My theories of how the world will end:
The sun exploding, destroying earth and every other planet and moon in the solar system.
The sun warms up the Earth too much and it's too hot to live on any more.
Flooding of the whole Earth (Have a nice 1,000 year wait, rivers.)
We destroy the Earth as we know it, using nuclear weapons, guns, throwing trash about, etc...
Quite possibly an alien super weapon also.
Super volcano erupt, the smoke will block all the sunlight, and everything is going to die
and this