Twentieth-century physics was a long, strange trip indeed. Stranger still is what might lie ahead. In this startling book, science writer Tom Siegfried takes us into a weird world of quark nuggets, selectrons, quintessence, and quantum cosmology and introduces us to some of the most imaginative ideas being batted about by scientists today, from funny energy to mirror matter to two-timing universes. In addition, he reviews theories of the past both proven and unproven-offering us a grounding in our scientific history as well as an informed and intriguing look at the possibilities of tomorrow.