Time Travel in Harry Potter and the Prisoner of Azkaban

Harry Potter and the Prisoner of Azkhaban has an example of time travel through a device called a Time Turner. While the entire plot of the film is a little too much to explore, the basic gist of the use of time travel is that the character Sirius Black gets captured and taken to prison while the main characters are powerless at the time to stop it due to being injured by creatures named ‘dementors’. As such, they wake in hospital and are prompted by the headmaster to time travel with the warning that they should avoid running into their past selves. This leads to a whole range of interesting scenarios in which noises or events that went unexplained in the first aspect of the film are explained by the time traveler’s presence. The first of these is that a Griffin that was seemingly executed was in fact saved by the future versions of the main characters, with the executioner instead smashing a pumpkin with his axe in frustration, rather than the Griffin’s neck. The second is that the past versions of the main characters are saved by a mysterious stranger that turns out to be a future version of one of the main characters. Furthermore, the character Hermione uses the time turner device throughout the film in order to attend two conflicting classes at the same external time.

Harry and Hermione use the time turner image

Overall, the movie is consistent with Lewis account of time travel in that the main, external time, remains the same (Lewis 1976, pp. 146-148). While the time travellers cause the past, the past was also always that way and as such it is consistent in the Lewis sense of time travel (Dowe 2000, p. 444). All the actions that the time travellers take, such as saving the griffin, always had happened and it was ignorance that prevented them from realizing. This applies also to Harry saving himself, as the future Harry simply did not realize until he did it that it was himself that saved his past self. As a further interesting note, the main characters had already saved Sirius Black when Dumbledore told them to go and save him. It was only in their personal time lines that they did not realize they had; an all knowing bystander would have known they had already done so.

Harry Potter attempts to undermine the double occupancy problem by suggesting that double occupancy that occurs in a paradoxical manner will simply violate the boundary conditions of the universe and hence it is alluded to that some sort of strange, and likely destructive, common place solution will come about (Grey 1999, pp. 60-62). Interestingly, Hermione uses double occupancy to attend multiple conflicting classes at once by attending a class, then travelling backwards in time to attend the conflicting class.

Hermione, the Time Turner and Classes

Hermione uses the time turner device to travel back in time and attend classes that conflict with other classes on ther timetable. This idea is fine in a Lewis-based conception of time as there are simply two versions of Hermione in the external time, but only one in Hermione’s personal time. This double occupancy also inherently resolves itself as the first Hermione will disappear when she travels back to attend the second class. As such, any witnessing bystander would see two versions of Hermione, with one destined to disappear as she traveled back in time to be the second.

The movie skips the problem of what would happen to the time travelers as they are traveling backwards in time by having them disappear when they begin to travel, allowing those in the same room to walk through them. It thus seems that the problem of what time travelers are in the external time is resolved by simply having them ephemeral and near non-existent.

Reference:

Dowe, Phil 2000, ‘The Case for Time Travel’, Philosophy, vol. 75, no. 293, pp. 441-451.
Grey, William 1999, ‘Troubles with Time Travel’, Philosophy vol. 74, no. 287, pp. 55-70.
Lewis, David 1976, ‘The Paradoxes of Time Travel’, American Philosophical Quarterly, vol. 13, no.2, pp. 145-152.

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