We once had to abandon the idea of earth being at the centre of the universe. Now, we need to confront an even more profound possibility: the universe itself might just be one universe among many. In Search of the Multiverse takes us on an extraordinary journey, examining the most fundamental questions in science. What are the boundaries of our universe? Can there be different physical laws from the ones we know? Are there in fact other universes? Do we really live in a multiverse? This book is a search – the ultimate search – exploring the frontiers of reality. Ideas that were once science fiction have now come to dominate modern physics. And, as John Gribbin shows, there is increasing evidence that there really is more to the universe than we can see. Gribbin guides us through the different competing theories (there is more than one multiverse!) revealing what they have in common and what we can come to expect. He gives a brilliant tour of the current state of cosmology. John Gribbin is our best, most accessible guide to the big questions of science. And there is no bigger question than our search for the multiverse.

Critical acclaim for John Gribbin "The master of popular science." —Sunday Times (London) "Gribbin explains things very well indeed, and there's not an equation in sight." —David Goodstein, The New York Times Book Review (on Almost Everyone's Guide to Science) "Gribbin breathes life into the core ideas of complexity science, and argues convincingly that the basic laws, even in biology, will ultimately turn out to be simple." —Nature magazine (on Deep Simplicity) "Gribbin takes us through the basics [of chaos theory] with his customary talent for accessibility and clarity. [His] arguments are driven not by impersonal equations but by a sense of wonder at the presence in the universe and in nature of simple, self-organizing harmonies underpinning all structures, whether they are stars or flowers." —Sunday Times (London) (on Deep Simplicity) "In the true quantum realm, Gribbin remains the premier expositor of the latest developments." —Booklist (on Schrödinger's Kittens and the Search for Reality)

One of the most controversial, cutting-edge ideas in cosmology—the possibility that there exist multiple parallel universes—in fact has a long history. Tom Siegfried reminds us that the size and number of the heavens have been contested since ancient times. His story offers deep lessons about the nature of science and the quest for understanding.

Max Tegmark leads us on an astonishing journey through past, present and future, and through the physics, astronomy and mathematics that are the foundation of his work, most particularly his hypothesis that our physical reality is a mathematical structure and his theory of the ultimate multiverse. In a dazzling combination of both popular and groundbreaking science, he not only helps us grasp his often mind-boggling theories, but he also shares with us some of the often surprising triumphs and disappointments that have shaped his life as a scientist. Fascinating from first to last—this is a book that has already prompted the attention and admiration of some of the most prominent scientists and mathematicians.

A major scientific revolution has begun, a new paradigm that rivals Darwin's theory in importance. At its heart is the discovery of the order that lies deep within the most complex of systems, from the origin of life, to the workings of giant corporations, to the rise and fall of great civilizations. And more than anyone else, this revolution is the work of one man, Stuart Kauffman, a MacArthur Fellow and visionary pioneer of the new science of complexity. Now, in At Home in the Universe, Kauffman brilliantly weaves together the excitement of intellectual discovery and a fertile mix of insights to give the general reader a fascinating look at this new science--and at the forces for order that lie at the edge of chaos. We all know of instances of spontaneous order in nature--an oil droplet in water forms a sphere, snowflakes have a six-fold symmetry. What we are only now discovering, Kauffman says, is that the range of spontaneous order is enormously greater than we had supposed. Indeed, self-organization is a great undiscovered principle of nature. But how does this spontaneous order arise? Kauffman contends that complexity itself triggers self-organization, or what he calls "order for free," that if enough different molecules pass a certain threshold of complexity, they begin to self-organize into a new entity--a living cell. Kauffman uses the analogy of a thousand buttons on a rug--join two buttons randomly with thread, then another two, and so on. At first, you have isolated pairs; later, small clusters; but suddenly at around the 500th repetition, a remarkable transformation occurs--much like the phase transition when water abruptly turns to ice--and the buttons link up in one giant network. Likewise, life may have originated when the mix of different molecules in the primordial soup passed a certain level of complexity and self-organized into living entities (if so, then life is not a highly improbable chance event, but almost inevitable). Kauffman uses the basic insight of "order for free" to illuminate a staggering range of phenomena. We see how a single-celled embryo can grow to a highly complex organism with over two hundred different cell types. We learn how the science of complexity extends Darwin's theory of evolution by natural selection: that self-organization, selection, and chance are the engines of the biosphere. And we gain insights into biotechnology, the stunning magic of the new frontier of genetic engineering--generating trillions of novel molecules to find new drugs, vaccines, enzymes, biosensors, and more. Indeed, Kauffman shows that ecosystems, economic systems, and even cultural systems may all evolve according to similar general laws, that tissues and terra cotta evolve in similar ways. And finally, there is a profoundly spiritual element to Kauffman's thought. If, as he argues, life were bound to arise, not as an incalculably improbable accident, but as an expected fulfillment of the natural order, then we truly are at home in the universe. Kauffman's earlier volume, The Origins of Order, written for specialists, received lavish praise. Stephen Jay Gould called it "a landmark and a classic." And Nobel Laureate Philip Anderson wrote that "there are few people in this world who ever ask the right questions of science, and they are the ones who affect its future most profoundly. Stuart Kauffman is one of these." In At Home in the Universe, this visionary thinker takes you along as he explores new insights into the nature of life.

The structure of the multiverse, the nature of each universe within it and the relationships among the various constituent universes, depend on the specific multiverse hypothesis considered. Multiple universes have been hypothesized in cosmology, physics, astronomy, religion, philosophy, transpersonal psychology, and fiction, particularly in science fiction and fantasy. In these contexts, parallel universes are also called "alternate universes," "quantum universes," "interpenetrating dimensions," "parallel dimensions," "parallel worlds," "alternate realities," "alternate timelines," and "dimensional planes," among other names. The physics community continues to fiercely debate the multiverse hypothesis. Prominent physicists disagree about whether the multiverse may exist, and whether it is even a legitimate topic of scientific inquiry. Serious concerns have been raised about whether attempts to exempt the multiverse from experimental verification may erode public confidence in science and ultimately damage the nature of fundamental physics. Some have argued that the multiverse question is philosophical rather than scientific because it lacks falsifiability; the ability to disprove a theory by means of scientific experiment has always been part of the accepted scientific method. Paul Steinhardt has famously argued that no experiment can rule out a theory if it provides for all possible outcomes. This book discusses the numerous concepts and theories concerning multiple universes.

Physicists argue from different perspectives for and against the idea of the existence of multiple universes.