The next field to adopt the word was astrophysics. If a massive star undergoes a supernova explosion, its remnant eventually collapses to the point of apparently zero volume and infinite density, and a “singularity” is created at its center. Because light was thought to be unable to escape the star after it reached this infinite density,16 it was called a black hole.17 It constitutes a rupture in the fabric of space and time.