How was the universe born, how was the universe born, and has it remained the same as it is now, or has it evolved gradually?
These questions arise when humanity looks up for the first time and sees the vast expanse of the sky and the glittering stars.
Regarding the cause of the universe, human beings have been constantly exploring, and there are roughly several hypotheses, the first hypothesis is the theory of cosmic eternity.
This hypothesis holds that the space-time of the universe is infinite, that time and space in the universe are infinite, and that the universe is infinite and eternal.
That is to say, the universe is infinite in space, and the universe exists forever without a flag in time. The universe does not exist, and there is no end to the beginning. The universe is stable on a holistic scale, and even if it changes, it is only a local change. The second hypothesis is the view of cosmic stratification, which holds that the structure of the universe is hierarchical. Stars are a level, a collection of stars makes up a galaxy is a level, a number of galaxies combined together to form a galaxy cluster is a level, and some galaxy clusters form superclusters. Become a higher level.
The third hypothesis is the Big Bang theory that many scientists have so far agreed with.
This begins with a shocking scientific discovery published by astronomer Hubble in 1929 that all extragalactic galaxies are moving away from us, that is, the universe is expanding at a high speed. This discovery prompted some astronomers to think that since the universe was expanding. Then there could be a starting point for expansion, and the Belgian physicist Georges Lemaëtre believes that the current universe was formed by the explosion of a primordial atom, which was the predecessor of the Big Bang book. The Russian-American astronomer Gamov and the Soviet physicist Alexander Friedhau accepted and developed Lemaët's ideas. In 1948, the Big Bang theory of the origin of the universe was formally proposed.
Scientists who hold this scholarship believe that about two billion years ago, the material of the celestial bodies we see today was concentrated together. Form a primordial fireball with a very high density and a temperature of up to 10 billion degrees. Perseverance and care of this period. Doesn't exist. Later, for some unknown reason, the material that formed the fireball from the big explosion that occurred in this original fireball was erupted in all directions. And gradually cooled down, the density began to decrease. About 10,000 years after the formation of the nuclei of heavy elements after the explosion, hydrogen and helium atoms were produced in this 10,000 years, and the material scattered in space condensed into the stars of nebula galaxies.
Most of the gas became a star during the development of the nebula, and due to the gravitational pull of the star, some of the material became the interstellar medium.
But so far, there is no unified theory of the origin of the universe, waiting for further investigation and study.