Our universe is a vast open space comprising of the stars, star systems and the galaxies. It has been a subject of discussion amongst many astronomers, cosmologists and scientists. They have tried to estimate the exact age of the universe and the way it came in to existence. As no one was physically present at that time, today scientists with the help of technology have tried to estimate the story behind its evolutions.
Researches, experiments and studies have led to short listing of mainly three theories that are supposed to be the way our universe actually came in to existence. Those three theories are namely the Big Bang Theory, The Steady State Theory and the Pulsating theory.
Amongst these theories, the one that has gained maximum acceptance is the Big Bang Theory. This one has been accepted by most scientists and the common man is made to believe this to be the story behind the evolution of our beautiful universe.
It is believed now, according to Edwin Hubble’s Law that the galaxies near our own galaxy, The Milky Way, are moving away from us. The speed at which they are moving away is directly proportional to their distance from us. This moving away is happening due to the expansion of the universe.
Hence, if we go back in time all of the celestial bodies in the universe must have been a dense point from everything appeared. This dense point must be extremely high in temperature which cannot be experienced in a normal world, hotter than the fire. Because of the high density and temperature the point blasted and threw everything apart from it. This explosion has been named The Big Bang. Due to the big bang the matter in that dense point flew away forming clouds of dust and gases which accumulated together to form various celestial bodies that exist today. These are the planets, the sun and the galaxies which are known to be the part of our huge universe.
It took 13.7 billion years for the whole universe to form. What actually happened before this big bang is something that no one knows. The whole of the 13.7 billion years have been broken down by the scientists in to eras.
The first one is Planck Era that lasted from 0 to 10-43 seconds after the Big Bang took place. This is supposed to be the shortest period of time one can estimate of. What happened in this era is something which cannot be vaguely estimated. A need for a theory of quantum gravity needs to be founded for better understanding.
The second was the Grand Unification Era which between the time period 10-43 seconds to 10-36 seconds after the Big Bang. During this era it is supposed that the force of gravity detached itself from other forces. Again the exact movements and what actually happened then are unproven.
The third was the Inflationary Era that lasted between 10-36seconds to 10-12 seconds after the Big Bang. It is assumed that the temperatures started dropping in this time period.
The fourth is the Quark Era. This lasted between 10-12 seconds to 10-6 seconds after the Big Bang. This marked the individual functioning of all the forces.
The fifth is the Hadron Era that lasted from 10-6 seconds to 1 second after the Big Bang. Next was the Lepton Era. It lasted between 1 second to 10 seconds after the Big Bang.
Photon Era is seventh era after the Big Bang whose energy lasted up to 300,000 years and began after 10 seconds and lasted till 3 minutes. Then came the Nucleo-synthesis Era lasting from 3 minutes to 20 minutes and the last was the Dark Age that lasted till 377,000 years after the Big Bang.
This whole story comes under the Big Bang theory which is assumed to be the way our Universe was created.
