From the point of view of astronomy, the Universe is considered the largest object available for observation. In fact, it turns out that the boundary of the visible space coincides with the boundary of the Universe, and everything that is further is available only for the theoretical research of physicists.
How does the Universe work according to astronomers? Our Earth is one of the planets in the solar system. The sun is in the Milky Way galaxy, and the Milky Way galaxy is in a cloud of other galaxies. Many clouds of galaxies form a structure called a metagalaxy. The metagalaxy occupies the entire visible region of the Universe. Therefore, the Universe consists of very rarefied interstellar gas; stars unevenly distributed in space and forming clusters and galaxies; planets, comets, dust clouds and other cold objects falling into the gravitational field of stars and star clusters. This is what the macro world looks like.
But the above approximate picture of how the Universe works is not complete. It does not take into account that other objects may exist beyond the visible boundary of space,different from those seen inside. The fact is that the point of view about the infinity of the Universe is not entirely correct. The universe must have some kind of boundary, albeit a very remote one. This follows at least from the most popular theory of how the birth of the Universe happened - the Big Bang theory.
Based on the theory of the Big Bang, the emergence of the Universe is due to the existence of some superdense substance, which exploded. As a result of the explosion, in the first three minutes, all the elementary particles of the Universe appeared, which were grouped into larger formations. But the consequences of the explosion can still be observed: the space of the Universe is expanding, and galaxies are flying apart in all directions from each other.
It is logical to assume that the original substance (or energy) should have had a finite volume and be in some other space, which, perhaps, still exists and is located outside the Universe.
What is called infinity in physics, in fact, mathematical infinity. It arises where equations and theory cannot describe the existing phenomenon. Therefore, it remains only to speculate about how the Universe works where the most powerful telescopes and the mathematical apparatus of theorists cannot look. In particular, we cannot know exactly what the edge of the universe looks like.
Physicists believe that in answering the question of how the Universe works, the study of elementary particles should help. Experiencesshow that the "most elementary" subatomic particles behave like bundles of energy. And there is nothing else but energy. Even space, long considered an entity in its own right, is now seen as a reservoir of energy. But between elementary particles, for example, protons and neutrons in the nucleus of an atom, there is a very large distance. Therefore, from the position of the microworld, the Universe looks like point energy clusters scattered at a very large distance from each other.
