Everyone kws that there are things one can see, for example, the air you're breathing or a black hole, to be more exotic. But t everyone kws that what we can see makes up only 5 percent of the Universe. The rest is totally invisible to us. The invisible stuff comes in two varieties--dark matter and dark energy. One holds the Universe together while the other tears it apart. What these forces really are has been a mystery for as long as anyone has suspected they were there, but the latest discoveries of experimental physics have brought us closer to that kwledge. Particle physicist Dan Hooper takes his readers, with wit, grace, and a keen knack for explaining the toughest ideas science has to offer, on a quest few would ever have expected: to discover what makes up our dark cosmos.