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60 of 68 people found the following review helpful
on November 26, 2010
This book was a big disappointment. The style is really hard to plod through; every sentence reminds you that English isn't Bojowald's native language. The book starts by covering a lot of preliminaries about quantum mechanics and general relativity, and it doesn't do that very well. This first half of the book is in particularly in need of some diagrams. E.g., there is a description of the Bohr model of the atom in words, with no diagram of the circular orbits. Rather than useful scientific diagrams, most of the illustrations in the book are photos of abstract sculptures. Once he gets into the quantum gravity stuff, there are some descriptions of contact with observation, but these are already out of date. He discusses tests of dispersion of the vacuum, which the LQG community has already disowned as a prediction of the theory. He also devotes some space to Smolin's cosmological natural selection, which has recently been falsified by the observation of a high-mass neutron star. Amazingly for a book about LQG, there are absolutely no drawings of spin networks.
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22 of 27 people found the following review helpful
on December 3, 2010
Considering that there is scant little published material on LQC (aside from the deplorable book published by Books, LLC which is a collection of Wikipedia articles), I was highly excited by the author, quality and the size of the 'Once Before Time: A Whole Story of the Universe.' However, you do not judge a book by its cover--a lesson that is difficult for a self-professed bibliophile--and I have to somewhat agree with the above reviewer in that I was somewhat left waiting for the punch line. That is to say, I understand that many popular level books have to start out by stating the same foundational issues many physics books seem pressured to lay out the same foundation only this book lays it out in such a way as to presume that one would have some working knowledge of classical and non-classical physics. This book accomplishes what it sets out to accomplish; namely, teaches you everything you wanted to know about LQC regardless of some outdated scientific notions (that are irrelevant anyway). Moreover, it is organized enough so that the "patient" reader can get through this book without too much pain.

You will not find any chapter containing long descriptions of Einstein's light clock or the twin paradox. And, this is actually one of the good things one can state about the writing style and approach. Many of the chapters--at least at the beginning--are not torturously long. That is why I would give this book a 3+ star rating. Contrary to the reviewer above, the book is worth more than 1-star and I would not dismiss the author too quickly as there is a measure of subjectivity when reading. Some chapters are three pages in length and very readable. That is to say, you do not lose touch with where the author is going--at least during the first half of the book.

I have given this book 3 stars because it shares stories that you won't find in other books, such as stories regarding some heroes of physics such as Lee Smolin. Moreover, it delivers on what is promised by way of a description and process leading up to LQC. But, this does not say much as far as substance and after page 100--when the unfamiliar reader may find themselves in troubled waters. However, you are not going to find very many books written on LQC anywhere else (presently), and especially by someone that is credited for being the first to utilize QLG and Einstein's GTR to create LQC. For these reasons, and many others that are laid out throughout this 320 page book, I would recommend it simply because of its historic value and its content. It is definitely not a 1 star book.
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16 of 20 people found the following review helpful
on February 6, 2011
This review was published in slightly shorter form in the Pittsburgh Post-Gazette, and I retained rights to republish it elsewhere.

Move over, Stephen Hawking. Make way for Penn State physics professor Martin Bojowald!

Bojowald's new book, Once Before Time: A Whole Story of the Universe, describes what may turn out to be a definitive breakthrough toward solving the greatest problem in modern physics. Though no one expects the professorial Bojowald to outsell the charismatic Stephen Hawking, Once Before Time is a more worthy successor to Hawking's 1980s mega-seller, A Brief History of Time, than is Hawking's own new book, The Grand Design.

Bojowald's story begins in 2000 when he was a 27-year-old postdoctoral researcher in cosmology at Penn State. Understanding the behavior of the universe as a whole requires a solid grasp of two remarkably successful but apparently incompatible theories: general relativity and quantum mechanics.

General relativity runs counter to our intuitive distinctions between space and time and between mass and energy. It describes gravity as the result of the warping of spacetime due to the distribution of mass-energy within it.

Quantum mechanics describes the subatomic realm, again in counter-intuitive ways. Waves and particles become two faces of the same phenomenon, described mathematically as a wave function.

The two theories, as currently constituted, are incompatible in a significant way. General relativity assumes that space and time can take on any value along a continuum, while quantum mechanics gets its name because properties of mass and energy only take on discrete values-states described by a set of quantum numbers.

Unfortunately, these apparently mismatched theories must both apply in two extreme but important cosmological circumstances: the Big Bang "singularity," in which our universe of matter, energy, space, and time emerged from a timeless, infinitely dense state; and a similar singularity that exists in the heart of a black hole.

Singularity is a mathematical term for the infinity that arises in the continuous mathematics of general relativity, a point where physical interpretation breaks down. An infinite result is likewise incompatible with the discrete, finite mathematics of quantum theory.

Since all entities in the universe appear to be quantized, the resolution to this incompatibility seems to lie in finding a way to quantize general relativity. That is what Bojowald was trying to do when he ignored a piece of conventional wisdom, and, in what he describes as a fortunate accident, emerged with a mathematical description with surprising consequences.

That approach has come to be called "loop quantum cosmology." The name is a result of its connection to loop quantum gravity, a theoretical alternative to the family of approaches that are known collectively as string theory.

That's where Hawking's new book comes in. Like Hawking, Bolowold manages to describe these complicated ideas without bogging down in mathematical notation. And like Hawking, he manages to help readers over the difficult spots with entertaining and literate prose.

But unlike Hawking, he shows a way to turn the spacetime continuum into a fabric knitted together from discrete spacetime loops, making it possible to avoid the singularity. This leads to what he calls "The astonishing result: ...unflinchingly, the wave function of the universe wends its way before and behind the big bang, without even taking notice of the potential singularity."

The astonishment arises because the theory makes it possible to speak of, and even discover, some properties of a predecessor universe. It removes a philosophical sticking point that many physicists have had with existing theories. No longer do they have to say that there was no such thing as time or space before the Big Bang.

Loop quantum cosmology is also much more satisfying than Hawking's candidate for "The Grand Design," a version of string theory called M-theory, which postulates a multiplicity of universes far more numerous than the number of protons in this one. On the other hand, Bojowald's discovery, when fully developed, has the potential to be "the ultimate theory explaining not only the temporal course of the universe but also the fact that there is only a single universe."

Yet Bojowald never loses sight of the many open questions that could completely derail his work. His closing is a refreshing contrast to Hawking, who claims that M-Theory enables science to subsume philosophy and even theology by answering the ultimate question of why a universe such as ours exists.

Instead, Bojowald closes with humility about his own theory and science in general. Science's great strength is its ability to describe the practical "what" and "how" and leave the grand "why" to philosophy. "Despite the almost intoxicating progress in science," he writes, "one must always keep in mind its limitations, which become especially clear at its frontiers."

Fred Bortz is a physicist and author of the twentieth-century scientific history, Physics: Decade by Decade (Twentieth-Century Science), and eighteen other books for young readers.
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5 of 6 people found the following review helpful
on December 13, 2010
The author is one of the physicists working on loop quantum gravity which was pioneered by Lee Smolin and is an alternative to string theory (and twistors from Penrose) as a candidate 'theory of everything'. Without getting very specific about why, he states that loop quantum gravity (LQG) has enabled him to conclude that before the big bang there was a collapse from a previous, homogenous universe, due to the fact that a singularity of infinite density (as suggested by einstein's g. rel.) is impossible, that fundamental units of loops that make up space and time would prevent compression and cause an expansion. This is his basic point, but the book tends to plod in elaborating on that idea. As with most general interest physics books along this vein he summarizes recent theories including general relativity and gravity, and quantum physics and the standard model, as well as string theory, which he is quite sympathetic to throughout the book (despite its being fundamentally at odds with LQG). Towards the end the book really drags as he goes into the mythology of cyclic universes throughout human history-- not clear how this is relevant at this late stage in the thesis.
I was a bit disappointed in the lack of real hard scientific information, with most of the book appearing like an advertisement for his line of work (LQG). Some of his quote are very very oddly chosen as well (most chapters begin with a literary quote of questionable artistic merit).
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3 of 4 people found the following review helpful
on May 2, 2011
This is a semi-popular discussion of loop quantum gravity and its applications to black holes and cosmology. Although avoiding the formulas and equations which so discomfort some folk, it requires a reasonable familiarity with modern physics.

The book opens with introductions to gravity and quantum theory, giving a particularly interesting account of general relativity, using the GPS as an example. These themes combine in the central chapter describing loop quantum gravity, a candidate 'theory of everything'. Essentially it is a quantum version of Ashtekar's formulation of general relativity based on space alone rather than space-time. ( Its widely followed rival, string theory, is more of a fresh start, based on complicated geometries of many dimensions. ) The fundamental unit is the loop as a quantum of space, determined by its quantised area and orientation; with space being a discrete 'wave function' of a vast grid of intersecting loops. Its successive states may be numbered in order, to play the role of time, and they evolve according to difference equations rather than the familiar differential equations. However a fully covariant list of equations has yet to be found.

A big advantage of loop quantum gravity is that infinities of compression are prevented as intense energy waves, unable to be accommodated by the grid, turn into a repulsive force. This leads to very different accounts of black holes and the big bang from those of general relativity with its singularities. In cosmology, extrapolating back to to the beginning of our universe, Bojowald himself was able to formulate and solve simplified equations to show that space would pass through a single empty cell to an inside-out 'mirror' space, where each loop has a reversed orientation. In physical reality the discreteness of time would 'jump' the universe across the gap, missing out the single empty cell. Another chapter discusses the issues of inflation and dark energy in this context.

A chapter on black holes points out the recent realisation that the singularity attributed to a black hole in general relativity is a final time for its interior, rather than a final destination within it. Under loop quantum gravity a black hole could be passed through, perhaps into a daughter universe. Alternatively, when the event horizon of a black hole eventually evaporates through Hawking radiation, its compressed interior could be released with a huge amount of energy.

There is a more philosophical chapter seeking to remove the fish-hooks from the notion of the 'arrow of time' and from common considerations of the entropy of the universe. The passage on the arrow of time is in itself worth the price of this volume, though I feel that the remarks on entropy do not finally clinch the matter. Beyond this the book tails off in short chapters on wider issues such as the history of cosmogony and the limits of science.
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2 of 2 people found the following review helpful
on October 7, 2011
This book is on the Rorotoko list. Professor Bojowald's interview on "Once Before Time" ran as the Rorotoko Cover Feature on March 9, 2011 (and can be read in the Rorotoko archive).
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on September 18, 2015
This is an excellent book for the lay reader on the current attempt to apply loop quantum gravity to cosmology. Bojowald
provides the reader with a nice overview of general relativity (GR) and quantum mechanics (QM) and then addresses current attempts by physicists to merge GR and QM into a theory of Quantum Gravity. He gives the reader an intuitive feel for the two major current theories of Quantum gravity; string theory and loop quantum gravity. In addition , he discusses black holes, the arrow of time, and cosmogony. Bojowald concludes the book with chapters on a theory of everything and the limits of science. This book does not read like
a light novel but for anyone wanting to delve into a theory which may take us to a time before the big bang, it is a great read.
Finally, the current low price allows anyone to obtain an excellent book on current attempts to create a new theory of gravity and it also takes the reader to the cutting edge of contemporary theoretical physics. If you have ever wondered about the beginning of time and space and what may have come before, spend a few bucks and get a copy of this book.
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on June 20, 2014
Reasonably well written by an active cosmologist familiar with the latest ideas on loop quantum gravity and cosmology. Although the mathematics is not presented (apparently even world-class mathematicians have difficulty understanding the math), the presentation requires a significant effort on behalf of the reader to understand the concepts. Worth the effort though. Flex your mind.
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on October 23, 2013
With a brilliant literary style and a refreshing quest for clarity, Martin Bojowald, in his new book, Once Before Time: A Whole Story of the Universe, takes you on an exuberant ride of mental calisthenics and never allows you to rest. You feel his deep passion for science throughout the reading--as though he found his way into your mind and endeavors to challenge your own mental programming. One of the most brain-stimulating books I've encountered in years.

While his book discusses the big bang and what it means, the larger question is, did something come before it and if so, what was it? He first examines the main arena of theoretical physics--an opportunity to find the kind of inconsistencies to control an argument. Such a way of thinking opens the doors to speculation--a rather fundamental tool of theoretical physics. These are the directions of his position, to acknowledge the wide gulf between the two worlds--the very large and very small.

He considers the importance of the theory of Quantum Mechanics, which is the fundamental tool to describe matter in the universe, and General Relativity to explain gravity, space and time. He is attempting to find a place for the relatively new area of concern: quantum gravity, which remains extremely complex in mathematical terms.

The book hopes to establish a first-hand report of the relevant research that is making an effort to combine the two seemingly disparate theories. He draws the analogy of the first stages of assembling a jigsaw puzzle, where the picture is starting to take form, but we are not quite sure what it is.

Although this book allows the joys of mental stimulation to thrive, it invigorates the spirit of curiosity to reconsider some of the deepest and most haunting speculations of all: what's it all about.
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on December 28, 2012
The author does a fairly good job in presnting his vew of the cosmic puzzle but I think it's wrong to claim that his book is a "whole story", but rather is just a piece of the cosmic puzzle in my opinion. We still have a long way to go to realize the whole story -
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