Freeman Dyson is a celebrated theoretical physicist whose dream of cruising the galaxies became the Orion project; George Dyson is his dropout son who lives in a British Columbian treehouse and cruises the Inside Passage in handmade canoes and kayaks. Brewer introduces father and son, rare constellations of eccentricity and talent, in this elegant, zingy expedition. The space cadet wants to colonize asteroids and looks for HO out there; the boat builder and rain-forest resident looks for dry havens and champions epoxy. Freeman's friends design nuclear reactors on their vacations; George knows a woman who eats only crows and potatoes, a man who lives in a hammock, and a poet who writes in pre-Babylonian tongues. Freeman's model starship, a joint venture with Ted Taylor and similar brains, successfully exploded its nuclear bomb propellants without ever leaving the ground; George's first boat, improving on the Nunivak Eskimo classic with modern materials, was tippy. Freeman's ""hot-rod"" model lifted off to scientific acclaim; George's second boat nearly flew, and his next, ""the Queen Mary of kayaks,"" became a local totem. Brower clearly enjoys his crafty counterpoint, appreciative of the father but more sympathetic to the son, noting the foibles and impassable barriers--they were estranged for several years--as he grapples with celestial mechanics over hamburgers, shinnies up George's tree for sunflower seeds, and witnesses a tentatively cordial reunion. Freeman is a man offered jobs with stock options: ""Apparently a brain like Freeman's meant a whole franchise; it was like signing O. J. Simpson or Abdul-Jabbar."" George as a child cut short a camping trip because his companion was a compulsive marshmallow eater. But it is the son who acts when two loggers capsize--reenacting, in an instant, the father's dream from 20 years before. In the tradition of Carl Sagan and John McPhee, a bracing cerebral voyage past intergalactic hoopla and backwoods retreats.