The original version of this story appeared in Quanta Magazine.
To understand the universe, scientists look to its outliers. “You always want to know about the extreme cases—the special cases that lie at the edge,” said Carsten Gundlach, a mathematical physicist at the University of Southampton.
Black holes are the enigmatic extremes of the cosmos. Within them, matter is packed so tightly that, according to Einstein’s general theory of relativity, nothing can escape. For decades, physicists and mathematicians have used them to probe the limits of their ideas about gravity, space, and time.
But even black holes have edge cases—and those cases have their own insights