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A predestination paradox (also called
causal loop, causality loop, and
(less frequently) closed loop or closed time loop) is a paradox of time travel that is
often used as a convention in science fiction. It exists when a time
traveller is caught in a loop of events that "predestines" or
"predates" them to travel back in 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
must happen. A time traveler attempting to alter the past in this
model, intentionally or not, would only be fulfilling their role in
creating history as we know it, not changing it. Or that the
time-traveler's personal knowledge of history already includes
their future travels to their own experience of the past.
In layman's terms, it means this: the time traveller is in the
past, which means they were in the past before. Therefore,
their presence is vital to the future, and they do something that
causes the future to occur in the same way that their knowledge of
the future has already happened. It is very closely related to the
ontological paradox and usually
occurs at the same time.
The predestination paradox is controversial because it seemingly
negates the "common
sense" notion that we are responsible for our own destinies,
and, with adequate knowledge and preparation, we can alter their
courses. The predestination paradox says the exact opposite,
leaving doubt in believers' minds if they really are independent,
or just puppets on
strings.
Examples
A dual example of a predestination paradox is depicted in the
classic Ancient Greek play 'Oedipus':
Laius hears a prophecy that his son will kill him and marry
his wife. Fearing the prophecy, Laius pierces Oedipus' feet and
leaves him out to die, but a herdsman finds him and takes him away
from Thebes. Oedipus, not knowing he was adopted, leaves home in
fear of the same prophecy that he would kill his father and marry
his mother. Laius, meanwhile, ventures out to find a solution to
the Sphinx's riddle. As prophesied, Oedipus crossed paths with a
wealthy man leading to a fight in which Oedipus slays him.
Unbeknownst to Oedipus the man is Laius. Oedipus then defeats the
Sphinx by solving a mysterious riddle to become king. He marries
the widow queen Jocasta not knowing she is his mother.
A typical example of a predestination paradox (used in The Twilight
Zone episode "No Time Like the Past") is as
follows:
A man travels back in time to discover the cause of a famous
fire. While in the building where the fire started, he accidentally
knocks over a kerosene lantern and causes a fire, the same fire
that would inspire him, years later, to travel back in
time.
A variation on the predestination paradoxes which involves
information, rather than objects, traveling through time is similar
to the self-fulfilling prophecy:
A man receives information about his own future, telling him
that he will die from a heart attack. He resolves to get fit so as
to avoid that fate, but in doing so overexerts himself, causing him
to suffer the heart attack that kills him.
Here is a peculiar example from Barry Dainton's Time and
Space:
Many years from now, a transgalactic civilization has
discovered time travel. A deep-thinking temporal engineer wonders
what would happen if a time machine were sent back to the
singularity from which the big bang emerged. His calculations yield
an interesting result: the singularity would be destabilized,
producing an explosion resembling the big bang. Needless to
say, a time machine was quickly sent on its way.[1]
A final example is:
A man is hunting when someone shoots him. Surviving, he
resolves to go back in time to stop the sniper. Appearing at the
place of the incident, he sees someone approaching, and shoots the
man, believing the man is the sniper. Later, he realises that the
man he shot was a past version of himself, and so he was both the
sniper and the victim.
In all five examples, causality is turned on its head, as the
flanking events are both causes and effects of each other, and this
is where the paradox lies. In the second example, the person would
not have traveled back in time but for the fire that he or she
caused by traveling back in time. Similarly, in the third example,
the man would not have overexerted himself but for the future
information he receives.
In The Big Loop the Big Bang owes its causation to the temporal engineers.
Interestingly enough, it seems the engineers could have chosen not
to send the time machine back (after all, they knew what the result
would be), thereby failing to cause the Big Bang. But the Big Bang
failing to happen is obviously impossible because the universe
does exist, so perhaps in the situation where the engineers decide
not to send a time machine to the Big Bang's singularity, some
other cause will turn out to have been responsible.
In most examples of the predestination paradox, the person
travels back in time and ends up fulfilling their role in an event
that has already occurred. In a self-fulfilling prophecy, the
person is fulfilling their role in an event that has yet
to occur, and it is usually information that travels in time (for
example, in the form of a prophecy) rather than a person. In either
situation, the attempts to avert the course of past or future
history both fail.
Examples
from fiction
Time
travel
Many fictional works have dealt with various circumstances that
can logically arise from time travel, usually dealing with
paradoxes. The predestination paradox is a common literary device
in such fiction.
- In The Twilight Zone 2002-2003
revival, there is an episode in which a character (played by Katherine
Heigl) goes back in time to assassinate Adolf Hitler while he
is a baby. She kills the baby (whom she presumes to be actual Adolf
Hitler), but the nanny (discovering the death) replaces the baby
with a street gypsy's baby, and she presents this baby to the
father as his own. The father proceeds to introduce this son to his
guests as "Adolf", presumably the Adolf Hitler known to history in
the first place.
- In the Spongebob Squarepants episode "SB-129", Squidward
inadvertently creates the sport of jellyfishing while in the past,
which is the reason he ended up in the freezer, for if the sport
had not been invented, the chain of events would have not happened.
This is another example of a causal loop.
- In television, the episode "Roswell That Ends Well" of the
animated television series Futurama puts a more humorous spin on the
paradox. In the episode, the main characters are thrown back in
time to Roswell, New Mexico, in 1947,
sparking the Roswell UFO Incident. Meanwhile,
Philip J. Fry,
told that the death of his grandfather Enos would nullify his own
existence, becomes obsessed with protecting the man. To this end,
he shuts Enos in a deserted house in the middle of the desert in
order to protect him, failing to realize that the house is in fact
on a nuclear testing site. The resulting atomic test kills Enos,
but Fry does not disappear. Fry later comforts Enos' fiancée, no
longer believing her to be his future grandmother. He has sex with
her, only to realize afterward (thanks to the Professor) that she
was/will be his grandmother after all because Fry has just made her
pregnant, making him his own grandfather. Meanwhile it is also
revealed that the UFO that landed in Roswell was actually Bender the robot, and the alien they found
was Dr. Zoidberg.
- The video game Prince of Persia: Warrior Within, the
second in the Prince of Persia trilogy, centers heavily
around predestination paradoxes. In the game, the Prince is being
chased by the Dahaka, a being whose purpose is to
preserve the timeline by erasing the Prince from it. Unable to
fight the monster, the Prince travels to the Island of Time in
order to kill the Empress of Time, who created the
time-manipulating sands from the first game. In doing so, he hopes
to prevent the sands from being created, since it was the existence
of the sands that put him in his current predicament. However, the
Prince realizes too late that killing the Empress is what creates
the sands, and hence he becomes the architect of his own fate. A
secondary paradox is the Sand Wraith, who seems to stalk the Prince
throughout the first half of the game, even trying to kill him at
one point. The wraith is killed by the Dahaka shortly before the
Prince kills the Empress. After killing the Empress, the Prince
realizes that he can change his fate by using the Mask of the
Wraith, which transforms him into the Sand Wraith and sends him
back in time a short distance. He learns that the wraith (who he
now understands to be his future self) was trying to protect him,
rather than attack him. Upon reaching the point at which the Dahaka
is supposed to kill him, the Prince uses his knowledge of the
encounter to have his younger self die instead, ending the mask's
power and creating a grandfather paradox as well.
- The film Donnie Darko incorporates an example
of fictional predestination paradox. Donnie avoids death by a jet
engine that appears out of nowhere, only to later, because of
information he has learned since, send the engine back in time
himself so that he may die by it. He thereby negates all activity
that occurred between the appearance of the engine and him sending
it back, including his learning of the reason that he must die.
This is explained through use of a tangent universe and a physical
and temporal theory.
- In Harry Potter and The Prisoner of
Azkaban, Harry is saved from the dementors by a stag
patronus. At that time, he thought it was his dead father's spirit
of some sort watching over him (his father's Animagus form is a
stag). After traveling back in time, he realizes he was the one who
produced the patronus- after watching himself being attacked and
seeing that no one had produced the stag patronus- he himself casts
the spell, producing the stag patronus he had seen earlier.
Similarly, in the film,
Harry and his friends are alerted to the presence of the Minister
for Magic when a rock hits Harry in the head; but after traveling
back in time, Hermione recognizes the same rock and throws it at
Harry herself. Note that, had this rock not been thrown by her in
the first place, she wouldn't have recognized it later on, and
wouldn't have known to throw it. Also, after throwing the rock,
Hermione hears a strange snapping sound coming from behind her.
When they travel back in time, Hermione accidentally steps on a
twig and breaks it when trying to inspect her hair from the
back.
- In the Legacy of Kain video game series,
more specifically Soul Reaver, Soul Reaver 2, and Defiance, the
predestination is evident in the Soul Reaver as well as Raziel,
whose soul is contained inside. Through the storyline of the 3
games it is learned that Raziel's soul must become part of the
Reaver, despite the fact that it has been a part of the weapon the
whole time. Defiance ends in Raziel being stabbed by the Reaver,
allowing his soul to be transferred to it, however because of the
purification his soul had gone through earlier the cycle is broken
rather than beginning again.
Dr.
Miles Bennett Dyson examines the right arm
of the first Terminator in
Terminator 2: Judgment
Day.
- In the Terminator films, Skynet, a
computer program that controls nearly the whole world in the
future, sends a machine to the past in order to kill John Connor, the future
leader of the human resistance, at different points of his life:
once before he is conceived (by killing his mother, Sarah Connor), again when he
is 13 years old (in Terminator 2: Judgment Day) and a
final time a few days before Judgment Day happens
(Terminator 3: Rise of the Machines). In the second movie
Dr. Dyson (Joe Morton), the lead scientist for the
Skynet project, explains that the surviving arm and CPU chip of the
original Terminator was analyzed and found that the technology was
so advanced, they (humans) would have never invented the technology
themselves and was used to create Skynet in the first place. In the
final movie, the humans, who have successfully invaded the complex
in which the time machine is placed and have finally defeated the
machines, always manage to send someone else to the past so that
the Connors can be protected, which is what starts the series. In
The Terminator, the machines send the T-800 and the humans send Kyle Reese: the first
will give the people in the past the necessary components that will
end up starting the Skynet project, and Kyle will be John Connor's
father (that is, if the time travel hadn't happened then Skynet
wouldn't have been created and John Connor wouldn't have been
born). In (Terminator 3: Rise of the Machines) the TX
terminator injects nano-probes into the primitive T1 -suggesting
that her advanced technology is partly responsible for the
terminators of the future. It is interesting to note that it does
not occur to any of the main characters that the war cannot be
stopped for one obvious reason: there are Terminators in their time
period. The chronological series of events are: Terminator
components found in 1984 leads to Skynet; Skynet starts the war;
after the war Skynet begins to exterminate the human race; the
resistance forms; Skynet knows the war is lost and develops
time-travel; various Terminators are sent back in time to kill
Sarah, John etc. The existence of Terminators in our time means the
war happened in the future.
- In the episode He's Our You of the television series
Lost, several characters travel
back into the 1970s. One of them, Sayid Jarrah, encounters the younger
version of Benjamin Linus, the leader of the Others,
and a man who has committed various acts such as betraying the
Dharma Initiative and causing their complete genocide by the
Others, the manipulation and deceit towards various people on the
show and caused much strife to Sayid personally including
recruiting him to become an assassin during his wife's funeral.
When Sayid meets Ben's younger version he believes that it is his
destiny to kill him and prevent all of the bad things he does from
ever happening. However when he does this by shooting him, Ben is
taken to the Others where they state that they could heal him in a
mysterious temple but, "his innocence would be lost" and he would
"always be one of them." By trying to prevent Ben from doing the
things he did, Sayid actually caused him to become the evil
manipulator that he is and caused all of the evil acts he
committed.
- In Artemis Fowl: The Time Paradox, Artemis's mother contracts
the deadly magical disease, Spelltropy. To save his mother, he
travels into the past to save the Silky Sifaka lemur, which he kills at age
10 by handing to the Extinctionists. In the past, Artemis the elder
meets Opal Koboi, who follows Artemis into the future. In the
present, Opal gives Artemis's mother Spelltropy-like symptoms,
which causes Artemis to time-travel in the first place.
- In the 2008 episode of Doctor Who: The
Doctor's Daughter, the TARDIS takes the Doctor, Donna, and
Martha to find the source of the Doctor's Daughter's signal.
However, the TARDIS arrives early, which leads the Doctor to the
accidental creation of his daughter, thus activating the
signal.
- In Red vs Blue when the character Church is
thrown back in time in Episode 50, he tries to prevent certain
things from happening, in the process leading to everything
becoming the way it was: kicking dirt on a switch hoping it to be
replaced, instead it was kept and later got stuck; giving his
captain antibiotics to prevent a heart attack, but killing him
because the captain is allergic to aspirin; trying to make the tank
not kill him by disabling the friendly-fire protocol, which later
proves his death; telling the tank and robot that they should not
leave and build a robot army, thereby giving them the idea to do
it; trying to shoot O'Malley with the rocket launcher only to shoot
Tucker because of the launcher's highly defective targeting
system.
- In the video game Fallout the player character is
cast out of their home to find a replacement water chip. In the
sequel in a random event called The Guardian of Forever the player
character enters the vault shortly before the events of Fallout 1
and breaks the water chip.
Prophecies
Prior to the use of time travel as a plot device, the self-fulfilling prophecy
variant was more common.
Shakespeare's Macbeth is a classic example of this. The
three Weird Sisters give Macbeth a prophecy that he will eventually
become king, but the offspring of his best friend will rule after
him. Macbeth kills his king and his friend Banquo. In addition to these prophecies, other
prophecies foretelling his downfall are given, such as that he will
not be attacked until a forest moves to his castle, and that no man
ever born of a woman can kill him. In the end, fate is what drives
the House of Macbeth mad and ultimately kills them, as Macbeth is
killed by a man who was never 'born' as the man was torn from his
mother's womb by cesarian
section.
In the Philip
K. Dick short story "The Minority Report", murders are
prevented through the efforts of three psychic mutants who can see crimes
before they are committed. When police chief John Anderton is
implicated in a murder-to-be, he sets out on a crusade to figure
out why he would kill a man he has yet to meet. Many of the
signposts on his journey to meet fate were predicted exactly as
they occur, and his search leads him inexorably to the scene of the
crime, where he cannot stop himself from killing the other man. In
the end, the prediction itself is what had set the chain of events
in motion.
In Lost, Desmond Hume's future flashes regarding Charlie's deaths
eventually lead to his death. Desmond has a vision in which Charlie
pushes a button below a flashing light which allows the other
castaways to be rescued just before he drowns. However when the
event occurs, events happen slightly differently than in Desmond's
vision and it is suggested that Charlie may have been able to save
himself without jeopardizing the hopes of rescue, if he had not
believed his death was crucial in the rescue of the other
castaways.
Yet there are examples of prophecies that happen slowly, if at
all. In Red Dwarf:
Stasis
Leak, when Lister
travels back in time to meet with Kochanski to marry her, he finds
out from his future self from 5 years later that he is going to
pass through a wormhole and end up in a parallel universe version
of Earth in 1985 but after 8 whole series, this has never
happened (although similar events happen in Backwards).
References
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