Unruly Universe

How the quest to determine a single number—the expansion rate of the universe—is upending our understanding of the cosmos.For more than a century, ever since Edwin Hubble discovered that galaxies are receding from us, cosmologists equipped with powerful space telescopes have sought to pin down the Hubble constant, the rate at which the universe expands. By the start of the twenty-first century, a consensus seemed within reach. Then came a surprise. Measurements of the faint afterglow of the big bang pointed to a significantly slower expansion. The two approaches stubbornly refused to agree.In The Unruly Universe, Nobel Prize–winning cosmologist Adam G. Riess and science writer Donald Goldsmith chronicle the high-stakes quest to describe the universe with a single number. What emerges is a sobering possibility. The standard model of cosmology—our best account of dark matter, dark energy and gravity, and even cosmic history—may be incomplete.Abandoning a model that has explained so much would be no small step. But as Riess and Goldsmith show, the universe has no obligation to conform to our expectations. It may be more complex, more surprising, and more unruly than we imagined.