Note: this is another older piece of writing (I’m transfering some stuff across from an old blog), but interesting thinking nonetheless. Be warned! It’s quite long.
I actually got thinking about this concept after re-watching the Stargate SG1 episode 1969, when I got rather annoyed about the obvious problem in a discussion between the team about the so-called “grandfather paradox.”
So, it’s a widely accepted theory that there is a paradoxical clause in the theory of travelling backwards in time, in order to change an event or occasion. This is because, theoretically, if the person attempting to change something was successful, then in their future the event would be changed, and thus the person would never have intended to go back in time and change it.
One major flaw in the grandfather paradox; sure, if you only apply it specifically to the act of going back in time to kill one of your own direct ancestors, than yes, you would not be born, so you would not go back in time to change it, so that person would not be killed by you, etc. However, if you apply the concept more broadly, then there arises the issue of whether direct intended action/intervention in a particular activity (eg. World War II) would only affect that, or would affect numerous other things; history would be changed completely. Again, there arises the argument that if, for example, WWII were effectively prevented, in the future the person would not travel back in time to prevent it.
What about if you went back in time to try and change occurrence X, and didn’t manage to change that, but instead inadvertantly changed some other major aspect of history, occurrence Y. If that hadn’t been your intent, then the changed future resulting from the change to occurrence Y would not affect your desire to go back in time to change occurrence X. By the same token, changing occurrence Y could have such major ramifications that you never exist. The grandfather paradox is a rather simplistic view of the complications of time travel.
Also, does this paradox only apply to backwards? What if someone were to travel forwards in time and change something? Again, if the intention to change something was not the driving force behind this change, theoretically it is possibly to inadvertently change history. The bad thing there being that you cannot go back in time to deliberately change a particular thing that you want changed. I guess as far as forwards time travel (assuming you subscribe to the linear model of time/space relations, which I don’t), it’s all a matter of how much you believe in pre-destined fate. Or perhaps not.
Let’s say that Person A lives in England in the year 3000AD. And Person B lives in the year 3000BC. If Person B could somehow transport to the year 1066, and prevent the William the Conqueror from taking control and introducing the feudal system, how would that apply to Person A? If time travel were to be possible, then time would have to be non-linear (even with the possibility of light speed travel, that covers distance, not time, and wormholes would not likely allow for time travel), which means that that change (preventing the introduction of the feudal system) would have to occur across every instance of time, instantaneously, rather than the change gradually evolving to create a new “true” history across the linear span of time. This leaves us with a problem; if all instances of time occur at once, there arises a new paradox, whereby Person B could not change the occurrence, because at the exact instance they do, it’s already done, so there is nothing to change. Alternately, this could be seen as the formation of a parallel universe.
My theory is that all time and all space exist at once and in the exact same place, because neither really exists in the first place. So arguing what’s at the end of the universe, or what occurs outside that exact instant in which all time occurs is immaterial, because they are all encompassing and at the same time to not exist. They are everything in their nothingness. In relation to parallel universes, I believe that they are formed at each possible choice in the entire universe. So for every possibility, there are a million others, creating an infinite number of parallel universes.
So, going back to the grandfather paradox, if one went back in time and killed their own grandfather, then they would simply create more parallel universes based on that action. They aren’t really changing history, per se, more like creating multiple alternate possibilities, which would all manifest as parallel universes. Of course, this brings up this issue of whether the aspects of Person X which exist simultaneously in Parallel Universe A, Parallel Universe B, Parallel Universe C, etc, are all individually consciously aware, or are in fact all just aspects of one consciousness, which is segmented. Or perhaps there are several, and it depends on how large the divergence between the universes is. This is a possible explanation of deja vu. So, if it is only a single individual sentient consciousness per universe, then yes, that person has changed history, as far as they are aware.
However, if one is going to rely on the theory of the creation of parallel universes as a result of changes made to the human construct of linear time, then you have to take into consideration, you also have to consider the possiblity that that means it is impossible to change the past linear history within any given parallel universe. If a new universe is created for the possibility of every divergence, then that means the instant you make that change, you enter into the parallel universe of that particular divergence. The history in the universe you left remains exactly the same. In which case, do dopplegangers become an issue? Intruiging.
If the theory of the above paragraph holds true though, one would have to consider all occurrences, people and events as unmeasured entities, or abstract concepts, or else the entire thing is in defiance of quantum theory, which states that when an unmeasured entity singularises, it has only one probably outcome. Unless each parallel universe is created not as an alternative to a possibility, but as a creation resulting from the different process by which any given entity has become singularised. After all, quantum theory does state that everything exists as an infinite composition of possibilities. Which makes sense, because the measure of an entity results in singularising its number of probable states to achieve a single outcome; so there are infinite possibilities, and thus the possibility of the creation of infinite parallel universes.
And just now, having browsed some sites discussing the grandfather paradox, it seems I’m not the only one who thinks that it’s a misconception regarding the nature of causality. Except that, being something like 15 at the time I originally wrote this, I didn’t express it quite so eloquently. 😛