Philip Jose Farmer 
Tongues of the Moon 

OUT FROM THE GREEN WORLD: Humans had colonized the planets & lost its birthright. Civilization was a lonely chain of space stations linked by terror. The Empire kept the pioneers enslaved with a weapon that shattered any protest into screaming insanity.All they had left was the dream of someday returning home. Until their dream exploded in the holocaust that destroyed the Earth. But the embers of their dead planet sparked a brain-blasting revolution that swept the galaxy: a revolution of exiles in an alien universe-with nothing left to lose.