No hypothetical creatures of physics appeal to the imagination quite as vividly as black holes -- those insatiable gravitational maws that gobble up everything within reach, not even allowing light to escape. Now it seems more likely than ever that one of these bizarre celestial objects is lurking at the center of the Milky Way galaxy, the island of stars inhabited by the sun and the earth.
In a paper published this month in the British journal Nature, six astronomers reported that they had made the most precise measurement yet of an object at the galactic center within Sgr A*, which...