Is the universe finite or infinite?

Is the universe finite or infinite? What shape is it? There is no definitive answer yet.

Let's start with the origin of the universe. The mainstream view holds that the universe was born in the Big Bang, including time, space and all the substances produced by that Big Bang. Scientists have determined that the universe was born 65.438+038 billion years ago, and the Hubble volume radius is about 46 billion light years.

Hubble volume is a spherical area with a radius of about 46 billion light-years centered on human observers. Some people may have questions? The universe is only 65.438+0.38 billion years old. Why is the radius of Hubble volume 46 billion light years? Because the universe has been expanding since its birth. Space expansion drives matter away from each other, as if matter were spreading outward. When the light from distant celestial bodies reaches the earth, the celestial bodies themselves are far away from the earth. When we received the light from the celestial body more than 65.438+0.3 billion years ago, the position of the celestial body has changed, and the celestial body is now more than 40 billion light years away from us.

At the beginning of the last century, astronomer Hubble discovered by analyzing the spectrum of celestial bodies that the galaxies outside the river are moving away from us, and the farther away the galaxies are, the faster the return speed is. At a distance of 65.438+0.4 billion light years, the expansion speed has reached the speed of light.

With the improvement of cognitive ability, human's view of the universe is constantly changing. In the early days, people thought that the sky was round, and Magellan's voyage around the world confirmed that the earth was round. From the center of the earth to Heliocentrism, and then to the discovery of galaxies outside the river, the progress of science has improved the world outlook of mankind.

In Newton's time, due to the invention of astronomical telescope, human beings had a better understanding of the universe. In the era of classical physics, it is considered that the universe is an open and straight space, the universe is static and infinite, and matter is evenly distributed in space. Obviously, if the universe is infinite, there will be infinite matter and infinite gravity, and such a universe is unstable.

Einstein's theory of relativity has opened a new door for human beings to understand the universe. Relativity holds that space-time is four-dimensional and consists of three-dimensional space and one-dimensional time. Later superstring theory even thought that our world should be 1 1 dimensional.

Although matter can bend space-time, the distribution of matter is relatively uniform on a large scale, and space-time is relatively flat as a whole. It's just that local space is badly curved, such as black holes and the space-time around them. Because the distribution of matter on a large scale is uniform, and no matter where it is observed in the universe, the result is the same, which is called isotropy.

According to the big bang theory, the universe is finite and has no boundaries, so it has no center. In an infinitely bounded universe, space should be closed, similar to a closed two-dimensional sphere, and the galaxies in the universe are distributed on a three-dimensional hypersphere.

For example, ants living on a two-dimensional sphere can never find the boundary no matter which direction they climb, as long as they don't leave the sphere. When this sphere is big enough for ants, ants will think that their world is flat. Just like we live on the earth. If the sphere is infinite, then the sphere can be regarded as an infinitely extending plane.

Because of the influence of curvature of spacetime, we think that light travels in a straight line in a vacuum, but in fact it travels along geodesic lines in space. Our universe is so big that it is difficult for us to determine the shape of the universe.

To sum up, according to the mainstream view of the current scientific community, my universe is dynamic, closed, finite and unbounded, uniform and isotropic.

what do you think? Everyone is welcome to express their opinions.

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