Approaching the singularity

What happens at the black hole event horizon, where time stands still and intuition breaks down? In the opening chapter of his new book, Einstein's Monsters, astronomer and popular science writer Chris Impey puts the problem succinctly: "It made no sense for a physical object to have zero size and infinite mass density. Einstein's theory had created something monstrous." Despite a few shortcomings, the book will be sure to capture the imagination of most who pick it up, simultaneously convincing the reader that these monsters should be loved and not feared.