An ontological paradox is a paradox of time travel that questions the existence and creation of information and objects that travel in time. It is very closely related to the predestination paradox and usually occurs at the same time.
Because of the possibility of influencing the past while time traveling, one way of explaining why history does not change is by saying that whatever has happened was meant to happen. A time traveler attempting to alter the past in this model, intentionally or not, would only be fulfilling his role in creating history, not changing it. The Novikov self-consistency principle proposes that contradictory causal loops cannot form, but that consistent ones can.
However, a scenario can occur where items or information are passed from the future to the past, which then become the same items or information that are subsequently passed back. This not only creates a loop, but a situation where these items have no discernible origin. Physical items are even more problematic than pieces of information, since they should ordinarily age and increase in entropy according to the Second law of thermodynamics. But if they age by any nonzero amount at each cycle, they cannot be the same item to be sent back in time, creating a contradiction.
The paradox raises the ontological questions of where, when and by whom the items were created or the information derived. Time loop logic operates on similar principles, sending the solutions to computation problems back in time to be checked for correctness without ever being computed “originally.”
Examples in film and television:
In the film Somewhere in Time based on the Richard Matheson novel Bid Time Return , Christopher Reeve’s character is given a pocket watch by an old lady. He then goes back in time and gives the pocket watch to the old lady’s younger self, played by Jane Seymour, which prompts her to seek him out years in the future and give him the watch, resulting in the watch having no apparent origin.
In Back to the Future, Marty McFly steps in for the guitarist at his parent’s school dance and plays Chuck Berry’s “Johnny B. Goode”, an oldie from when Marty hails (1985), but non existent in 1955. Marvin Berry, the band’s guitarist, calls his cousin Chuck and tells him that he found the “new sound” Chuck was looking for. In the same film, after the dance and the Johnny B. Goode performance, Marty says goodbye to his 1950s parents who have just had their first kiss. After he leaves, his mother absentmindedly says, “Marty – such a nice name…” implying that he inspired her to name her future son Marty.
In the 2008 television miniseries The Andromeda Strain, the aforementioned disease is sent back in time via a wormhole by the citizens of future Earth, who cannot stop the disease because a required bacterium has gone extinct and only exists in the past. Scientists in the past manage to utilize this bacteria and kill the virus, but a single sample is saved and stored in the International Space Station at the series’ end. It can be speculated that this sample is the cause of a viral outbreak on the future Earth, causing its citizens to once again send the virus back and hope that it can be destroyed in the past. This creates a further paradox due to the fact that Andromeda seems to have no origin and only exists in the past because it was sent from the future, whose citizens kept a sample from the past and then sent it back again, creating a never-ending loop.
