The next version of the structure of the Universe was put forward by physicist Frank Steiner from the University of Ulm (Universität Ulm), who, together with his colleagues, re-analyzed the data collected by the Wilkinson Microwave Anisotropy Probe (WMAP) space probe, which was once launched for detailed photography of the cosmic microwave background radiation.

However, do not rush to talk about the edges of the Universe. The fact is that this polyhedron is closed on itself, that is, having reached one of its faces, you will simply get back inside through the opposite side this multidimensional “Möbius loop”.

Interesting conclusions follow from this presentation. For example, that by flying on some “high-speed” rocket in a straight line, you can eventually return to the starting point, or, if you take a “very large” telescope, you can see in different sides space the same objects, only due to the finiteness of the speed of light - at different stages life.

Scientists tried to make such observations, but nothing similar to “mirror reflections” was found. Either because the model is incorrect, or because the “range” of modern observational astronomy is not enough. Nevertheless, the discussion about the shape and size of the Universe continues.

Now Steiner and his comrades have added new wood to the fire.

Planck weighs about two tons. It should cruise around the Lagrange point L2. As the satellite rotates around its axis, it will gradually capture a complete map of the microwave background with unprecedented accuracy and sensitivity (illustrations by ESA/AOES Medialab and ESA/C. Carreau).

The German physicist compiled several models of the Universe and checked how microwave background density waves are formed in them. He claims that the closest match to the observed cosmic microwave background radiation is provided by the donut universe, and even calculated its diameter. The “donut” turned out to be 56 billion light years across.

True, this torus is not quite ordinary. Scientists call it a 3-torus. Its actual form is difficult to imagine, but researchers explain how to at least try.

First, imagine how a regular “donut” is formed. You take a piece of paper and roll it into a tube, gluing two opposite edges together. Then you roll the tube into a torus, gluing its two opposite “exits” together.

With a 3-torus, everything is the same, except that the starting ingredient is not a sheet, but a cube, and you need to glue not the edges of the planes, but each pair of opposite faces. Moreover, glue it in such a way that, having left the cube through one of its faces, you will find that you again got inside through its opposite face.

Several experts who commented on Steiner's work noted that it does not definitively prove that the Universe is a “multidimensional donut”, but only that this shape is one of the most likely. Some scientists also add that the dodecahedron (which is often compared to a soccer ball, although this is incorrect) is still a “good candidate.”

Frank's answer to this is simple: the final choice between forms can be made after more accurate measurements of the cosmic microwave background radiation than those carried out by WMAP. And such a survey will soon be carried out by the European satellite Planck, which is scheduled to launch on October 31, 2008.

“From a philosophical point of view, I like the idea that the Universe is finite and one day we might be able to fully explore it and know everything about it. But since questions in physics cannot be solved by philosophy, I hope that Planck will answer them,” says Steiner.

In addition to classical cosmological models, general relativity allows us to create very, very, very exotic imaginary worlds.

There are several classical cosmological models constructed using general relativity, supplemented by the homogeneity and isotropy of space (see PM No. 6, 2012, How the expansion of the Universe was discovered). Einstein's closed universe has a constant positive curvature of space, which becomes static due to the introduction of the so-called cosmological parameter into the general relativity equations, which acts as anti-gravity field. In an accelerating de Sitter universe with uncurved space, there is no ordinary matter, but it is also filled with an anti-gravitational field. There are also closed and open universes of Alexander Friedman; the border world of Einstein - de Sitter, which gradually reduces the expansion rate to zero over time, and finally, the Lemaitre universe, the progenitor of Big Bang cosmology, growing from an ultra-compact initial state. All of them, and especially the Lemaitre model, became the predecessors of the modern standard model of our Universe.

There are, however, other universes, also generated by a very creative, as they say now, use of the general relativity equations. They correspond much less (or do not correspond at all) to the results of astronomical and astrophysical observations, but are often very beautiful, and sometimes elegantly paradoxical. True, mathematicians and astronomers have come up with them in such quantities that we will have to limit ourselves to only a few of the most interesting examples imaginary worlds.

From string to pancake

After the seminal works of Einstein and de Sitter appeared (in 1917), many scientists began to use the equations of general relativity to create cosmological models. One of the first to do this was the New York mathematician Edward Kasner, who published his solution in 1921.

His universe is very unusual. It contains not only gravitating matter, but also an anti-gravitating field (in other words, there is no Einstein cosmological parameter). It would seem that in this ideally empty world nothing can happen at all. However, Kasner admitted that his hypothetical universe would evolve differently in different directions. It expands along two coordinate axes, but narrows along the third axis. Therefore, this space is obviously anisotropic and geometrically similar to an ellipsoid. Since such an ellipsoid stretches in two directions and contracts along a third, it gradually turns into a flat pancake. At the same time, Kasner’s universe does not lose weight at all; its volume increases in proportion to age. IN starting moment this age is zero - and, therefore, the volume is also zero. However, Kasner's universes are born not from a point singularity, like Lemaitre's world, but from something like an infinitely thin spoke - its initial radius is equal to infinity along one axis and zero along the other two.

What is the secret of the evolution of this empty world? Since its space “shifts” in different ways along different directions, gravitational tidal forces arise, which determine its dynamics. It would seem that you can get rid of them if you equalize the expansion rates along all three axes and thereby eliminate the anisotropy, but mathematics does not allow such freedom. True, one can set two of the three velocities equal to zero (in other words, fix the dimensions of the universe along two coordinate axes). In this case, Kasner’s world will grow only in one direction, strictly proportional to time (this is easy to understand, since this is how its volume must increase), but that’s all we can achieve.

Kasner's universe can remain itself only if it is completely empty. If you add a little matter to it, it will gradually begin to evolve like the isotropic Einstein-de Sitter universe. In the same way, when a non-zero Einstein parameter is added to its equations, it (with or without matter) will asymptotically enter the regime of exponential isotropic expansion and turn into a de Sitter universe. However, such “additives” really only change the evolution of the already existing universe. At the moment of its birth, they practically do not play a role, and the universe evolves according to the same scenario.

Although the Kasner world is dynamically anisotropic, its curvature at any time is the same along all coordinate axes. However, the equations of general relativity allow for the existence of universes that not only evolve at anisotropic rates, but also have anisotropic curvature. Such models were built by the American mathematician Abraham Taub in the early 1950s. Its spaces can behave like open universes in some directions, and like closed ones in others. Moreover, over time they can change sign from plus to minus and from minus to plus. Their space not only pulsates, but literally turns inside out. Physically, these processes can be associated with gravitational waves, which deform space so strongly that they locally change its geometry from spherical to saddle-shaped and vice versa. All in all, strange worlds, although mathematically possible.

Vibrations of worlds

Soon after the publication of Kasner's work, articles by Alexander Friedman appeared, the first in 1922, the second in 1924. These papers presented amazingly elegant solutions to the equations of general relativity, which had an extremely constructive impact on the development of cosmology. Friedman's concept is based on the assumption that, on average, matter is distributed over outer space as symmetrically as possible, that is, completely homogeneous and isotropic. This means that the geometry of space at each moment of a single cosmic time is the same at all its points and in all directions (strictly speaking, such time still needs to be correctly determined, but in in this case this problem is solvable). It follows that the rate of expansion (or contraction) of the universe at any given moment is again independent of direction. Friedmann's universes are therefore completely different from Kasner's model.

In the first paper, Friedman built a model of a closed universe with constant positive curvature of space. This world arises from an initial point state with an infinite density of matter, expands to a certain maximum radius (and, therefore, maximum volume), after which it collapses again into the same special point (in mathematical language - a singularity).

However, Friedman did not stop there. In his opinion, the found cosmological solution does not necessarily have to be limited to the interval between the initial and final singularity; it can be extended in time both forward and backward. The result is an endless cluster of universes strung on a time axis, which border each other at singularity points. In the language of physics, this means that Friedmann's closed universe can oscillate endlessly, dying after each compression and being revived to new life in the subsequent expansion. This is a strictly periodic process, since all oscillations last the same length of time. Therefore, each cycle of the existence of the universe is an exact copy of all other cycles.

This is how Friedman commented on this model in his book “The World as Space and Time”: “Further, cases are possible when the radius of curvature changes periodically: the universe contracts into a point (into nothing), then again from a point it brings its radius to a certain value, then again, reducing the radius of its curvature, it turns into a point, etc. One involuntarily recalls the legend of Hindu mythology about the periods of life; It is also possible to talk about “the creation of the world from nothing,” but all this should still be considered as curious facts that cannot be reliably confirmed by insufficient astronomical experimental material.”

A few years after the publication of Friedman's articles, his models gained fame and recognition. Einstein became seriously interested in the idea of ​​an oscillating universe, and he was not alone. In 1932, Richard Tolman, a professor of mathematical physics and physical chemistry at Caltech, took on it. He was neither a pure mathematician, like Friedman, nor an astronomer and astrophysicist, like de Sitter, Lemaitre and Eddington. Tolman was a recognized authority on statistical physics and thermodynamics, which he first combined with cosmology.

The results turned out to be very non-trivial. Tolman came to the conclusion that the total entropy of the cosmos should increase from cycle to cycle. The accumulation of entropy leads to the fact that an increasing part of the energy of the universe is concentrated in electromagnetic radiation, which from cycle to cycle influences its dynamics more and more. Because of this, the length of the cycles increases, each next one becomes longer than the previous one. The oscillations remain, but cease to be periodic. In addition, in each new cycle the radius of Tolman's universe increases. Consequently, in the stage of maximum expansion it has the smallest curvature, and its geometry approaches Euclidean more and more and for a longer and longer time.

Richard Tolman missed one thing when designing his model interesting opportunity, which was brought to the attention of John Barrow and Mariusz Dąbrowski in 1995. They showed that the oscillatory mode of the Tolman universe is irreversibly destroyed when an antigravitational cosmological parameter is introduced. In this case, the Tolman universe at one of the cycles no longer contracts into a singularity, but expands with increasing acceleration and turns into a de Sitter universe, which the Kasner universe also does in a similar situation. Antigravity, like diligence, overcomes everything!

Universe in Mixer

In 1967, American astrophysicists David Wilkinson and Bruce Partridge discovered that cosmic microwave radiation, discovered three years earlier, from any direction arrives at Earth with almost the same temperature. Using a highly sensitive radiometer invented by their compatriot Robert Dicke, they showed that fluctuations in the temperature of relict photons do not exceed a tenth of a percent (according to modern data, they are much less). Since this radiation occurred earlier than 400,000 years after the Big Bang, Wilkinson and Partridge's results suggested that even if our Universe was not almost perfectly isotropic at the moment of its birth, it acquired this property without much delay.

This hypothesis posed a considerable problem for cosmology. In the first cosmological models, the isotropy of space was incorporated from the very beginning simply as a mathematical assumption. However, back in the middle of the last century it became known that the equations of general relativity make it possible to construct many non-isotropic universes. In the context of these results, the almost perfect isotropy of the cosmic microwave background radiation required an explanation.

This explanation appeared only in the early 1980s and turned out to be completely unexpected. It was built on a fundamentally new theoretical concept of ultra-fast (as they usually say, inflationary) expansion of the Universe in the first moments of its existence (see PM No. 7, 2012, Almighty inflation). In the second half of the 1960s, science was simply not ripe for such revolutionary ideas. But, as you know, in the absence of stamped paper they write on simple paper.

The prominent American cosmologist Charles Misner, immediately after the publication of the article by Wilkinson and Partridge, tried to explain the isotropy of microwave radiation using completely traditional means. According to his hypothesis, the inhomogeneities of the early Universe gradually disappeared due to the mutual “friction” of its parts, caused by the exchange of neutrino and light fluxes (in his first publication, Misner called this supposed effect neutrino viscosity). According to him, such viscosity can quickly smooth out the initial chaos and make the Universe almost perfectly homogeneous and isotropic.

Mizner's research program looked good, but did not bring practical results. The main reason for its failure was again revealed by microwave analysis. Any processes involving friction generate heat; this is an elementary consequence of the laws of thermodynamics. If the primary inhomogeneities of the Universe were smoothed out due to neutrino or some other viscosity, the energy density of the cosmic microwave background radiation would differ significantly from the observed value.

As the American astrophysicist Richard Matzner and his already mentioned English colleague John Barrow showed in the late 1970s, viscous processes can eliminate only the smallest cosmological inhomogeneities. To completely “smooth out” the Universe, other mechanisms were required, and they were found within the framework of inflationary theory.

But still Mizner obtained many interesting results. In particular, in 1969 he published a new cosmological model, the name of which he borrowed... from a kitchen electrical appliance, a home mixer produced by the company Sunbeam Products! Mixmaster Universe all the time it beats in severe convulsions, which, according to Misner, force light to circulate along closed paths, mixing and homogenizing its contents. However, later analysis of this model showed that, although photons in Miesner's world do indeed travel long distances, their mixing effect is very insignificant.

Nevertheless Mixmaster Universe very interesting. Like Friedmann's closed universe, it arises from zero volume, expands to a certain maximum and contracts again under the influence of its own gravity. But this evolution is not smooth, like Friedman’s, but absolutely chaotic and therefore completely unpredictable in detail. In its youth, this universe oscillates intensely, expanding in two directions and contracting in a third - like Kasner. However, the orientations of expansions and contractions are not constant - they change places chaotically. Moreover, the frequency of oscillations depends on time and tends to infinity as it approaches the initial instant. Such a universe undergoes chaotic deformations, like jelly trembling on a saucer. These deformations can again be interpreted as the manifestation of gravitational waves moving in different directions, much more violent than in the Kasner model.

Mixmaster Universe entered the history of cosmology as the most complex of the imaginary universes created on the basis of “pure” general relativity. Since the early 1980s, the most interesting concepts of this kind began to use the ideas and mathematical apparatus of quantum field theory and the theory elementary particles, and then, without much delay, superstring theory.

> What is the shape of the Universe?

In what form does the Universe exist?: exploration of infinite space, WMAP cosmic microwave background map, geometry of the Universe and estimated shapes with photos.

Is it even worth thinking about what shape the Universe is? What are we dealing with? Sphere? Cone? Flat? And how to determine this?

The Universe is the only place in which we exist and beyond which we cannot escape (because there are none). Thanks to physical laws, natural constants and erupting heavy metals, we managed to create life on a small rocky ball, lost in one of many galaxies.

But don't you want to know where you live? Just get the opportunity to look at everything from the outside, as we did with our native planet Earth. For you to see? Endless darkness? Lots of bubbles? Snow globe? A rat maze in the hands of aliens or something else? What is the shape of the Universe?

Well, the answer is much simpler, but also stranger. People began to think about the shape of the Universe back in ancient times. And people, due to lack of information, offered some pretty wonderful things. In Hindu texts it was an egg in the shape of a man. The Greeks saw an island floating in the void. Aristotle says that the Universe has the shape of an infinite sphere or simply a turtle.

Interestingly, Albert Einstein's contributions help test each of these models. Scientists have come up with three favorite shapes: positively curved, negatively curved and flat. We understand that the Universe exists in 4 dimensions and any of the figures border on crazy Lovecraftian geometry. So use your maximum imagination and let's go!

With the positively curved version, we get a four-dimensional sphere. This variety has an end, but does not have a clear border. More precisely, two particles would cross it before returning to the start. You can even test it at home. Take balloon and draw a straight line until it returns to the starting point.

This species fits into three dimensions and appears if there is a huge amount of energy in space. To completely bend or close, the space would have to stop expanding. This will happen if a large-scale energy reserve appears that can create an edge. Current evidence shows that expansion is a never-ending process. So this scenario is out of the question.

The negatively curved shape of the Universe is a four-dimensional saddle. It is open, without boundaries in space and time. There is little energy here, so the Universe will not stop expanding. If you send two particles along straight lines, they will never meet, but will simply diverge until they go in different directions.

If a critical amount of energy fluctuates between extremes, then after infinity the expansion will stop. This is a flat Universe. Here the two particles will travel in parallel, but will never separate or meet.

It's easy to imagine these three shapes, but there are many more options. The soccer ball is reminiscent of the idea of ​​a spherical universe. The donut is technically flat, but connected at certain points. Some believe that huge warm and cool spots speak in favor of this option. You can see the supposed shapes of the Universe in the photo.

And now we come to the pipe. This is another type of negative curvature. One end will be narrowed, and the other will be wide. In the first half, everything seemed narrow and existed in two dimensions. And in a wide one it would be possible to travel maximum distances, but you would have to return in reverse side(the direction changes during the bend).

Then what? What are we dealing with? Bagel? Wind instrument? A giant head of cheese? Scientists have not yet ruled out options with a pipe and a saddle.

Grumps will argue that all this is pointless and we will never know the truth. But let's not be so categorical. Planck's latest data show that our Universe is... flat! Infinitely finite, completely uncurved and with a precise critical amount of energy.

It's unthinkable that not only can we find out what the Universe looks like, but there are people who are constantly trying to find even more information. If “flat” seems boring to you, then don’t forget that we don’t have enough information yet. So it's entirely possible that we could all exist in a giant donut.

Such statements are akin to those great ideas that radically change the view of our place in this world. One of these revolutions in consciousness occurred in 1543, when Nicolaus Copernicus showed that the Earth is not the center of the Universe. In the 20s of the 20th century, Edwin Hubble, noticing that galaxies in the Universe were moving away from each other, gave birth to the idea that our Universe did not exist forever, but was formed as a result of a certain event - the Big Bang. Now we are on the verge of a new discovery. If the limits of the Universe are found, we will be faced with a new, even more difficult question: what is there on the other side of the boundaries?

Let's navigate by the stars

The infinity of the Universe implies that it must be infinite not only in space, but also in time, and therefore have an infinite number of stars. In this case, our sky would be completely dotted with luminaries and dazzlingly bright around the clock. However, the darkness of the sky indicates that the cosmos did not exist forever. According to the popular theory, it all began with the Big Bang, which gave rise to the very existence and expansion of matter. This concept itself refutes the idea of ​​the eternity of the Universe, and therefore undermines the belief in its infinity. At the same time, the Big Bang theory creates certain difficulties for astronomers searching for the boundaries of our outer space.

“The fact is that traveling over vast distances takes light years, and therefore scientists always receive outdated data. The space traversed by light in the early Universe grew due to its subsequent expansion. The stars closest to us are relatively young; distant objects are already thousands of years old, and if you look at other galaxies, then billions. However, we do not see all galaxies. 13.7 billion years is the maximum available to us,” explains Neil Cornish, an astrophysicist from the Montana State University. A kind of barrier to our vision is the relict radiation, formed approximately 380 thousand years after the Big Bang, when the Universe expanded and cooled so much that atoms appeared. This radiation is something like a child's photograph of space, in which it is captured even before the stars appeared. Behind it there can exist both boundaries and an endlessly continuing Universe. But, despite the power of telescopes, this area remains invisible.

Space music

CMB prevents scientists from peering into the farthest reaches of space, but at the same time it carries very valuable information contained in the microwave background. Scientists suggest that if the Universe were of unlimited size, waves of all possible lengths could be found in it. However, in fact, the wave spectrum of space is very narrow: truly large waves NASA's WMAP apparatus, designed to study cosmic microwave background radiation, has never detected it. "The universe has properties musical instrument, inside which the wavelength cannot exceed its length. We realized that the Universe does not vibrate at long wavelengths, which confirmed its finitude,” says Jean Pierre Luminet from the Paris Observatory in France.

The only thing left to do is to determine its boundaries and shape. Glen Starkmann, a physicist from Canada working at Cleveland's Case Western University, believes he has found a way to determine the boundaries of the Universe, even if they are further than our line of sight. This can be done again using waves. “The sound waves that spread throughout the Universe during its youth can tell a lot. The shape of the Universe, like the shape of a drum, determines what type of vibrations will occur in it,” says Glen. His team plans to use spectral analysis to our Universe in order to determine its shape based on the sounds it makes. True, these studies are long-term, and it may take years to find an answer.

We live in a donut...

However, there is another way to find out whether the Universe has boundaries. This is what Zhanna Levin, a theorist from Cambridge University, is currently doing. She explains the principle of building the Universe using the good old computer game “Asteroids” as an example. If a player-controlled spaceship goes up, off the screen, it will immediately appear below. Such a strange maneuver becomes understandable if you mentally roll the screen into a tube, like a magazine: it turns out that the device is simply moving in a circle.
“In the same way, we, living inside the Universe, cannot get out. We do not have access to a dimension from which we could look at our three-dimensional Universe from the outside. Take, for example, a donut - this, by the way, is a completely suitable form for the Universe in this case - although its surface is clearly defined, none of those living inside will stumble upon its limits: it seems to them that no boundaries exist,” says Zhanna.

However, there is still a chance to recognize these limits, albeit scanty - you need to monitor how the light behaves. Let's imagine that the Universe is a room, and you, armed with a flashlight, stand in its center. The light from the flashlight will reach the wall behind you and then reflect off the wall opposite. and you will see the reflection of your own back in it. The same rules can work in limited space. "Light portraits" can be reflected from supposed space walls and thus duplicated many times, but with some changes. And be the Universe a little more than Earth, the light would instantly circle around it, and distorted images of the planet would appear throughout the sky. But space is so vast that light will take billions of years to travel around it and be reflected.

But let's return to our “steering wheels”. Zhanna Levin, with her theory of the donut-shaped Universe, found support in the person of Frank Steiner from the University of Ulm in Germany. After analyzing the data obtained using WMAP, this scientist concluded that the Donut Universe provides the greatest agreement with the observed cosmic microwave background radiation. His team also tried to guess the likely size of the Universe - according to research, it could reach 56 billion light years across.

...or in a soccer ball?

Jean Pierre Luminet, with all his respect for Ms. Levine's donut, is still confident that the Universe is a spherical dodecahedron or, more simply, a soccer ball: twelve pentagonal rounded surfaces arranged symmetrically. In fact, the theory of the French scientist does not particularly contradict the scientific research of Zhanna Levin with her game of “Asteroids”. The same scheme works here - leaving one of the sides, you find yourself on the opposite. For example, if you fly in a straight line on some “high-speed” rocket, you can eventually return to the starting point. Jean-Pierre does not deny the principle mirror reflections. He is confident that if a super-powerful telescope existed, it would be possible to see the same objects in different directions of space, only at different stages of life. But when the edges of the dodecahedron are billions of light years away, faint reflections on them cannot be noticed even by the most observant astronomers.

Let us note that Lumine with his concept soccer ball an ally was found - mathematician Geoffrey Weeks. This scientist claims that the waves in the cosmic microwave background look exactly the same as they would look if they appeared inside a regular geometric figure with twelve pentagonal faces.

Inflation on a universal scale

The first moment of the life of the Universe played huge role in its further evolution. Scientists are still building complex hypotheses about inflation - a very short period of time, much less than a second, during which the size of the Universe increased a hundred trillion times. Most scientists are inclined to believe that the expansion of the Universe is still continuing. And it would seem that the theory of the infinity of space is a logical continuation of the idea of ​​inflation.

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Computer model of the Universe

However, Andy Albracht, a theoretical physicist at the University of California, Davis, has a different opinion on this matter: although the expansion of the Universe continues to this day, this process still has limits. To explain his theory, Andy chose a metaphor for the universe soap bubble. Traditional inflation theory allows for an infinite expansion of this bubble, but even kindergarteners know that sooner or later the bubble must burst. Andy believes that, having reached its maximum, inflation should stop. And this maximum is not as great as we think. According to Olbracht, the Universe is only 20% larger than the space we see. “Of course, it is incredibly difficult to come from infinity to such a tiny size - only some 20% larger! I even started to feel claustrophobic,” the scientist jokes. Of course, Olbracht’s conclusions are very controversial and require factual confirmation, but for now most astronomers believe that inflation will not die out very soon.

Dark Stream and Other Universes

The expansion of the Universe, by the way, is the best explanation for the movement of galaxies in the territory visible to us. True, some features of this galactic movement are puzzling. A group of NASA specialists led by astrophysicist Alexander Kashlinsky, studying microwave and X-ray radiation, discovered that about eight hundred distant galaxy clusters are moving together in one direction at a speed of a thousand kilometers per second, as if they are attracted by some kind of magnet. This universal movement was called the "dark flow." According to the latest data, it already covers 1400 galaxies. They are heading towards an area located more than three billion light years from Earth. Scientists suggest that just somewhere there, beyond the limits of observation, there is a huge mass that attracts matter. However, according to the existing theory, the matter after the Big Bang, which gave birth to our Universe, was distributed more or less evenly, which means that there cannot be concentrations of masses with such fantastic power. Then what's there?

The answer to this question was given by theoretical physicist Laura Mersini-Hoftan, leader of the group from the University of North Carolina. She seriously considers the existence of another Universe located next to ours. Her conclusions, which seem incredible at first glance, are quite compatible with the theory of inflation and the “soap bubble” voiced by Andy Albracht, as well as with the “dark flow” of Alexander Kashlinsky. Now the research of these scientists will form a single picture like a puzzle. The dark flow observed in our outer space may be provoked by one of the neighboring “bubbles” - another Universe.

Hoftan explains the multiplicity of universes using the theory of probability. She considers the birth of our world a miracle; it could easily not have appeared: the chances of its occurrence are negligible and amount to 1 in 10133.

“We can ask the question about the origin of the Universe when we have a multiple structure in which it was formed - places in which conditions are favorable for its origin. In other words, we can imagine many Big Bangs and many universes,” notes Hoftan. For clarity, she compares these favorable places to hotel rooms. The universe can only originate in a free “room” and exist there alone. However, this does not mean that another such cosmoworld cannot move into the “room” through the wall. But if our Universe is a hotel room, should we be able to hear our neighbors? In 2007, the WMAP apparatus recorded an unusual region of significantly reduced background radiation, which indicates the absence of matter in it. According to the scientist, the only explanation for such a cold and absolute void is that some other forces are at work there, perhaps the presence of another Universe, the huge mass of which attracts neighboring matter. And although these “alien” objects are beyond our sight, our neighbor still makes itself felt with messages in the form of a cold spot and a stream of galactic clusters.

Of course, the scientific community has had mixed reactions to the findings about multiple universes. However, scientists trying to characterize outer space are ready for new revolutions in science. Our Universe, previously considered infinite, may cease to be so and take its rightful place in space, among such a number of universes that it is impossible to even imagine.

Cosmogonist scientists still do not know the exact answer to the question about the shape of the Universe. As, indeed, to questions about its finitude-infinity or closedness-openness. Many cosmogonists are united by the Big Bang hypothesis, which in a simplified presentation looks like this. The Big Bang: how it all began... Before the Big Bang, there were no concepts of “here” and “there”, “before” and “after”. All the matter of the world was concentrated at one point with practically zero size and, accordingly, almost infinite density. Time did not exist either, because nothing happened at the point itself, and beyond its boundaries nothing existed and, therefore, could not happen. Then, for some reason, the point (it is also called a “cosmic egg”) exploded. The newborn matter quickly, at the speed of light, poured into the surrounding “nothing”. Energy and forces appeared - nuclear, electromagnetic, gravitational. Time appeared and began to flow. Matter began to swirl in spirals of nebulae. Stars appeared, and then planets. Billions of years later, on the third planet, an unremarkable, ordinary yellow dwarf, located on the periphery of an unremarkable, ordinary spiral galaxy, the first protobacterium crawled out of the primordial ocean onto land. And after another billion years, the descendants of this protobacterium began to puzzle over various cosmogonic questions. The universe is great but finite The Big Bang hypothesis puts the age of the Universe at 15 (approximately!) billion years. If the hypothesis is incorrect, then the age estimate is incorrect. Maybe there was no explosion, and the Universe has always existed? But if the hypothesis is correct, then the answer to the question about the size of the Universe becomes clear. If it is correct, every schoolchild can easily calculate the size of the Universe. In fact, you just need to multiply time (15 billion years) by the speed of matter expansion. That is, at the speed of light - 300,000 kilometers per second. Most likely, this speed becomes somewhat less over the years, but for ease of calculation we will consider it constant. Have you multiplied it? Yes, it turned out to be a huge number, with many zeros... but still not infinite. Conclusion: The Universe is great, but finite. And therefore, it must have not only size, but also shape. And this is where the fun begins.

The universe can be the most different forms: flat, open or closed On the question of the shape of the Universe It is most logical and simplest to assume that the Universe has the shape of a sphere. In fact, if matter scatters from a single center at a constant speed, then what could it be if not a sphere? But if the speed is not constant and the Universe is not closed and homogeneous, then it can be any shape. For example, a straight or curved four-dimensional plane. In this case, the Universe is not closed, eternal and infinite. Scientists are trying to obtain information about the shape of the Universe by studying the so-called cosmic microwave background radiation. The beginning of all beginnings, or the Big Bang, was accompanied by the release of not only matter, but also radiation. This electromagnetic radiation, called relict radiation, has its own, unchanging physical characteristics, which allow astrophysicists to distinguish it from the vast variety of other "cosmic rays". It is believed that cosmic microwave background radiation still uniformly fills the Universe. Its existence was experimentally confirmed in 1965. Is the universe shaped like a bottle?

This is what a Klein bottle looks like (a closed one-sided surface) While studying cosmic microwave background radiation, the Soviet scientist D.D. Back in the middle of the last century, Ivanenko put forward the assumption that the Universe, firstly, is closed, and secondly, does not everywhere obey the laws of Euclidean geometry. Not conforming to Euclidean geometry means that somewhere there are places where parallel lines intersect and even flow into one another. The closedness of the Universe means that it may be “closed on itself”: having set off on a journey from one point (say, from planet Earth) and moving, as it seems to us, strictly in a straight line, we will eventually find ourselves there, on Earth - although after a very long time large number years. Indirect confirmation of the theory of D.D. Ivanenko and his followers were received in 2001. The American space probe WMAP (Wilkinson Microwave Anisotropy Probe) transmitted to Earth data on fluctuations (changes, fluctuations) in the temperature of the cosmic microwave background radiation. Astrophysicists were interested in the size and nature of the distribution of these fluctuations. Computer modeling was carried out, showing that such a nature of fluctuations can be observed only if the Universe is limited and closed on itself. Even a ray of light, propagating in space, must return to its starting point after a certain (long) period of time. This means that astronomers on Earth can, for example, observe the same galaxy in different parts sky, and from different sides! If the WMAP data is confirmed, our views on the Universe will change very much. Firstly, it will be relatively small - no more than 10 billion light years in diameter. Secondly, its shape may turn out to be a torus (donut), or even something completely exotic, for example, a Klein bottle closed on itself. In addition, this will mean that we will be able to observe the entire Universe and make sure that everywhere the same physical laws apply.