''If you are looking for a bracing alternative vision of physics built from the ground up, Smolin's ''Time Reborn'' will take you to the mountaintop.'' -- NPR What is time? It's the sort of question we rarely ask because it seems so obvious. And yet, to a physicist, time is simply a human construct and an illusion. If you could somehow get outside the universe and observe it from there, you would see that every moment has always existed and always will. Lee Smolin disagrees, and in ''Time Reborn'' he lays out the case why. Recent developments in physics and cosmology point toward the reality of time and the openness of the future. Smolin's groundbreaking theory postulates that physical laws can evolve over time and the future is not yet determined. Newton's fundamental laws may not remain so fundamental.'' Time Reborn'' serves as a popular primer and investigation of time, both what it is and how the true nature of it impacts our world. ''He challenges not only Einstein's relativity, but also the very notion of natural laws as immutable truths.'' -- ''Economist'' ''One of the essential books of the twenty-first century . . . Smolin provides a much-needed dose of clarity about time, with implications that go far beyond physics to economics, politics, and personal philosophy.'' -- Jaron Lanier, author of ''You Are Not a Gadget''