The universe was formed approximately 13.77 billion years ago, but its expansion makes it impossible for humans to determine the center of the universe.
Image captured by the James Webb Space Telescope reveals some of the oldest and most distant galaxies ever observed. (Photo: NASA/ESA/CSA/STScI)
The universe is incredibly vast, and from a human perspective, it seems Earth is at the center of everything. But does a 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 is it heading? To answer these questions, let’s rewind to about 100 years ago.
In the 1920s, astronomer Edwin Hubble made two remarkable discoveries. At the start of the decade, he observed galaxies far beyond Earth. By the end of the decade, he discovered that, in general, all galaxies are moving away from our blue planet.
Fortunately, the scientific community had a theoretical explanation for these observations. Einstein’s General Theory of Relativity predicted that the universe is dynamic – either expanding or contracting. This contradicted the widely held view at the time that the universe was completely static. Subsequently, four scientists worked to develop the Friedmann-Lemaître-Robertson-Walker solution to Einstein’s equations, laying the groundwork for modern cosmology.
The Hubble Space Telescope captures images of three spiral galaxies poised for collision in the constellation of Eridanus. (Photo: NASA/ESA)
The solution to Einstein’s equations, along with the impressive observations from the Hubble Space Telescope, indicates that we live in an expanding universe. On average, every galaxy is moving farther away from every other galaxy, and for a long time, all matter in the universe was compressed into an infinitely small point known as a singularity – the starting point of the Big Bang.
So, where is the Big Bang? This would certainly be the true center of the universe. However, the information humans have about the universe is still insufficient to provide a clear, simple explanation. That’s because the universe has no center and no edge. The universe did not expand from a point, nor does it expand into anything.
First, let’s address the issue of edges. By definition, the universe includes everything that exists. An edge would imply a division between one area and another. But if the universe encompasses all areas, then there cannot be an edge. This means that the universe could be infinitely vast, making it impossible to find the center of an infinite space.
Another possibility is that the universe is finite. However, this would mean that on an extremely large scale—much larger than what humans can observe—the universe would curve back on itself. Thus, the universe also has no center.
To compare, consider Earth. One can point out the center of the three-dimensional planet—the molten core—but cannot pinpoint the center of Earth’s surface: it could be at the intersection of latitude 0 and longitude 0, at the poles, or even at someone’s home. Any point is equally valid.
Thus, the Big Bang occurred simultaneously everywhere in the universe. It happened in the room you are sitting in and also in the farthest galaxy visible to humans. The Big Bang is not a point in space but a moment in time.
One can identify the center of the three-dimensional Earth—the molten core—but cannot pinpoint the center of the planet’s surface. Photo: Salon
However, there is an interesting twist: The universe is approximately 13.77 billion years old. Because the speed of light is so fast, only a small portion of the universe is illuminated for humans. What humans can observe is limited, and the boundary of this observable universe is about 45 billion light-years away from Earth. This occurs because the universe is expanding faster than the speed of light.
A large portion of the universe remains hidden from humans: Like a flashlight beam in a distant forest, humans can only see what is within the illuminated range. From a human perspective, all other galaxies are moving away from the Milky Way. Thus, it seems like humans are at the center of the entire universe. Of course, the same could be true for any other galaxy. From the perspective of these galaxies, they are also at the center of the observable region, with all other galaxies receding.
This is the intriguing aspect of an expanding universe: it has no center, yet one could argue that every location is a center. All observers, including humans, can claim to be in the middle of it all.
