Synopsis: Our cosmos, throughout it enormous length of galaxies, and down to its smallest molecules, obeys the same laws of physics and chemistry from one end to the other. But it is now suspected that somewhere in the vast reaches of space, there may well be other universes with completely different natural laws. But even on those worlds, foreign beyond imagining, there may yet be great adventurers - alien Magellans and Columbuses whose thirst for exploration cannot be assuaged. Intelligent beings who would risk anything to know what lies over the horizon, beyond the parameters of the known world. (from the back cover of the DAW first printing)