About 14 billion years ago, everything we know began with the Big Bang. But it wouldn’t be right to really think of it as an explosion. When the universe began, space and time appeared. To imagine it as an explosion also makes us think it started from a single point, but that’s not the case.
The Big Bang happened everywhere at the same time. And when astronomers say everywhere, they really mean everywhere. There was no single point where it all started, all distances in the universe were zero, so every point in the universe was virtually in the same place: everywhere…
Therefore, if you encounter a question like “where is the center of the universe”, the answer is simple: “There is no such center.”
The visible universe is about 94 billion light-years across. These are just all we can see. If we think that it consists only of the part we can see, we can say that we are at the center of the universe. What we see has two very important characteristics defined by cosmologists: being isotropic and uniform. Being isotropic means it looks the same no matter which way you look at it, and being uniform means it’s the same everywhere at the largest scale.
These facts tell us a little about the universe as a whole, which is much larger than the universe we can see. We don’t yet know how big the universe is or what the whole universe looks like, so the part of the universe we are in may be different from the rest, special or represent the whole.
The simplest scenario: The universe is infinite
The simplest scenario imaginable is that the universe is infinite. Something infinite has no center. However, while our weaker brains have not evolved to visualize the concept of infinity, we can say that if something goes on forever, there is no particular center point.
However, we cannot guarantee that the universe continues forever, and it may have an end.
Unfortunately, our experiences do not express the universe as a whole because the geometry we are most familiar with is not the geometry of a finite universe. We have to deal with the concept of curvature, and once again our brains are not developed to deal with curvature in three dimensions.
We can make a problematic but easier analogy. “If you think about the surface of a sphere, if that’s all, the sphere has no center,” said Peter Coles, Professor of theoretical physics at Maynooth University, in an interview with IFLScience. The center of the sphere is outside that field, right? This is not a real thing,” he said, and continued: “You think of a sphere as embedded in a three-dimensional space, and the center is in that three-dimensional space. But if everything is two-dimensional space, it has no center.”
To repeat… The only thing to say is that the universe has no center. As far as we can perceive, our physics operates on the four-dimensional space-time continuum. When viewed in greater dimensions, the curvature may imply a central location. But if it has a center, it is not part of our universe as we understand it.
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