[ninty]

if you understood up to the 7th, you can understand the whole thing. It's just taking the group and putting it into a point. Really, after the 4th, it's all just recycled information just in a larger sense.

It's really not difficult to understand at all. However, at the present time, it is very difficult to prove. There are things that can lead us to believe this is true...especially with string theory, but proving something on a quantum string theory level is very difficult.