Astronomers tell us the universe came about through a Big Bang 13.8 billion years ago. This is when the universe began as a tiny, dense, fireball that exploded.  However it would be prudent to remember that this is a theory and theories can change.  During medieval times the universal belief was that the world was flat and situated at the centre of our solar system.  This belief has certainly changed.  With the arrival of science mankind has had to rethink its ideas about our origins.  But who knows whether we have it right.  Perhaps future scientists will look on our beliefs as ridiculous.

Scientists hypothesise, work out mathematical calculations, and devise theories on the basis of their sums, which they publish for other scientists to mull over.  And hey presto a new theory is born.  Their colleagues then conduct their own calculations on the basis of the last theory and so on and on it goes one the