No one who looks up at the sky on a starry night can avoid wondering how large the universe is, where it comes from, how old it is, and what its final destiny will be. For the first time in history, science can today address long-standing questions concerning the evolution of the cosmos, its spatial and temporal extension, and its constituent elements. Our current wide-ranging description is, however, incomplete: 95% of the universe comprises forms of dark matter and energy, invisible but detectable via multiple indirect observations. Today we know that dark matter allows galaxies to form and that dark energy is at the origin of the universe’s accelerated expansion, discovered in 1998. But many questions still await an answer. This book traces the history of one of the most exciting challenges facing current science: shedding light on the dark side of the universe.

Luca Amendola teaches Theoretical Physics at the University of Heidelberg and coordinates the Euclid Consortium’s Theory Working Group.