. Thorne reluctantly concludes that things really don't look very good for wormholes, especially for time travel -- though he does leave a tiny ray of hope for some super-advanced future civilization to make wormholes for space travel [note 4]. Thorne notes that our grasp of basic physics is so crude that we can really only understand maybe 5% of the stuff that fills our universe -- the "normal" baryonic matter that makes up people, planets and stars. Thorne guesses that 35% of the universes's mass is in some unknown form of "cold dark matter", and the remaining 60% is some even more mysterious form of "dark energy" -- so there's certainly plenty of room left for discovery! The book concludes with a nice explanation of why good popular-science books are needed, by noted pop-science writer Timothy Ferris, and with Alan Lightman's essay on "The Physicist as Novelist". Lightman, a former student of Thorne's, went on to write Einstein's Dreams and other well-regarded novels.
The Future of Spacetime is written for a general audience -- aside from Hawking's essay, everything should be understandable to any science-literate reader. I particularly recommend it to readers who've liked Thorne's earlier pop-science works.
______________________
Note 1). a clever play on festschrift, the traditional name for such a tribute volume.
Note 2). As Hawking cheerfully points out, "closed timelike curve" is just physics-speak for time travel, because you can't admit you're studying that sci-fi stuff in a grant proposal...
Note 3). Arthur C. Clarke notes that "the most convincing argument against time travel is the remarkable scarcity of time travellers..."
Note 4). As you may know, a faster-than-light spaceship could also be used as a time-machine, another reason why most physicists think FTL travel is very unlikely. I'd love to see a theoretical treatment of FTL travel that wouldn't violate Hawking's "Chronology Protection Clause"... Note also that there's no theoretical barrier to wormhole spaceships travelling a bit *slower* than light.
Review first published at SF Site:
http://www.sfsite.com/11a/fs139.htm
Rating: 
Summary: Garbage
Review: I'm usually wary of books that are collections of essays, especially essays by several different people. Like many such books, The Future of Spacetime is something of a hodgepodge. Still, when I saw that the authors included Stephen Hawking, Kip Thorne, Timothy Ferris, Alan Lightman and Igor Novikov, it seemed to be worth taking a look. That decision was very well rewarded.
The five essays in The Future of Spacetime were first presented as talks for a celebration of the 60th birthday of Kip Thorne, a leading theoretical physicist. Three of them, plus a brief introduction by physicist Richard Price, deal with relativity, and especially with the possibility and implications of "closed timelike curves" in spacetime--time travel for short. In addition, Tim Ferris writes insightfully about why it is so important for scientists and science writers to do a better job of informing people about scientific theories and discoveries, but even more importantly clueing them in about how science works. He points out that it may take 1,000 years for a concept to penetrate to the core of society. Since modern science is at best 500 years old, there's lots left to be accomplished. Alan Lightman, who is both a physicist and a novelist, beautifully describes the creative process that lies at the heart of both science and creative writing. Scientists and novelists, he argues, are simply seeking different kinds of truths.
The three physics essays are gems. Each sheds at least some light on the nature of spacetime, on the possibility (or impossibility, or improbability) of time machines and time travel, and on intimately related issues such as causality and free will. Novikov, for example, concludes that the future can influence the past, but not in such a way as to erase or change an event that has already happened. Hawking argues that time travel is happening all the time at the quantum level, but that nature would protect against an attempt to use a time machine to send a macroscopic object, such as a human being, back in time. I was particularly impressed by Kip Thorne's essay, in which he makes a series of predictions concerning what physicists and cosmologists will discover in the next thirty years. He explains the importance of the gravity-wave detectors that are now starting to come on line. They promise to let us read the gravitational signals of such primordal events as the collision of black holes and even the big bang itself. It is as fascinating to get to piggyback on how these great minds think as it is to read their conclusions.
In short, The Future of Spacetime is a bit of a salad, but an extremely delicious and satisfying one.
Robert E. Adler, author of Science Firsts: From the Creation of Science to the Science of Creation (Wiley & Sons, 2002).
Rating: 
Summary: The Future of Spacetime
Review: It is easy to recommend this book. The five authors of the articles in the book are all prominent in the field os cosmology and its interpretation. The editor, Richard Price, presents a good introduction of the subject of spacetime. It is not for the novice, but it is good. The sections by Hawking and Novikov are part of symposium in honor Kip Thorn's sixtieth burthday. Ferris and Lightman are excellent popularizers of difficult physics. The best part of this book is it shows that physics is fun. All of the authors obviously know each other and enjoy each other's company. This book is almost like sitting around a dinner table and overhearing the authors needle each other but still explain the basis of the universe as we understand it.
This is the best book I have read on this subject in years.
Rating:
Summary: Garbage
Review: It is incredible how they trust blindly in EVERY aspect of General Relativity. Space-time warpages and singularities happens ONLY in mathematics! There is no way out. It is funny how Scientific American gives credibility to such a kind of science-fiction. It is time to stop lying to the public!
Hawking and Thorne, grasp it: Time-travel is physically IMPOSSIBLE.
Rating: 
Summary: Sorry, grandma, I won't be seeing you again anytime soon.
Review: Time travel appears pretty impractical based on this book. Maybe it's mathematically possible to fold time and punch wormholes in it in theory, but I don't think NASA or Greyhound is going to be offering trips back and forth through our lives. However, it's always intriguing to read what really smart people come up with, because they make a lot of it seem so obvious, even though I could never come up with it on my own.
Rating:
Summary: Sorry, grandma, I won't be seeing you again anytime soon.
Review: Time travel appears pretty impractical based on this book. Maybe it's mathematically possible to fold time and punch wormholes in it in theory, but I don't think NASA or Greyhound is going to be offering trips back and forth through our lives. However, it's always intriguing to read what really smart people come up with, because they make a lot of it seem so obvious, even though I could never come up with it on my own.
Rating: 
Summary: Spacetime = Matter + Energy
Review: We have 4 scientific essays here, about space, gravity and possibilities of traveling in time, many drawings, figures and pictures and only two math equations.
However, this writings are, in my opinion, for "advanced" laymen, who collect, cherish and have fully digested at least a "Brief History of Time" or other popular science books dealing with cosmology, quantum and relativity.
Introduction (essay number one) by Richard Price presents known facts about relativity, but author uses innovative way to teach us about different types of transformation between reference frames. With elegance he introduces concept of spacetime diagrams and worldliness. Good beginning.
Then comes Igor Novikov: his essay straightforward and easy to read. Supported by well designed drawings it explains how the wormhole can work and why it is rather impossible to kill your grandfather by traveling to the past.
If you have his book "River of Time", you will know what I am talking about.
Third essay by Stephen Hawking is rather hardly digestible highbrow dissertation, with plenty of inward shortcuts. Drawings and figures are not clear and without indications to which part of the text they belong. This part of the book is least meritorious, but... help can be found later.
The most impressive essay by Kip Thorne creates the hub of the book. Kip Thorne has proposed Laser Interferometer Gravitational Wave Observatory in 1984 and is a cofounder of this project. He also believes in potential of a String Theory.
Thorne's current writing is an excellent addition to his famous book "Black Holes and Time Warps" published 8 years ago. He predicts now many interesting discoveries related to LIGO/LISA gravity waves project. If successful, this project will greatly contribute to new theory connecting general relativity with quantum fields and will help to solve mysteries of neutron stars and singularities. History of Thorne's bets with Hawking is funny and adds flavor to this chapter.
End of the book contains Glossary (whole 17 pages of it) and I read it with a big pleasure since this helped me to understand Hawking's text.
Last two essays about skills of popular writing in science were also interesting but of a less importance to me...
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