The Galactic Odd Couple; Reality-Bending Black Holes; Special Editions; by Kimberly Weaver; 8 Page(s)

Black holes have a bad reputation. In many ways, it is deserved. They are the most efficient engines of destruction known to humanity. Their intense gravity is a one-way ticket to oblivion for anything that strays too close; inside them is undiscovered country from whose bourn no traveler returns. We see them only because the victims do not go quietly to their doom. Material spiraling into a black hole can heat up to millions of degrees and glow brightly. Some of its kinetic energy and momentum may be transferred to a jet of particles flowing outward at close to the speed of light. Black holes of various sizes take the rap for fusillades of radiation and plasma that astronomers observe all over the cosmos.

Yet black holes are not all-powerful. Even those found at the centers of many galaxies, supermassive black holes--whose very name connotes a voracious monster that rules its galactic roost--are minuscule by cosmic standards. They typically count for less than a percent of their galaxy's mass, and their gravity is highly concentrated. Accordingly, astronomers long assumed that supermassive holes, let alone their smaller cousins, would have little effect beyond their immediate neighborhoods. Star formation farther out in the galaxy was thought to march to the beat of a different drummer.