Books that go beyond the multiverse? Doesn't have to be good, just contain interesting ideas.

I've been working on an Omniverse Epic. I'm curious to see what others have done with the concept.

Concepts I'm curious about.

-Travel between higher dimensions. Especially between those with vastly different physics.

• Alien Species that exist in universes with chaotic laws of physics.

• The Unimaginable. Alternate realities so strange they cannot rationally be talked or theorized about.

• The Outerverse. The nothingness outside the multiverse.

• Higher and Lesser "Gods" throughout all dimensional levels.

• The Impossible. Things that cannot exist anywhere in the omniverse.