What is the universe exactly? And is there anything beyond its limits that we know?

To answer the question, is there anything out of the universe that we need first to define exactly what we mean by the universe?

A meaningless question.

When you imagine the universe thinking of a giant ball full of stars and galaxies and all sorts of interesting astrophysical objects, you might imagine that an astronaut can see it from the outside, like seeing the Earth from orbit above it in space.

In fact, the question, "What is outside the universe?" is like, "What sound does purple make?" It's an illogical question, because you're trying to combine two unrelated concepts, there's nothing in mathematics that describes the universe that has outside.

Physicist Stephen Hawking says that the whole question is meaningless; the question of what lies behind the universe is like the question of what lies north of the Arctic.

Beyond the universe.

The definition of "beyond the universe" implies that the universe has a edge, but scientists are not sure that such a thing exists.

The answer depends on how one looks at the question, says Jesse Mespak, co-author of "Life Science".

Somebody asks: can you go somewhere where you can look beyond the universe in the way that one can look beyond the edge of the window or look out the window to see the exterior surface of the building? the answer to that question is "maybe not."

The size of the universe.

Paul M. Sutter, an astrophysicist at the State University of New York, Stony Brook (S & T) and the Flatiron Institute, author of "How to Die in Space", also gave his answer to this question.

"If the size of the universe is unlimited, there is no need to worry about this question," Sutter wrote in an article on "Space". "As the universe is everything that exists, it is infinitely large and has no edge, so there is no outside until we can talk about it."

He adds that there is certainly a part of the universe that is still beyond our observations, that the universe is very old, and that nothing can be known about the universe except through light, and despite the speed of light that it travels, we have not received light from every galaxy throughout the history of the universe.

Astronomers try to find out if the universe is flat or self-reliant, if the universe is completely flat, its size can be infinite, but if it's as flat as the Earth's surface, its size will be limited.

Although current observations and measurements suggest that the universe is almost completely flat, this certainly does not mean that the universe is infinite, because even in the case of a flat universe, the universe need not be infinitely large.

The universe can be flat, but it's enclosed on itself like the surface of a cylinder, so the loose lines drawn on the surface remain redundant, and this is one of the definitions of "flattening," but it's of a limited size, and the same can apply to the universe.

But even if the universe is limited, it doesn't necessarily mean that there's a edge or something exogenous, that our three-dimensional universe could be embedded in a larger, multidimensional structure, but right now we don't have a way to test that.

The balloon universe.

So, although the balloon surface is a limited number of regenerative units, there's no edge and no limit, so you can go forever in any direction.

In parallel to that, there is no "center" on the spherical surface of the balloon, the universe is a three-dimensional version of the balloon surface.

"We're looking for recurring points in the sky," Mac adds, if astronomers find two places on both sides of the sky that are perfectly identical, that would be a strong indicator of the universe bending in this way, and yet there are no guarantees.

All of this means that if there is an end to the universe, humans may never be able to see it, and there's a real possibility that the universe has been shaped so that it can't have borders to begin with.

The universe expands.

Mac says that the actual size of the universe is 46 billion temporal years in any direction, and although the universe started only 13.8 billion years ago, this still puts a limit on the size that humans can see called "the universe."

And Mac adds that assuming inflation happens, the universe is actually 1,023 times larger than the 46 billion years humans can see, so, if there's a edge to the universe, it's so far away that the people of Earth can't see it and they'll never see it.