Stages of the origin of the universe since Big Bang
Big Bang is a massive explosion happened, since 15000 million years, resulted in it all the forms of matter, energy and time, It is the expansion of the universe and merging of atomic particles forming helium and hydrogen gases.
How did the universe originate?
There was no one to relate what happened but the discoveries in the physics and the astronomy enabled the scientists to trace the history of the universe from the first-second fraction of its evolution.
Many scientists believe that the universe emerged from a massive explosion called Big Bang, They believe that before the explosion, The universe matter was a gaseous ball of high pressure, high temperature and small in volume, It is in constant expansion.
Since about 15000 million years, the universe was very small and very hot, due to the explosion, all forms of matter, energy, space and time resulted in it.
Through Big Bang, the process of expansion and changing of the gaseous ball components started and it continues to this day, through 1 second after the explosion, The temperature decreased to about 10000 million ( 10 billion ) degrees.
Within minutes after the explosion, The atomic particles produced from the explosion merged together producing gaseous clouds of hydrogen and helium with a ratio of 75 % : 25 % respectively.
After 1000 million ( 1 billion ) years from the Big Bang, The gaseous clouds merged to form the masses that will produce the matter of the galaxies.
Within 2000: 3000 million ( 2 : 3 billion ) years from the Big Bang, The gravity helped in a gathering of more masses forming (Ancestral galaxies) leaving areas of empty space between them.
After 10000 million ( 10 billion ) years from the Big Bang, The Sun was born, Then the Earth and the planets were created, After 12000 million ( 12 billion ) years from the Big Bang, Earliest life forms began to appear on the Earth.
After 15000 million ( 15 billion ) years from the Big Bang, The Universe as it now, In 1964, The scientists discovered radio waves that come from the space, They concluded that these waves are a type of the echo coming from the Big Bang, TV sets can receive such signals on the Earth.
What is the future of the Universe?
The scientists have different theories about the history of the Universe, Some of them are the Open Universe theory and the Closed Universe theory.
In the Open Universe theory, The scientist sees that there is no definite end to the Universe, While in the Closed Universe theory, the scientists see that the Universe will stop to expand and it will begin to contract until it becomes very compact or very hot preparing for a new Big Bang.
You can see this video on Youtube about Big Bang.