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In Heroes, Hiro Nakamura, Peter Petrelli, Arthur Petrelli, Arnold, Daphne Millbrook (when supercharged) and Samuel Sullivan (when sent back in time by Arnold) had the ability to travel forwards and backwards in time, and have (to some degree) the ability to alter historical events. However, their power still obeys some underlying rules.
Temporal Mechanics Primer
Space-Time, Entropy, and the Arrow of Time
In 1905, Albert Einstein proposed a theory that unified mass, energy, motion through space, the relativity of time, and formed a new mathematical concept called spacetime. All objects in the universe move through spacial dimensions while time passes, but the rate at which time passes is relative to the velocity that you are traveling. We humans experience three dimensions on a daily basis (our frame of reference), and within our frame of reference, time "flows" at a rate of 1 second per second. Observers from a different frame of reference will see our frame moving faster or slower than theirs, but they will still measure time in their frame at 1 second per second.
Some physicists have hypothesized that time "flows" because of a property of matter called entropy defined in the Second Law of Thermodynamics. Entropy is the measurement of how energy will disperse in a given system, such that energy will always move from a higher state to a lower equilibrium state. It is proposed that the entire universe is "unwinding" from its initial high energy state (the "Big Bang") creating the dimension of "time" as the universe expands.
In physics, the mathematics behind the known laws of space-time are symmetric; in other words, the formulas are the same for an object moving forward in the time as an object moving backwards in time. Knowing an object's current position and velocity lets you determine where an object was (backwards in time) and where an object is going (forwards in time).
However, we humans do not perceive time flowing in both directions. For us, the arrow of time points "forward". We have a memory of where we have been, but no perception of what we are going to do; we can only perceive the probability of events that will occur as derived from our current conditions.
Cause and Effect
In the direction of forward flowing time, an action (cause) will have a predictable outcome (effect) according to the laws of physics, where the cause always precedes effect.
If alteration of a sequence of events (via time travel) were to occur where an effect no longer had a cause, the situation would result in a paradox. Perhaps the most common thought experiment is the grandfather paradox, where a time traveler goes back in time and inadvertently causes the death of his own grandfather (effect) before his father's conception. If his father were never born, then the traveler himself would never be born, and thus he could never go back in time, and thus never cause the death of his grandparent. If the grandfather is not dead, then he has a child, who has a child who becomes the time traveler, and the cycle loops.
The results of encountering a paradox are unknown. Science fiction writers envision temporal paradoxes having catastrophic effects, ranging from violent explosions to "winking out of existence".
Principle of Self-Consistency
It is assumed that if time-travel were possible in the future, then statistically someone is traveling into their past (our present) with the intent to change it, yet somehow, paradoxes are not being observed (in the present). The Principle of Self-Consistency states that the probability of events that result in a paradox is zero.
This essentially states that logical paradoxes that result from time traveling are self-correcting, such that a time traveler cannot alter history in such a way that would be inconsistent with the reasons for time traveling in the first place. Either the traveler is prevented from making their intended change to the past through an unexpected sequence of events, or any change made to the past was always meant to happen and is incorporated in the history of the time traveler.
The self-consistency principle is often controversial due to the implications that the time traveler has no free will while traveling in the past, yet does have free will when in the present and future.
Mechanics of Time Travel
Fixed Time Theory
In a universe with a single timeline, all events that occur at every point in history (past, present and future) must not only be self-consistent, but immutable. A time traveler moving in the past is simply acting out a role; they cannot change anything that would alter the chain of events that eventually lead to their decision to go back in time. Every action that occurs was predestined to occur.
Multiple Universe Theory
The Multiple Universe theory allows that every probable outcome of any event spawns a new universe with its own timeline, and that a time traveler simply moves up and down the timelines, taking different branches along the way. A time traveler moves from the present back in time to undo a great injustice. They succeed and return to the present, however, are they really returning to "their" present?
Contrary to the Fixed Time Theory, the Multiverser theory states that the universe's timeline acts more like a record head on a VCR; jumping forward in time allows all events in the universe to play out as if the traveler were not there, and jumping backwards "overwrites" any events that occurred in between. The theory allows for free will in every timeline, and multiple timeline rewrites are allowed to occur, but all events in every timeline adjustment must be causally self-consistent or a "time loop" will occur.
References by Episode
- Multiverser: In Don't Look Back, Hiro jumps forward in time to November 8th. When Hiro is arrested and the detectives call Japan, Ando replies he has not seen Hiro in 5 weeks. However, when Hiro returns to the past, he immediately contacts Ando, invalidating that future statement. In the future Hiro also witnesses the nuclear explosion that destroys New York and barley teleports back to his own time before it consumes him. Witnessing this event causes Hiro to become determined to change it. Also, Hiro buys issue #14 of 9th Wonders! (which hadn't come out yet in his time) which helps guide his and Ando's actions in the present. This was later regarded as Hiro, instead of time traveling, speeding up time around him.
- Multiple Universes: In Collision, Hiros and String Theory, Future Hiro travels back in time to warn Peter Petrelli to "save the cheerleader, save the world" in order to stop the explosion future by preventing Sylar from getting Claire's regeneration power so Hiro can kill him and change the future. Peter succeds in saving Claire, but the future doesn't change much, changing so Peter explodes instead, Claire is still alive and Future Sylar is impersonating Future Nathan.
- Multiverser: In Seven Minutes to Midnight, a photo of Charlie's birthday party is seen containing just Charlie. After Hiro travels to the past, Ando sees Hiro and Charlie standing in the photo.
- Fixed Time / Multiple Universes (Same Universe): In Six Months Ago, Hiro travels into the past to save Charlie. He attempts to call Ando in Tokyo, Japan, but instead gets "himself" on the phone, and quickly hangs up. Hiro is exactly where he would be (at work at Yamagato Industries) six months prior to Homecoming, long before he realized he had the ability to manipulate time.
- Fixed Time / Multiple Universes (Same Universe): In Saving Charlie, Hiro makes several trips back and forth in time in his efforts to romance Charlie and to save her. Every time he comes close to physical intimacy with Charlie, he is forcibly teleported back to where he should be at that time (i.e. his cubicle in Japan) or to someplace relevant to his destined mission (i.e. the morgue where James Walker's body is being held). Eventually, he and Charlie spend a final night together before she goes into work, knowing full well that she is going to die. Her thought processes are not described in detail, but it is suggested that she knows her fate and that she pretends not to recognize Hiro when he meets her for the first time. Hiro then waits until after he originally left to save Charlie and then "returns" to meet-up with Ando, thus catching-up with the alternative timeline.
- Paradox: Hiro travels to the past to save Charlie from being murdered, and offers a trip to Japan to Charlie. If Charlie goes with Hiro, then she will not be in the restaurant when Sylar kills her. If she is not killed, Hiro will not travel back into the past to save her. This paradox is resolved by having Hiro forcefully return to the future without saving Charlie.
- Multiverser: In Five Years Gone, Hiro travels five years into the future. Because of this, he does not stab Sylar and stop the explosion, which causes the dystopian future to occur. By going back to his present time, Hiro overwrites all the events between his time and five years later, allowing him to change the future.
- Fixed Time: In Five Years Gone, Future Hiro reveals that he traveled back in time to visit Peter to create a chain of events that would stop the explosion. However, when he returned to his own time, he found that nothing had changed; his actions had not altered the outcome of events.
- Multiple Universes: In Five Years Gone, despite Hiro traveling into the future and negating his presence for the past five years, his future self has had a marked effect on events leading from the explosion to its fifth anniversary. Also, he has no memory of any of the alterations to his past, particularly that Claire's life was saved and that he once traveled five years into the future. This seems to suggest that the dystopian future presented in Five Years Gone lies on an alternate timeline than that of present-day Hiro Nakamura.
- Paradox: Hiro's journey to feudal Japan in Four Months Later seemingly causes a paradox when Hiro finds that his actions have lead toward the destruction of a village that Kensei was meant to save.
- Fixed Time: Hiro's actions throughout the first half of Season Two and the eventual resolution of his conflict with Kensei suggest that rather than causing a paradox with his time-travel, Hiro was predestined to become the Kensei of legend.
- Paradox: Hiro is forced to abandon Yaeko, in order to prevent the paradoxes that would be caused by his absence in the present, his continued presence in feudal Japan and by the stories of Kensei ending with the real Kensei (Hiro) living happily ever after with his princess.
- Fixed Time: Hiro time travels to the day of Kaito's murder to try to change the past. He arrives hours before and attempts to convince Kaito not to stay and die, but he refuses. Hiro teleports them both to his mother's funeral to show Kaito how sad Kaito was and how sad he will be, but it's not enough. Hiro encounters his younger self and the encounter causes him to realize that he can't change this and after paying their respects to Ishi, Hiro and Kaito return to the right time where Kaito is murdered as he was meant to be. Before Kaito is killed however, Hiro freezes time to see the identity of Kaito's killer, not intervening, just observing to learn who to get justice against and learns it is Adam Monroe. (Cautionary Tales)
- Fixed Time: Hiro time travels to 1977 in order to witness Adam being locked up and find out the location of the Shanti virus. Hiro finds out the location and teleports away without interfering or his presence even being noticed. (Truth and Consequences)
- Multiple Universes: In The Second Coming, Hiro travels five months into the future and sees Ando kill a future version of Hiro, indicating that Hiro has travelled to a universe in which Hiro didn't go to the future, but instead stayed in the present during the five months. This notably differs from Hiro time-traveling in Don't Look Back in which Hiro travels into the future, but Ando reports that he has been missing in the interim.
- Multiple Universe: Peter travels to four years in the future where everyone has abilities in I Am Become Death. This future is the same future that Hiro witnessed in The Second Coming in which the formula becomes public. There, his presence causes that future to change somewhat as indicated by Usutu's paintings as his presence leads to the destruction of Costa Verde and the death of Future Daphne. While in the future, Peter also gets the power of intuitive aptitude from Future Gabriel and kills Future Nathan when he loses control of his new power before returning to the present. After his return, Peter changes the timeline by destroying the formula and killing Arthur Petrelli.
- Fixed Time: Hiro is ordered to kill Ando by Knox in order to prove himself as "bad-ass" to him so Hiro instead freezes time and teleports to a store with props. There he switches the sword Knox gave him with a fake one with a retractable tip and takes some fake blood as well. Hiro then teleports two hours into the past and sticks the fake blood into Past Ando's jacket and warns him that he will pretend to kill him in two hours and for Ando to pretend to die before returning to his own time. There he unfreezes time and stabs Ando with the fake sword. Thanks to the fake blood he planted earlier and his warning, Ando is able to fake being killed and Knox believes the deception, allowing Hiro to succesfully infiltrate Pinehearst. (Angels and Monsters, Dying of the Light)
- Paradox / Multiple Universe: In Our Father, Hiro and Claire travel to 1991. Claire's attempt to change the course of the catalyst results in it being transfered to future Hiro. If the catalyst had originally been given to baby Claire, Hiro and Claire’s history changing actions could have caused a paradox resulting in a very different future timeline. However, since only Kaito knew who the host of the catalyst was, as stated in It's Coming, it it is unknown how much the timeline would change when they return. Also, Hiro attempts to destroy the formula in the past to prevent its use in the present, but is only able to tear it in two before Kaito returns and tries to kill him before Ando and Daphne rescue Hiro using Ando's new power
- Fixed Time: Alternatively, all events in Our Father happened in the original timeline. It is implied that the formuala was in two parts in The Second Coming because Hiro split it in two in the past. Therefore, Claire was never the host of the catalyst, as she had thought, but instead it was Hiro, then Arthur. All other events of 1991, such as Claire meeting Noah, played out as they originally had.
- Multiple Universes: In Orientation and Jump, Push, Fall, Hiro's time travel and teleportation powers suddenly re-manifest themselves while he's reflecting on a carnival he visited 14 years before where getting his fortune told caused him to start on his path to being a hero and he accidentally time travels and teleports there. At the carnival in the past he takes the picture he was reflecting on for his past self and contemplates stopping himself from getting his fortune told. He decides not to, but Samuel Sullivan (refered to by Hiro as "Butterfly Man") time-travels back with the help of his friend Arnold and suggests Hiro start fixing tiny mistakes that won't cause much difference in the grand scheme of things. He demonstrates with a stack of milk jugs how one small thing won't nessacarily change a lot and shoves Hiro in front of a Slushy Ando spills on Kimiko, making her hate him. Hiro gets hit by the Slushy instead and suddenly teleports back to his office in the present. There, he learns that Kimiko never grew to hate Ando as a result of the Slushy incident and instead they fell in love that night at the carnival and not long after Hiro's return end up engaged. Besides fixing Ando and Kimiko's relationship, there doesn't seem to be any other changes to the timeline and Hiro decides to start fixing tiny mistakes he's made. With this its multiple universes and not a paradox as Hiro time-traveled by accident while reflecting and did not go back to fix Ando and Kimiko's relationship.
- Multiple Universes: In Acceptance, Hiro witnesses a former coworker, Tadashi commit suicide by jumping from the roof of Yamagto and it causes him to time travel to try to fix it. Hiro prevents him from photocopying his butt (the reason he got fired), but discovered he did it a different way and Tadashi commits suicide again. Hiro repeatedly time travels (47 times) to try to fix it, but fails as Tadashi finds 47 different ways to do the same thing. After returning from the past the last time, Hiro changes events by sitting down and talking with Tadashi before he jumps and convincing him its not worth it to kill yourself over losing a job you hate (the real reason Tadashi got himself fired so much) and to find a job he loves and do it. Hiro also admits to Tadashi that he's dying, something that only Ando knew before that and Tadashi gets off the roof and leaves. The experience also makes Hiro accept his condition and reveal it to his sister.
- Paradox / Multiple Universes: In Once Upon a Time in Texas, Hiro accidentally (he can't control his restored power completly) teleports back to Midland Texas on the day of Charlie's death and sets out to change things. He's warned by Samuel Sullivan (teleported from the future by Arnold, another time-traveler) that messing with events at that point in time can seriously change the future as so many people's destinies converged there, but Hiro goes ahead anyway but tries to preserve the future as much as possible. He saves Charlie from Sylar by stopping time, wheeling a tied-up Sylar to a bus to Odessa (he can't control his teleportation ability) and trapping him in a bus compartment. He then tells his past self that his destiny is to "save the waitress" and that the cheerleader will be fine and has him go back six months in time, thus preserving Hiro and Charlie falling in love in the past. After he informs Past Ando of what happens and tells him to wait for Past Hiro, Hiro finds that he is in Charlie's birthday picture like he should be and Charlie remembers him. However, Charlie starts to succumb to her blood clot and Hiro, remembering Sylar said he could fix it, enlists Sylar's help with a promise to tell Sylar his future if he saves Charlie. Sylar removes Charlie's blood clot with telekinesis and Hiro returns him to Odessa (after telling him he will become a powerful villan who will die alone and unmissed) where he chases after Claire, leading to the events of Homecoming, minus Charlie's power which he now never got. When Hiro teleports back to the present with Samuel, the future seems mostly un-changed, however what impact Charlie's survival had is unclear as she was meant to die and didn't, thus eliminating Hiro's reason for traveling to the past in the first place. Also, what effect Hiro's information on the future had on Sylar is also unclear, however he may have chosen to ignore what he learned and just continued on like he had before, only minus Charlie's power, however this may cause problems in events such as Road Kill. In the present, Sylar seems more hesitant to kill, not killing Samuel for his ability and empathically taking Lydia's ability rather than killing her. Lydia says that as a result of what Hiro has told him, he is afraid of dying alone now.
- Multiple Universes: Hiro manages to travel back eight weeks to get a film from Mohinder Suresh before Samuel kills him. He gets the film, but protects Mohinder with a bullet proof vest so that it only appears like Samuel killed him and keeps history on track. Hiro knew what was going to happen to Mohinder as his first teleport took him ten minutes too far and what he saw "wasn't pretty." When Mohinder then refuses to keep out of sight for eight weeks, Hiro teleports him to Florida and traps him in a mental institution there in order to keep the timeline as preserved as possible.
- Fixed Time: Hiro and Lydia time travel back eight weeks to learn the truth of Joseph's death. The two don't meddle with time, they just simply observe the course of events and learn that Samuel murdered Jospeh. Before they can be found and potentaily alter time by their presence, Hiro manages to teleport the two back to the present where they've been gone a while with their absence being noticed by the suspious Samuel (Thanksgiving).
- Multiple Universes: Arnold teleports Charlie to Milwaukee on January 26, 1944 and leaves her trapped there. Charlie starts a new life for herself in the past, working at a war factory and marrying with four children and seven grandchildren. Due to Hiro and Past Sylar's efforts, her blood clot never bothers her again and she lives a full life, but by the time she catches up to the present, she's dying again of old age. Charlie encounters Hiro in the present and reveals all of this to him and he offers to go back to that place and time and return Charlie to her own time after she arrives, but Charlie convinces Hiro to keep history as it is as she lived her life and that life and her family would never exist if he fixed this, so Hiro leaves it alone and says a final goodbye to Charlie. (Once Upon a Time in Texas, Brave New World)
|See Also: 9 • Red • Time travel|