From what sounds like static, astronomers can discern an image of the entire universe.

Explaining how they pull off this trick is the job of writers like Caleb Scharf, director of astrobiology at Columbia University. In Gravity's Engines (Scientific American/Farrar, Straus and Giroux, 272 pages, $26), Scharf attempts to turn two centuries of science about black holes into popular nonfiction. It's a bumpy ride.

To see where Scharf fails to achieve orbit, let's start with the mental picture he draws to explain how black holes work: These massive pinpricks in the fabric of space-time, he explains, swallow huge gulps of interstellar dust and gas and then "blow bubbles" measuring tens of thousands of light-years across. It's not an image Scharf invented, but neither is it one he explains very well. Do the bubbles inflate outward in all directions like ripples on a pond, or sideways like a baseball player blowing bubble gum? Do the bubbles appear one at a time or in a swarm? Scharf's book is unclear. It's important, because it is this cycle of black holes gobbling up matter and blowing out bubbles of hot gas, Scharf argues, that both drives and impedes the formation of new stars, new planets and, ultimately, life in the cosmos.

Scharf's vague metaphors dumb down these complex processes. Gravity's Engines would also benefit from illustrations to untangle some of this graduate-level science for the general reader. Instead, it includes only a few grainy, black-and-white photos and diagrams that look as if they were drawn on a cocktail napkin.

Where Scharf shows his star stuff is in conveying the vast scope of the universe, whether he's detecting X-rays from a galaxy 12 billion light-years away or describing the Perseus galaxy cluster, which, if visible to the naked eye, would fill a patch of sky four times the size of the full moon. Too bad he never quite captures the wonder of scientific endeavor with the same sense of grandeur.

GO: Caleb Scharf reads at Powell's City of Books, 1005 W Burnside St., 228-4651, on Wednesday, Sept. 12. 7:30 pm. Free.