There Is No Darkness — Jack C. Haldeman

A young man must fight -- literally -- for the opportunity to escape his backwater home planet and journey to the stars.

A towering young giant growing up on a high-gravity world of perilous plants and savage creatures, Carl Bok is thrilled when he's offered a one-year scholarship to Starschool. As a new student aboard the space-traveling institution, Carl will get the opportunity to visit and learn from sixteen colonized worlds. Best of all, he'll finally escape the dangerous and grueling life of his home planet.
 
A poor “country boy” cast among rich children of privilege, Carl perseveres as he and his classmates prepare to rocket from world to world. While he's still on Earth, however, an unexpected and desperate need for funds forces him to become a professional fighter, a job that well suits his massive size and experience.
 
Carl hopes to earn the money he needs to continue with Starschool by battling a slew of human and bestial adversaries for the entertainment of others. But there are forces behind the scenes with an alien agenda that Carl can neither see nor comprehend -- as he and a cadre of young companions undertake an educational odyssey that carries them from Earth to the astonishing artificial planet Construct to a war-torn world called Hell.
 
A Science Fiction Grand Master, the acclaimed author of The Forever War, and the winner of numerous awards including the Hugo and Nebula, Joe Haldeman collaborated with his brother, biologist and science fiction writer Jack C. Haldeman II, to create this gripping tale of a young man's self-discovery and remarkable intergalactic adventures.