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Last Updated on May 6, 2015, by eNotes Editorial. Word Count: 1747

The reader who has finished The Fabric of the Cosmos: Space, Time, and the Texture of Reality is left with a sense of fascination and bewilderment. Author and physicist Brian Greene seeks to explain to the average reader the fundamentals of space and time and how they interconnect to create the sum total that is the universe itself. Greene also asks questions usually only undertaken by philosophers, theologians (and other scientists): Did something exist before the universe itself?

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To tackle these issues, Greene divides his book into five parts. In the first part, he covers the fundamentals of physics by introducing (for those not already familiar with them) Sir Isaac Newton and Albert Einstein. Newton realized that if there were two objects rotating independently of each other (such as a bucket and its contents simultaneously), those individual objects would still move in relation to some larger object Newton could not see. Newton theorized that this object was the whole of space itself. When asked what this absolute space is, Newton gamely replied that absolute space could not be defined because it is already well known to everyone who experiences it. (In other words, Newton did not answer the question at all.) His theories of motion would eventually become the foundation of classic physics.

While Newton's principles applied to the majority of objects that scientists could observe, there were objects that did not behave exactly as Newton's equations said they should. Gravity affects everything, including space itself, and Einstein realized that objects on a grand scale—whole planets, stars, and so on—bend the shape of space around them. Einstein pictured space around these objects as pliant and bending itself around each object in turn. A mosquito on the surface of water will bend the surface it stands on very slightly, while planets shape the space around them on a much larger scale. Phenomena Newton's laws could not explain precisely, such as the planet Mercury's irregular orbit around the Sun, could now be computed exactly with Einstein's general theory of relativity. Einstein's general theory of relativity and his special theory of relativity—that time moves more slowly for an object going faster and faster—shaped the discipline of physics even further.

What Newton and Einstein did for the macro-scale universe, Erwin Schrödinger did for the micro-scale universe. Objects on the subatomic scale, such as atoms, behave very differently than do objects on a macro scale. Schrödinger believed that reality is observed and that, until it is, every reality is happening at the exact same time (later to be known as the Many Worlds interpretation). For example, is a cat trapped in a box alive or dead? According to Schrödinger, until one looks inside, the cat exists in both states simultaneously. To add to the intricacies of quantum physics, Werner Heisenberg realized that the harder one tries to pinpoint the whereabouts of a subatomic particle, the more unlikely one would be to find it. Trying to shine a light on a subatomic object makes it less likely one will be able to find said object, because the light actually has a force that knocks the subatomic particle away. Mathematically, one could only deduce either the velocity or position of a particle but never both. This is known as the Heisenberg uncertainty principle.

In part 2, Greene deals with the concept of time and the way time flows from past to present. This leads to the question of whether physics allows time to flow backward. Through examples ranging from the chicken-and-egg scenario through that of taking the same egg and breaking it on the ground (and reassembling it again), Greene points out that physics does not say that time cannot flow backward. Everyone would agree that time only flows in one direction—from past to future—so the fact that time actually (and mathematically) can be shown to flow backward without consequence is a bit of a shock. Even though Greene says that time can be shown mathematically to flow in either direction, obviously this is not the case, so there must be another element in the works that directs the flow of time.

Dipping back into quantum mechanics, Greene explains that while objects on the macro level may be unaffected, on the microscopic level even the tiniest variation (even on the order of 1033 centimeters, a Planck length) can make a gigantic difference. Even quantum physics does not say that time must flow in one direction, but at the universe's birth this may not have been the case. Maybe time's direction was set at the beginning of the universe after the very instant of its creation. In part 3, “Cosmology,” Greene theorizes about exactly how the universe began, what it evolved into, and how its evolution may have affected time's flow.

There is a point at which macro-scale theories will work (as penned by Einstein) and one at which subatomic theories work (such as those of quantum mechanics), but where is the point at which they meet? In part 4, Greene conjunctures that the answer involves string theory. Strings are units of vibrating energy that are one-dimensional yet play a part in how everything, big and small, interacts. Greene says in order for string theory to work, one has to imagine that there are more than the four dimensions (length, width, height, and time) to which most people are accustomed. With string theory and, later, Edward Witten's M-theory, four dimensions are now eleven; what once were unthinkable problems seem to make perfect mathematical sense when the number of theoretical dimensions is higher.

Finally, in part 5, Greene paints a picture of what the future may hold by trying to tie everything together into a neat package. After presenting all of the different theories in previous chapters, Greene uses part 5 to map the direction in which these theories and ideas may go in the future. Greene also delves further into time's arrow (yet again) by hypothesizing about the reality of time travel and teleportation, staples of science fiction. He gives two examples of time travel paradoxes, with one of them being a slight variation of the classic thought puzzle of a time traveler going back in time to kill his father (if he kills his father, then his father could not have married his mother, and yet if they never met the time traveler would not have been born and gone back in time to kill his father). Even though Greene does not believe time travel is possible, because it is an uncharted territory he leaves the door open slightly. Also, because he leaves the problem of time travel until near the very end of the book, Greene can then draw upon everything he discussed earlier to make his case.

An interesting idea that Greene presents at the end is a theory about how the universe may be made up of holograms. Holograms are ways of constructing a three-dimensional object from a two-dimensional surface (for example, credit cards now have on their flat surface a theft-protection picture that, when looked at a certain way, appears thicker than the card it rests on). Greene explains this idea that the universe—and everything in it—may be created on top of a two-dimensional surface. It is like picking up a line drawn on a piece of paper and having a three-dimensional image appear from a point on that line. Again, this theory has not been tested, but it would not have made sense without understanding everything Greene has laid out up to this point.

The theory that everything in the universe is somehow connected is comforting, as long as one is willing to believe in the possibility that there are hidden dimensions and that the universe may be a hologram and other theories that seem to come more from science fiction than reality. Yet, as Greene shows again and again, fiction and reality may, at times, be the same thing. Greene writes about such topics both as a fan of speculative ideas and as someone who uses the scientific method to see if physics can prove those ideas.

Greene's awareness of popular culture is apparent. He uses examples with Apu, Bart, Lisa, and the Kwik-E-Mart (from The Simpsons), Mulder and Scully (from The X-Files), and others to try to make his writing reader-friendly. Because, however, he uses these examples irregularly, they distract more than they inform. Conversely, the examples Greene uses to illustrate his ideas are not the examples most people would be familiar with, whether they read physics or not. For example, rather than using the classic time-traveler-cannot-kill-his-own-father scenario, of which many people have heard, Greene uses a much more cryptic example in order to make the same point (basically, that time cannot be changed once it happens).

Other reviews of Greene's book have argued both for and against his examples: He does not talk down to his audience, but his examples are just as hard to understand as the principles of physics itself. If he can write his book without math, supposedly for the common reader, why does he make his examples so hard to follow? Science writers such as John Gribbin (In Search of Schrödinger's Cat: Quantum Physics and Reality, 1984) and Michio Kaku (Hyperspace: A Scientific Odyssey Through Parallel Universes, Time Warps, and the Tenth Dimension, 1994) have written about physics and have used clearer examples in their books. Also, some reviewers have noted that both The Fabric of the Cosmos and Greene's first book, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory (2000), cover primarily the same ground, making The Fabric of the Cosmos a retread of familiar material.

The Fabric of the Cosmos, though, is truly remarkable because Greene covers so much information and gives credit to numerous scientists from all over the world as he recounts their discoveries. Greene also layers each section of the book so that topics flow easily. The examples may be confusing at times, but the overall structure builds perfectly from one idea to the next. As long as readers know what they are about to get into, The Fabric of the Cosmos is worth the effort.

Review Sources

American Scientist 92, no. 4 (July/August, 2004): 371.

Booklist 100, no. 12 (February 15, 2004): 1013.

The Economist 371, no. 8371 (April 17, 2004): 82.

Library Journal 129, no. 5 (March 15, 2004): 103.

Los Angeles Times, March 07, 2004, p. R4.

Nature 428, no. 6980 (March 18, 2004): 257.

New Scientist 182 (April 10, 2004): 52.

The New York Review of Books 51, no. 8 (May 13, 2004): 16.

The New York Times Book Review 153 (April 11, 2004): 12.

Newsday, February 22, 2004, p. D30.

Publishers Weekly 251, no. 6 (February 9, 2004): 74.

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