An engaging but limited examination of one of the most mysterious and elusive concepts in physics—time travel.
“WHAT IS TIME?” asks James Gleick, in this history of time travel. “We know that it is imperceptible. It is immaterial. We cannot see it, hear it or touch it. Time is what clocks measure. But what is a clock? An instrument for the measurement of time. The snake swallows its tail again!” This is the kind of circular logic that the author tries to break, in this engaging foray into one of the most mysterious concept that has intrigued man since the 19th century.
Scholarly journal papers that announce new breakthroughs invariably begin with a review of past literature. Once in while, the literature review becomes bigger than any new concept that is being announced and in extreme cases, we end up with what is known as a review paper that merely surveys the subject without offering anything new. So is the case with this book. Rather than offering any new insight or even a clear exposition of any specific point of view, the author leads us through a grand tour of the various perspectives that scientists, philosophers and literary personas have explored in their efforts to put a structure around this most mysterious and elusive idea of time.
Given the breadth of subjects addressed, the depth is limited, but at least it creates a map of the terrain that the reader can explore on his own. This is the true value of the book under review.
Time as a matter of discussion entered the public domain with the HG Wells classic The Time Machine, that set the tone for a whole genre. A science fiction story set in a different era—complete with gadgets and behaviours that are dramatically different from what the author and his readers are accustomed to—is one way of travelling into the future or the past. But the real flavour of time travel is revealed when the protagonists move forward and backwards in time, into other eras or epochs. Such travel creates contradictions, like a man meeting his self in the past or the future or murdering his father and negating his existence, which forms the backbone of many interesting novels that are discussed in this book.
Authors writing about time travel usually drift into philosophical discourses on the nature of time. Is it like a river? And if it is, is the observer standing on the bank or a boat floating along with the river? Is it just the flexibility of the English language that allows us to save time, to spend time or even to waste time or do these verbs connect with certain real properties of time? These are questions that appear again and again, but answers remain elusive to the original authors, the current author and certainly to the reader. In fact, the author admits: “I doubt any phenomenon…has inspired more perplexing, convoluted and ultimately futile philosophical analysis that time travel has.”
The book becomes more interesting when it eventually moves into science. The publication of The Time Machine by Wells was nearly simultaneous with some far-reaching scientific study of time as a physical dimension that eventually culminated in Einstein’s relativity. This, paradoxically, demolished the concept of simultaneity, which forms the basis of all mechanisms to measure time. All laws of physics, except the second law of thermodynamics, are indifferent to the direction of time and in principle, should allow people to move back and forth in time as they do as in left and right, or up and down. But of course, the ability to do so comes with the paradox of going back to the past and changing the course of history and hence it is ruled out, not by science but by logic. However, Godel, the man who had upended the apple cart of mathematics with his Theorems of Incompleteness, has shown that such situations are not logically impossible and there could be physical worlds where there is no logical bar on time travel. This, along with the loss of simultaneity, leads to the concept of retro-causation where effect “precedes” cause and makes us wonder whether our language can support a discussion of such constructs.
Unfortunately, most of these deeper concepts are glossed over as the author James Gleick regales us with descriptions of time travel that appear in various literary works. These I am sure are worth reading, not to understand the concept of time, but for the sheer pleasure of reading well-written novels.