Is there the center of the universe?: Why this scientific question challenges the limits of our imagination

The scientists soon realized that Einstein's theory did not claim that the universe had to be static, but also could support an expanding universe.

In fact, using the same mathematical tools as Einstein's theory, scientists created new models that demonstrated that the universe was, in fact, dynamic and evolved.

I have been trying to understand general relativity decades, even in my current work as a physics teacher teaching courses on the subject.

I know that becoming the idea of ​​a constantly expansion universe can be discouraging, and part of the challenge is to cancel our natural intuition about the functioning of things.

For example, it is difficult to imagine that something as great as the universe does not have a center, but physics says that is reality.

First, let's define what is meant by “expansion”.

On earth, “expansion” means that something is growing. And with respect to the universe, that is more or less true.

Expansion could also mean that “everything moves away from us”, which is also true in relation to the universe. If we point a telescope to distant galaxies, they all seem to get away from us. Moreover, the farther they are, the faster they seem to move.

These galaxies also seem to get away from each other. So it is more accurate to say that everything in the universe is moving away from everything else, all at once. This idea is subtle but fundamental.

It is easy to think about the creation of the universe as if they were fireworks: it begins with a big bangand then all the universe galaxies fly in all directions from some central point.

But that analogy is not correct. Not only does it falsely imply that the expansion of the universe started from a single point, which is not true, but also suggests that galaxies are what moves, which is not entirely exact.

It is not so much the galaxies that move away from each other, but the space between them, the fabric of the universe itself, which expands as time passes.

In other words, it is not the galaxies themselves that move through the universe, but it is the universe itself that moves them away as it expands.

A common analogy is to imagine that some points are glued on the surface of a balloon. When inflating, it expands and, as the points are attached to the surface, they move away.

Although they seem to move, they actually remain exactly where you put them and the distance between them simply increases by virtue of the expansion of the globe.

Now he thinks that the points are galaxies and the globe is the fabric of the universe, and you will begin to get an idea.

Unfortunately, although this analogy is a good start, nor does it capture the details.

Regarding any analogy, it is important to understand its limitations.

Some defects are obvious. For example, a balloon is so small that it fits in hand, but the universe is not.

Another defect is more subtle. The balloon has two parts: its latex surface and its interior full of air.

These two parts of the globe are described differently in mathematical language. The surface of the globe is two -dimensional. If we walk through it, we could move forward, backwards, to the left or the right, but not up or down without leaving the surface.

It may seem that we are naming four directions – a long, back, left and right – but they are only movements along two basic trajectories: side by side and from front to back. That is what makes the surface two -dimensional: length and width.

The interior of the globe, on the other hand, is three -dimensional, so you could move freely in any direction, even up or down: length, width and height.

This is where confusion lies. What we consider the “center” of the globe is a point located inside, in the space full of air under the surface.

But in this analogy, the universe looks more like the latex surface of the globe. The interior of the globe, full of air, has no equivalent in our universe, so we cannot use that part of the analogy: the surface only matters.

So asking where the center of the universe is is something like asking: “Where is the center of the surface of the globe?” Simply, there is not.

You could travel along the surface of the globe in any direction, during all the time you wanted, and you would never get to a place that you could call its center, because you would never leave the surface.

In the same way, you could travel in any direction in the universe and you would never find its center because, like the surface of the globe, it simply does not have it.

Part of the reason why this can be so difficult to understand is due to the way in which the universe is described in the language of mathematics.

The surface of the globe has two dimensions and its interior, three. But the universe exists in four dimensions, because it is not just about how things move in space, but how they move over time.

Our brains are designed to think about space and time separately. But in the universe, they are intertwined in a single fabric, called “space-time.”

This unification changes the functioning of the universe with respect to what our intuition expects.

And this explanation does not even begin to answer the question of how it is possible that something expands indefinitely: scientists continue to try to decipher what this expansion drives.

When asking ourselves for the center of the universe, we face the limits of our intuition.

The answer we find – all, expanding everywhere, all at the same time – is a hint of how strange and beautiful our universe is.

*Rob Coyne is a physics professor at Rhode Island University.

This article was published in The Conversation and reproduced here under the Creative Commons license. You can read the original English version here.

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