Post by swamprat on Jun 27, 2012 13:09:57 GMT -6
The Hidden Reality
By bob Greene
Knopf, 370 pages, $29.95
Book Review By JOHN GRIBBIN
The multiverse is an idea whose time has come. Not so long ago, back in the 20th century, the idea that our entire universe might be just one among many universes (perhaps infinitely many) was the stuff of science fiction; now numerous serious scientists consider it to be the best explanation for the existence of the kind of universe we live in.
The laws of physics do, indeed, allow for the existence of different kinds of universe, and no fundamental reason has yet been discovered why the world we see around us should have been singled out by those laws.
To take a simple example, if the force of gravity were stronger than it is in our universe, but all other properties remained the same, stars would have to burn more fiercely to hold themselves up against the pull of gravity. They would use up their fuel more quickly and burn out in a few million years, not allowing time for life forms like us to evolve on planets orbiting those stars. So why should gravity, and the other properties of our universe, be "just right" for us to exist?
There are two possibilities, often expressed in terms of an analogy with a man who buys a suit that is a perfect fit. Either the suit has been specifically tailored for the client—made to measure—or he has visited a large store with an array of suits in all possible sizes, choosing the one right for him off the peg. The best interpretation of the laws of physics as we understand them is that we live in an off-the-peg universe. A vast array of universes exist in the multiverse, many (perhaps most) of them sterile, but since life forms like us can only exist in universes like ours, it is no surprise that we live in such a universe.
So far, so philosophical. But bob Greene is one of the physicists who have turned such philosophical speculation into hard science (to a physicist, that means backing it up by calculations that have predictive power). A professor at Columbia University, Mr. Greene is widely known as the author of two best-selling science popularizations, "The Elegant Universe" and "The Fabric of the Cosmos." Unfortunately, the science he describes in "The Hidden Reality" is "hard" in both senses of the word: It incorporates many equations, and most of them are difficult for any nonphysicist to understand.
Mr. Greene, though, does a valiant job of making the arcane world of what is known as string theory at least semi-intelligible. Briefly, string theory asserts that interactions between objects called "strings," occurring in multiple dimensions, cause the phenomena that we observe in our universe of three space dimensions and one time dimension. As readers of his earlier books will be aware, string theory is meat and drink to Mr. Greene. Yet his buildup to the sensational meat of this book—in which he proposes a system that uses string theory to explain and argue for multiverse theory—is cautious, perhaps in the hope of not frightening his readers with too much too soon.
Like many familiar accounts of our universe, Mr. Greene's begins with the Big Bang. Along the way he presents one of the best explanations that I have seen of the idea of inflation—a rapid early phase of expansion in the first split-second of the life of the universe, thought to explain the nature of the Big Bang itself. "Inflationary cosmology is a key chapter in our story," the author explains, "because scientists have gradually realized over the last few decades that the most convincing versions of the theory yield a vast collection of parallel universes, radically transforming the complexion of reality."
Following the edict that "in an infinite universe anything is possible," Mr. Greene introduces the idea of an infinite number of almost identical copies of our universe, infinitely far away from us, and the idea of universes that follow one another in time, like beads on a string. The "parallel worlds" of quantum physics, which are different from the many dimensions of string theory, make an appearance (along with Schrödinger's famous cat). There is also an all-too-brief discussion of the possibility that either our universe has been manufactured by beings in another universe or we are living in a computer simulation like that of the "Matrix" series of movies.
Read more: online.wsj.com/article/SB10001424052748703779704576074370184436248.html
By bob Greene
Knopf, 370 pages, $29.95
Book Review By JOHN GRIBBIN
The multiverse is an idea whose time has come. Not so long ago, back in the 20th century, the idea that our entire universe might be just one among many universes (perhaps infinitely many) was the stuff of science fiction; now numerous serious scientists consider it to be the best explanation for the existence of the kind of universe we live in.
The laws of physics do, indeed, allow for the existence of different kinds of universe, and no fundamental reason has yet been discovered why the world we see around us should have been singled out by those laws.
To take a simple example, if the force of gravity were stronger than it is in our universe, but all other properties remained the same, stars would have to burn more fiercely to hold themselves up against the pull of gravity. They would use up their fuel more quickly and burn out in a few million years, not allowing time for life forms like us to evolve on planets orbiting those stars. So why should gravity, and the other properties of our universe, be "just right" for us to exist?
There are two possibilities, often expressed in terms of an analogy with a man who buys a suit that is a perfect fit. Either the suit has been specifically tailored for the client—made to measure—or he has visited a large store with an array of suits in all possible sizes, choosing the one right for him off the peg. The best interpretation of the laws of physics as we understand them is that we live in an off-the-peg universe. A vast array of universes exist in the multiverse, many (perhaps most) of them sterile, but since life forms like us can only exist in universes like ours, it is no surprise that we live in such a universe.
So far, so philosophical. But bob Greene is one of the physicists who have turned such philosophical speculation into hard science (to a physicist, that means backing it up by calculations that have predictive power). A professor at Columbia University, Mr. Greene is widely known as the author of two best-selling science popularizations, "The Elegant Universe" and "The Fabric of the Cosmos." Unfortunately, the science he describes in "The Hidden Reality" is "hard" in both senses of the word: It incorporates many equations, and most of them are difficult for any nonphysicist to understand.
Mr. Greene, though, does a valiant job of making the arcane world of what is known as string theory at least semi-intelligible. Briefly, string theory asserts that interactions between objects called "strings," occurring in multiple dimensions, cause the phenomena that we observe in our universe of three space dimensions and one time dimension. As readers of his earlier books will be aware, string theory is meat and drink to Mr. Greene. Yet his buildup to the sensational meat of this book—in which he proposes a system that uses string theory to explain and argue for multiverse theory—is cautious, perhaps in the hope of not frightening his readers with too much too soon.
Like many familiar accounts of our universe, Mr. Greene's begins with the Big Bang. Along the way he presents one of the best explanations that I have seen of the idea of inflation—a rapid early phase of expansion in the first split-second of the life of the universe, thought to explain the nature of the Big Bang itself. "Inflationary cosmology is a key chapter in our story," the author explains, "because scientists have gradually realized over the last few decades that the most convincing versions of the theory yield a vast collection of parallel universes, radically transforming the complexion of reality."
Following the edict that "in an infinite universe anything is possible," Mr. Greene introduces the idea of an infinite number of almost identical copies of our universe, infinitely far away from us, and the idea of universes that follow one another in time, like beads on a string. The "parallel worlds" of quantum physics, which are different from the many dimensions of string theory, make an appearance (along with Schrödinger's famous cat). There is also an all-too-brief discussion of the possibility that either our universe has been manufactured by beings in another universe or we are living in a computer simulation like that of the "Matrix" series of movies.
Read more: online.wsj.com/article/SB10001424052748703779704576074370184436248.html