It’s hard for an ordinary person to imagine the universe. But how big is outer space? Does it have a beginning and an end, any boundaries?
The concept of the boundaries of the universe
According to scientific studies, the universe has no boundaries. When it comes to the "edges" of the Universe, a slightly different concept is implied. These edges cannot be felt or stumbled upon in any way, as if on a wall. The fact is that the region in cosmic terms is the limit of what a person is able to see. For this, various equipment is used. There is a certain line beyond which nothing is visible. However, this does not mean at all that at this boundary the Universe abruptly breaks off. It is customary to say that the universe has no edges, but there are horizons.
In cosmology, there is such a thing as an observable Universe. By it is meant the part of the Universe whose past the observer sees. The fact is that during the period when signals from the farthest point of the Universe reach the Earth (that is, an observer), the Universe will already advance forward for a certain time. Thus, what a person sees has already happened before. The face that a person is able to see is called the cosmological horizon. All objects that are located on it have an infinite redshift. On the cosmological horizon, there are about 500 billion galaxies and more.
The part of the visible Universe that can be studied using modern astronomical methods is called the Metagalaxy. Instruments are gradually being modernized, improved, and at the same time, the size of the Metagalaxy is increasing.Scientists can only voice hypotheses about what lies beyond the horizon of the universe. It is customary to call these objects extrametagalactic. Moreover, the Metagalaxy can be both practically the entire Universe and only a small part of it.
Interesting fact: as soon as the Metagalaxy appeared, its gradual uniform expansion began. Scientist Edwin Hubble in 1929, through research and experiments, established that there is a certain relationship between the distance to the galaxies and their redshift. This dependence is called the Hubble law, which describes the expansion of the universe. According to the law, outer space on the scale of the Universe is expanding non-stop, and distances between galaxies are increasing.
In theory, the facet of the observed Universe is the cosmological singularity - this is the state in which the Universe was when the Big Bang occurred. That is, it is assumed that for some time the Universe was static. Then came the Big Bang, which triggered an expansion that continues to this day. Moreover, it is believed that recently the expansion of the Universe has accelerated.
In practice, only relict radiation was considered. Its origin is also directly related to the Big Bang theory - it is assumed that before the Universe consisted of hot plasma. Modern science has succeeded in observing the scattering surface. This is so far the most distant object.
Since the Universe began to expand rapidly, this confirms the presence of two forces - gravity and antigravity. Within the observable Universe, universal anti-gravity prevails over gravity.According to available estimates, the diameter of the part of the universe that is to be observed is 93 billion light-years or 28.5 gigaparsecs. Then a logical question arises: "Why is the diameter of the Universe 93 billion light years, if scientists determined its age - 13.7 billion years?"
The fact is that the further the zones of the Universe are located, the faster their expansion occurs compared to the speed of light. At the same time, it is not the objects themselves that move faster, but the space within which they are located.
From the foregoing, it turns out that if the Universe continues to expand in the future, faster and faster, then in a certain period the remaining galaxies that are not part of the Supercluster of galaxies will cross the horizon of the Universe. Accordingly, they can no longer be considered.
Is it possible to get to the edge of the universe?
Given all the features of the universe, is there a possibility that a person will ever get to its borders? This question can be called both very simple and complex at the same time. To date, the edge of the universe is considered the most remote area that can be seen with a telescope, and this is about 15 billion light years. To look further, you will have to wait for the invention of even more powerful telescopes.
However, in any case, it will not work to get there, even if the spacecraft were moving at the speed of light. For example, a distance of 300 thousand kilometers is scanty in space. Light travels from the Sun to Earth in eight minutes. So, if the supply of light ceases, then humanity will know about it only after 8 minutes. Thus, the image of the Sun is how it looked in the past. Because of this feature, the Universe got the name "time machine".
Interesting fact: according to one of the theories about the Universe, it may have no boundaries at all. Scientists believe it is likely that if an object moves for a long time in one direction within the Universe, then, sooner or later, it will reach its original point of departure.
For example, from the star Proxima Centauri (closest to the Sun), light has been going on for 4 years. Andromeda (a large galaxy close to the Milky Way) sends signals for 2 million years. As for the border of the Universe, not a single astronaut is able to cover a distance of 15 billion years, respectively, it is impossible to travel to the border. In addition, spacecraft are not able to overcome the speed of light or even come close to such indicators (at the current level of development).
In the science of outer space, it is customary to say that the Universe has no edges, but there are horizons. The cosmological horizon is the face of the Universe that a person is able to see with the help of the most powerful telescope. Part of the observable Universe is called the Metagalaxy. With the advent of new equipment, the Metagalaxy will expand. Also, this issue is closely related to the expansion of the Universe - in the future it is possible that distant galaxies will go beyond the visible horizon.It is impossible to get to the edge of the Universe, since the distance to the most distant visible region is about 15 billion years.
