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Time travel through film |
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Author Guy Micklethwait, whose PhD thesis is entitled: Models of Time: a comparative study using film. |
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Poster from the classic film, The Time Machine, originally starring Rod Taylor, and re-made in 2002 with Guy Pearce.
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Filmmakers have been using ideas about time, time travel and other temporal phenomena as plot devices for years, but how likely is it that these scenarios will one day become a reality? And if we do find ways of travelling through time, what consequences might we face? These are tricky questions, but first we need to consider the physics of time travel.
Einstein's Special Theory of Relativity argues for the existence of a four-dimensional 'space-time continuum'. This is made up of the three dimensions of space: width, breadth and depth. We can see and touch all of these things. The fourth dimension is time, which we cannot see or touch, but whose passing we can experience. A physicist would say that we are experiencing ourselves passing through the dimension of time.
These four dimensions all relate to a constant. So, for example, the faster a rocket moves through the three dimensions of space, the slower it moves through the dimension of time. This means that the rocket's on-board clock is ticking more slowly than a clock back on earth - a concept known as 'time dilation'. When the rocket returns, less time will have passed for its passengers, so they will have aged less than the people back on earth. In the extreme case, they may return to the earth's distant future, as in Planet of the Apes (1968).
Forward time travel may be possible, but backwards time travel is a little trickier.
Scientists have speculated that, if space can be curved enough, a wormhole could be constructed to shortcut from one side of the universe to the other. If one of the mouths of the wormhole was made to travel very fast compared to the other one, then there would be a time difference between the two. Passing through the hole one way would allow you to move forward in time, and passing back the other way would allow you to move backwards in time.
However, you would never be able to travel back to any date prior to the construction of the wormhole. Such a wormhole occurs naturally in Donnie Darko (2001), where a jet engine falls off a plane and then passes through a space-time anomaly, which causes it to travel back 20 days before crash landing.
If you were able to curve space, what would happen if you curved it right around to the point where you made a loop? This happened to the character Phil Connors in Groundhog Day (1993), who kept waking up each morning to find he had returned to the start of the previous day.
One of the most famous temporal paradoxes thrown up by backwards time travel is the 'Grandfather Paradox' used as a plotline in Back to the Future (1980) where Marty McFly goes back in a time machine and meets his parents before they were married. His presence causes his mother to fall in love with him and reject his father. Marty fears this will prevent his birth, so spends the rest of the film trying to get his parents back together again.
If you were to travel back in time and send your grandfather to an untimely grave, there is a possibility your own timeline would continue unharmed. In 1955, the physicist Hugh Everett III suggested that when we measure quantum objects the world actually splits into two parallel realities.
An example of parallel worlds is seen in the movie Sliding Doors (1998) which follows two parallel lives that branch out from each other after a brief time reversal.
What if you go back in time and your actions cause an event that later becomes the reason why you originally went back in time? This would mean that you would be predestined to go back in time in order to create a self-consistent timeline. This is known as the 'Predestination Paradox' and is used in the plotline of The Terminator (1984) when a man is sent back from the future to protect Sarah Conner, the mother of his comrade, John. He gets her pregnant and thus becomes John's father. Therefore John is predestined to send him back in time so that he can be born and keep the timeline self-consistent.
In the mid-1980s, Dr Igor Novikov developed the Novikov Self-Consistency Conjecture, which stated that, if time travel were possible, there must be a law of physics that would prevent time travellers from doing any action that would cause an inconsistency and hence a paradox. This can be seen in Terminator 3 - Rise of the Machines (2003). No matter what they do, the protagonists can't stop the inevitable rise of the machines. The war has to take place for the robots to be sent back in time and for Sarah Conner to give birth to her son.
Forward time travel is a reality. However, backwards remains speculative. But just as one day people dreamed of a rocket reaching the moon...
This is an edited extract of an article that first appeared in ScienceWise, the magazine of the Australian National University (ANU). Guy Micklethwait is writing up his PhD thesis, Models of Time: a comparative study using film jointly at Centre for the Public Awareness of Science and the Research School of Physics and Engineering at ANU.
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Some of our best-loved movies involve concepts of time and time travel. Among the most engaging and provocative are the following classics:
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1960's The Time Machine (AKA H.G. Wells' The Time Machine), staring Rod Taylor, is about a man from Victorian England who travels into the fourth dimension and finds that humanity has divided into two hostile species. It was re-made it 2002, featuring Australia's Guy Pearce.
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Adapted from sci-fi writer, Kurt Vonnegut's book of the same name, Slaughterhouse Five (1972) is the story of Billy Pilgrim who becomes "unstuck in time" and experiences life along a fixed timeline, but in a seemingly random order.
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In 12 Monkeys (1995), director Terry Gilliam tells the story of convict James Cole (Bruce Willis) who volunteers to go into the future (2035) to gather information in exchange for his release.
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Frequency (2000) is about changing the present by communicating with people in the past, and tells the story of father and son, Frank and John Sullivan.
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In the film, The Butterfly Effect (2004), Ashton Kutcher goes back in time and makes a few changes at a critical point in his childhood, which causes his original timeline to disappear and a new timeline to form from that point onwards.
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Déjà Vu (2006) features Denzel Washington as special agent, Douglas Carlin, who travels back in time to prevent a domestic terrorist attack that takes place in New Orleans.
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