Things Ain’t What They Used To Be

Guardians of Time Poul Anderson

Policing the past in Poul Anderson’s classic tales. This edition published by Pan Books 1964. Cover art by W F Phillipps.

The ‘butterfly effect’, a term coined by the mathematician Edward Lorenz in describing chaos theory, suggests that small causes can result in large effects.  Sometimes a seemingly minor event in history can have a wide-ranging effect on what follows thereafter.  So time travel into the past, should such a thing ever be possible, stands the risk of making significant changes to the present as we know it.  We discuss this intriguing subject in the latest edition of Odyssey, which has just been issued.

Michael Crichton’s 1999 science fiction novel Timeline describes a group of people travelling back to medieval France.  The author makes clear his view that time travel itself is impossible, but applies the ideas of quantum physics to suggest that alternate universes exist, and travelling into those universes can have much the same effect as travelling into our own past.  Indeed, the exploits of his adventurers who have been transported into the fourteenth century have consequences, albeit in a small way in the overall scheme of things, for their own present day.

It’s inevitable that any alteration to our past must change the way things happen afterwards, so we must assume that any travel back in time would need to be subject to exceptionally careful precautions to prevent unwelcome effects.  Yet Ray Bradbury’s 1952 short story A Sound of Thunder shows how even the most cautious protection against disrupting the timeline may fail – and then the present, once one returns to it, would never be the same again.

The answer may well be to have a form of time police to supervise the process of time travel and deal with infringements (or, more likely these days, some governmental Office of Time Management to lay down the rules and monitor compliance).  Poul Anderson’s Time Patrol stories, collected in Guardians of Time published in 1961 and which we touch on in Odyssey, envisage precisely this.  The Patrol has been “set up to police the time lanes”, preventing unwelcome changes or establishing “counteracting influences in later periods which will swing history back to the desired track.”

But the Patrol assumes the opposite to the ‘butterfly effect’.  As is explained in Brave to be a King, whilst repairing the history of the ancient Persian Empire, “except at the crucial points, time always reverts to its own shape.”  Only at key instants do “the effects multiply with passing time”.  Hence Patrolmen seem to adopt a fairly cavalier approach to the results of their actions on the future.

In The City on the Edge of Forever, a popular 1967 episode of the original Star Trek television series, history is altered when McCoy travels back in time and unwittingly causes Nazi Germany to win the Second World War.  The starship Enterprise, and the entire United Federation of Planets, cease to exist.  But Kirk and Spock know the past as it should have been, and can take steps to put it right.

And there’s the problem.  If the past changes, the “present” that we experience now would change in every respect to adapt to the new version of the past.  Our memories of everything that has ever occurred to us, along with every book, computerised record and each piece of evidence about our past, will reflect history as it now is, not as it was before the change.  We cannot know any different.

Changes might be occurring all the time but we wouldn’t know it.  You and I might be absolutely certain that, as things stand now, we know everything about our past.  But it might not have been the same “past” as it was even a few minutes ago.  It’s the same sort of argument as the paradox suggested (probably not too seriously) by the philosopher Bertrand Russell in his 1921 book The Analysis of Mind – we can’t actually prove that the entire world didn’t come into existence a few minutes ago, full of people remembering a wholly illusory past.  That’s surely going too far, though.

Richard Hayes, Assistant Editor (Odyssey)

With a lifetime’s interest in science, history and human behaviour, Richard Hayes focuses his writing on how the imagination has created the world in which we live, and where it may lead us in the future.  Odyssey, the e-magazine of the British Interplanetary Society, draws on the rich treasury of science fiction to explore many fields of speculation, enabling us to glimpse what might yet be, both here on Earth and out amongst the stars.

For related Odyssey posts, please click here: Meeting Yourself Coming Backwards| Talking to the Past


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