In War Times (Dance Family #1)
by Kathleen Ann Goonan
Sam Dance is a young enlisted soldier in 1941 when his older brother Keenan is killed at Pearl Harbor. Afterwards, Sam promises that he will do anything he can to stop the war.

During his training, Sam begins to show that he has a knack for science and engineering, and he is plucked from the daily grunt work of twenty-mile marches by his superiors to study subjects like code breaking, electronics, and physics in particular, a science that is growing more important to the war effort. While studying, Sam is seduced by a mysterious female physicist that is teaching one of his courses, and given her plans for a device that will end the war, perhaps even end the human predilection for war forever. But the device does something less, and more, than that.

After his training, Sam is sent throughout Europe to solve both theoretical and practical problems for the Allies. He spends his free time playing jazz, and trying to construct the strange device. It's only much later that he discovers that it worked, but in a way that he could have never imagined.
http://www.goodreads.com/book/show/812490.In_War_Times



This Shared Dream (Dance Family #2)
by Kathleen Ann Goonan
Kathleen Ann Goonan introduced Sam Dance and his wife, Bette, and their quest to alter our present reality for the better in her novel In War Times (winner of the John W. Campbell Memorial Award for Best Novel and ALA’s Best Science Fiction Novel of 2008). Now, in This Shared Dream, she tells the story of the next generation.

The three Dance kids, seemingly abandoned by both parents when they were younger, are now adults and are all disturbed by memories of a reality that existed in place of their world. The older girl, Jill, even remembers the disappearance of their mother while preventing the assassination of John F. Kennedy.

Goonan has created a new kind of utopian SF novel, in which the changes in history have created a present world that is in many ways superior to our own, while in other worlds people strive to prevent their own erasure by restoring the ills to ours. This Shared Dream is certainly the most provocative SF speculation of the year, and perhaps the decade.