. It's like you throw an apple into the air and know that it is bound to fall down, but it moves further and further away from you.
It became clear that acceleration was influenced by a certain force. Moreover, it seems that the wider the Universe, the more “power” this force gains. Scientists decided to call it dark energy.
