If you are a scientist and you send someone back in time to try and alter history, what happens to the people left behind in that present? For my first blog I want to discuss these questions and the philosophy of time travel, using as reference two real instances of time travel, Marty McFly in back to the future part 2, and Arnie in The Terminator.
Ok these are not real instances, but they do pose real questions as to how time travel would work if it were ever created. In Terminator someone gets sent back in time, and in Back to the future 2 someone gets sent forward in time. I'm going to discuss traveling forward in time first.
Firstly let me assure you that I am completely unqualified to speak with any morsel of conviction about time travel, all I bring to the table is 9 GCSE's 3 A levels and a degree in Sport Science (which is more complicated than you might think) (trust me). I have however seen a lot of films like: The Time Machine, 12 Monkeys, Time Cop, the new Star Trek, as well as all the Back To The Future's and Terminator Films, plus Lost and Quantum Leap on tv so I'm not completely ignorant to the complicated process of time travel. Anyway...
In Back to the future 2, Marty McFly is told by Doc Brown that his future self is in trouble, and bad things will happen if they don't intervene. They get into the Delorean and zip to 2015, where there seems to be a late 1980's revival going on, jackets have hair dryers built in, miniature pizzas are 're-hydrated' in seconds to full size ones, and people wear their clothes inside out. Anyway Marty and Doc go to Hilldale where future Marty lives, and Marty from 1985 spies on his future self. Surely this is impossible???
No not the rehydrating pizzas, the traveling forward in time and seeing yourself part! If Marty traveled in time in 1985, then when he got to 2015, if he tried to find himself then anyone who knew him in the past would say, "Yeah I knew Marty McFly, he vanished in 1985 and noone ever saw him again, say you look a lot like him!" Because if Marty sets off time traveling in 1985 to 2015 , then he no longer exists in the 30 years between 1985 and 2015. So he can't get to 2015 and find another Marty McFly wearing a twin tie thing and getting fired by fax, UNLESS he:
A. in 1985 simultaneously time travelled forwards 30 years and left another identical version of himself in the present to carry on living his life, so when he got to 2015 he could see how the other identical Marty McFly had turned out, OR
B. he time traveled to a parallel universe, which is where everything starts getting complicated. Later in the film he goes back to 1985 and its not the original 1985 and everything is different, his mum has huge tits and is married to Biff, AHHH! But in the end everything gets put back to normal (until Doc ends up in 1885!)
If there were such a thing as parallel universes, then I don't think you could jump between them, if you have a problem with the past and you send someone back to try and fix it, (like in Terminator) would you ever see the effect? or would you be stuck in your present, while the time traveler creates a new past (and new future). Here's the scenario:
2029, Cyberdine Systems have lost the war against the humans, and as a last ditch attempt they send Arnold Schwarzenegger back to 1984 to try and kill Sarah Connor before she gives birth to John Connor who eventually grows to lead the humans against the machines (and lighting technicians!). So after Arnie has gone back in time, the other terminators will be standing around, and lets say that Arnie did manage to kill Sarah Connor before Michael Biehn got there (if she was higher up in the phone book) so John Connor never gets born, would the terminators in 2029 seconds after Arnie had stripped down to his naked suit and vanished, suddenly in a flash forget all about John Connor because he never existed, and would they suddenly not even be standing in the time travel area because they never had to go there in the first place because they have won the war against the humans. Would all that just happen in a second, or ..... would nothing happen, and they just go on as normal, loosing to the humans, because John Connor has already existed and done the damage, and what has happened has happened? I think that if Arnie had killed Sarah Connor in 1984, then the time line would split at the exact moment that Sarah Connor is killed, and the future would head in another direction. It would not be a future where Terminators would loose the war against the humans and have to send Arnold back in time. Therefore those terminators would never see the results of Arnie's success and to them, whether Arnie is successful in terminating Sarah Connor or not, their future will continue on its original course.
So if this is true then it is theoretically impossible to change the past, you can only create new time lines. If a person is sent back in time, you cannot send him back to 1955 then look up wikipedia and search "1955 man arrives from future" and suddenly find it there, because that would mean that in the seconds after the person has gone back in time, everyone on the planet and all the records everywhere are suddenly updated in a flash, then everyone remembers the man arriving from the future in 1955....
In closing, I have come to the conclusion that time travel is very complicated and there are many different things that could happen if someone were to go forwards or backwards in time. There is only one film where it shows someone time traveling and I though, yeah that looks possible. The Time Machine (the remake not the original.) Basically Guy Pearce gets into the time machine in the 19th century, and stays static in time while everything ages around him. So he is basically in suspended animation like on Red Dwarf. There is no complicated mechanisms to travel through time, only a mechanism to stop time penetrating the forcefield which Guy Pearce is sitting in, so he doesn't age a second but the world goes on around him and when he feels like he has gone far enough forward he stops the machine and time starts for him again, and its 800,000 years in the future (and Samantha Mumba somehow still has a career!). If we could create a device that stops time affecting a person, like a suspended animation booth, then people could travel forward in time, but not back obviously. This type of machine would be very useful in deep space travel when it takes ages to get anywhere (or in flights to Australia which also take forever.)
