You probably think that the universe is infinite? May be so. It is unlikely that we will ever know this for sure. It will not be possible to take in our entire universe with a glance. Firstly, this fact stems from the concept of the “big bang”, which states that the universe has its own birthday, so to speak, and, secondly, from the postulate that the speed of light is a fundamental constant. By now, the observable universe, which is 13.8 billion years old, has expanded in all directions to a distance of 46.1 billion light years. The question arises: what was the size of the universe then, 13.8 billion years ago? This question was asked to us by someone Joe Muscarella. Here's what he writes:

“I have seen different answers to the question of what the size of our universe was shortly after the period of cosmic inflation ended. One source says 0.77 centimeters, another says it's the size of a soccer ball, and a third says it's larger than the size of the observable universe. So which one is it? Or maybe something in between?”

Context

How dark matter shaped the Universe

The New Republic 11/01/2015

Big Bang and "black hole"

Die Welt 02/27/2015

How the Universe created man

Nautilus 01/27/2015 By the way, last year just gives us a reason to talk about Einstein and the essence of space-time, because last year we celebrated our centenary general theory relativity. So let's talk about the universe.

When we observe distant galaxies through a telescope, we can determine some of their parameters, for example the following:

- redshift (i.e. how much the light emitted by them has shifted relative to inertial system countdown);

— object brightness (i.e. measure the amount of light emitted by a distant object);

— angular radius of the object.

These parameters are very important, because if the speed of light is known (one of the few parameters that we know), as well as the brightness and size of the observed object (we also know these parameters), then the distance to the object itself can be determined.

In fact, you have to be content with only approximate characteristics of the brightness of the object and its size. If an astronomer observes a supernova explosion in some distant galaxy, then the corresponding parameters of other supernovae located in the neighborhood are used to measure its brightness; we assume that the conditions under which these supernovae exploded are similar, and between the observer and space object there is no interference. Astronomers identify the following three types of factors that determine the observation of a star: stellar evolution (difference between objects depending on their age and distance), exogenous factor(if the real coordinates of the observed objects differ significantly from the hypothetical ones) and the interference factor (if, for example, the passage of light is affected by interference, such as dust) - and this is all in addition to other factors unknown to us.

By measuring the brightness (or size) of the observed object, using the brightness/distance ratio, you can determine the distance of the object from the observer. Moreover, from the redshift characteristics of an object, one can determine the extent of the expansion of the universe during the time during which the light from the object reaches the Earth. Using the relationship between matter-energy and space-time, which is explained by Einstein's general theory of relativity, we can consider all possible combinations various forms matter and energy available on this moment in the Universe.

But that is not all!

If you know what parts the universe consists of, then using extrapolation you can determine its size, as well as find out what happened at any stage of the evolution of the universe, and what the energy density was at that time. As you know, the universe consists of the following components:

— 0.01% — radiation (photons);

- 0.1% - neutrinos (heavier than photons, but a million times lighter than electrons);

- 4.9% - ordinary matter, including planets, stars, galaxies, gas, dust, plasma and black holes;

- 27% - dark matter, i.e. the kind of it that participates in gravitational interaction, but different from all particles Standard model;

— 68% — dark energy, which causes the expansion of the universe.

As you can see, dark energy is an important thing; it was discovered quite recently. For the first nine billion years of its history, the universe consisted primarily of matter (a combination of ordinary matter and dark matter). However, during the first few millennia, radiation (in the form of photons and neutrinos) was an even more important construction material than matter!

Note that each of these components of the universe (i.e. radiation, matter and dark energy) has a different effect on the rate of its expansion. Even if we know that the universe is 46.1 billion light years in extent, we must know the exact combination of its constituent elements at each stage of its evolution in order to calculate the size of the universe at any point in time in the past.

- when the universe was about three years old, the diameter of the Milky Way was one hundred thousand light years;

- when the universe was one year old, it was much hotter and denser than it is now; average temperature exceeded two million degrees Kelvin;

- one second after its birth, the universe was too hot for stable nuclei to form in it; at that moment, protons and neutrons were floating in a sea of ​​hot plasma. In addition, at that time the radius of the universe (if we take the Sun as the center of the circle) was such that only seven of all the currently existing star systems closest to us could fit into the described circle, the most distant of which would be Ross 154 (Ross 154 - a star in the constellation Sagittarius, distance 9.69 light years from the Sun - approx. lane);

- when the age of the universe was only one trillionth of a second, its radius did not exceed the distance from the Earth to the Sun; in that era, the expansion rate of the universe was 1029 times greater than it is now.

If you wish, you can see what happened at the final stage of inflation, i.e. just before the Big Bang. To describe the state of the universe at its most early stage its birth, one could use the singularity hypothesis, but thanks to the inflation hypothesis, the need for a singularity disappears completely. Instead of a singularity, we talk about a very rapid expansion universe (i.e., inflation) that occurred for some time before the hot, dense expansion that gave rise to the present universe occurred. Now let's move on to final stage inflation of the universe (time interval between 10 minus 30 - 10 minus 35 seconds). Let's look at what the size of the universe was when inflation stopped and the big bang happened.

Here we are talking about the observable part of the universe. Its true size is certainly much larger, but we don't know how much. At the best approximation (based on data contained in the Sloan Digital Sky Survey (SDSS) and information received from space observatory Planck), if the universe is curved and folded, then its observable part is so indistinguishable from the “uncurved” one that its entire radius must be at least 250 times greater than radius observed part.

In truth, the extent of the universe may even be infinite, since the way it behaved early stage inflation is unknown to us except for the last fraction of a second. But if we talk about what happened during inflation in the observable part of the universe at the very last moment (between 10 minus 30 and 10 minus 35 seconds) before the Big Bang, then we know the size of the universe: it varies between 17 centimeters (at 10 at minus 35 seconds) and 168 meters (at 10 at minus 30 seconds).

What is seventeen centimeters? That's almost the diameter of a soccer ball. So, if you want to know which of the indicated sizes of the universe is closest to the real one, then stick to this figure. What if we assume dimensions smaller than a centimeter? This is too little; however, if we take into account the limitations imposed by space microwave radiation, then it turns out that the expansion of the universe could not end at such high level energies, and therefore the above-mentioned size of the universe at the very beginning of the “Big Bang” (i.e., a size not exceeding a centimeter) is excluded. If the size of the universe exceeded the current one, then in this case it makes sense to talk about the existence of an unobservable part of it (which is probably correct), but we have no way to measure this part.

So, what was the size of the universe at the time of its origin? According to the most authoritative mathematical models, describing the stage of inflation, it turns out that the size of the universe at the time of its origin will fluctuate somewhere between the size of a human head and a city block built up with skyscrapers. And there, you see, only some 13.8 billion years will pass - and the universe in which we live appeared.

Did you know that the Universe we observe has fairly definite boundaries? We are used to associating the Universe with something infinite and incomprehensible. However modern science to the question about the “infinity” of the Universe offers a completely different answer to such an “obvious” question.

According to modern ideas, the size of the observable universe is approximately 45.7 billion light years (or 14.6 gigaparsecs). But what do these numbers mean?

The first question that comes to mind to an ordinary person– how can the Universe not be infinite? It would seem that it is indisputable that the container of all that exists around us should have no boundaries. If these boundaries exist, what exactly are they?

Let's say some astronaut reaches the boundaries of the Universe. What will he see in front of him? A solid wall? Fire barrier? And what is behind it - emptiness? Another Universe? But can emptiness or another Universe mean that we are on the border of the universe? After all, this does not mean that there is “nothing” there. Emptiness and another Universe are also “something”. But the Universe is something that contains absolutely everything “something”.

We arrive at an absolute contradiction. It turns out that the boundary of the Universe must hide from us something that should not exist. Or the boundary of the Universe should fence off “everything” from “something”, but this “something” should also be part of “everything”. In general, complete absurdity. Then how can scientists declare the limiting size, mass and even age of our Universe? These values, although unimaginably large, are still finite. Does science argue with the obvious? To understand this, let's first trace how people came to our modern understanding of the Universe.

Expanding the boundaries

Since time immemorial, people have been interested in what the world around them is like. There is no need to give examples of the three pillars and other attempts of the ancients to explain the universe. As a rule, in the end it all came down to the fact that the basis of all things is the earth's surface. Even in the times of antiquity and the Middle Ages, when astronomers had extensive knowledge of the laws of planetary motion along the “stationary” celestial sphere, The Earth remained the center of the Universe.

Naturally, back in Ancient Greece there were those who believed that the Earth revolves around the Sun. There were those who spoke about the many worlds and the infinity of the Universe. But constructive justifications for these theories arose only at the turn of the scientific revolution.

In the 16th century, Polish astronomer Nicolaus Copernicus made the first major breakthrough in knowledge of the Universe. He firmly proved that the Earth is only one of the planets revolving around the Sun. Such a system greatly simplified the explanation of such a complex and intricate movement of planets in the celestial sphere. In the case of a stationary Earth, astronomers had to come up with all sorts of clever theories to explain this behavior of the planets. On the other hand, if the Earth is accepted as moving, then an explanation for such intricate movements comes naturally. This is how I became stronger in astronomy new paradigm called heliocentrism.

Many Suns

However, even after this, astronomers continued to limit the Universe to the “sphere fixed stars" Until the 19th century, they were unable to estimate the distance to the stars. For several centuries, astronomers have tried to no avail to detect deviations in the position of stars relative to the Earth’s orbital movement (annual parallaxes). The instruments of those times did not allow such precise measurements.

Finally, in 1837, the Russian-German astronomer Vasily Struve measured parallax. This marked new step in understanding the scale of space. Now scientists could safely say that the stars are distant similarities to the Sun. And our luminary is no longer the center of everything, but an equal “resident” of an endless star cluster.

Astronomers have come even closer to understanding the scale of the Universe, because the distances to the stars turned out to be truly monstrous. Even the size of the planets’ orbits seemed insignificant in comparison. Next it was necessary to understand how the stars are concentrated in .

Many Milky Ways

The famous philosopher Immanuel Kant anticipated the foundations of the modern understanding of the large-scale structure of the Universe back in 1755. He hypothesized that the Milky Way is a huge rotating star cluster. In turn, many of the observed nebulae are also more distant “milky ways” - galaxies. Despite this, until the 20th century, astronomers believed that all nebulae are sources of star formation and are part of the Milky Way.

The situation changed when astronomers learned to measure distances between galaxies using . The absolute luminosity of stars of this type strictly depends on the period of their variability. Comparing them absolute luminosity with visible, possible with high accuracy determine the distance to them. This method was developed in the early 20th century by Einar Hertzschrung and Harlow Scelpi. Thanks to him, the Soviet astronomer Ernst Epic in 1922 determined the distance to Andromeda, which turned out to be an order of magnitude larger size Milky Way.

Edwin Hubble continued Epic's initiative. By measuring the brightness of Cepheids in other galaxies, he measured their distance and compared it with the redshift in their spectra. So in 1929 he developed his famous law. His work definitively disproved the established view that the Milky Way is the edge of the Universe. Now he was one of the many galaxies that had once considered him integral part. Kant's hypothesis was confirmed almost two centuries after its development.

Subsequently, the connection discovered by Hubble between the distance of a galaxy from an observer relative to the speed of its removal from him, made it possible to draw a complete picture of the large-scale structure of the Universe. It turned out that the galaxies were only an insignificant part of it. They connected into clusters, clusters into superclusters. In turn, superclusters form the largest of known structures in the Universe there are threads and walls. These structures, adjacent to huge supervoids (), constitute the large-scale structure of the currently known Universe.

Apparent infinity

It follows from the above that in just a few centuries, science has gradually fluttered from geocentrism to a modern understanding of the Universe. However, this does not answer why we limit the Universe today. After all, until now we were talking only about the scale of space, and not about its very nature.

The first who decided to justify the infinity of the Universe was Isaac Newton. Discovering the law universal gravity, he believed that if space were finite, all her bodies would sooner or later merge into a single whole. Before him, if anyone expressed the idea of ​​​​the infinity of the Universe, it was exclusively in a philosophical vein. Without any reason scientific justification. An example of this is Giordano Bruno. By the way, like Kant, he was many centuries ahead of science. He was the first to declare that stars are distant suns, and planets also revolve around them.

It would seem that the very fact of infinity is quite justified and obvious, but the turning points of science of the 20th century shook this “truth”.

Stationary Universe

The first significant step towards developing a modern model of the Universe was taken by Albert Einstein. Your model stationary universe the famous physicist introduced it in 1917. This model was based on the general theory of relativity, which he had developed a year earlier. According to his model, the Universe is infinite in time and finite in space. But, as noted earlier, according to Newton, a Universe with a finite size must collapse. To do this, Einstein introduced the cosmological constant, which compensated gravitational attraction distant objects.

No matter how paradoxical it may sound, Einstein did not limit the very finitude of the Universe. In his opinion, the Universe is a closed shell of a hypersphere. An analogy is the surface of an ordinary three-dimensional sphere, for example, a globe or the Earth. No matter how much a traveler travels across the Earth, he will never reach its edge. However, this does not mean that the Earth is infinite. The traveler will simply return to the place from which he began his journey.

On the surface of the hypersphere

In the same way, a space wanderer, traversing Einstein’s Universe on a starship, can return back to Earth. Only this time the wanderer will move not along the two-dimensional surface of a sphere, but along the three-dimensional surface of a hypersphere. This means that the Universe has a finite volume, and therefore a finite number of stars and mass. However, the Universe has neither boundaries nor any center.

Einstein came to such conclusions by connecting in his famous theory space, time and gravity. Before him, these concepts were considered separate, which is why the space of the Universe was purely Euclidean. Einstein proved that gravity itself is a curvature of space-time. This radically changed early ideas about the nature of the Universe, based on classical Newtonian mechanics and Euclidean geometry.

Expanding Universe

Even the discoverer himself " new universe“was not a stranger to delusions. Although Einstein limited the Universe in space, he continued to consider it static. According to his model, the Universe was and remains eternal, and its size always remains the same. In 1922 Soviet physicist Alexander Friedman significantly expanded this model. According to his calculations, the Universe is not static at all. It can expand or contract over time. It is noteworthy that Friedman came to such a model based on the same theory of relativity. He managed to apply this theory more correctly, bypassing the cosmological constant.

Albert Einstein did not immediately accept this “amendment.” This new model came to the aid of the previously mentioned Hubble discovery. The recession of galaxies indisputably proved the fact of the expansion of the Universe. So Einstein had to admit his mistake. Now the Universe had a certain age, which strictly depends on the Hubble constant, which characterizes the rate of its expansion.

Further development of cosmology

As scientists tried to solve this question, many other important components of the Universe were discovered and various models of it were developed. So in 1948, George Gamow introduced the “hot Universe” hypothesis, which would later turn into the big bang theory. The discovery in 1965 confirmed his suspicions. Now astronomers could observe the light that came from the moment when the Universe became transparent.

Dark matter, predicted in 1932 by Fritz Zwicky, was confirmed in 1975. Dark matter actually explains the very existence of galaxies, galaxy clusters and the Universal structure itself as a whole. This is how scientists learned that most of the mass of the Universe is completely invisible.

Finally, in 1998, during a study of the distance to, it was discovered that the Universe is expanding at an accelerating rate. This next turning point in science gave rise to modern understanding about the nature of the Universe. The cosmological coefficient, introduced by Einstein and refuted by Friedman, again found its place in the model of the Universe. The presence of a cosmological coefficient (cosmological constant) explains its accelerated expansion. To explain the presence of a cosmological constant, the concept was introduced - a hypothetical field containing most mass of the Universe.

Modern understanding of the size of the observable Universe

The modern model of the Universe is also called the ΛCDM model. The letter "Λ" means the presence of a cosmological constant, which explains the accelerated expansion of the Universe. "CDM" means that the Universe is filled with cold dark matter. Latest Research they say that the Hubble constant is about 71 (km/s)/Mpc, which corresponds to the age of the Universe 13.75 billion years. Knowing the age of the Universe, we can estimate the size of its observable region.

According to the theory of relativity, information about any object cannot reach an observer at a speed greater than the speed of light (299,792,458 m/s). It turns out that the observer sees not just an object, but its past. The farther an object is from him, the more distant the past he looks. For example, looking at the Moon, we see it as it was a little more than a second ago, the Sun - more than eight minutes ago, nearest stars– years, galaxies – millions of years ago, etc. In Einstein's stationary model, the Universe has no age limit, which means its observable region is also not limited by anything. The observer, armed with increasingly sophisticated astronomical instruments, will observe increasingly distant and ancient objects.

We have a different picture with modern model Universe. According to it, the Universe has an age, and therefore a limit of observation. That is, since the birth of the Universe, no photon could have traveled a distance greater than 13.75 billion light years. It turns out that we can say that the observable Universe is limited from the observer to a spherical region with a radius of 13.75 billion light years. However, this is not quite true. We should not forget about the expansion of the space of the Universe. By the time the photon reaches the observer, the object that emitted it will be already 45.7 billion light years away from us. years. This size is the horizon of particles, it is the boundary of the observable Universe.

Over the horizon

So, the size of the observable Universe is divided into two types. Apparent size, also called the Hubble radius (13.75 billion light years). And the real size, called the particle horizon (45.7 billion light years). The important thing is that both of these horizons do not at all characterize the real size of the Universe. Firstly, they depend on the position of the observer in space. Secondly, they change over time. In the case of the ΛCDM model, the particle horizon expands at a speed greater than the Hubble horizon. Modern science does not answer the question of whether this trend will change in the future. But if we assume that the Universe continues to expand with acceleration, then all those objects that we see now will sooner or later disappear from our “field of vision”.

At the moment the most distant light, observed by astronomers, is the cosmic microwave background radiation. Peering into it, scientists see the Universe as it was 380 thousand years after the Big Bang. At this moment, the Universe cooled down enough that it was able to emit free photons, which are detected today with the help of radio telescopes. At that time, there were no stars or galaxies in the Universe, but only a continuous cloud of hydrogen, helium and an insignificant amount of other elements. From the inhomogeneities observed in this cloud, galaxy clusters will subsequently form. It turns out that precisely those objects that will be formed from inhomogeneities in the cosmic microwave background radiation are located closest to the particle horizon.

True Boundaries

Whether the Universe has true, unobservable boundaries is still a matter of pseudoscientific speculation. One way or another, everyone agrees on the infinity of the Universe, but interprets this infinity in completely different ways. Some consider the Universe to be multidimensional, where our “local” three-dimensional Universe is only one of its layers. Others say that the Universe is fractal - which means that our local Universe may be a particle of another. Don't forget about various models The multiverse with its closed, open, parallel universes, wormholes. And many, many more different versions, the number of which is limited only by human imagination.

But if we turn on cold realism or simply step back from all these hypotheses, then we can assume that our Universe is an infinite homogeneous container of all stars and galaxies. Moreover, at any very distant point, be it billions of gigaparsecs from us, all the conditions will be exactly the same. At this point, the particle horizon and the Hubble sphere will be exactly the same, with the same relict radiation at their edge. There will be the same stars and galaxies around. Interestingly, this does not contradict the expansion of the Universe. After all, it is not just the Universe that is expanding, but its space itself. The fact that at the moment of the Big Bang the Universe arose from one point only means that the infinitely small (practically zero) dimensions that were then have now turned into unimaginably large ones. In the future, we will use precisely this hypothesis in order to clearly understand the scale of the observable Universe.

Visual representation

IN various sources All kinds of visual models are provided to help people understand the scale of the Universe. However, it is not enough for us to realize how big the cosmos is. It is important to imagine how concepts such as the Hubble horizon and the particle horizon actually manifest themselves. To do this, let's imagine our model step by step.

Let's forget that modern science does not know about the “foreign” region of the Universe. Discarding versions of multiverses, the fractal Universe and its other “varieties”, let’s imagine that it is simply infinite. As noted earlier, this does not contradict the expansion of its space. Of course, we take into account that its Hubble sphere and particle sphere are respectively 13.75 and 45.7 billion light years.

Scale of the Universe

Press the START button and discover a new one, unknown world!
First, let's try to understand how large the Universal scale is. If you have traveled around our planet, you can well imagine how big the Earth is for us. Now imagine our planet as a grain of buckwheat moving in orbit around a watermelon-Sun the size of half a football field. In this case, Neptune’s orbit will correspond to the size of a small city, the area will correspond to the Moon, and the area of ​​​​the boundary of the influence of the Sun will correspond to Mars. It turns out that our Solar System is just as more than Earth How much bigger is Mars than buckwheat? But this is just the beginning.

Now let’s imagine that this buckwheat will be our system, the size of which is approximately equal to one parsec. Then the Milky Way will be the size of two football stadiums. However, this will not be enough for us. The Milky Way will also have to be reduced to centimeter size. It will somewhat resemble coffee foam wrapped in a whirlpool in the middle of coffee-black intergalactic space. Twenty centimeters from it there is the same spiral “crumb” - the Andromeda Nebula. Around them there will be a swarm of small galaxies of our Local Cluster. The apparent size of our Universe will be 9.2 kilometers. We have come to an understanding of the Universal dimensions.

Inside the universal bubble

However, it is not enough for us to understand the scale itself. It is important to realize the Universe in dynamics. Let's imagine ourselves as giants, for whom the Milky Way has a centimeter diameter. As noted just now, we will find ourselves inside a ball with a radius of 4.57 and a diameter of 9.24 kilometers. Let’s imagine that we are able to float inside this ball, travel, covering entire megaparsecs in a second. What will we see if our Universe is infinite?

Of course, countless galaxies of all kinds will appear before us. Elliptical, spiral, irregular. Some areas will be teeming with them, others will be empty. main feature will be that visually they will all be motionless while we are motionless. But as soon as we take a step, the galaxies themselves will begin to move. For example, if we are able to discern a microscopic Solar System in the centimeter-long Milky Way, we will be able to observe its development. Moving 600 meters away from our galaxy, we will see the protostar Sun and the protoplanetary disk at the moment of formation. Approaching it, we will see how the Earth appears, life arises and man appears. In the same way, we will see how galaxies change and move as we move away from or approach them.

Therefore, the more distant galaxies We will peer, the more ancient they will be for us. So the most distant galaxies will be located further than 1300 meters from us, and at the turn of 1380 meters we will already see relict radiation. True, this distance will be imaginary for us. However, as we get closer to the CMB, we will see interesting picture. Naturally, we will observe how galaxies will form and develop from the initial cloud of hydrogen. When we reach one of these formed galaxies, we will understand that we have covered not 1.375 kilometers at all, but all 4.57.

Zooming out

As a result, we will increase in size even more. Now we can place entire voids and walls in the fist. So we will find ourselves in a rather small bubble from which it is impossible to get out. Not only will the distance to objects at the edge of the bubble increase as they get closer, but the edge itself will shift indefinitely. This is the whole point of the size of the observable Universe.

No matter how big the Universe is, for an observer it will always remain a limited bubble. The observer will always be at the center of this bubble, in fact he is its center. Trying to get to any object at the edge of the bubble, the observer will shift its center. As you approach an object, this object will move further and further from the edge of the bubble and at the same time change. For example, from a formless hydrogen cloud it will turn into a full-fledged galaxy or further galaxy cluster. In addition, the path to this object will increase as you approach it, since the surrounding space itself will change. Having reached this object, we will only move it from the edge of the bubble to its center. At the edge of the Universe, relict radiation will still flicker.

If we assume that the Universe will continue to expand at an accelerated rate, then being in the center of a bubble and shaking time by billions, trillions and even more high orders years ahead, we will notice an even more interesting picture. Although our bubble will also increase in size, its changing components will move away from us even faster, leaving the edge of this bubble, until each particle of the Universe wanders separately in its lonely bubble without the opportunity to interact with other particles.

So, modern science does not have information about the real size of the Universe and whether it has boundaries. But we know for sure that the observable Universe has a visible and true boundary, called respectively the Hubble radius (13.75 billion light years) and the particle radius (45.7 billion light years). These boundaries depend entirely on the observer's position in space and expand over time. If the Hubble radius expands strictly at the speed of light, then the expansion of the particle horizon is accelerated. The question of whether its acceleration of the particle horizon will continue further and whether it will be replaced by compression remains open.

The diameter of the Moon is 3000 km, the Earth is 12800 km, the Sun is 1.4 million kilometers, while the distance from the Sun to the Earth is 150 million km. The diameter of Jupiter itself big planet our solar system - 150 thousand km. It’s not for nothing that they say that Jupiter could be a star; in the video, next to Jupiter is located working star, its size () is even smaller than Jupiter. By the way, since we touched on Jupiter, you may not have heard, but Jupiter does not revolve around the Sun. The fact is that the mass of Jupiter is so large that the center of rotation of Jupiter and the Sun is located outside the Sun, thus both the Sun and Jupiter rotate together around general center rotation.

According to some calculations, there are 400 billion stars in our galaxy, which is called the Milky Way. This is far from the most large galaxy, in neighboring Andromeda there are more than a trillion stars.

As stated in the video at 4:35, in a few billion years our Milky Way will collide with Andromeda. According to some calculations, using any technology known to us, even improved in the future, we will not be able to reach other galaxies, since they are constantly moving away from us. Only teleportation can help us. This is bad news.

The good news is that you and I were born in good time, when scientists see other galaxies and can theorize about the Big Bang and other phenomena. If we had been born much later, when all the galaxies would have scattered far from each other, then most likely we would not have been able to find out how the universe arose, whether there were other galaxies, whether there was a Big Bang, etc. We would believe that our Milky Way (united by that time with Andromeda) is the only one and unique in the entire cosmos. But we are lucky and we know something. Maybe.

Let's get back to the numbers. Our small Milky Way contains up to 400 billion stars, neighboring Andromeda has more than a trillion, and in total there are more than 100 billion such galaxies in the observable universe. And many of them contain several trillion stars. It may seem incredible that there are so many stars in space, but somehow the Americans took and directed their mighty hubble telescope to a completely empty space in our sky. After watching him for several days, they received this photograph:

In a completely empty area of ​​our sky, they found 10 thousand galaxies (not stars), each of which contains billions and trillions of stars. Here is this square in our sky, for scale.

And we don’t know what’s going on outside the observable universe. The size of the universe that we see is about 91.5 billion light years. What's next is unknown. Perhaps our entire universe is just a bubble in a swirling ocean of multiverses. In which other laws of physics may even apply, for example, Archimedes’ law does not work and the sum of the angles is not equal to 360 degrees.

Enjoy. Dimensions of the universe on video:

Instructions

“The abyss has opened and is full of stars; the stars have no number, the abyss has its bottom,” wrote the brilliant Russian scientist Mikhail Vasilyevich Lomonosov in one of his poems. This is a poetic statement of the infinity of the Universe.

The age of “being” of the observable Universe is about 13.7 billion earthly years. Light that comes from distant galaxies “from the edge of the world” takes more than 14 billion years to reach Earth. It turns out that the diametrical dimensions of the Universe can be calculated if approximately 13.7 is multiplied by two, that is, 27.4 billion light years. The radial size of the spherical model is approximately 78 billion light years, and the diameter is 156 billion light years. This is one of the latest versions American scientists, the result of many years astronomical observations and calculations.

There are 170 billion galaxies like ours in the observable universe. Ours seems to be in the center of a giant ball. From the farthest space objects a relict light is visible - fantastically ancient from the point of view of humanity. If you penetrate very deep into the space-time system, you can see the youth of planet Earth.

Exists final limit age of luminous space objects observed from Earth. Having calculated age limit, knowing the time it took light to travel the distance from them to the surface of the Earth, and knowing the constant, the speed of light, using the formula S=Vxt known from school (path = speed multiplied by time), scientists determined the probable dimensions of the observable Universe .

To imagine the Universe in the form of a three-dimensional ball is not the only way building a model of the Universe. There are hypotheses suggesting that the Universe has not three, but infinite number measurements. There are versions that it, like a matryoshka doll, consists of infinite number spherical formations nested within each other and spaced apart from each other.

There is an assumption that the Universe is inexhaustible according to various criteria and different coordinate axes. People thought the smallest particle matter “corpuscle”, then “molecule”, then “atom”, then “protons and electrons”, then we started talking about elementary particles, which turned out to be not at all elementary, about quanta, neutrinos and quarks... And no one can guarantee that there is not another Universe inside the next supermicrominiparticle of matter. And vice versa - that the visible Universe is not just a microparticle of matter of the Super-Mega-Universe, the dimensions of which no one can even imagine and calculate, they are so large.

17:45 23/06/2016

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The scale of space is difficult to imagine and even more difficult to accurately determine. But thanks to the ingenious guesses of physicists, we think we have a good idea of ​​how big the cosmos is. “Let us take a walk around,” was the invitation American astronomer Harlow Shapley made to an audience in Washington, D.C., in 1920. He took part in the so-called Great Debate on the scale of the Universe, along with his colleague Heber Curtis.

Shapley believed that our galaxy was 300,000 in diameter. This is three times more than is thought now, but for that time the measurements were quite good. In particular, he calculated the generally correct proportional distances within the Milky Way - our position relative to the center, for example.

At the beginning of the 20th century, however, 300,000 light years seemed somehow absurd to many of Shapley’s contemporaries a large number. And the idea that others like the Milky Way - which were visible in - were as large was not taken seriously at all.

And Shapley himself believed that the Milky Way should be special. "Even if the spirals are present, they are not comparable in size to ours star system", he told his listeners.

Curtis disagreed. He thought, and rightly so, that there were many other galaxies in the Universe, scattered like ours. But his starting point was the assumption that the Milky Way was much smaller than Shapley had calculated. According to Curtis's calculations, the Milky Way was only 30,000 light-years in diameter - or three times smaller than modern calculations show.

Three times more, three times less - we're talking about about such enormous distances that it is quite understandable that astronomers who thought about this topic a hundred years ago could be so mistaken.

Today we are fairly confident that the Milky Way is somewhere between 100,000 and 150,000 light years across. The observable Universe is, of course, much, much larger. It is believed to be 93 billion light years in diameter. But why such confidence? How can you even measure something like this with ?

Ever since Copernicus declared that the Earth is not the center, we have always struggled to rewrite our ideas about what the Universe is - and especially how big it can be. Even today, as we will see, we are gathering new evidence that the entire Universe may be much larger than we recently thought.

Caitlin Casey, an astronomer at the University of Texas at Austin, studies the universe. She says astronomers have developed a set of sophisticated instruments and measurement systems to calculate not only the distance from Earth to other bodies in our solar system, but also the gaps between galaxies and even to the very end of the observable universe.

The steps to measuring all of this go through the distance scale of astronomy. The first stage of this scale is quite simple and these days relies on modern technology.

“We can simply bounce radio waves off nearby ones in the solar system, like and, and measure the time it takes for those waves to return to Earth,” Casey says. “The measurements will thus be very accurate.”

Large radio telescopes like the one in Puerto Rico can do this job - but they can also do more. Arecibo, for example, can detect flying around our solar system and even create images of them, depending on how radio waves are reflected from the surface of the asteroid.

But using radio waves to measure distances beyond our solar system is impractical. The next step in this cosmic scale is the measurement of parallax. We do this all the time without even realizing it. Humans, like many animals, intuitively understand the distance between themselves and objects due to the fact that we have two eyes.

If you hold an object in front of you - your hand, for example - and look at it with one with an open eye, and then switch to the other eye, you see your hand move slightly. This is called parallax. The difference between these two observations can be used to determine the distance to the object.

Our brains do this naturally with information from both eyes, and astronomers do the same with nearby stars, only they use a different sense: telescopes.

Imagine two eyes floating in space, on either side of our Sun. Thanks to the Earth's orbit, we have these eyes, and we can observe the displacement of stars relative to objects in the background using this method.

“We measure the positions of stars in the sky in, say, January, and then wait six months and measure the positions of the same stars in July when we are on the other side of the Sun,” Casey says.

However, there is a threshold beyond which objects are already so far away - about 100 light years - that the observed shift is too small to provide a useful calculation. At this distance we will still be far from the edge of our own galaxy.

The next step is main sequence installation. It relies on our knowledge of how stars of a certain size - known as main sequence stars - evolve over time.

First, they change color, becoming redder as they age. By accurately measuring their color and brightness, and then comparing this with what is known about the distance to main sequence stars, as measured by trigonometric parallax, we can estimate the position of these more distant stars.

The principle behind these calculations is that stars of the same mass and age would appear equally bright to us if they were at the same distance from us. But since this is often not the case, we can use the difference in measurements to figure out how far they really are.

The main sequence stars used for this analysis are considered to be one of the " standard candles" - bodies whose size (or brightness) we can calculate mathematically. These candles are scattered throughout space and predictably illuminate the Universe. But main sequence stars are not the only examples.

This understanding of how brightness relates to distance allows us to understand distances to even more distant objects - like stars in other galaxies. The main sequence approach will no longer work because the light from these stars - which are millions of light years away, if not more - is difficult to accurately analyze.

But in 1908, a scientist named Henrietta Swan Leavitt from Harvard made a fantastic discovery that helped us measure these colossal distances. Swan Leavitt realized that there was special class stars - .

"She noticed that a certain type of star changes its brightness over time, and this change in brightness, in the pulsation of these stars, is directly related to how bright they are by nature," Casey says.

In other words, more bright Star Cepheid class will "pulse" more slowly (over many days) than a fainter Cepheid. Because astronomers can quite easily measure the Cepheid's pulse, they can tell how bright the star is. Then, by observing how bright it appears to us, they can calculate its distance.

This principle is similar to the approach with main sequence in the sense that brightness is key. However, the important thing is that the distance can be measured different ways. And the more ways we have to measure distances, the better we can understand the true scale of our cosmic backyard.

It was the discovery of such stars in our own galaxy that convinced Harlow Shapley of its large size.

In the early 1920s, Edwin Hubble discovered a Cepheid at the nearest one and concluded that it was only a million light years away.

Today, according to our best estimates, this galaxy is 2.54 million light years away. Therefore, Hubble was wrong. But this in no way detracts from his merits. Because we're still trying to calculate the distance to Andromeda. 2.54 million years - this number is essentially the result of relatively recent calculations.

Even now, the scale of the Universe is difficult to imagine. We can estimate it, and very well, but, in truth, it is very difficult to accurately calculate the distances between galaxies. The universe is incredibly big. And it is not limited to our galaxy.

Hubble also measured the brightness of the exploding type 1A. They can be seen in fairly distant galaxies, billions of light years away. Because the brightness of these calculations can be calculated, we can determine how far away they are, just as we did with Cepheids. Type 1A supernovae and Cepheids are examples of what astronomers call standard candles.

There is one more feature of the Universe that can help us truly measure long distances. This is redshift.

If you've ever heard the siren of an ambulance or police car rush past you, you're familiar with the Doppler effect. When the ambulance approaches, the siren sounds shriller, and when it moves away, the siren fades again.

The same thing happens with light waves, only on a small scale. We can detect this change by analyzing the light spectrum of distant bodies. There will be dark lines in this spectrum because individual colors are absorbed by elements in and around the light source - the surfaces of stars, for example.

The further objects are from us, the further towards the red end of the spectrum these lines will shift. And this is not only because objects are far from us, but because they are also moving away from us over time, due to the expansion of the Universe. And observing the redshift of light from distant galaxies actually provides us with evidence that the Universe is indeed expanding.