Where is the center of the universe?

The universe is extremely vast and from a human perspective, it seems that the Earth is in the middle of everything. But does the center of the universe exist, and if so, where is it? If the Big Bang gave birth to the universe, where did it come from and where will it go? To answer these questions, let’s go back about 100 years.

In the 1920s, astronomer Edwin Hubble made two startling discoveries. Early in the decade, he noticed that galaxies were very far away from Earth. By the end of the decade, he discovered that, on average, all galaxies were receding from our planet.

Luckily, scientists have a theoretical explanation for the above. Einstein’s theory of general relativity predicted that the universe is dynamic – expanding or contracting. This went against the popular view at that time that the universe was completely static. After that, four scientists worked hard to develop the Friedmann-Lemaitre-Robertson-Walker solution to Einstein’s equation, laying the foundation for modern cosmology.

The solution to Einstein’s equation mentioned above and the impressive observations of the Hubble space telescope show that humans live in an expanding universe. On average, every galaxy is moving farther and farther away from every other galaxy, and long ago, all the matter in the universe was compressed into an infinitely tiny point called the singularity – the starting point of the supernova. Big Bang explosion.

So where was the Big Bang? This would certainly be the true center of the universe. However, the information that humans know about the universe is still not enough to provide any simple, clear explanation. That’s because the universe has neither a center nor an edge. The universe did not expand from a point nor did it expand into anything.

First, let’s tackle the fringe issue. By definition, the universe is everything that exists. While the edge is what separates one area from another. But if the universe includes all regions, there can be no edges. This means that the universe can be infinitely large and finding the center of an infinite space is impossible.

Another possibility is that the universe is finite. But this means that, on an extremely large scale – much larger than what humans can observe – the universe will curve in on itself. Thus, the universe also has no center.

For comparison, consider the Earth. One can point to the center of the three-dimensional planet—the molten core—but not the center of the Earth’s surface: It could be at the intersection of zero latitude and zero longitude, or at the poles, or even in someone’s house. Any point would be equally suitable.

Thus, the Big Bang occurred simultaneously everywhere in the universe. It’s happening in the room you’re sitting in and also in the farthest galaxy that humans can see. The Big Bang was not a point in space but a place in time.

But here’s an interesting twist: The universe is old, about 13.77 billion years old. Because the speed of light is so fast, only a small portion of the universe is illuminated by human light. There is a limit to what humans can observe, and the edge of that limit is about 45 billion light years away from Earth. This happens because the universe is expanding faster than the speed of light.

Much of the universe is hidden from humans: Like a flashlight in a distant forest, humans can only see things within the limits of their illumination. From a human perspective, all other galaxies are moving away from the Milky Way. Therefore, it seems that man is at the center of the entire universe. Of course, the same could happen to any other galaxy. From the perspective of these galaxies, they are also at the center of the observed region and every other galaxy is receding.

This is the interesting point of an expanding universe: it has no center, and it can be said that everywhere is the center. All observers, including humans, can claim to be in the middle.