There are several explanations about the origin of the universe. There are religious and scientific explanations on this subject. We will deal here with scientific insightthat is, how scientists try to explain the phenomena they observe in the universe.
It is not known for sure, but scientists estimate that the universe began to exist about 15 billion years ago. It seems impossible to say such a thing - 15 billion years is a long time!
What led scientists to think that the universe had a beginning?
The Hubble telescope can capture starlight, which shows what they looked like billions of years ago. By analyzing the light of the stars, it is possible to know the speed with which they are moving closer or closer to us, their chemical composition, age, temperature and mass, among other aspects.
The scientists then discovered something unexpected: the galaxies are moving away from earth!
To get a better understanding of what is going on, make several ink balls with a pen on a bladder eraser (birthday balloon) and start blowing. See what happens to the distance between the ink marks.
Starlight analysis shows that galaxies are moving away from each other, as are bladder markings. This is because the universe, like the bladder in our example, is expanding.
But if they are expanding, we can conclude that in the past galaxies were closer together. The more we go back in time, the closer they were.
We can then suppose a moment when all the matter of the universe was compressed into one point, infinitely long at enormous temperatures. That's what happened, what siethists call "the big bang" or, in English, the big bang. It was the beginning of the universe, which would have been about 15 billion years ago.
After the explosion, the initial temperature, which was over one trillion degrees Celsius, began to decrease, and atoms as they form matter today originated from protons, electrons, and other particles.
First, atoms grouped into clouds of gases. About a billion years later, the first stars and galaxies emerged.
And before the big bang?
Scientists cannot say. Since there was neither time nor space before the great explosion, some find it difficult to say that there was anything previous. According to them, the whole universe came into existence only from the great explosion.
But science does not yet have an answer to this discussion. Neither does it have for the future of the universe.