Keith Laumer 
Galaxy Builder 

The world, as Lafayette O’Leary knew it, disappeared in a flash. Perhaps it was his own doing — after all, he had the uncanny gift of creating alternate realities by sheer mental power.But the result was a nightmare gone out of control. All O’Leary wanted was to find his wife and return to the familiar world of Artesia. Yet no sooner did he manage to extricate himself from one bizarre situation than he was thrust into another, equally threatening…There was only one thing to do: he had to penetrate the very center of power from which his destiny was being controlled and — take it into his own hands!