In The Hidden Reality, Brian Greene, professor of physics and mathematics at Columbia University, leads the general reader on an excursion to the farthest and most mind-bending reaches of speculative physics. It’s a journey that explores the concepts and theories that underlie nine contending versions of parallel universes, or multiverses. “Each envisions our universe as part of an unexpectedly larger whole,” Greene writes, “but the complexion of that whole and the nature of the member universes differ sharply among them.”
As readers of his previous bestsellers—The Elegant Universe and The Fabric of the Cosmos—know, Greene is a particularly good guide in these heady realms. Mathematics is the language of theoretical physics, but Greene has an uncanny ability to find metaphors and analogies to substitute for mathematical explanations (while allowing those interested in the math to explore it in the footnotes). The narrative flows from easily comprehensible theories of the inflationary universe, through challenging concepts evolving from string theory, to wildly provocative theories of virtual multiverses. Each chapter also progresses from easily grasped ideas to the more abstract, with Greene offering encouraging summaries and escape hatches along the way.
Does Greene himself believe any of these theories? He remains skeptical, he says. There is as yet little to no experimental data to support these theories; as he frequently points out, experimental proof would require resources far beyond those currently available on Earth. On the other hand, counterintuitive aspects of quantum mechanics have been proven, so we already know that the deeper reality of the cosmos is far stranger and more varied than our human walking-around reality. Furthermore, he writes, “all of the parallel-universe proposals that we will take seriously emerge unbidden from the mathematics of theories developed to explain conventional data and observations.” In other words, Greene remains open to the possibilities.
Likewise, lay readers with open minds and some patience will find The Hidden Reality an exhilarating—if sometimes vertigo-inducing—journey.