Universe is the sum total of all the potentially knowable objects. The study of Universe on a grand scale is called Cosmology. There are about 100 billion galaxies in the Universe. Every galaxy is composed of about 100 billion Stars.You Might Also Like::
Evolution of Universe and Various Theories
(1) Big Bang Theory
- It is the most acclaimed theory, proposed by E George Lamantor in 1960-70.
- The Big Bang theory proposes that the Universe was once extremely compact, dense and hot.
- Some original event, a cosmic explosion called the big bang, occurred and the Universe has since been expanding and cooling.
- According to this theory, our Universe sprang into existence as "singularity" around 13.7 billion years ago.
- The recent experiments at the Large Hadron Collider (LHC), built by the European Organization for Nuclear Research beneath the Franco-Swiss border near Geneva, Switzerland, aims to recreate conditions just after big bang to have a better understanding of the phenomenon.
- Big Bang was an explosion that occurred 15 billion years ago, leading to formation of galaxies of stars and other heavenly bodies.
(2) Steady State Theory
- Bondi, Gold and Fred Hoyle developed this theory.
- According to this theory, the number of galaxies in the observable Universe is constant and new galaxies are continuously being created out of empty space, which fill up the gaps caused by those galaxies, which have crossed the boundary of the observable Universe. As a result of it, the overall size of mass of the observable Universe remains constant. Thus, a stead state of the Universe is not disturbed at all.
(3) Pulsating Theory
- According to this theory, the universe is supposed to be expanding and contracting alternately i.e., pulsating. At present, the universe is expanding. According to Pulsating Theory, it is possible that at a certain time, the expansion of the Universe may be stopped by the gravitational pull and it may contract again. After it has been contracted to a certain size, explosion again occurs and the Universe will start expanding. The alternate expansion and contraction of the Universe give rise to pulsating Universe.