The size of the universe is from an atom to. Size of the universe

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, when asked about the “infinity” of the Universe, offers a completely different answer to such an “obvious” question.

According to modern concepts, 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 the mind of an ordinary person is 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 movement along the “fixed” celestial sphere, the Earth remained the center of the Universe.

Naturally, even 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. Thus, a new paradigm called “heliocentrism” took hold in astronomy.

Many Suns

However, even after this, astronomers continued to limit the Universe to the “sphere of 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 a 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. By comparing their absolute luminosity with the visible one, it is possible to determine the distance to them with high accuracy. 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 than the size of the 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 it was one of many galaxies that had once been considered part of it. 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 known structures in the Universe—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. Having discovered the law of universal gravitation, he believed that if space were finite, all its 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 scientific basis. 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. The famous physicist introduced his model of a stationary Universe 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 a cosmological constant, which compensated for the gravitational attraction of 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 these conclusions by connecting space, time and gravity in his famous theory. 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 of the “new Universe” himself 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 latest turning point in science gave birth to our modern understanding of 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 of a hypothetical field containing most of the mass of the Universe was introduced.

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. Recent studies indicate 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 as it was a little more than a second ago, the Sun - more than eight minutes ago, the 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 the modern model of the 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”.

Currently, 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. We should not forget about the various models of the Multiverse with its closed, open, parallel Universes, and wormholes. And there are many, many 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

Various sources provide all sorts of visual models that allow people to 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, let's 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, 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 as much larger than the Earth as Mars is larger 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. The 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.

Consequently, the more distant galaxies we look at, 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 cosmic microwave background radiation, we will see an 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 shapeless hydrogen cloud it will turn into a full-fledged galaxy or, further, a galactic 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 the bubble and moving time forward by billions, trillions and even higher orders of years, 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.

Which are on it. For the most part, we are all chained to the place where we live and work. The size of our world is amazing, but it is absolutely nothing compared to the Universe. As the saying goes - "born too late to explore the world, and too early to explore space". It's even insulting. However, let's get started - just be careful not to get dizzy.

1. This is Earth.

This is the same planet that is currently the only home for humanity. The place where life magically appeared (or maybe not so magically) and in the course of evolution you and I appeared.

2. Our place in the solar system.

The closest large space objects that surround us, of course, are our neighbors in the solar system. Everyone remembers their names from childhood, and during lessons about the world around them they make models. It so happened that even among them we are not the biggest...

3. The distance between our Earth and the Moon.

It doesn't seem that far, right? And if we also take into account modern speeds, then it’s “nothing at all.”

4. In fact, it’s quite far away.

If you try, then very accurately and comfortably - between the planet and the satellite you can easily place the rest of the planets of the solar system.

5. However, let's continue talking about planets.

Before you is North America, as if it were placed on Jupiter. Yes, this small green speck is North America. Can you imagine how huge our Earth would be if we moved it to the scale of Jupiter? People would probably still be discovering new lands)

6. This is Earth compared to Jupiter.

Well, more precisely six Earths - for clarity.

7. Rings of Saturn, sir.

The rings of Saturn would have such a gorgeous appearance, provided they revolved around the Earth. Look at Polynesia - a bit like the Opera icon, right?

8. Let's compare the Earth with the Sun?

It doesn't look that big in the sky...

9. This is the view of the Earth when looking at it from the Moon.

Beautiful, right? So lonely against the backdrop of empty space. Or not empty? Let's continue...

10. And so from Mars

I bet you wouldn't even be able to tell if it was Earth.

11. This is a shot of Earth just beyond the rings of Saturn

12. But beyond Neptune.

A total of 4.5 billion kilometers. How long would it take to search?

13. So, let's go back to the star called the Sun.

A breathtaking sight, isn't it?

14. Here is the Sun from the surface of Mars.

15. And here is its comparison with the Scale of the star VY Canis Majoris.

How do you like it? More than impressive. Can you imagine the energy concentrated there?

16. But this is all bullshit if we compare our native star with the size of the Milky Way galaxy.

To make it more clear, imagine that we have compressed our Sun to the size of a white blood cell. In this case, the size of the Milky Way is quite comparable to the size of Russia, for example. This is the Milky Way.

17. In general, stars are huge

Everything that is placed in this yellow circle is everything that you can see at night from Earth. The rest is inaccessible to the naked eye.

18. But there are other galaxies.

Here is the Milky Way compared to the galaxy IC 1011, which is located 350 million light years from Earth.

Let's go over it again?

So, this Earth is our home.

Let's zoom out to the size of the solar system...

Let's zoom out a little more...

And now to the size of the Milky Way...

Let's continue to reduce...

And further…

Almost ready, don't worry...

Ready! Finish!

This is all that humanity can now observe using modern technology. It’s not even an ant... Judge for yourself, just don’t go crazy...

Such scales are hard to even comprehend. But someone confidently declares that we are alone in the Universe, although they themselves are not really sure whether the Americans were on the Moon or not.

Hang in there guys... hang in there.

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