Many have heard that the diameter of the visible Universe is 93 billion light years and have seen pictures depicting our Universe as in the image below. At the same time, the majority has a question, what is further, outside this sphere? Let’s look at this issue together.
There is no single point of view, whether the Universe is really infinite or is it finite in space and volume, does not exist. However, we can consider the most plausible theories about this.
Despite a lot of research, scientists are still not entirely sure whether our universe is infinite or just very large. To determine between these two options, astronomers look at the curvature of space-time on the scale of the entire universe. On such a large scale, it speaks of the very shape of our Universe, and if it is geometrically completely flat, then it can be truly infinite.
Current observations and measurements of the curvature of the universe show that it is 99.99% flat. You might think that this means that the universe is infinite, but it’s not that simple. Even in the case of a flat universe, space does not have to be infinitely large. If, for example, we take the surface of a cylinder, it is geometrically flat, because the parallel lines on its surface do not intersect, but the cylinder has a finite size. It can also be with the Universe, that is, it can be flat, but at the same time closed in itself and have a limited volume.
If these boundaries exist and the Universe has a limited volume, then we do not have an exact understanding of what is behind them, and most likely never will. But there are a number of theories that explain what lies outside our universe.
According to one of them, the so-called “super” Universe can exist outside our Universe. That is, such a space outside our Universe, which extends infinitely and in which our Universe can expand forever. And at a distance of hundreds of billions of light years from us there may be other universes similar to ours. At this point, the question arises: why then do we not see them?
The most likely explanation for this is that these universes are so far away that by the time their light reaches Earth, it may have lost so much energy that we physically cannot notice it, or even our universe may die if it is not eternal. , by the time this light reaches us.
According to another theory: outside of our expanding universe, there is another space-time universe, with more dimensions, in which our universe is expanding. Since this universe has a higher dimension, we cannot see, reveal or comprehend it.
In a word, there are many similar theories about what could be outside of our Universe, if these limits exist, and they all boil down to the fact that outside either another, larger universe, or there is absolute nothing, which is impossible to describe. , because there is no space itself.
In this photo you can see a galaxy discovered, as they say: at the edge of the universe. But on which edge? At the visible edge of the universe.
The edge of the visible Universe is a sphere centered at the location of the observer (in this case, on the Earth). The radius of this sphere can be determined by the time it took for light to reach us since the Big Bang. In fact, the distance from the Earth to the edge of the visible Universe should be about 13.7 billion light years, but since the universe continued to expand during the flight of photons towards us, the distance is about 46-47 billion light years.
And every place in the Universe has its own visible spherical edge of the Universe, accessible for observation. Also, we cannot see what is beyond this edge, but according to cosmological principles, there should be the same space as ours, the same stars and galaxies as those that surround us.
Author: Alexey Nimchuk. Edited by Fedor Karasenko.
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