The Big Bang Not really an explosion, Universe expanded rapidly as a whole (Universe is still expanding today as a result of the Big Bang) Matter was created in the form of tiny particles (protons, neutrons, electrons) Too hot for normal stuff to form (eg atoms, molecules)
Gravitational Collapse We started with a uniform gas Small regions became more dense The denser regions had larger gravity and started to pull other particles towards them The gaseous Universe began to look clumpy
Stars, galaxies Temperature increases FUSION! A star is born Stars congregate Together to form Galaxies.. Galaxies Also congregate...
Future? The Universe is still expanding All galaxies are moving apart The explosion of the big bang is still happening! It may contine expanding forever Or is may stop expanding, and fall inwards in a big CRUNCH!