Where is the center of the universe?

For more than a century, scientists have debated the shape and structure of the universe. Does the universe have a 'center'? If so, where is it? And why do galaxies seem to be moving away from each other at ever-increasing speeds?

In space, there are four dimensions: length, width, height and time - Photo: NASA

More than a century ago, scientist Albert Einstein believed that the universe was static and proposed the "cosmological constant". But then astronomical discoveries changed all that: the universe is not static, but is constantly expanding over time.

What's even more surprising is that the universe doesn't have a single "center." And to understand this, we need to look at the world from a completely new perspective.

The stationary universe hypothesis

In 1915, Albert Einstein published his theory of general relativity, a theory that changed the way humanity understood space and time. Einstein assumed that the universe was static: Its size and shape did not change over time. Galaxies stood still in an infinite, eternal space.

However, some time later, astronomers began observing distant galaxies with more powerful telescopes and discovered that the light from these galaxies was "redshifted," a physical phenomenon that showed the galaxies were moving away from Earth.

Specifically, astronomer Edwin Hubble made two revolutionary discoveries.

In the early 1920s, Hubble demonstrated that the "island universes" that scientists had been talking about were actually galaxies, and they were located much further away than our Milky Way.

Later that decade, he further shocked the world by discovering that on average all galaxies are moving away from us.

This meant a truth that was hard to believe at the time: the universe was not standing still. Hubble's discovery ushered in a new era in cosmology, laying the foundation for the concept of an expanding universe as we know it today.

This was a historic turning point: the universe was not standing still, but constantly expanding. Einstein later had to admit that his initial assumption was wrong, and he called it "the biggest blunder of his life".

The universe is expanding but has no "center"

The universe contains countless mysteries that humans do not fully understand - Photo: AI

It sounds strange: if the universe is expanding, where is its center? Is the Earth the center?

The answer is no.

Imagine this: when we look through a telescope at galaxies in every direction, they all appear to be moving away from us. In fact, the more distant the galaxies, the faster they are moving away. This doesn’t mean that Earth is the center, but that all of space is expanding at the same time.

In other words: It's not that the galaxies are "flying away", but that the space between them is expanding over time.

A familiar example is a balloon. Imagine you glued dots to the surface of a balloon. As you blow up the balloon, the dots get farther apart, even though they are not moving across the surface. The distance increases not because the dots are moving, but because the surface of the balloon is expanding.

The same is true in the universe. Galaxies are like dots on the surface, and space is the shell of the ball. As the universe expands, all galaxies move away from each other simultaneously, without a fixed center.

Space, time and the "fourth dimension"

One of the reasons why it is difficult for us to visualize the universe is because our intuition is used to seeing the world in three dimensions: length, width, height. But our universe has not only three dimensions, but also a fourth dimension: time.

In general relativity, space and time are combined into a single concept called “spacetime”. As the universe expands, not only does the distance between galaxies change, but time is also part of that change.

So the question "where is the center of the universe?" is essentially unanswerable. It's like asking "where is the center of the surface of a ball?" There is no single point. Every point in the universe is the same, and from any galaxy you look at, you'll see other galaxies moving away from you.

Scientists are still trying to figure out what is causing the universe to expand at an ever-increasing rate. Many theories suggest that it is due to a form of energy that is not yet fully understood, called dark energy. But no matter how advanced technology is, the universe still holds mysteries beyond human imagination.

Understanding the expansion of the universe not only helps us explore the history of the universe, but also opens up a new perspective on the place of Earth and humanity in the grand scheme of space and time.

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MINH HAI

Source: https://tuoitre.vn/trung-tam-vu-tru-nam-o-dau-2025090814153114.htm