The earth is the homeland of human existence, and beyond the earth is the vast and mysterious universe. After mankind entered the age of science and technology, he began to research and explore the universe outside the earth.
Through continuous research and exploration, modern science generally believes that the origin of the universe is a singularity that was born 13.8 billion years ago. The universe after the birth of the Singularity Big Bang is not fixed. While it is expanding rapidly, it is undergoing various evolutions at the same time, gradually evolving into the current cosmic space.
There are many mysteries in the vast universe waiting for us to solve, and two of them can be called the ultimate mystery, one is the origin of the universe, and the other is whether there is space outside the universe. If there is space, then the universe What is the outside of?
So is there space outside the universe? The scientific community has been conducting various discussions on the answer to this question. However, we can initially find the answer from a simple cosmic phenomenon. This phenomenon is the constant expansion of the universe. I believe that everyone is familiar with expansion. In our real life, many things can expand, and everyone knows. It should be the inflation of the balloon.
A small balloon, as long as you keep blowing air into it, it will continue to expand and become bigger. If the material of the balloon is infinitely strong, theoretically the balloon can expand to infinite size. So what is the premise of the balloon being able to expand continuously? Some people may say that it is we who keep blowing into it. But the real answer is not so. Its premise is that there must be enough space outside the balloon.
If the outer space of the balloon is very small or there is not enough space for it to expand, then no matter how much you blow into it, it will stop expanding. The expansion of the universe is naturally incomparable with the expansion of balloons, but from a scientific point of view, the universe wants to expand continuously, indicating that there is space outside it, otherwise it cannot continue to expand.
There is no definite answer to how big the universe has expanded. And we often hear an astronomical term: the observable universe, so what is the observable universe? In human research and exploration of the universe, the word observable universe appears very frequently.
The origin of the observable universe, we need to start with the Big Bang. After Einstein proposed general relativity in the last century, a broad-phase cosmology came out in the scientific community. Because many scientists deduced from the general theory of relativity that the universe is a dynamic process, and Lemaitre further proposed the primitive atom hypothesis. In fact, this is the predecessor of the big bang theory of the universe. It happens that Hubble observes the farther the universe. Departs at a faster rate, so the expansion of the universe comes from this.
Scientists observe distant galaxies in the depths of the universe and find that their speed away from us is accelerating as the distance increases. The universe is constantly expanding, which shows that it has an initial singularity. This is an important basis for the big bang to be universally recognized by the scientific community.
After the Big Bang, there is a mass of energy. When the time reaches 10^-6S, electrons, quarks and photons appear in the universe. After that, quarks form baryons such as neutrons and protons under the strong action! After that, as the temperature continues to drop, protons combine with protons and neutrons to form independent protons of hydrogen and helium and a trace amount of lithium nuclei.
The temperature of the newly born universe was extremely high, and photons were still trapped in it at this time until 380,000 years later. As the universe expands, the temperature gradually cools down and photons are released. The released photons continue to diffuse in the universe and begin to form matter with other basic elements.
After the formation of matter, there are no stars in the universe at this time, and it is a completely dark era. The universe continues to expand, and matter gradually forms stars under the action of gravity. The stars bring a little light to the dark universe and also bring more opportunities for evolution. The star itself is a powerful refinement and processing plant for elemental matter.
Large-mass stars have a relatively short lifespan. After reaching the end, supernova explosions occur in the stars. In this process, various heavy elements are also born, thus enriching the elemental matter of the universe. With stars under the action of gravity, various galaxies continue to form, and stars are also the origin of black holes. The continuous collision and fusion of a large number of black holes form supermassive black holes. With this as the center, under the action of gravity, the Milky Way is gradually formed. Such a large galaxy.
The final universe is what we see now. The observable universe is mainly based on photons. We all know that the speed of light is the speed of light. We can observe galaxies in the universe. The photons in this galaxy entered our telescope.
The time required for a photon to reach the earth is also related to the expansion of the universe. If the expansion speed of the universe exceeds the speed of light, then the photon will never reach the earth, and we will not be able to observe the galaxy information brought by the photon. So does the expansion speed of the universe exceed the speed of light? The answer is yes.
The expansion speeds of different spaces in the universe are different. Galaxies that are far away from us will expand farther away from us. The farthest celestial body we can currently observe is GN-Z11, which is 13.4 billion light-years away. This galaxy is indeed It is too far away. According to the expansion of the universe, it is about 30 billion light years away.
We cannot observe the universe outside the GN-Z11 galaxy. The reason is that the expansion speed of the space exceeds the speed of light, and electromagnetic information such as photons cannot be transmitted to the earth. To truly observe the universe outside the GN-Z11 galaxy, we need to develop observation tools with other powerful modes.
Since the universe is constantly expanding, it means that there is space outside the universe, so what kind of existence is this space? From the big bang theory, the universe has no outside, because the entire universe was created by the big bang, time and space and matter are in the universe, and the outside is chaos.
However, with the continuous improvement of human cognition of the universe, scientists began to believe that there is space outside the universe, and multiverse theory is a conjecture aspect of this. Some scientists believe that there is a larger universe outside the universe, where there are countless large and small universes, and our universe is just one of them.
Before human beings walked out of the earth, they also believed that our earth is infinite, and it is the entire universe. But when we walked out of the earth, we discovered that there are countless other planets that are similar to the earth. For the same reason, we still have no ability to reach the edge of the universe, let alone get out of the earth, so our perception is very limited.
Perhaps in the infinite future, mankind will become the overlord of the universe, free to travel all corners of the universe, and can walk out of this cosmic space, perhaps we will see an even more vast and incredible outer space. Exploring the world beyond the universe is still too far away for mankind. It may be the ultimate mystery of the universe, and it may take us to develop technology to the end before we can hope for it. We can only look forward to this day.