Dear Readers,
Current affairs is an important component of several competitive exams such as the UPSC Civil Services Examination, SSC-CGL, Bank PO & PSU entrance tests, etc. Therefore, understanding the terms/concepts/events that make news is critical for aspirants. We at PaGaLGuY bring you this series of articles explaining some of these important concepts/events. In this article, we are discussing the origin of the Universe.
There are 4 major theories regarding the origin of the Universe.
1 ) The Big Bang theory
a) This theory is also called the expanding universe hypothesis. According to this, the universe is presently expanding. Edwin Hubble provided evidence about expansion of the universe in 1920.
b) This theory advocates the idea that all the matter in the universe was in form of one ‘tiny ball’ (singular atom) with small volume, infinite temperature and infinite density.
c) This tiny ball exploded around 13.7 billion years ago and lead to the expansion of universe.
d) This state of expansion is a result of primordial explosion of the universe. Due to this, the universe was fragmented and galaxies were formed. The universe is still expanding due to the flight of galaxies, which are moving away and apart from each other.
2. Continuous Creation theory / Steady State theory
a) This theory explains the formation of new galaxies in the universe by the flight of galaxies.
b) This theory explains that the spatial and temporal density of the universe is constant.
c) To maintain the spatial and temporal density of universe, the continuous process of flight of galaxies form new galaxies in void.
d) This view was later rejected because it does not explain the source of matter and energy released for the formation of new galaxy.
3. Oscillating Universe theory
a) This theory combines both Big Bang and Big Crunch theories.
b) It tends to explain alternate stages of universe which are as follows:
* Sate of Explosion/ Expansion: The state of expansion is due to the sudden release of heat and pressure in the cosmos. Due to this, the density eventually declines.
* State of Implosion/Contraction: The state of implosion is the hypothetic state wherein the expansion of the universe eventually reverses and the universe recollapses, ultimately ending in a black hole singularity or causing a reformation of the universe starting with another big bang. There will be increase in density during the state of implosion.
c) Each state occurs for 41 billion years.
d) At present, the universe is in the state of expansion. This state will continue for next 28 billion years. Once completed, the universe will not be able to hold the mass and volume and hence it will start contracting.
4. Quasi Steady State Cosmology (QSS)
This is the latest view on the origin of universe.
This theory was given by Fred Hoyle, Geoffrey Burbidge and Jayant Naralikar in 1993.
The theory explains the ‘Creation Field’ that is the source of matter & energy in the universe for creation of new galaxies.
These creation fields are also called mini-bangs or mini-creation events.
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