The universe and the starry sky have always filled human beings with endless reverie, and now with the continuous progress of astronomy, we gradually realize the vastness of the universe, and we find that the vastness of the universe is unimaginable, and the universe we can observe alone is as long as 93 billion light years, and the age of the universe is also speculated, which was born about 13.8 billion years ago.
Speaking of which, many people may wonder, since the universe was born 13.8 billion years ago, what did the universe exist before it was born, and what did he look like
In modern scientific theory, the origin of the universe is recognized by most scientists as the Big Bang theory, which holds that our universe exploded from a singularity 13.8 billion years ago, and at first all matter was concentrated in this infinitely dense hot energy singularity
When after the Big Bang, space expanded at an extremely fast rate, energy began to convert into matter, initially only neutrons, protons, neutrinos and other elementary particle forms existed, and as the temperature cooled, and then formed atoms, molecules, and then combined into a gas nebula, and finally the gas nebula collapsed into stars, slowly evolved into the universe we see now.
In fact, the origin of the universe 13.8 billion years ago is not a completely fantasy theory by scientists, but a theory that is based on evidence and deduction.
In 1929, an astronomer from the United States, Edwin Hubble, discovered that most galaxies in the universe have redshifts. The so-called redshift phenomenon is that when the light of a celestial body is far away from us, the light waves are elongated, and the color will move towards the red end
Hubble discovered the commonality of these galaxies, indicating that distant galaxies are moving away from us at a very fast speed, and also found that the regressive speed of galaxies is proportional to the distance. That is to say, the farther away the galaxy is, the faster it is moving away from us, thus proving that the universe is constantly expanding.
So now that we know that the universe is constantly expanding, we can deduce the age of the universe, according to Hubble's law, if we reverse the speed of the galaxy away from us, like an image backwards, and back to 13.8 billion years ago, the original state of the universe is an infinitely dense high temperature singularity.
This singularity is incomprehensible to us, it can be called a singular point whose physical properties are completely beyond the scope of existing physics!
So it doesn't really make sense for us to talk about what existed before the Big Bang, because before the Big Bang, space and time and any laws of physics didn't exist, and these were all created after the Big Bang! So we can't use current physics and cosmology to study what happened before the Big Bang. We can understand that there was nothing before the Big Bang, that everything didn't exist.
But then again, the above is not to say that the origin of the universe was really born from the explosion of the singularity, but it is just the most reasonable statement at present! And if we continue to ask why the universe exploded from the singularity, in fact, all of this is beyond the scope of our human understanding! No one can give an answer!