Editorial Review Book Description From reviews of the first edition: "Here's a gem of a book...all peppered with delightful notes from science fiction films, novels, and comics. I can't turn a page without finding a jewel." Clifford Stoll, University of California, Berkeley (author of "The Cuckoo's Egg") From the Foreword by Kip Thorne (author of "Black Holes and Time Warps"): "In browsing this revised edition, I have been struck by the richness and complexity of the tapestry of ideas that Nahin presents. His interweaving of physics and fiction is done adeptly and keeps the book flowing.... Like a good journalist, Nahin simply reports what he sees in the physics and science fiction literature, commenting lucidly and often pointedly on the interconnections, contradictions, and controversies, but leaving it to his readers to form their own final judgments.... Nahin's book, with its complex tapestry of ideas and possibilities, may well remain the most readable and complete treatise on time travel in science and science fiction." Time Machines explores the idea of time travel from the first account in English literature to the latest theories of physicists such as Kip Thorne and Igor Novikov. This fascinating and very accessible book covers a variety of topics including the history of time travel in fiction; the fundamental scientific concepts of time, space-time, and the fourth dimension; the speculations of Einstein, Richard Feynman, Kurt Goedel, and others; time travel paradoxes, and much more. The new edition is substantially enlarged and updated throughout. ... Read more Customer Reviews (11)
Suffers from being written by a nonscientist
While Nahin is certainly to be admired for attempting to tackle so great a concept as time travel, one needs to approach his resulting product with great caution.
A full discussion of time travel should include the following elements:
1)A presentation of the various arrows of time and a discussion of their fact like or law like nature, by way illustration being:
1 a) The perceptual arrow of time or time as percieved by the human observer.Interestingly enough, this sometimes runs at GREAT variance from the actual movement of local time in nature;
1 b) The cosmic expansion arrow of time believed by conventional wisdom to be THE arrow of time from which all others are derived;
1 c) The gravitional arrow of time; and
1 d) The quantum arrow of time including a discussion of K particles which unlike any other matter in nature actually show a time asymmetry.It is for this reason that Oxford's Roger Penrose has suggested that K particles or Kaons might themselves be responsible for being THE arrow of time.
2)A discussion of the different methods that have been proposed for evading the implications of these arrows of time:
2 a) Starting with Einsteinian relativity whose precepts allow for a limited time travel of sorts in that they permit local observers through greater excelleration towards light speeds to experience time more slowly than their nonaccelerated peers;
2 b) Kurt Godel's solutions of Einstein's equations allowing for time travel in a rotating universe (unlike ours) which is also smaller than ours;
2 c) Kip Thorne's black hole wormhole solutions which also suggest the possiblity of time travel...albeit at only subatomic levels;
2 d) J Richard Gott's black hole solutions which both allow time travel when the universe's mass is compressed to subatomic levels and interestingly enough allow the universe to create itself;
2 e) J Richard Gott's supposed cosmic strings which would allow time travel assuming the existence of as yet undiscovered cosmic strings;
2 f) And now -- since the publication of this book -- U Connecticut's Ronald Mallett's gravitional laser solutions which attempt to capitalize on the premise that sufficient amounts of laser light do create a gravitional force which can be capitalized on to stir time and create a local field variance to allow for the sending of signals through time.
Such a book would also discuss the fact that:
3)The various arrows of time and the ways in which they have been proposed to be manipulated are all but the academic side of what is an eternal human yearning to revisit the past and remedy its wrongs or re-enjoy its joys a task that may occur anyway owing to:
4)The argument that reality is not a discrete entity but rather a normalization of one possibility wave function of reality.Contrary to the assertions of Nahin, even no less than Stephen Hawking has suggested that the existing universe might be best seen as the product of its wave function.Likewise, noted physicists Paul Davies and Michio Kaku have ably described both the fact and reasons for this view.Accordingly, so viewed:
5)There is reasonable support for the proposition that the so called time travel paradoxes that so plague philosophical discussions of time fail to likewise plague the actual physical realities of time travel itself.
Although Nahin admittedly covers these bases his work nonetheless suffers from its lack of scientific understanding.
True, our current state of knowledge may cast a dim light on the potential of time travel.That being said, all we really know about what lies beyond the event horizon of black hole or in the 10 the 43rd power of the first second of the universe and with it multiple universes and quantum gravitiy and time travel is that we have a lot to learn.
For your purposes however, you should probably best do your learning from Paul Davies (About Time), Deiter Zeh (The Physical Basis for the Direction of Time), Kip Thorne (Gravitation and his Black Holes and Time Warps), Stephen Hawking (A Brief History of Time and Black Holes and Baby Universes), as well as the likes of H.G. Wells (Time Machine).
They speak just fine on their own and do not need an intermediary.
Awfully weak
I got the second edition (1999) of this book.I was hoping for something interesting.After all, there was even a forward by none other than Kip Thorne!
But this book was an awful disappointment.First, Nahin did his readers no favor by utterly failing to understand the writings of Hospers.On pages 289-290 and elsewhere, Nahin criticizes Hospers strongly, but Nahin is seriously in error.For one thing, Nahin claims that Hospers says that one can not go back in time while Nahin says it is possible.In fact, the reverse is true.Hospers says that time travel is possible and Nahin actually is arguing against it.To put it mildly, Nahin is an intellectual lightweight who has become totally confused by the plethora of time-travel paradoxes.
Nahin is so sure that there is only one worldline and so sure that anyone who disagrees with him does not understand this that he simply refuses to read anything which hints at multiple world lines.However, if he wants to disagree with those who discuss the concept of multiple world lines, he ought to read what they say first and even try to understand it!
On top of this, I was amazed at the amount of material (some of it interesting and some of it nonsense) written about people travelling to the past, as opposed to people merely sending signals to the past.A fundamental scenario would be to send a book to a time 50 years earlier, thereby "creating" information (the author, having already received the book, might no longer need to write it).Or perhaps sending instructions to the past on how to build a camera, so that various famous historical events could be filmed and sent back to the "future."I think topics such as these would have merited some discussion.
Too much compilation, too little synthesis
Mr. Nahin obviously is very interested in the topic of time travel. He has read tons of sci-fi stories, has spoken with many physicists and/or read their books. But he is a journalist, not a physicist. And he makes little or even no effort to synthesise. As a result the book reads mostly like a list of everything that has been written by sci-fi writers, scientists and philosophers about the subject. But not like a book by someone who truly understands what is going on - provided it is possible to understand. In my view this is a good book because of all the material in it, all the references. But it is not a good book per se. I gave it 3 out of 5, including 1 point for all the references.
A very good discussion of time travel, one error of omission
As I have always been fascinated by the idea of time travel, I very much enjoyed its discussion both in 'strictly scientific' terms and from a philosophical, literary, and, essential, pop-culture perspective. Sadly, Nahin completely ignores one aspect that features prominently in many modern time travel narratives: the idea of alternate universes / alternate realities and, tied to that, the narrative perspective of sequentiality, which follows the POV of the protagonist of a narrative and projects his continuity against the alterations his actions cause. As a result, a number of time travel stories are missing, while others show flaws/inconsistencies in their interpretations. For instance, Isaac Asimov's The End of Eternity (1955), which deals with the idea of realities literally being 'engineered' through minimum manipulations in the course of history, thus weeding out 'mishaps' like world wars and famines but at the same time stalling natural progress, remains completely unmentioned. On the other hand, Nahin points to the 'flaw' in the end of Back to the Future I that the shopping mall should always have been "Lone Pine Mall" and never "Twin Pines Mall" as it was called in the beginning because taken from a timeline perspective, Marty had already been to 1955 and run over one of the twin pines with the DeLorean when the temporal experiment #1 took place in the parking lot in 1985. However, taken from this perspective, Marty's family should have been healthy and wealthy from the beginning on as well, which would undermine the whole plot idea of changing history (which is, added to that, even expressedly discussed in detail in the also unmentioned Back to the Future II). Nevertheless, Nahin gives a lot of food for thought on the idea of time travel, and the rather extensive bibliography supplies a very good reference for further individual exploration.
A good discussion of time travel, with one error of omission
As I have always been fascinated by the idea of time travel, I very much enjoyed its discussion both in 'strictly scientific' terms and from a philosophical, literary, and, essentially, pop-culture perspective. Sadly, Nahin completely ignores one aspect that features prominently in many modern time travel narratives: the idea of alternate universes / alternate realities and, tied to that, the narrative perspective of sequentiality, which follows the POV of the protagonist and projects his continuity against the alterations his actions cause. As a result, a number of time travel stories are missing, while others show flaws/inconsistencies in their interpretations. For instance, Isaac Asimov's "The End of Eternity" (1955), which deals with the idea of realities literally being 'engineered' through minimum manipulations in the course of history, thus weeding out 'mishaps' like world wars and famines but at the same time stalling natural progress, remains completely unmentioned. On the other hand, Nahin points to the 'flaw' in the end of "Back to the Future" that the shopping mall should always have been 'Lone Pine Mall' and never 'Twin Pines Mall' as it was called in the beginning because taken from a timeline perspective, Marty had already been to 1955 and run over one of the twin pines with the DeLorean when the temporal experiment #1 took place in the parking lot in 1985. However, taken from this perspective, Marty's family should have been healthy and wealthy from the beginning on as well, which would undermine the whole plot idea of changing history (which is, added to that, even expressedly discussed in detail in the also unmentioned "Back to the Future II"). Nevertheless, Nahin gives a lot of food for thought on the idea of time travel, and the rather extensive bibliography supplies a very good reference for further individual study.
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