IAS Prelims : GS Physical Geography : Origin of the Universe

The most popular theory that explains the origin of our universe is the Big Bang Theory. It is also called Expanding Universe Hypothesis. The Big Bang Theory was first suggested by A Belgian priest named Georges Lemaître in the 1920s. He proposed that the universe began from a single primordial atom. This idea was supported in 1929 by the observation of Edwin Hubble that the universe is expanding

According to this theory the present day universe has grown out of a ‘singularity’ some 13.7 billion years ago. The singularity consisted of a tiny ball with an unimaginably small volume, infinite temperature and infinite density. Prior to the singularity, nothing existed.
The tiny ball exploded violently leading to rapid expansion of the constituents. This expansion is occurring till date though at a slower speed. First atom began to form within first three minutes from the Big Bang event. During the billions of years that followed, stars, planets and galaxies formed as we see it today.

Evidences for the Big Bang

In the 1960s, The CMB (Cosmic Microwave Background) signal was detected by Penzias and Wilson. The CMB signal is often described as the signature of the Big Bang event. Penzias and Wilson shared in the 1978 Nobel Prize for Physics for their discovery.

In 1996, NASA's Cosmic Background Explorer (COBE) satellite also confirmed that the primordial background radiation pointed to an explosive start of the universe.
The abundance of the "light elements" Hydrogen and Helium found in the universe are thought to support the Big Bang Theory.

Though we have several evidences to support the Big Bang Theory, it does not answer all the questions. It leaves several major questions unanswered like it does not explain the original cause of Big Bang and why a singularity was formed at the first place.

Hoyle’s concept of steady state

An alternative to the Big Bang Theory is Hoyle’s concept of steady state. It considers the universe to be roughly the same at any point of time. However, the available information about the universe does not support this concept.

Important Points

1.    The most popular theory that explains the origin of our universe is the Big Bang Theory.

2.    In 1929 Edwin Hubble suggested that the universe is expanding.

3.    According to this theory the present day universe has grown out of a ‘singularity’ some 13.7 billion years ago.

4.    In the 1960s, The CMB (Cosmic Microwave Background) signal was detected by Penzias and Wilson.

5.    In 1996, NASA's Cosmic Background Explorer (COBE) satellite also confirmed that the primordial background radiation pointed to an explosive start of the universe.

6.    An alternative to the Big Bang Theory is Hoyle’s concept of steady state.

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