The question of what's outsideThe representatives of the human race have been asking themselves for more than one century. But an approximate understanding of what our cosmic home is, appeared (by the standards of the same Universe) quite recently. Today we know that the Universe was born about 14 billion years ago as a result of the Big Bang and has since expanded with acceleration, cooling in parallel. It seems to contradict common sense, but to understand the amazing laws of the cosmos and how they work, the smartest of us have worked for generations. But the knowledge accumulated over the years, alas, still does not allow us to put the puzzle together. Yes, we know what the observed Universe looks like - with the help of powerful telescopes, scientists map not only stars, but billions of galaxies and their clusters, looking further and further into the past, right up to the Big Bang. But can they find out if something is outside of our universe? Is there anything out there where it is not only impossible to send the most powerful tools, but also to simply look?
What do we know about the universe?
To answer the question of what is behindoutside the universe, you first need to define exactly what we mean by "the universe." If you take it literally as all things that can exist in all space and time, then there can be nothing outside the universe. Even if you imagine that the universe has a certain finite size, and imagine something outside this volume, then everything that is outside must also be included in the universe.
Even if the universe isformless, nameless emptiness - absolutely nothing - it is still something and is included in the list of "all that exists" - and, therefore, by definition, is part of the universe. If the universe is infinite in size, then you really don't need to worry about this puzzle. The universe, being all that is, is infinitely large and has no edge, so there is nothing “external” to talk about.
On the other hand, of course, there is an outer sideour observable portion of the universe. Space is old and light is spreading fast. Thus, in the entire history of the universe, we have not received light from every single galaxy. At present, the width of the observable Universe is about 90 billion light years... And there appear to be billions of other random stars and galaxies beyond that border.
But is there something beyond that?
See also: Is it possible to solve the mystery of the expansion of the Universe?
The boundaries of the universe
Cosmologists are not sure if the universe isinfinitely large or just extremely large. To measure the universe, astronomers look at its curvature instead. The geometric curve on a large scale of the universe speaks of its general shape. If the universe is perfectly geometrically flat, then it can be infinite. If it is bent like the surface of the Earth, then it has a finite volume.
As written in the article for Space.com astrophysicist Paul Sutter, current observations and measurements of the curvature of the universe show that it is almost perfectly 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.
“Take the surface of a cylinder, for example.It is geometrically flat because parallel lines drawn on a surface remain parallel (this is one definition of "flatness"), and yet it has a finite size. The same can be said about the universe: it can be completely flat, but closed in itself. ”- Paul Sutter, astrophysicist at SUNY Stony Brook and the Flatiron Institute in New York.
But even if the universe is finite, it is notnecessarily means that somewhere there is its edge. Perhaps our 3D universe is embedded in some kind of larger multidimensional structure. This is perfectly normal and is indeed part of some exotic physics model. But scientists currently have absolutely no way to verify this.
This is interesting: Why do physicists believe that we live in the Multiverse?
The universe can be thought of as a giant ballfilled with stars, galaxies and all kinds of interesting astrophysical objects. How these objects look from the outside is also easy to imagine - remember the famous photographs of astronauts from space - they often look at the globe from a serene orbit above. But this general perspective is hardly necessary for the universe to exist, because it just is.
"When you imagine the universe as a ball floating in the middle of nothingness, you are playing a mental trick on yourself that mathematics does not require," Sutter writes.
In general, given the accumulated array of data onthe observable universe (and on reflection), it seems that the question of whether there is something outside of it simply does not make sense. It's like asking "What sound does purple make?" A frankly meaningless question because we are trying to combine two unrelated concepts in it. What do you think, is there something outside the universe and is it not a meaningless question? We will wait for the answer in our Telegram chat, as well as in the comments to this article.