Most Helpful Customer Reviews
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27 of 38 people found the following review helpful:
5.0 out of 5 stars
Strings that make you go "Hmmm", 23 Jul 2006
Leonard Susskind is one of the world's most original and inspired theoretical physicists. The culmination of his life's work is described without mathematics in this book. His brilliance of lateral thinking is on a par with Einstein. He turns conventional big bang theory on its head and explains with stunning simplicity how our Universe could have been so astonishingly fine-tuned as to allow intelligent life. I just wish I could remember all the detail in between without having to read and reread and ...
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5.0 out of 5 stars
A brilliant tour de force with manyfold implications beyond Physics, 6 Jul 2009
Leonard Susskind is one of the most renowned physicists alive, and his insights have been confirmed again and again. In this book, he takes on the anthropic principle and uses it for his own purposes, which are none other than proving that our universe is indeed a pocket universe in a megaverse with thousands, perhaps millions of other universes under a perpetually inflationary landscape.
His prose is not always easy or engaging, but the effort the reader may put into plodding thourhg the pages will be handsomely rewarded with new paradigms in cosmology and physics with profound philosophical and spiritual implications.
Nothing less than the basis of a new cosmology and a new worldview from one of the greatest scientific minds of our time.
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3.0 out of 5 stars
Mostly an unconvincing justification of string theory, 22 Jun 2009
The first thing to note is Professor Susskind's insistence on using 14 billion years as the time since the Big Bang whereas most authorities today give 13.7 billion years. That of course is a minor point. More troubling is Susskind's unconvincing and quixotic support of the anthropic principle in cosmology. He characterizes the principle as "really shorthand for a much richer set of concepts that I will make clear in the chapters that follow." (p. 7)
Unfortunately--perhaps revealing the poverty of my discernment--after reading nearly four hundred pages of rather dense text I was not able to appreciate his "richer set of concepts." What I do know is that "The Anthropic Cosmological Principle" (title of John D. Barrow and Frank J. Tipler's book from 1986), which I like to call the "anthropic cosmological fallacy," is really a kind of mystical expression that declares we are here only because of a miraculous series of events or conditions, when in fact we are here precisely because we are the sort of creatures that those events and conditions allow.
A better way to state the cosmological anthropic principle is simply this: if things in the universe were not as they are we would not be here. This avoids the unfortunate suggestion that somehow we cause the universe to be the way it is. We cause nothing. We are a result--an example--of what is possible considering the way the universe is. Notice "a" result, "an" example. Other beings might be here if the laws were different.
On page 363 Susskind writes that the anthropic principle "provides marvelous explanatory power for questions like, why is the cosmological constant small?" But this is not so. It happens that a small cosmological constant is compatible with a universe that allows life as we know it to exist. Again there is no causation, and life itself provides no explanation for a small cosmological constant. If aphids appear in your garden we can say that they would not appear in your garden if you grew cacti instead of vegetables. This does not mean that the growing of vegetables caused the existence of aphids. It merely says that of all the places that aphids could exist, your vegetable garden is one of them.
In the glossary Susskind defines the anthropic principle as "The principle that requires the laws of nature to be consistent with the existence of intelligent life." If we turn this around and say that "the physical characteristics of intelligent life must be consistent with the laws of nature," we can better see the direction of causality and why most physicists consider the anthropic principle to be vacuous.
It would help a lot if Susskind and others when they use phrases such as "for life to develop" to include the left-out qualification "for life to develop AS WE KNOW IT." That way they will be reminded that all this "fine-tuning"(a phrase that implies a fine-tuner, by the way) they are raving about is just an after-the-fact projection of an anthropomorphic perspective.
Another problem I had with this book is Susskind's unrelenting endorsement of string theory as something proven and true, as something "discovered." Also annoying is his answer to the fact that string theory has no--zero--experimental support: namely that experimental support isn't really necessary. See especially Chapter Nine "On Our Own?" in which he speculates on whether the Standard Model in particle physics (and of course string theory) could have been discovered without experimental verification. It might be better if Susskind said that he and the others "designed" or "created" string theory instead of saying they "discovered" it, which suggests that string theory is somehow true. A mathematical representation of the world is what they "discovered."
I also don't think that Susskind did a very good job of explaining why we should believe that string theory is an accurate description of our universe. I had the sense of a man trying to support his prodigal son by saying "Trust me he's going to turn out right" despite the fact that he hasn't done anything yet to prove it. "Just see how good-looking he is!" Well string theory may be a beautiful mathematical edifice, but until some beautiful experimental support comes along, it will remain as it objectively is, just one way of describing reality.
Curiously, after all the confident expressions about the truth of string theory, Susskind describes string theory as "our best guess for a theory of nature." (p. 302) A guess!
By the by, Susskind explains that after many years famed physicist Stephen Hawking gave up his heretical idea that information is lost in black holes and came around to agree with Susskind and most physicists that information cannot be lost. What is not mentioned in this book is Hawking's addendum. I suspect it is not mentioned since it amounts to a satire on Susskind's position. What Hawking said was that the information lost in black holes in this part of the "megaverse" would be preserved in other parts in which there are no black holes. In other words, Hawking came up with an argument, like that of Susskind's Landscape, which relied on information from parts of the universe which can never be reached! The salient point is that his statement, like the reality of Susskind's "Landscape," cannot be proven one way or the other
Sometimes we reveal ourselves and our ideas without meaning to. In reference to the idea of supersymmetry, Susskind writes, "...the whole exercise was only a mathematical game, a pure theoretical exploration of a new kind of symmetry that a world--some world not our own--might possess." (p. 241)
Could this be an unconscious but accurate expression of the true nature of string theory?
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by Leonard Susskind
by Leonard Susskind
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