In cosmology, there is still no clear answer to the question that affects the age, shape and size of the Universe, and there is also no consensus about its finiteness. Because if the universe is finite, then it must either contract or expand. In the event that it is infinite, many assumptions lose their meaning.

Back in 1744, astronomer J.F. Shezo was the first to doubt that the universe

It is infinite: if the number of stars has no boundaries, then why does the sky not sparkle and why is it dark? In 1823, G. Albes argued for the existence of the boundaries of the Universe by the fact that the light coming to the Earth from distant stars should become weaker due to absorption by matter that is on their way. But in this case, this substance itself should be heated and glow no worse than any star. found its confirmation in modern science, which claims that the vacuum is "nothing", but at the same time it has real physical properties... Of course, absorption by a vacuum leads to an increase in its temperature, which results in the fact that the vacuum becomes a secondary source of radiation. Therefore, if the dimensions of the Universe are really infinite, then the light of stars that have reached the limiting distance has such a strong redshift that it begins to merge with the background (secondary) radiation of the vacuum.

At the same time, we can say that what is observed by humanity are finite, since the Distance itself is finite at 24 Gigaparsex, which is the boundary of the light cosmic horizon. However, due to the fact that it is increasing, the end of the universe is at a distance of 93 billion

Most important result cosmology was the fact of the expansion of the universe. It was obtained from observations of redshift and then quantified according to Hubble's law. This led scientists to conclude that the Big Bang theory is being confirmed. According to NASA,

which were obtained with the help of WMAP, starting from the moment of the Big Bang, equals 13.7 billion years. However, this result is possible only if it is assumed that the model that underlies the analysis is correct. When using other estimation methods, completely different data are obtained.

Touching upon the structure of the Universe, one cannot but say about its form. So far, no three-dimensional figure has been found that would best represent its image. This complexity is due to the fact that it is still not known exactly whether the Universe is flat. The second aspect is connected with the fact that it is not known for certain about its multiple connections. Accordingly, if the dimensions of the Universe are spatially limited, then when moving in a straight line and in any direction, you can find yourself at the starting point.

As we can see, technological progress has not yet reached the level to accurately answer questions regarding the age, structure and size of the Universe. Until now, many theories in cosmology have not been confirmed, but have not been refuted either.

Portal site is information resource, where you can get a lot of useful and interesting knowledge related to Space. First of all, we will talk about our and other Universes, about celestial bodies, black holes and phenomena in the bowels of outer space.

The totality of all that exists, matter, individual particles and the space between these particles is called the Universe. According to scientists and astrologers, the age of the universe is approximately 14 billion years. The visible part of the Universe is about 14 billion light years in size. And some argue that the universe is 90 billion light-years across. For greater convenience in calculating such distances, it is customary to use the parsec value. One parsec equals 3.2616 light years, which means a parsec is the distance over which the average radius of the Earth's orbit is viewed at an angle of one arc second.

Armed with these indicators, you can calculate the cosmic distance from one object to another. For example, the distance from our planet to the Moon is 300,000 km, or 1 light second. Consequently, this distance to the Sun increases to 8.31 light minutes.

Throughout their history, people have tried to solve the riddles associated with the Cosmos and the Universe. In the articles of the portal site you can learn not only about the Universe, but also about modern scientific approaches to its study. All material is based on the most advanced theories and facts.

It should be noted that the Universe includes a large number known to people various objects. The most widely known among them are planets, stars, satellites, black holes, asteroids and comets. About the planets at the moment it is clear most of all, since we live on one of them. Some planets have their own moons. So, the Earth has its own satellite - the Moon. In addition to our planet, there are 8 more that revolve around the sun.

There are many stars in the Cosmos, but each of them is not alike. They have different temperatures, sizes and brightness. Since all stars are different, they are classified as follows:

White dwarfs;

Giants;

Supergiants;

Neutron stars;

Quasars;

Pulsars.

The densest substance we know of is lead. In some planets, the density of their own matter can be thousands of times higher than the density of lead, which poses many questions for scientists.

All planets revolve around the Sun, but it also does not stand still. Stars can gather in clusters, which, in turn, also revolve around a center that is not yet known to us. These clusters are called galaxies. Our galaxy is called the Milky Way. All the research done to date says that most of the matter that galaxies create is still invisible to humans. Because of this, it was called dark matter.

The centers of galaxies are considered to be the most interesting. Some astronomers believe that the possible center of the galaxy is the Black Hole. This is a unique phenomenon formed as a result of the evolution of a star. But so far all these are just theories. Experimenting or researching similar phenomena not yet possible.

In addition to galaxies, the Universe contains nebulae (interstellar clouds consisting of gas, dust and plasma), relic radiation that permeate the entire space of the Universe, and many other little-known and even generally unknown objects.

The ether circuit of the Universe

Symmetry and balance of material phenomena is the main principle of structural organization and interaction in nature. Moreover, in all forms: stellar plasma and matter, world and released ethers. The whole essence of such phenomena consists in their interactions and transformations, most of which are represented by the invisible ether. It is also called relic radiation. This is a microwave cosmic background radiation with a temperature of 2.7 K. There is an opinion that it is this vibrating ether that is the fundamental principle for everything that fills the Universe. The anisotropy of the ether distribution is associated with the directions and intensity of its movement in different areas of the invisible and visible space. All the difficulty of studying and researching is quite comparable with the difficulties of studying turbulent processes in gases, plasmas and liquids of matter.

Why do many scientists believe that the universe is multidimensional?

After conducting experiments in laboratories and in the Cosmos itself, data were obtained from which it can be assumed that we live in the Universe, in which the location of any object can be characterized by time and three spatial coordinates. Because of this, the assumption arises that the universe is four-dimensional. However, some scientists, developing theories of elementary particles and quantum gravity, may come to the conclusion that the existence of a large number of dimensions is simply necessary. Some models of the Universe do not exclude as many of them as 11 dimensions.

It should be noted that the existence multidimensional universe possibly with high-energy phenomena - black holes, big bangs, busters. At least this is one of the ideas of leading cosmologists.

The expanding universe model is based on general relativity. It was proposed to adequately explain the redshift structure. The expansion began at the same time as the Big Bang. Its state is illustrated by the surface of an inflated rubber ball on which dots - extragalactic objects - have been applied. When such a balloon is inflated, all its points move away from each other, regardless of position. According to the theory, the universe can either expand infinitely or contract.

Baryon asymmetry of the universe

The observed in the Universe a significant increase in the number of elementary particles over the entire number of antiparticles is called baryon asymmetry. Baryons include neutrons, protons and some other short-lived elementary particles. This imbalance happened in the era of annihilation, namely three seconds after the Big Bang. Up to this point, the number of baryons and antibaryons corresponded to each other. During mass annihilation of elementary antiparticles and particles, most of them combined into pairs and disappeared, thereby giving rise to electromagnetic radiation.

Age of the Universe on the portal site

Modern scientists believe that our universe is about 16 billion years old. The minimum age is estimated to be 12-15 billion years. The minimum repels from the oldest stars in our Galaxy. Her real age can be determined only with the help of Hubble's law, but real does not mean exact.

Visibility horizon

A sphere with an equal radius of distance that light travels during the entire existence of the Universe is called its visibility horizon. The existence of the horizon is directly proportional to the expansion and contraction of the universe. According to Friedmann's cosmological model, the Universe began to expand from a singular distance about 15-20 billion years ago. For all time, light travels in the expanding Universe the residual distance, namely 109 light years. Because of this, each observer of the moment t0 after the beginning of the expansion process can observe only a small part bounded by a sphere that has a radius I at that moment. Those bodies and objects that are outside this boundary at this moment, in principle, are not observable. The light bounced off them simply does not have time to reach the observer. This is not possible even if the light came out at the beginning of the expansion process.

Due to absorption and scattering in the early Universe, given the high density, photons could not propagate in a free direction. Therefore, the observer is able to fix only that radiation that appeared in the era of the Universe transparent to radiation. This epoch is determined by the time t "300,000 years, the density of the substance r" 10-20 g / cm3 and the moment of hydrogen recombination. From the foregoing, it follows that the closer the source is in the galaxy, the greater the redshift value for it.

Big Bang

The moment of origin of the Universe is called the Big Bang. This concept is based on the fact that initially there was a point (singularity point) in which all energy and all matter was present. The basis of the characteristic is considered to be the high density of matter. What happened before this singularity is unknown.

There is no exact information regarding the events and conditions that occurred before the onset of the moment 5 * 10-44 seconds (the moment of the end of the 1st time quantum). In physical terms of that era, one can only assume that then the temperature was about 1.3 * 1032 degrees with a density of matter of about 1096 kg / m 3. These values ​​are the limit for the application of existing ideas. They appear due to the ratio of the gravitational constant, the speed of light, the Boltzmann and Planck constants and are referred to as "Planck".

Those events, which are associated with 5 * 10-44 for 10-36 seconds, reflect the model of the "inflationary Universe". The moment of 10-36 seconds is referred to as the "hot Universe" model.

In the period from 1-3 to 100-120 seconds, helium nuclei and a small number of nuclei of the rest of the lungs were formed chemical elements... From that moment, the ratio of hydrogen 78%, helium 22% began to be established in the gas. Before one million years, the temperature in the Universe began to drop to 3000-45000 K, the era of recombination began. Before, free electrons began to combine with light protons and atomic nuclei. Atoms of helium, hydrogen and a small number of lithium atoms began to appear. Has become transparent substance, and the radiation, which is still observed, is disconnected from it.

The next billion years of the Universe's existence was marked by a decrease in temperature from 3000-45000 K to 300 K. This period for the Universe, scientists called the "Dark Age" due to the fact that no sources of electromagnetic radiation have yet appeared. In the same period, the inhomogeneities of the mixture of the original gases were compacted due to the influence of gravitational forces. By simulating these processes on a computer, astronomers saw that this irreversibly led to the appearance of giant stars millions of times larger than the mass of the Sun. Due to such a large mass, these stars heated up to incredibly high temperatures and evolved over a period of tens of millions of years, after which they exploded like supernovae. Heating up to high temperatures, the surfaces of such stars created strong currents ultraviolet radiation... Thus, the period of reionization began. Plasma, which was formed as a result of such phenomena, began to strongly scatter electromagnetic radiation in its spectral short-wave ranges. In a sense, the universe began to plunge into a thick fog.

These huge stars became the first sources of chemical elements in the Universe, which are much heavier than lithium. Space objects of the 2nd generation began to form, which contained the nuclei of these atoms. These stars began to form from mixtures of heavy atoms. There was a repeated type of recombination of most of the atoms of intergalactic and interstellar gases, which, in turn, led to a new transparency of space for electromagnetic radiation. The universe has become exactly what we can observe now.

The observable structure of the Universe on the website portal

The observed part is spatially inhomogeneous. Most clusters of galaxies and individual galaxies form its cellular or honeycomb structure. They construct cell walls that are a couple of megaparsec thick. These cells are called "voids". They are characterized by a large size, tens of megaparsecs, and at the same time there is no substance with electromagnetic radiation in them. About 50% of the total volume of the Universe falls to the share of "voids".

Instructions

“An abyss has opened, full of stars; the stars are innumerable, the bottom of the abyss, ”wrote the genius Russian scientist Mikhail Vasilyevich Lomonosov in one of his poems. This is a poetic statement of the infinity of the universe.

The age of the "existence" of the observable Universe is about 13.7 billion Earth years. The light that comes from distant galaxies "from the edge of the world" has been traveling to Earth for more than 14 billion years. It turns out that the diametrical dimensions of the universe can be calculated if approximately 13.7 times two, that is, 27.4 billion light years. The spherical model has a radial size of about 78 billion light years and a diameter of 156 billion light years. This is one of latest versions American scientists, the result of many years of astronomical observations and calculations.

There are 170 billion galaxies like ours in the observable universe. Ours is, as it were, in the center of a giant ball. From the most distant space objects, relic light is visible - fantastically ancient from the point of view of mankind. If you penetrate very deeply into the space-time system, you can see the youth of planet Earth.

There is a finite age limit for luminous space objects observed from Earth. By calculating age limit, knowing the time it took for light to travel the distance from them to the Earth's surface, and knowing the constant, the speed of light, according to the formula S = Vxt (path = speed multiplied by time) known from school, scientists determined the probable dimensions of the observable Universe ...

Representing the universe as a three-dimensional ball is not the only way to model the universe. There are hypotheses suggesting that the universe has not three, but an infinite number of dimensions. There are versions that it, like a nesting doll, consists of an infinite number of nested and spaced spherical formations.

There is an assumption that the Universe is inexhaustible according to various criteria and different coordinate axes. People considered the smallest particle of matter to be a "corpuscle", then a "molecule", then an "atom", then "protons and electrons", then they started talking about elementary particles, which turned out to be not at all elementary, about quanta, neutrinos and quarks ... And no one will give a guarantee that the next Universe is not located inside the next supermicro-particle of matter. And vice versa - that the visible Universe is not only a microparticle of the matter of the Super-Mega-Universe, the size of which is not even given to anyone to imagine and calculate, they are so large.

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

Shapley believed that our galaxy was 300,000 across. This is three times more than people think 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 absurd to many of Shapley's contemporaries. a large number... And the idea that others like the Milky Way - which were visible in - were just 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 our 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 calculated. According to Curtis's calculations, the Milky Way was only 30,000 light-years in diameter - or three times smaller than current calculations indicate.

Three times more, three times less - we are talking about such huge distances that it is quite understandable that astronomers who pondered on this topic a hundred years ago could be so wrong.

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, much more. It is believed to be 93 billion light years across. But why such confidence? How can you even measure something like that with?

Ever since Copernicus stated that the Earth is not the center, we have always had a hard time rewriting our ideas about what the universe is - and especially how big it can be. Even today, as we will see, we are collecting 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 that astronomers have developed a set of ingenious instruments and measurement systems to calculate not only the distance from Earth to other bodies in our solar system, but also the chasms between galaxies and even to the very end of the observable universe.

The steps to measuring it all go across the distance scale in astronomy. The first rung of this scale is fairly straightforward and relies on modern technology these days.

“We can just bounce radio waves from the nearest ones in the solar system, like and, and measure the time it takes for these waves to return to Earth,” Casey says. "The measurements will thus be very accurate."

Large radio telescopes like those in Puerto Rico can do the job - but they can do more as well. 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 outside our solar system is impractical. The next step in this cosmic scale is parallax measurement. We do it all the time, without even realizing it. People, like many animals, intuitively understand the distance between themselves and objects, thanks to the fact that we have two eyes.

If you hold an object in front of you - a hand, for example - and look at it with one 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 using other senses: telescopes.

Imagine that there are 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 position of stars in the sky, say, in January, and then we wait six months and measure the position of the same stars in July, when we find ourselves on the other side of the sun,” Casey says.

However, there is a threshold beyond which objects are already so distant - about 100 light-years - that the observed displacement 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 the main sequence installation. It draws on our knowledge of how stars of a certain size - known as main sequence stars - evolve over time.

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

The principle behind these calculations is that stars of the same mass and age will 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 away they really are.

The main sequence stars used for this analysis are considered to be one of the " standard candles»- bodies, the size of which (or brightness) we can calculate mathematically. These candles are scattered throughout space and predictably illuminate the universe. But main sequence stars aren't 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. A basic 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 of Harvard made a fantastic discovery that helped us measure these colossal distances. Swan Leavitt realized that there is a special class of stars -.

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

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

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

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 the Cepheids in 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 does not diminish his merits in the least. Because we are still trying to calculate the distance to Andromeda. 2.54 million years - this number is, in fact, 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 large. And our galaxy is not limited.

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

There is another feature of the universe that can help us measure really great distances. This is the redshift.

If the siren of an ambulance or police car has ever whizzed past you, you are familiar with the Doppler effect. When the ambulance approaches, the siren sounds shrill, and when it moves away, the siren dies down again.

The same thing happens with waves of light, only on a small scale. We can fix this change by analyzing the light spectrum of distant bodies. There will be dark lines in this spectrum as 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 move. And this is not only because objects are far from us, but because they also move away from us over time, thanks to the expansion of the Universe. And observing the redshift of light from distant galaxies, in fact, provides us with evidence that the universe is indeed expanding.

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Do we need to send signals into space with the coordinates of the Earth?

You probably think the universe is infinite? May be so. It is unlikely that we will ever know about this for sure. It will not be possible to cover our entire universe with a glance. Firstly, this fact follows from the concept of the "big bang", which claims that the universe has its own, so to speak, birthday, and, secondly, from the postulate that the speed of light is a fundamental constant. So far, the observable portion of the 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 by someone Joe Muscarella. Here's what he writes:

“I have seen different answers to the question of what was the size of our universe shortly after the end of the period of cosmic inflation (cosmic inflation - the phase preceding the Big Bang - approx. Transl.). In one source it is indicated - 0.77 centimeters, in another - the size of a soccer ball, and in the third - larger than the size of the observable universe. So which one? Or maybe some kind of intermediate one? "

Context

The Big Bang and the Black Hole

How the Universe Created Man

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 with respect to the inertial frame of reference);

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

Is the corner radius of the object.

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

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

By measuring the brightness (or size) of the observed object, using the ratio "brightness / distance", you can determine the distance of the object from the observer. Moreover, according to the characteristics of the object's redshift, it is possible to determine the scale 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, about which Einstein's general theory of relativity speaks, it is possible to consider all kinds of combinations of various forms of matter and energy that are currently 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 in the evolution of the universe, and what the energy density was at that time. As you know, the universe consists of the following component parts:

- 0.01% - radiation (photons);

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

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

- 27% - dark matter, i.e. this kind of her, which participates in gravitational interaction but different from all particles Standard model;

- 68% - dark energy, causing 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 mainly of matter (in the form of a combination of ordinary matter and dark matter). However, for the first few millennia, radiation (in the form of photons and neutrinos) was even more important. construction material than matter!

Note that each of these constituent parts 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 long, 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 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; the 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 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, a distance of 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. The singularity hypothesis could be used to describe the state of the universe at the earliest stage of its birth, but thanks to the inflation hypothesis, the singularity is completely unnecessary. Instead of a singularity, we are talking about a very rapid expansion of the universe (i.e. inflation) that took place for some time before the hot and dense expansion took place that marked the beginning of the present universe. Now let's move on to the final stage of the inflation of the universe (the time interval between 10 to minus 30 - 10 to minus 35 seconds). Let's see what the size of the universe was when inflation stopped and the big bang occurred.

Here we are talking about the observable part of the universe. Its true size is certainly much larger, but we do not know how much. At the best possible approximation (judging by the data contained in the Sloan Digital Sky Survey (SDSS) and information obtained from the Planck Space Observatory), if the universe is curved and collapsed, then its observable part is so indistinguishable from the "non-curved" part that the entire its radius should be at least 250 times the radius of the observed part.

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

What is seventeen centimeters? It's almost the diameter of a soccer ball. So, if you want to know which of the indicated dimensions of the universe is closest to the real one, then stick to this figure. And if we assume the size is less than a centimeter? This is too little; however, if we take into account the limitations imposed by cosmic microwave radiation, it turns out that the expansion of the universe could not end with such high level energies, and hence the above-mentioned size of the universe at the very beginning of the "Big Bang" (ie, the size not exceeding a centimeter) is excluded. If the size of the universe exceeded the current size, 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 inception? 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 inception 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.