Big Bang Theory is a secret achievement for the map Moon. It requires the player to gain "sweet, sweet revenge". To get this achievement, the player must finish both parts of Richtofen's Grand Scheme.
This achievement only exists on Xbox 360 and PC, and there is no trophy equivalent of it on PlayStation 3 and PlayStation 4. In addition, it does not appear in Black Ops III.
- This achievement is named after the theory of the explosion that created the universe, "The Big Bang".