Fred Hoyle is of course the lively astronomical popularizer and controversial ""steady state"" cosmologist who every so often teams up with his son Geoffrey to knock off a science fiction novel. This one is a bouncy but formless invention, set on an Earth wholly dependent on the alien technology of the ""Outlanders."" The hero is a young Outlander raised as a human and unexpectedly thrust into the cloak-and-laser struggles of Outlander intelligence to maintain their say-so over Earth's power supply. From there, the Hoyles dream up wrinkles--including the most original skiing sequence in light-years--with the speed of a kid aging a pair of blue jeans. AH very sprightly, but curiously half-finished, or perhaps halfbegun.