Theory:

The origin of life is connected with the origin of earth. The most basic question which led to many active and vigorous discussions among the scientists and researchers is that when and how did the universe evolve?
Out of the numerous theories proposed to answer this question the Big Bang Theory clearly explains the origin of universe.
Big bang theory:
Important!
Georges Lemaitre a Belgian cosmologist is the father of big bang theory.
 
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Georges Lemaitre
According to this theory, \(15\)billion years ago, the universe had a massive explosion of cosmic material that resulted in hydrogen and other nuclei, which organized to form galaxies.
The universe started as a tiny spot of a hot and massive ball. The explosion threw the contents within the ball into all directions of space.
 
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Image illustrating the Big Bang Theory
 
After this big bang explosion, the universe began to expand, and it continues to expand today. The universe expanded and cooled according to time, leading to the origin of life found on earth.
The sub-atomic particles such as neutrons, protons gave rise to atoms, stars etc.
The collapse of the gaseous clouds created the milky way and further the solar system due to its gravity of forming atoms and particles. These atoms, dust grains and gaseous discs aggregated to give rise to planets.
 
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Solar system
 
A galaxy is a complex structure made up of millions or billions of stars, as well as gas and dust, that is kept together by gravity. The beginning of life is closely connected to the beginning of the Earth.
 
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Milky way galaxy
  
There were many theories and opinions about how life began on Earth.
Earth is thought to have formed approximately \(4.5\)billion years ago. \(500\)million years after the earth's origin, life appeared.
They lacked experimental proofs, however. The contemporary idea of Origin of Life, on the other hand, is largely recognized around the world.
Reference:
https://en.wikipedia.org/wiki/Georges_Lema%C3%AEtre#/media/File:Georges_Lema%C3%AEtre_1930s.jpg
https://en.wikipedia.org/wiki/Big_Bang#/media/File:CMB_Timeline300_no_WMAP.jpg
https://www.publicdomainpictures.net/en/view-image.php?image=180438&picture=milky-way