The most important current theory for the origin of the universe is the Big Bang Theory. according to this theory, the universe started with the huge explosion. It was not an explosion like the ones with which we are familiar with start from a definite centre and spread out. it was an explosion which occurred everywhere in space at the same time.It Build all space from the beginning with every particle of matter rushing apart from every other particle. this was not a burst of matter into space but rather than explosion of space itself.Every particle of matter rushed away from every other particle. it is so far impossible to picture the first movement of creation of the universe.
100 of a second after the creation of the universe is the earliest time about which scientist can speak with any confidence.At this instant the temperature of the universe was about 100 billion degree centigrade.This is much hotter than in the centre of even the hottest star. At such temperature none of the component of ordinary matter, Atoms, molecules or even nuclei of atoms could have held together. instead the matter rushing apart in the explosion consists of various type of elementary particles.The particles most abundant in the early universe was electrons, positions and neutrinos. There were also some proton and neutron. the rest of the universe was filled with energy. it was kind of cosmic suit.
As the explosion continued, matter and energy rushed, apart the universe expanded and the temperature dropped reaching 38 billion(3× 1010) degrees centigrade after about one tenth of the second; 10 billion degrees after about 1 second and 3 billion degrees after about 14 seconds. at the end of the first 3 minute the universe became cool enough (about 1 billion centigrade). Protons and neutrons begin to form simple nuclei.The first to be formed was the nucleus of heavy hydrogen which was made up of one proton and neutron.There was also Helium nuclei made up of two proton and neutron.It was still too hot for atoms to hold together they were ripped apart as soon as they were created. this matter continue to Rush Apart becoming stately cooler and less dense.
Many thousands of years later it became cool enough for electron to join with nuclei to form atoms of hydrogen and Helium. soon the resulting gas begin to form clumps under the influence of gravitation. this ultimately condense to form the galaxies and star of the present a universe, almost 5 billion years after the big ban.
There is another theory about the origin of Universe known as steady state theory which was proposed by singer of brabant In The 13th century.This theory holds that the universe has always been just about the same as it is now.As it expands new matter is created continuously to fill up the gap between the galaxies. Thus, the problem of the origin and early moments of the universe is banished there was no early universe.
However the big bang theory is the most favoured by the astronomers and astrophysics. this is due to the evidence based on observation which let support the big and universe.
Evidences Favouring The Big Bang Theory
One piece of evidence comes from the expansion of the universe which we have quality described. the expanding universe suggest that the matter was Packed much more densely in the early stages of the universe. the proof for this also comes from the distant object ‚quasars.
Another substantial bit of evidence for big bang theory comes from the cosmic background radiation. For many years the astronomer belived that if there was a cosmic explosion long agi, radiation from that event should still exist within the universe.This radiation maybe weak it may have lost his energy due to expansion and cooling of the universe but it should exist.Radio astronomers have indeed discovered faint single are constantly present background radio noise that provides all space. calculation done by astrophysicist show that this radiation call the cosmic microwave background radiation is a relic of the Ancient past when the universe was in its first Throes (agility)of creation in the big bang.
An additional Discovery made by astronomers during the past is that of the primordial abundance of elements that is the element hydrogen and Helium first created in the aftermath of creation are found to be most abundant in the universe.By examining the light coming from the various part of the universe as normal have found out that out of every hundred atoms always 93 of hydrogen atoms and 7 are Helium atoms.Elements heavier than Helium are present in traces only. this suggest that the universe started out with the Big Bang from a very hot and dense state and quickly cooled as it expanded.The hot and dense condition lasted long enough for some hydrogen to fuse into helium.But they did not last long to allow other heavier elements to form in significant amount was top these were made much later in the interior of massive stars.
