This is just a short post. I am, as many know, constantly engaging the philosophical issues surrounding our philosophies of time. Now, I think it is clear that on an A theory of time time travel is just metaphysically impossible. However, on a B theory of time, it is logically possible. Up to very recently I had always imagined a very tidy explanation for ‘B-theory Time-travel’ effects. Simply put, if you go back in time to stop yourself from being born, then you were already ‘there’ when you were being born, trying to stop yourself from being born. In other words, you know you ‘will’ fail, because you know that you are here, and the only mystery remains: how you failed. This raises similar problems to Newcomb’s paradox in which we might imagine being faced with an omniscient being and asking her something like: “what name will I write on this piece of paper?” If they answer ‘Julia’ then why can’t I, who have free will, set out to write the name ‘Spencer’ instead? If I do, then the omniscient being was wrong, but that’s not possible because the being is omniscient. When faced with these kinds of problems, philosophers can simply say that if I went to write ‘Spencer’ my hand would somehow slip and I would write ‘Julia’ by accident. Or perhaps I was so tired (or drunk, or some combination of the two) that I heard the name Julia, thought to myself I wanted to write anything but that name, and then somehow wrote the only name that came to mind without realizing it: Julia.
Either way, all of this assumes that the world is uniform from past to future in such a way that the world of the past has the same identity as the world of the future: it simply ‘is’ the same world, and the difference is simply ‘relational’.
An interesting thought. In 2000 there was somebody who showed up on online forums claiming that he had come from the future: John Titor. Although dismissed by most, he was also not ignored by many. He managed to play his role convincingly until eventually disappearing from the internet. He had some predictions about things, most of which were vague (there is one prediction about another world war in 2015, and one world-wide corporation controlling a monopoly on time-travel machines in 2036 – the year he claimed to come from). Now, of course, this is hardly believable, but people who became enamored with him and his story, and couldn’t shake how seemingly informed he was about the physics involved in time travel, took him seriously. He had suggested that going back in time wasn’t in the most literal sense going to ‘change’ the future, but rather, for every ‘contingent’ event, where things could have turned out one way or another, there were ‘branches’ of universes in which those respective possibilities would be expressed. In this way he had argued that going back in time too far would actually placed you in a different universe-time, such that if you went back 2000 years to meet Christ, you might end up in a world where he was never born – maybe even when the Jews never existed at all. (Theologically this would be impossible on a Christian view of the world, but this is just an example).
So that in traveling back in time, you could in one sense set in motion a causal chain of events leading to a radically new ‘future’ – a new way the world might be. Now, of course, this makes the real Titor’s story less believable, since he was trying to change the future so that his world would be different, and then go back to 2036, back to his family. If he could get back to his time-plane I wonder what difference he really could have made, and if all possible universes exist anyways then I wonder why he felt the need to be the causal agency to a better but ultimately unrelated universe to his own.
However, I have been asking myself the question “is the Titor-scenario logically possible” where not only are there really different universes in which different events happened and different histories exist, but they run parallel to ours. Infinitely many universes, a presumably infinite subset of which include universes where ‘I’ exist differently. I have always previously dismissed this as confused thinking for the sake of science fiction. However, now that I stare this absurd idea in the face, I cannot see how to demonstrate its inconsistency. If it were logically impossible then even if world war three was coming in 2015 it wouldn’t make Titor’s story more plausible (though thank goodness there are still some predictions to talk about which project beyond 2012). I cannot see, though, how to demonstrate its falsity. However, to punch a hole in the science-fiction fiction narratives out there, I would like to point out that going ‘back’ in time to change the future wouldn’t actually change anything in the ‘real worlds’ but rather only change in what world you continue to experience yourself – though I wonder what the world that originally contained you would look like the moment after you ‘went back in time’. Would your body disappear? Maybe people usually imagine that time travel involves the whole body. A fun science-fiction (time travel) show I was watching recently suggested that it might be easier to send things like text messages and ‘minds’ or ‘mental states’ backwards in time to an alternate world-plane… as a final thought, I wonder if Time travel is even possible from a Catholic perspective without stipulating that the body must itself be transposed from one ‘time’ to another ‘time’. Also, given the influence of St. Augustine’s philosophy and theology of time as expressed in his ‘the City of God’ I wonder if entertaining such a ‘Titor-scenario’ can really be taken seriously by a Catholic Theologian.
I suspect not.