Time travel is a recurring theme and part of the mythology on Lost. First hinted in the season 2 episode, "", the Island constantly moves, and by using an ancient wheel underneath the Orchid, the electromagnetic power on the Island allows the inhabitants to travel through time. Other cases feature the risks of time travel, which often end with death, due to the inability to find a constant.
FARADAY: The Island... Think of the Island like a record spinning on a turntable... only now, that record is skipping. Whatever Ben Linus did down at the Orchid station... I think... it may have... dislodged us.
Physical travel of both time and space
Confirmed non-human cases
When Sayid, Frank and Desmond leave the Island in "第4季 第5集", they and those on the island experience events in a different sequence, implying electromagnetic signals and a corpse travel through time. On the island, the Losties pull the body of the ship's doctor out of the water one morning. That evening, they contact the freighter by Morse code. On the freighter, Omar receives the Morse code message during the day, but the doctor's throat was slit at night and was thrown off the freighter at night.
In the Orchid orientation film, Dr. Edgar Halliwax talked of a how the Island's properties allow the DHARMA Initiative "to conduct unique experiments of both space and time". He placed rabbit number 15 inside a device he called the "vault", which was constructed adjacent to "negatively charged exotic matter". He explained how the rabbit would travel 100ms ahead of four dimensional space - three consisting of space and one of time. Template:Crossref
Another example was when Ben successfully moved the island. He accomplished this by placing metallic objects inside a chamber in the Orchid, something the orientation film had warned against, and blowing a hole through the wall of the chamber. This allowed him to access the frozen wheel. Template:Crossref
Confirmed human cases
When Ben turned the frozen wheel December 31, 2004, Template:Crossref he found himself in the Sahara Desert 10 months later on October 24, 2005. Template:Crossref The result of the wheel being turned was that the survivors remaining on the Island randomly traveled through time until Locke put the wheel back on its axis, as he too flashed to the exit in the Sahara Desert; in his case, emerging three years later in 2007. Template:Crossref
When the survivors left behind after Ben's wheel turning experienced a time travel change, there was a blinding purple flash (similar to when the Hatch imploded). After Locke fixed the wheel, there was one last flash, but this time the flash was bright white, rather than purple. In all instances, the travelers experienced severe head pain, most likely caused by the extremely loud noise occurring during the flashes.
People who weren't affected by the time travel appeared to be unaware of the blinding flash and loud noise. For example, Danielle didn't react to or mention the noise or light before Jin disappeared, and when he reappeared in her future, she thought Jin was sick because he disappeared Template:Crossref. Ethan also did not react to the noise or light when it began, but kept the gun aimed level at Locke, and said "Goodbye, John Locke" Template:Crossref. Desmond may have been the sole exception, as he appeared to react to both the noise and flash moments before Daniel disappeared in front of him. Template:Crossref
Time travel of the consciousness
JULIET: So, what, is this amnesia?
Confirmed non-human cases
Faraday demonstrated to Desmond that he could transport a rat's consciousness forward in time. He did that by using a machine of his own design which emitted an unknown radiation, set to 2.342 and oscillating at eleven hertz. Once exposed, the rat was able to move directly from one end of a maze to another. Faraday explained that he was not going teach the rat to run the maze for another hour. Later, however, the rat died of what Faraday said was likely a brain aneurysm. Template:Crossref
Confirmed human cases
Neither Desmond or Minkowski were in contact with the machine prior to moving through time; however it was implied that their proximity to the Island caused their temporal displacement to happen and that moving at a specified bearing when approaching or leaving the Island would avoid the phenomena.
Desmond's consciousness randomly travelled through time between December 24, 2004 and an unknown date in 1996. Faraday stressed that for a mind to survive the continued transitions of temporal displacement, and to make it stop, it needs to find a "constant", or anchor, to focus on. This constant must be something that means a great deal to the person, and it has to be present in both time periods. For his constant, Desmond chose Penny.
In his journal, Daniel noted that if things should go wrong, Desmond would be his constant. Minkowski did not survive the temporal displacement (presumably because he lacked a constant); he went into convulsions and died. Before he died, however, and during his convulsions, he stated his inability to "get back". Faraday implied this would happen; more precisely, he told Desmond that the travel would become increasingly chaotic and he'd be unable to tell which time was which. He'd also eventually find it increasingly difficult to "jump back" until it was impossible.Template:Crossref
Similarities and differences to flashbacks and flash-forwards
Unlike flashbacks and flashforwards, where a person's past or future experiences (relative to the current narrative) are shown, the person is conscious of their actions and surroundings and is aware of the fact that he or she is being/has been moved through time and/or space. They suffer from disorientation and confusion due to being unable to confirm to which time they belong. The transition on screen is sharp and comes without warning, as opposed to flashbacks which are smooth, have a signature sound, and sometimes allow sound to leak in from the past. They both are representations of a character's past and have exclusively taken place on or near the island. It has been neither confirmed nor denied that flashbacks are purely a literary device or not. Similarly, after using the fail safe key, Desmond suffers from a series of flashes which were disordered, unlike flashforwards which are shown in a linear fashion.
Temporal paradoxes and the rules of time travel
We really do not have time for me to try to explain. You have no idea how difficult that would be, for me to try to explain this--this phenomenon to a quantum physicist.
The linear view of time is when people see time as travelling in a straight line, so what has happened is in the past, the present is now, and the future, untouched, hasn’t happened yet, rendering it subject to change. One of the biggest challenges of time travel storytelling is presenting the non-linear view of time travel without creating a temporal paradox.
A temporal paradox is a "paradoxical situation in which a time traveler causes, through actions in the past, the exclusion of the possibility of the time travel that allowed those actions to be taken". One such temporal paradox is known as the Grandfather Paradox. This paradox relates to the questions raised if a time traveller killed his own grandfather before the traveller's father was fathered. Would the traveller cease to exist? And if the traveller did cease to exist, then who killed the grandfather?
Desmond had flashes of Charlie's death, and attempted to intervene; however, after each successful attempt, Desmond received a new flash, an alternate version of Charlie's death. The fact that Desmond succeeded at all in saving Charlie proved that details could be changed, but that the end result remained inevitable: Charlie had to die. Template:Crossref
Daniel Faraday, who spent his "his entire adult life studying space time" later stated that "You cannot change anything; you can't. Even if you tried to, it wouldn't work... whatever happened, happened". Template:Crossref The corresponding theory is the Novikov self-consistency principle or conjecture.
Sawyer expressed deep frustration, misery, and anger at these rules, and their inability to change events. When Sawyer believed Kate, Aaron, Sun, Jin, Jack, Desmond, Sayid, and Hurley died on the freighter, he furiously pounded on the Swan door to try and prove events could be changed, before relinquishing.
The time travelling of Desmond's consciousness between 1996 and 2004 led him to visit Faraday at Oxford. Template:Crossref Eight years later, Desmond visited Oxford once more while searching for Faraday's mother. Template:Crossref Faraday originally had no memory of that first meeting. While this could lead to a paradox where the individual would have conflicting memories, one with a meeting and one without, it was implied that Faraday's apparent memory loss from overexposure to radiation solved the paradox.Template:Cite It may also be part of the course correction of which Ms. Hawking spoke.
Theoretical models addressing paradoxes
Eternalism is a philosophy of the time that sees the flow of time as a property of our subjective experience rather than as an objective fact about time itself. In Eternalism, the events that happen in the course of time are fixed. Past, present, and future are ways of talking about what comes earlier than, simulataneous with, and later than the time of utterance. It is generally accepted among philosophers that Eternalism is the philosophy of time that fits best with Special Relativity (which implies that my second may take longer than your second), because Special Relativity precludes the possibility of an absolute present independent of any frame of reference. In the Block Universe what is happening is what happened.
- In a Block Universe, the sum of all the matter and energy in the universe must be static. Although it sounds like an obstacle, it actually permits Time Travel to occur. In a linear universe, a period with multiple Sawyers (the child James Ford and DI's James LaFleur) creates a void in one era and an overflow in another. In the Block Universe, there is always only one Sawyer even though his appearance may age and change. The potential for paradox is resolved because paradox is an error in perception, not an error in physics. The Block Universe precludes the possibility of changing the past, which is what generates temporal paradoxes in most time travel fiction.
Presentism is another philosophy of time that eliminates the potential of paradoxes. Time is perpetually in the moment. For the Eternalist, Past, Present, and Future are nothing more than Before and After. For the Presentist, Before and After have objective status that cannot be reduced to Before and After. There is an objective fact about which time is Now. In fact, Now is the only existent time. Presentism means there is no past or future to travel to. Paradoxes are removed because time travel is removed.
Physical effects of time travel
The effects of time travel on the traveller seem to be similar whether the travel is physical, or where just the consciousness travels. In both cases, temporal displacement causes nose bleeds, headaches, forgetfulness, and in the worst cases, death by apparent brain aneurysm. However, the severity of the effects appears to differ from person to person.
In some cases, traveling through time physically seems to cause temporal displacement of the human consciousness. This was the case with Charlotte, who first experience nose bleeds, headaches, and some minor memory loss, but eventually died when the flashes were too frequent and close together. Template:Crossref
Physical time travel is not necessary for temporal displacement to occur. Time travel of the consciousness can also cause the traveller to experience the same symptoms and eventual demise, as in the case of Minkowski and Daniel's rat. The finding of a constant, as Desmond did, nullifies the temporal displacement and its effect, allowing the traveller to survive. Template:Crossref
Proximity to pockets of electromagnetic energy appear to intensify the effects, where people near or on the Island experienced severe symptoms very quickly and some died, while the effects for Theresa appear to differ. Theresa is still alive after an extended, but undisclosed length of time, though she is experiencing temporal displacement like Charlotte experienced. Template:Crossref
During a time shift the traveler will only take those things with him that are physically attached to him (clothing, handcuffs et cetera).
Though Lost does not feature any alternate realities on equal footing with the original timeline, the show suggested the possibility of alternate realities caused by time travel during Season 5, and the flash sideways segments in Season 6 initially appeared to take place in such an alternate reality.
The concept of the butterfly effect holds that a minor change in circumstances of the past causes a large change in outcome of the future, thus causing an alternate reality. However, Daniel explains to Jack and Kate that a little pebble won't change the flow of a waterstream, but a big boulder will do the trick. He thinks that detonating the Jughead at the Swan site will change the course of history, negating the Island's electromagnetic energy and preventing the crash of Oceanic Flight 815. Template:Crossref
Most of Season 6 featured the flash sideways narrative device, depicting what appeared to be an alternate timeline in which Oceanic 815 never crashed. However, in the series finale, Christian Shephard reveals that all the characters in the flash-sideways have died, and that the flash-sideways world is a world they created together so they could find each other after death and prepare to move on. Template:Crossref Thus, it appears that Daniel was incorrect about their ability to make a change to the timeline by detonating the Jughead. The atomic blast was part of the Incident in the original timeline, and whatever happened did indeed happen.
Dr. Pierre Chang's transmission was sent forward 30 years into his future through a pinhole he was attempting to keep open. Dr. Chang informed viewers that he and many of his colleagues would be dead, killed in a kind of violent purge which he was "powerless to escape". Chang gave details anachronistic to his time, information he gathered from a source he calls credible. He stressed the importance of reconstituting the DHARMA Initiative and continuing his research, and then pleaded for help in changing the past and saving those who would be killed, before the transmission was shut off.
- a commercial for Mr. Cluck's Chicken Shack, featuring a lucky Hurley
- a commercial depicting Oceanic Airlines with a perfect safety record
- a fragment of America's Most Wanted, featuring Kate still on the run
These examples, released between Season 5 and 6, are related to the version of events we see in the flash-sideways timeline, and, like early episodes of Season 6, misled many viewers into believing the flash-sideways represented an alternate reality created by Jughead.