2) Something causes it to begin expanding.

3) That expansion is a cataclysm that happens everywhere.

4) 10^-43 seconds later, a moment known as Planck's Time, gravity "freezes out" from the original unified force, thereby establishing its individual presence and particles and anti-particles tumble forth in glorious profusion.

5) In the next moment of time, the strong nuclear force, which binds particles together, asserts itself, and the universe inflates.

6) The weak nuclear force, which has to do with radioactive decay and the electromagnetic force, become separate.

7) Quarks combine to form protons and neutrons.

8) Within three minutes, atomic nuclei begin to form.

9) Five hundred thousand years later, electrons swing into orbit around nuclei and form atoms.

10) A few hundred million years later, after the explosion, clouds of atoms collapse to form galaxies and the stars light up.

11) Space continues to expand, it is not that galaxies are racing away from one another, space itself is expanding and the galaxies are moving along with it.

- The Big Bang Theory is consistent with a number of important observations:
- If the universe is traveling away from us in all directions, it is a simple deduction then that in the past all objects were closer together and possibly at some time in the distant past, that all these objects were in the same place in an extremely compressed state.
- The observed abundance of helium, deuterium and lithium, three elements thought to be synthesized primarily in the first three minutes of the universe.
- In 1965, Arno Penzias and Robert Wilson discovered microwave radiation existed throughout the universe. This is the leftover heat from “Big Bang”.
- The cosmic microwave background radiation appears hotter in distant clouds of gas.
- Since light travels at a finite speed, we see these distant clouds at an early time in the history of the universe, when it was denser and thus hotter.

- In its current form, the big bang theory is not complete. It does not explain:
    - the origin of galaxies and the observed large-scale clustering of galaxies
    - the origin of the uniform distribution of matter on very large scales
 

Note: 
 
- If there is not enough mass or in other words if the universe is less than Critical Density, its expansion will go on forever. (Omega < 1)

- If the universe is at CD, its expansion will come to a halt some day. (Omega = 1)

- If it is above CD, the universe will reverse its outward motion and eventually collapse to what has been coined as a "Big Crunch". (Omega > 1)