Sunday, December 28, 2003
Profiles of the Future: Time Travel
pp. 131 - 133
Mr. Clarke spends a page or so discussing why traveling back into time is extremely unlikely. I thought I would take this opportunity to address a couple of issues I have with some things he mentions as they relate to what I think is the most likely way that time travel would effect history (setting aside how we might actually do it, which I personally think is wildly unlikely; which is not a reason, as Mr. Clarke takes pains to point out earlier, for thinking that it WON'T be done).
* "To change the past involves so many paradoxes and contradictions that we are, surely, justified in regarding it as impossible."
Since he does not list out what these paradoxes and contradictions might be, I cannot claim to address all of his concerns, but I suspect he is referring to such classic paradoxes of time travel as the scenario where you travel back into time and kill your own mother before you were ever conceived.
My personal belief is a variation on one that Clarke mentions in the next paragraph. The theory he quotes essentially states that if you go back into time and change something, it will change the future. My variation (and I have no doubt it is quite common) is based on my rudimentary understanding of quantum mechanics. It is that all possible futures are happening concurrently, we just live in the most probable one. If a person were to go back into time and kill their mother before that person was born, my thinking is just that this would switch them on to a parallel time track (to use Mr. Clarke's metaphor), splitting them off of the reality that created the opportunity for his birth to begin with, while that reality continued on unaffected.
It is probable, in fact, that just the act of appearing in the past would switch you on to a different track making it impossible for you to effect the timeline from which you originated. There would be no paradoxes in this case because the world you arrived in would be different from the one that created you, instantiated by the act of your arrival. So you could kill your mother before your birth because what you were killing was a particular instantiation of your mother, different from the one that continued on unaffected in the parallel timeline from which you came.
* "Other writers have developed the theme that, even if we could change individual events in the past, the inertia of history is so enormous that it would make no difference. This you might save Lincoln from Booth's bullet - only to have another Confederate sympathizer waiting with a bomb in the foyer. And so on..."
This argument appears to impose a will on the universe. The idea that certain things MUST be done in the course of history. There seems no reason, in my opinion, why this should be true. Believing in such a thing is tantamount to believing in the existence of gods, which, as yet, there is no compelling scientific evidence for.
If you were to save Lincoln from Booth, he would likely have survived beyond merely a few more minutes or hours. It's certainly possible that others were waiting in the wings to perform should Booth fail, but I don't imagine that that was the case in most of history. Lincoln would have to die (as yet no man can escape this fate), but swatting the hand of Booth would likely have had a dramatic impact on history...though not OUR history, as I mentioned above.
* "The most convincing argument against time travel is the remarkable scarcity of time travelers...Time traveling could never be kept secret for very long; over and over again down the ages...would get into trouble and inadvertently disclose themselves."
Again, if such travelers caused our history to split, carrying them away in a copy of our history, but not in the one that generated them, we wouldn't expect to see any visitors from the future. There are some interesting ethical implications of this kind of thinking, however. If you travel back in time and you get a copy of your mother, does that make it easier to kill her if the original would live on? Would that copy necessarily be any less real than the original?