Travel Essay, Research Paper
Exactly one hundred years ago, in 1895, H. G. Wells classic story The
Time Machine was first published in book form. As befits the subject
matter, that was the minus tenth anniversary of the first publication,
in 1905, of Albert Einstein’s special theory of relativity. It was
Einstein, as every schoolchild knows, who first described time as “the
fourth dimension” — and every schoolchild is wrong. It was actually
Wells who wrote, in The Time Machine, that “there is no difference
between Time and any of the three dimensions of Space, except that our
consciousness moves along it”.
Since the time of Wells and Einstein, there has been a continuing
literary fascination with time travel, and especially with the paradoxes
that seem to confront any genuine time traveller (something that Wells
neglected to investigate). The classic example is the so- called
“granny paradox”, where a time traveller inadvertantly causes the death
of his granny when she was a small girl, so that the traveller’s
mother, and therefore the traveller himself, were never born. In which
case, he did not go back in time to kill granny . . . and so on.
A less gruesome example was entertainingly provided by the science
fiction writer Robert Heinlein in his story By his bootstraps
(available in several Heinlein anthologies). The protagonist in the
story stumbles on a time travel device brought back to the present by
a visitor from the far future. He steals it and sets up home in a
deserted stretch of time, constantly worrying about being found by the
old man he stole the time machine from — until one day, many years
later, he realises that he is now the old man, and carefully arranges
for his younger self to “find” and “steal” the time machine. Such a
narcissistic view of time travel is taken to its logical extreme in
David Gerrold’s The Man Who Folded Himself (Random House, 1973).
Few of the writers of Dr Who have had the imagination actually to use
his time machine in this kind of way. It would, after all, make for
rather dull viewing if every time the Doctor had been confronted by a
disaster he popped into the TARDIS, went back in time and warned his
earlier self to steer clear of the looming trouble. But the implications
were thoroughly explored for a wide audience in the Back to the Future
trilogy, ramming home the point that time travel runs completely counter
to common sense. Obviously, time travel must be impossible. Only, common
sense is about as reliable a guide to science as the well known “fact”
that Einstein came up with the idea of time as the fourth dimension is
to history. Sticking with Einstein’s own theories, it is hardly common
sense that objects get both heavier and shorter the faster they move, or
that moving clocks run slow. Yet all of these predictions of relativity
theory have been born out many times in experiments, to an impressive
number of decimal places. And when you look closely at the general
theory of relativity, the best theory of time and space we have, it
turns out that there is nothing in it to forbid time travel. The theory
implies that time travel may be very difficult, to be sure; but not
impossible.