Outside Sources Frame a Galactic Puzzle

摘要

When astrophysicist Ivan King signed a copy of his 1976 textbook The Universe Unfolding for his student Francois Schweizer, he wrote in it: "Make as much of this obsolete as you can, Francois!" Schweizer followed his teacher's advice. In 1987, 13 years after finishing his studies at the University of California, Berkeley, he proposed a radical new theory about the cosmic objects known as globular clusters. Conventional wisdom held that the clusters―huge, dense balls of hundreds of thousands of stars―are among the oldest objects in the universe, born early in cosmic history when enormous clouds of gas collapsed under the pull of their own gravity, triggering huge bursts of star formation. Schweizer suggested that those primeval clusters are only part of the story: New globular star clusters, he proposed, are still forming where galaxies collide, deep in space.