Rest assured. This isn't another speculative flight about traveling into the future via black holes and wormholes, and apart from the rather strict definition of such 'travel' entailed by time dilation effects, and the prosaic observation that we are all in fact traveling into the future at the astonishing rate of 24hours per day, we are reminded that as much as we might like it to be otherwise, the very idea of time travel, particularly to the past, is essentially incoherent. But that doesn't mean there's nothing to say about it.
James Gleick (author of 'Chaos' - the definitive book on the new science - and the equally fascinating but more niche 'Genius' about physicist Richard Feynman), takes us on an often hilarious examination of the 'history' of Time Travel: our many and so-far futile attempts to understand time itself, and our cultural notions of the seemingly natural idea of traveling 'through' it, or 'in' it, along with some of the many angles that have been explored in books, movies and philosophical writings, from H.G.Wells' socially provocative 'The Time Machine', to the fairly recent movie 'Predestination', being the screen adaptation of Robert Heinlein's controversial novella, 'All You Zombies'. (His other re-working of the same concept in 'By His Bootstraps', also mentioned, is personally recommend to anyone interested in having their brain tied in knots).
But it's the multitude of angles that Gleik himself manages to find and somehow give sense to that makes this book so entertaining.
There's a lot here and I won't bother with a comprehensive precis. But simply as (another) definitive treatment of a subject we all find tantalizing, 'Time Travel' is well worth the read.
Time Travel: A History
4 4 out of 5 stars | 672 ratings
Price: 19.69
Last update: 05-23-2024
About this item
From the acclaimed author of The Information and Chaos, a mind-bending exploration of time travel: its subversive origins, its evolution in literature and science, and its influence on our understanding of time itself.
Gleick's story begins at the turn of the 20th century, with the young H. G. Wells writing and rewriting the fantastic tale that became his first book, an international sensation: The Time Machine. A host of forces were converging to transmute the human understanding of time, some philosophical and some technological - the electric telegraph, the steam railroad, the discovery of buried civilizations, and the perfection of clocks. Gleick tracks the evolution of time travel as an idea in the culture, from Marcel Proust to Doctor Who, from Woody Allen to Jorge Luis Borges. He explores the inevitable looping paradoxes and examines the porous boundary between pulp fiction and modern physics. Finally, he delves into a temporal shift that is unsettling our own moment: the instantaneous wired world, with its all-consuming present and vanishing future.
Top reviews from the United States
M. Hoste5.0 out of 5 stars
Everything you wanted to know about Time Travel
Reviewed in the United States on December 6, 2016
John Walker4.0 out of 5 stars
Excellent survey of time travel in literature, culture, and (to a lesser extent) science
Reviewed in the United States on October 28, 2019
In 1895, a young struggling writer who earned his precarious living by writing short humorous pieces for London magazines, often published without a byline, buckled down and penned his first long work, a longish novella of some 33,000 words. When published, H. G. Wells's
The Time Machine
would not only help to found a new literary genre—science fiction, but would introduce a entirely new concept to storytelling: time travel. Many of the themes of modern fiction can be traced to the myths of antiquity, but here was something entirely new: imagining a voyage to the future to see how current trends would develop, or back into the past, perhaps not just to observe history unfold and resolve its persistent mysteries, but possibly to change the past, opening the door to paradoxes which have been the subject not only of a multitude of subsequent stories but theories and speculation by serious scientists. So new was the concept of travel through time that the phrase “time travel” first appeared in the English language only in 1914, in a reference to Wells's story.
For much of human history, there was little concept of a linear progression of time. People lived lives much the same as those of their ancestors, and expected their descendants to inhabit much the same kind of world. Their lives seemed to be governed by a series of cycles: day and night, the phases of the Moon, the seasons, planting and harvesting, and successive generations of humans, rather than the ticking of an inexorable clock. Even great disruptive events such as wars, plagues, and natural disasters seemed to recur over time, even if not on a regular, predictable schedule. This led to the philosophical view of “eternal return”, which appears in many ancient cultures and in Western philosophy from Pythagoras to Neitzsche. In mathematics, the Poincaré recurrence theorem formally demonstrated that an isolated finite system will eventually (although possibly only after a time much longer than the age of the universe), return to a given state and repeat its evolution an infinite number of times.
But nobody (except perhaps a philosopher) who had lived through the 19th century in Britain could really believe that. Over the space of a human lifetime, the world and the human condition had changed radically and seemed to be careening into a future difficult to envision. Steam power, railroads, industrialisation of manufacturing, the telegraph and telephone, electricity and the electric light, anaesthesia, antiseptics, steamships and global commerce, submarine cables and near-instantaneous international communications, had all remade the world. The idea of progress was not just an abstract concept of the Enlightenment, but something anybody could see all around them.
But progress through what? In the fin de siècle milieu that Wells inhabited, through time: a scroll of history being written continually by new ideas, inventions, creative works, and the social changes flowing from these events which changed the future in profound and often unknowable ways. The intellectual landscape was fertile for utopian ideas, many of which Wells championed. Among the intellectual élite, the fourth dimension was much in vogue, often a fourth spatial dimension but also the concept of time as a dimension comparable to those of space. This concept first appears in the work of Edgar Allan Poe in 1848, but was fully fleshed out by Wells in The Time Machine: “ ‘Clearly,’ the Time Traveller proceeded, ‘any real body must have extension in four dimensions: it must have Length, Breadth, Thickness, and—Duration.’ ” But if we can move freely through the three spatial directions (although less so in the vertical in Wells's day than the present), why cannot we also move back and forth in time, unshackling our consciousness and will from the tyranny of the timepiece just as the railroad, steamship, and telegraph had loosened the constraints of locality?
Just ten years after The Time Machine, Einstein's special theory of relativity resolved puzzles in electrodynamics and mechanics by demonstrating that time and space mixed depending upon the relative states of motion of observers. In 1908, Hermann Minkowski reformulated Einstein's theory in terms of a four dimensional space-time. He declared, “Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.” (Einstein was, initially, less than impressed with this view, calling it “überflüssige Gelehrsamkeit”: superfluous learnedness, but eventually accepted the perspective and made it central to his 1915 theory of gravitation.) But further, embedded within special relativity, was time travel—at least into the future.
According to the equations of special relativity, which have been experimentally verified as precisely as anything in science and are fundamental to the operation of everyday technologies such as the Global Positioning System, a moving observer will measure time to flow more slowly than a stationary observer. We don't observe this effect in everyday life because the phenomenon only becomes pronounced at velocities which are a substantial fraction of the speed of light, but even at the modest velocity of orbiting satellites, it cannot be neglected. Due to this effect of time dilation, if you had a space ship able to accelerate at a constant rate of one Earth gravity (people on board would experience the same gravity as they do while standing on the Earth's surface), you would be able to travel from the Earth to the Andromeda galaxy and back to Earth, a distance of around four million light years, in a time, measured by the ship's clock and your own subjective and biological perception of time, in less than six and a half years. But when you arrived back at the Earth, you'd discover that in its reference frame, more than four million years of time would have elapsed. What wonders would our descendants have accomplished in that distant future, or would they be digging for grubs with blunt sticks while living in a sustainable utopia having finally thrown off the shackles of race, class, and gender which make our present civilisation a living Hell?
This is genuine time travel into the future and, although it's far beyond our present technological capabilities, it violates no law of physics and, to a more modest yet still measurable degree, happens every time you travel in an automobile or airplane. But what about travel into the past? Travel into the future doesn't pose any potential paradoxes. It's entirely equivalent to going into hibernation and awaking after a long sleep—indeed, this is a frequently-used literary device in fiction depicting the future. Travel into the past is another thing entirely. For example, consider the grandfather paradox: suppose you have a time machine able to transport you into the past. You go back in time and kill your own grandfather (it's never the grandmother—beats me). Then who are you, and how did you come into existence in the first place? The grandfather paradox exists whenever altering an event in the past changes conditions in the future so as to be inconsistent with the alteration of that event.
Or consider the bootstrap paradox or causal loop. An elderly mathematician (say, age 39), having struggled for years and finally succeeded in proving a difficult theorem, travels back in time and provides a key hint to his twenty year old self to set him on the path to the proof—the same hint he remembers finding on his desk that morning so many years before. Where did the idea come from? In 1991, physicist David Deutsch demonstrated that a computer incorporating travel back in time (formally, a closed timelike curve) could solve NP problems in polynomial time. I wonder where he got that idea….
All of this would be academic were time travel into the past just a figment of fictioneers' imagination. This has been the view of many scientists, and the chronology protection conjecture asserts that the laws of physics conspire to prevent travel to the past which, in the words of a 1992 paper by Stephen Hawking, “makes the universe safe for historians.” But the laws of physics, as we understand them today, do not rule out travel into the past! Einstein's 1915 general theory of relativity, which so far has withstood every experimental test for over a century, admits solutions, such as the Gödel metric, discovered in 1949 by Einstein's friend and colleague Kurt Gödel, which contain closed timelike curves. In the Gödel universe, which consists of a homogeneous sea of dust particles, rotating around a centre point and with a nonzero cosmological constant, it is possible, by travelling on a closed path and never reaching or exceeding the speed of light, to return to a point in one's own past. Now, the Gödel solution is highly contrived, and there is no evidence that it describes the universe we actually inhabit, but the existence of such a solution leaves the door open that somewhere in the other exotica of general relativity such as spinning black holes, wormholes, naked singularities, or cosmic strings, there may be a loophole which allows travel into the past. If you discover one, could you please pop back and send me an E-mail about it before I finish this review?
This book is far more about the literary and cultural history of time travel than scientific explorations of its possibility and consequences. Thinking about time travel forces one to confront questions which can usually be swept under the rug: is the future ours to change, or do we inhabit a block universe where our perception of time is just a delusion as the cursor of our consciousness sweeps out a path in a space-time whose future is entirely determined by its past? If we have free will, where does it come from, when according to the laws of physics the future can be computed entirely from the past? If we can change the future, why not the past? If we changed the past, would it change the present for those living in it, or create a fork in the time line along which a different history would develop? All of these speculations are rich veins to be mined in literature and drama, and are explored here. Many technical topics are discussed only briefly, if at all, for example the Wheeler-Feynman absorber theory, which resolves a mystery in electrodynamics by positing a symmetrical solution to Maxwell's equations in which the future influences the past just as the present influences the future. Gleick doesn't go anywhere near experiments with retrocausality or the “presponse” experiments of investigators such as Dick Bierman and Dean Radin. I get it—pop culture beats woo-woo on the bestseller list.
The question of time has puzzled people for millennia. Only recently have we thought seriously about travel in time and its implications for our place in the universe. Time travel has been, and will doubtless continue to be the source of speculation and entertainment, and this book is an excellent survey of its short history as a genre of fiction and the science upon which it is founded.
For much of human history, there was little concept of a linear progression of time. People lived lives much the same as those of their ancestors, and expected their descendants to inhabit much the same kind of world. Their lives seemed to be governed by a series of cycles: day and night, the phases of the Moon, the seasons, planting and harvesting, and successive generations of humans, rather than the ticking of an inexorable clock. Even great disruptive events such as wars, plagues, and natural disasters seemed to recur over time, even if not on a regular, predictable schedule. This led to the philosophical view of “eternal return”, which appears in many ancient cultures and in Western philosophy from Pythagoras to Neitzsche. In mathematics, the Poincaré recurrence theorem formally demonstrated that an isolated finite system will eventually (although possibly only after a time much longer than the age of the universe), return to a given state and repeat its evolution an infinite number of times.
But nobody (except perhaps a philosopher) who had lived through the 19th century in Britain could really believe that. Over the space of a human lifetime, the world and the human condition had changed radically and seemed to be careening into a future difficult to envision. Steam power, railroads, industrialisation of manufacturing, the telegraph and telephone, electricity and the electric light, anaesthesia, antiseptics, steamships and global commerce, submarine cables and near-instantaneous international communications, had all remade the world. The idea of progress was not just an abstract concept of the Enlightenment, but something anybody could see all around them.
But progress through what? In the fin de siècle milieu that Wells inhabited, through time: a scroll of history being written continually by new ideas, inventions, creative works, and the social changes flowing from these events which changed the future in profound and often unknowable ways. The intellectual landscape was fertile for utopian ideas, many of which Wells championed. Among the intellectual élite, the fourth dimension was much in vogue, often a fourth spatial dimension but also the concept of time as a dimension comparable to those of space. This concept first appears in the work of Edgar Allan Poe in 1848, but was fully fleshed out by Wells in The Time Machine: “ ‘Clearly,’ the Time Traveller proceeded, ‘any real body must have extension in four dimensions: it must have Length, Breadth, Thickness, and—Duration.’ ” But if we can move freely through the three spatial directions (although less so in the vertical in Wells's day than the present), why cannot we also move back and forth in time, unshackling our consciousness and will from the tyranny of the timepiece just as the railroad, steamship, and telegraph had loosened the constraints of locality?
Just ten years after The Time Machine, Einstein's special theory of relativity resolved puzzles in electrodynamics and mechanics by demonstrating that time and space mixed depending upon the relative states of motion of observers. In 1908, Hermann Minkowski reformulated Einstein's theory in terms of a four dimensional space-time. He declared, “Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.” (Einstein was, initially, less than impressed with this view, calling it “überflüssige Gelehrsamkeit”: superfluous learnedness, but eventually accepted the perspective and made it central to his 1915 theory of gravitation.) But further, embedded within special relativity, was time travel—at least into the future.
According to the equations of special relativity, which have been experimentally verified as precisely as anything in science and are fundamental to the operation of everyday technologies such as the Global Positioning System, a moving observer will measure time to flow more slowly than a stationary observer. We don't observe this effect in everyday life because the phenomenon only becomes pronounced at velocities which are a substantial fraction of the speed of light, but even at the modest velocity of orbiting satellites, it cannot be neglected. Due to this effect of time dilation, if you had a space ship able to accelerate at a constant rate of one Earth gravity (people on board would experience the same gravity as they do while standing on the Earth's surface), you would be able to travel from the Earth to the Andromeda galaxy and back to Earth, a distance of around four million light years, in a time, measured by the ship's clock and your own subjective and biological perception of time, in less than six and a half years. But when you arrived back at the Earth, you'd discover that in its reference frame, more than four million years of time would have elapsed. What wonders would our descendants have accomplished in that distant future, or would they be digging for grubs with blunt sticks while living in a sustainable utopia having finally thrown off the shackles of race, class, and gender which make our present civilisation a living Hell?
This is genuine time travel into the future and, although it's far beyond our present technological capabilities, it violates no law of physics and, to a more modest yet still measurable degree, happens every time you travel in an automobile or airplane. But what about travel into the past? Travel into the future doesn't pose any potential paradoxes. It's entirely equivalent to going into hibernation and awaking after a long sleep—indeed, this is a frequently-used literary device in fiction depicting the future. Travel into the past is another thing entirely. For example, consider the grandfather paradox: suppose you have a time machine able to transport you into the past. You go back in time and kill your own grandfather (it's never the grandmother—beats me). Then who are you, and how did you come into existence in the first place? The grandfather paradox exists whenever altering an event in the past changes conditions in the future so as to be inconsistent with the alteration of that event.
Or consider the bootstrap paradox or causal loop. An elderly mathematician (say, age 39), having struggled for years and finally succeeded in proving a difficult theorem, travels back in time and provides a key hint to his twenty year old self to set him on the path to the proof—the same hint he remembers finding on his desk that morning so many years before. Where did the idea come from? In 1991, physicist David Deutsch demonstrated that a computer incorporating travel back in time (formally, a closed timelike curve) could solve NP problems in polynomial time. I wonder where he got that idea….
All of this would be academic were time travel into the past just a figment of fictioneers' imagination. This has been the view of many scientists, and the chronology protection conjecture asserts that the laws of physics conspire to prevent travel to the past which, in the words of a 1992 paper by Stephen Hawking, “makes the universe safe for historians.” But the laws of physics, as we understand them today, do not rule out travel into the past! Einstein's 1915 general theory of relativity, which so far has withstood every experimental test for over a century, admits solutions, such as the Gödel metric, discovered in 1949 by Einstein's friend and colleague Kurt Gödel, which contain closed timelike curves. In the Gödel universe, which consists of a homogeneous sea of dust particles, rotating around a centre point and with a nonzero cosmological constant, it is possible, by travelling on a closed path and never reaching or exceeding the speed of light, to return to a point in one's own past. Now, the Gödel solution is highly contrived, and there is no evidence that it describes the universe we actually inhabit, but the existence of such a solution leaves the door open that somewhere in the other exotica of general relativity such as spinning black holes, wormholes, naked singularities, or cosmic strings, there may be a loophole which allows travel into the past. If you discover one, could you please pop back and send me an E-mail about it before I finish this review?
This book is far more about the literary and cultural history of time travel than scientific explorations of its possibility and consequences. Thinking about time travel forces one to confront questions which can usually be swept under the rug: is the future ours to change, or do we inhabit a block universe where our perception of time is just a delusion as the cursor of our consciousness sweeps out a path in a space-time whose future is entirely determined by its past? If we have free will, where does it come from, when according to the laws of physics the future can be computed entirely from the past? If we can change the future, why not the past? If we changed the past, would it change the present for those living in it, or create a fork in the time line along which a different history would develop? All of these speculations are rich veins to be mined in literature and drama, and are explored here. Many technical topics are discussed only briefly, if at all, for example the Wheeler-Feynman absorber theory, which resolves a mystery in electrodynamics by positing a symmetrical solution to Maxwell's equations in which the future influences the past just as the present influences the future. Gleick doesn't go anywhere near experiments with retrocausality or the “presponse” experiments of investigators such as Dick Bierman and Dean Radin. I get it—pop culture beats woo-woo on the bestseller list.
The question of time has puzzled people for millennia. Only recently have we thought seriously about travel in time and its implications for our place in the universe. Time travel has been, and will doubtless continue to be the source of speculation and entertainment, and this book is an excellent survey of its short history as a genre of fiction and the science upon which it is founded.
George McCully3.0 out of 5 stars
A "Very Good Read", Undermined by Intellectual Fallacies
Reviewed in the United States on December 27, 2016
This book has been very highly commended for its rich and fascinating discussion of the difficulties of defining "time" and "time travel", and for its astonishingly erudite and broad-ranging references to the vast documentary record of thinking about these subjects.
That said, it should also be noted that this is not, as its subtitle claims, a "history" in any conventional sense. It is not organized chronologically, or in a continuous narrative, or with any particular attention to or analysis of causal relations, illuminating a continuous development of anything.
It is, rather, an unorganized series of impressionistic discussions of various issues related to its main subject. It does not lead to any conclusions explaining its subject. Rich, yes; fascinating, no doubt; immensely learned—all of these. But its lack of intellectual discipline is a serious defect.
Its greatest fallacy is to confuse "time" and "history", as if the distinction between them were of no importance. Possibly this is in part commercial—"History Travel" or any variant thereof simply would not attract readers; but I can think of no other reason to ignore this fundamental issue. Much is made of the fact that physicists describe the world and time in mathematical terms that are supposed to be constants, having no historical content--no references to "past", "present" and "future." "Time" is no longer thought of as unidirectional, as an "arrow", in which case it might be travelled, back into the past or forward into the future, with all the practical problems that might entail. "History", however, is unidirectional, which is what makes "time travel" impossible.
There are other fallacies. If "time" were defined as "duration of motion" many conceptual problems would be cleared up. If "causation" were defined as "the co-incidence of mutually conducive conditions", there would be no need to worry about whether any event has a single cause, or whether a linear "chain" of causation ever exists.
Bottom line: this book is a good read for many reasons; but clarity and intellectual rigor on a fundamentally important subject are not among them.
That said, it should also be noted that this is not, as its subtitle claims, a "history" in any conventional sense. It is not organized chronologically, or in a continuous narrative, or with any particular attention to or analysis of causal relations, illuminating a continuous development of anything.
It is, rather, an unorganized series of impressionistic discussions of various issues related to its main subject. It does not lead to any conclusions explaining its subject. Rich, yes; fascinating, no doubt; immensely learned—all of these. But its lack of intellectual discipline is a serious defect.
Its greatest fallacy is to confuse "time" and "history", as if the distinction between them were of no importance. Possibly this is in part commercial—"History Travel" or any variant thereof simply would not attract readers; but I can think of no other reason to ignore this fundamental issue. Much is made of the fact that physicists describe the world and time in mathematical terms that are supposed to be constants, having no historical content--no references to "past", "present" and "future." "Time" is no longer thought of as unidirectional, as an "arrow", in which case it might be travelled, back into the past or forward into the future, with all the practical problems that might entail. "History", however, is unidirectional, which is what makes "time travel" impossible.
There are other fallacies. If "time" were defined as "duration of motion" many conceptual problems would be cleared up. If "causation" were defined as "the co-incidence of mutually conducive conditions", there would be no need to worry about whether any event has a single cause, or whether a linear "chain" of causation ever exists.
Bottom line: this book is a good read for many reasons; but clarity and intellectual rigor on a fundamentally important subject are not among them.