Where is the center of the universe?

Man cannot find the center of the universe at present. But scientists have been advancing their exploration of the universe.

Since ancient times, people can see the rising and setting of the sun every day, as if the sun goes around the earth, which naturally makes people think that the earth is the center of the universe. Later, this view was overthrown by Heliocentrism. Heliocentrism thinks that the sun is the center of the universe, and the earth just goes around the sun.

So what is the center of the universe? The earth, the sun, the Milky Way or other extragalactic galaxies, or the universe has no center at all?

In fact, people have been thinking about this issue for a long time. Scientists have formed some conclusions or opinions based on a large number of observations and recorded data, but so far there is no completely convincing statement.

Let's see what theoretical systems there are.

1) geocentric theory

In 90- 168, Ptolemy, an ancient Greek scholar, established the world's first complete geocentric universe system. On the basis of summarizing predecessors' viewpoints and measurement data, especially the observation results of planets at that time, he put forward the viewpoint that the earth is at the center of the universe and motionless. Stars are all located on a solid spherical shell called "star sky", and other celestial bodies such as the sun, the moon and the five planets revolve around the earth. Thus formed the geocentric theory.

2) Heliocentrism

Geocentric theory ruled 1400 years. Although some astronomers found that this theory frequently made mistakes in the actual calculation of celestial bodies, no one dared to refute it because of the strong support of the church.

In A.D. 1543, Copernicus, a Polish astronomer, challenged the traditional geocentric theory in his book On the Operation of Celestial Bodies. He thinks that there is only one ordinary planet on the earth that keeps spinning, the sun is the center of the universe, and other celestial bodies are revolving around the sun.

3) unintentional theory

In modern times, with the gradual recognition of the theory of cosmic expansion. Some people think that there is no center in the universe. The sun is only the center of the solar system, and the Milky Way has a center, but the universe has no center. According to the expansion theory of the universe, we can imagine the universe as an inflated balloon with galaxies all over the surface, and we human beings live at a certain point. In addition, we need to assume that galaxies can only move along the surface without entering the balloon, or move outward without leaving the surface of the balloon. In a sense, we are described as a person who exists in two-dimensional space. If the universe keeps expanding and the surface of the balloon keeps getting bigger, the distance between each point on the surface will also get bigger and bigger. Among them, if a certain point where someone is located is taken as a fixed point, this person will see that all other points are retreating, and the farther away from him, the faster he retreats.

Now, if we want to find the starting point of a point on the balloon surface, then we will find that it is not actually in the two-dimensional space on the balloon surface. Because the inflation of the balloon actually starts from the inner center in three-dimensional space, and our position is in two-dimensional space, we can't clearly detect things in three-dimensional space.

Similarly, the interior of the three-dimensional space is not the starting point of the expansion of the universe, but we can only move in the three-dimensional space of the universe. At some time in the past, when the universe began to expand, perhaps hundreds of millions of years ago, although we can see that we can get information from it, it is impossible to go back to that time. So the universe has no center.