The Practice Effect - David Brin

From one of the most critically acclaimed and well-loved authors of contemporary science fiction, a highly imaginative and exciting story as only David Brin can write . . .
"High spirits and inventiveness . . . Dennis's adventures, which can only be called rollicking, are legion."-Isaac Asimov's Science Fiction Magazine
Physicist Dennis Nuel was the first human to probe the strange realms called anomaly worlds-alternate universes where the laws of science were unpredictably changed. But the world Dennis discovered seemed almost like our own-with one perplexing difference. To his astonishment, he was hailed as a wizard and found himself fighting beside a beautiful woman with strange powers against a mysterious warlord as he struggled to solve the riddle of this baffling world.
"A delightful, often very witty story, with the underlying thoughtfulness we expect from David Brin."-Poul Anderson