T is for Time travel #atozchallenge

['Chaos Clock' by jayaprime on DA]

Today I'm continuing with the Blogging from A-Z Challenge hosted by Arlee Bird and his team of awesome bloggers. My theme is: Elements and features of speculative fiction and entertainment. So throughout April I will be blogging about characters, objects and themes that appear in sci-fi, fantasy and dystopian series. Today's post is all about Time travel.

Time travel is the concept of moving between different points in time-either back into the past or forward into the future. It has been a key feature of the sci-fi and fantasy genre since the 19th century, when H.G Well's novel The Time Machine popularised the idea.

Time Machines

Wells coined the term 'time machine' and inspired many stories about vehicles allowing the user to travel purposefully and selectively through time. Here are some recent examples of time machines:

•  In Back to the Future, Doc creates a time machine from a modified 1981 DeLorean DMC-12. The vehicle uses plutonium to power a device called the 'flux capacitator' which allows the car to travel to a programmed date when it reaches 88 miles per hour. 
• Dr.Who travels in the TARDIS (Time and Relative Dimension in Space)-a vehicle that looks like a blue police box on the outside but is vastly bigger on the inside, with a spaceship-style control panel. It was invented by the Time Lords to transport people to any point in time and any place in the universe. The TARDIS possess a degree of sentience-it's implied that it has its own personality and free will. It is also unreliable and unpredictable.
• In Star Trek, the Enterprise can serve as a time machine when they use a technique called 'the slingshot effect' or the 'light-speed breakaway factor'. It involves travelling towards a star or sun at an extremely high warp speed, allowing the gravitational pull to accelerate the vessel and then breaking away, creating a whiplash effect which sends the vessel back through time. 

Altering History and Time Paradoxes

A common trope in time travel fiction is when a character changes history using knowledge or technology from their own time and creates an alternate history, either purposefully or (more usually) accidentally.

• In Back to the Future, Marty accidentally prevents his parents from meeting and jeopardizes his family's existence. He carries a photography of him and his siblings, and they begin to fade from the picture as their destinies begin to change. Marty has to try to repair the damage to history by setting his parents up to fall in love with each other before he can return to his own time.
• In Harry Potter and the Prisoner of Azkaban, Hermione and Harry use the time turner to travel back in time to save Sirius Black and Buckbeak the Hippogriff from being executed. They are able to see their past selves during various stages of the mission, and must be careful not to be seen, as Hermione warns that terrible things have happened to wizards who have messed with time travel-they might see their future selves and think they had gone mad. At one point Harry sees his past-self being overwhelmed by Dementors. For a while he does nothing, as he remembers being saved by someone who performed a Patronus Charm. Eventually when he sees that no help is coming, he realises that the figure he saw was actually his future self, and he knows he must perform the spell.
• In Stephen Fry's hilarious novel Making History, a grad student and a German physicist use a time machine to go back and prevent Hitler's conception. However, this results in them accidentally creating a dystopian world that is even worse than ours in most ways. 
• In Star Trek: The Voyage Home, the crew travel back in time to the 1960s to save a pair of (now extinct) humpbacked whales- the only creatures able to respond to a probe that's creating havoc back on Earth. During their trip, Scott and McCoy visit a factory to acquire glass thick enough to build a tank to transport the whales in. As they don't have any money, Scott exchanges the formula for 'transparent aluminium' with the manufacturer. When McCoy informs Scott that they are altering the future by giving them the forumla, the engineer responds, "Why? How do we know he didn't invent the thing?" Meanwhile, when Kirk sells his antique glasses, Spock asks him: "Excuse me, weren't those a present from Doctor McCoy?" and he replies, "And they will be again, that's the beauty of it".
• In Star Trek (2009), Spock and Nero's ships are caught in a black hole, which creates a distrubance in the space-time continuum and sends both ships into the past. Nero's ship, the Narada, ends up over 150 years in the past, where it collides with the Kelvin, the ship that Kirk's father is on. Kirk's father is killed, creating an alternative future in which Kirk grows up never knowing his father. This also causes the young Spok and the old Spok to exist in the same time period. The older Spok deliberately makes Kirk believe that there could be 'universe-destroying paradoxes' if he told younger Spok the full truth. But apparently there would not be-this was just older Spok's way of ensuring Kirk and Spok became friends.

Recommended Reads:

If you had a time machine, what past or future time period would you visit?

Sources:
http://en.wikipedia.org/wiki/Time_travel