Evidence Favouring the Big Bang

One piece of evidence comes from the expansion of  the universe which we have already described. The expanding universe suggests that the matter was packed much more densely in  the early stages of  the universe. The proof for this also comes from the distant objects quasars. When we  'look'  at quasars situated 6 to 8 billion light years away, wc are looking at them as they existed  then.  If  the universe were more dense in that epoch, we should be able to sce some evidence of  that density in  the quasars. We do  see such high density among thc quasars. Another substantial hit of  evidcncc for the Big Bang theory comci from  thc cosmic background  radiation.

For many years the astronomers believed that if  there was a .cosmic explosion long ago, radiation from that event should still exist within the universe. This radiation may be weak, it may have lost its energy due to the expansion and cooling of  the universe, but it should exist. Radio-astronomers have, indeed, discovered faint signals-a  constantly present background  radio noise that pervades allspace.

Calculations done by astrophysicists show that this radiation, called the cosmic microwave background  radiation, is a relic of  the ancient past when the universe was inits first  throes  of  creation  in  the Big  Bang. An additional discovery made by astronomers in the past two decades is that of  the primordial abundance of  elements, i.e.  the elements hydrogen and helium first createdin the aftermath of  creation are found to be most abundant in the universe.

By examining the light coming from the various parts of  the universe, astronomers have found out that, out of every 100 atoms, almost 93 are hydrogen atoms and seven are helium atoms. Elements heavier than helium are present  in traces only. This suggests that the universe started out with a Big Bang from a very hot and dense state and quickly cooled as it expanded. The hot and dense conditions 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 amounts. These were made much later in the interior ofmassive stars.