Our earth is the unique part in the universe. Different scientists have different theories for the origin of universe. Before Big Bang Hypothesis many scientists proposed some theories and hypothesis.
In 1796 a mathematician Leplace proposed a theory of Nebular hypothesis. According to this hypothesis formation of planets occurs form the substance present on the moving clouds which were related with the young stage of the sun.
Thereafter, in 1900 Chamblerlain and Moulton said that a rambling star in universe passed near the sun. As a result, a small cheroot like substance spilt from the sun. When that rambling star moved away so far then this substance starting to move around the sun. Gradually this substance condense in the form of planet. Firstly Sir James Jeans and then Sir Harold Jeffery supported this theory. In 1950, Otto Schmidt form Russia and Carl Weizascar from Germany amended the Nebular hypothesis. From their view, Hydrogen, Helium and some dust particles surrounded the sun. Due to collision of this particles a flat plate was formed and through accretion planets were formed. In this way scientists tried to understand the origin of whole universe.
In modern time Big Bang Hypothesis is the universally accepted hypothesis. It is also called Expanding universe hypothesis. In 1920, Edwin Hubble proved that universe is expanding. With passing time galaxies were moving away from each other as a result universe is expanding. According to big band theory following are the region of expansion of universe.
- Earlier the substance which made universe were stayed in one point like a small atom. The temperature and density of that atom was infinity.
- A huge explosion occured in that atom during the process of big band theory. Scientists believed that this explosion was happened about 13.7 years ago.
- From big bang during 3 lakhs temperature downed around 4500 degree celsius. As a result substances were formed.