Doc knows he will invent time machine 30 years ahead and it doesnt change the future
In Back to the Future, Doc invented time machine in 1985 and he was really excited and little surprised that it worked. But later in movie, Marty goes back and tells young Doc about it.
Why was Doc so surprised about it, when he knew he is inventing it in 1985 since 1955?
But more serious question, when he knew it since 1955, wouldn't this knowledge change the date of first time travel (Make it sooner, because he had lots of information from the future, or even make it later, because he "knew" he will invent so he could stop trying)?
Or why he didn't change the place of meeting with Marty, to prevent attack from Libyans (any events in past could change that moment, when Marty escaped only because the gun has jammed). Is it because he do not want to ruin time-space-continuum?
I know this is not one specific question, more few confused questions, but I hope you understand what is blurry about this movie for me.
Best Answer
Technically, in 1955, Doc Brown didn't invent time travel, he got the idea for the flux capacitor "which makes time travel possible." Doc Brown would first need to actually build a flux capacitor, and then he would need to work out how to use it to build a time machine. Just knowing that something is possible or that it will work, does not tell you how to actually make it work.
As to the rest of your question, there are many different theories of time travel and how it can affect the time line. One of the areas of contention (for which we do not have an answer) is the overall stability of the time line. Some theories say that even a minute change will cause a magnified ripple effect of larger and larger side effects - this is commonly known as the butterfly effect. At the opposite end of the spectrum, some science fiction folks speculate that a time stream is inherently stable and events and circumstances will tend to stay, as closely as possible, to what they were originally. Some theories even hold that the time stream will constantly work to repair itself and, eventually, only the largest and most significant changes will have any lasting effects.
It seems that, for Back to the Future, the theory of time travel in operation is more towards the stable time-line end of the continuum, though definitely not self-repairing. For the most part, things will tend to be very much like they were before the changes introduced by Marty's time traveling. As a result, the completion of the time machine, and the first trip will end up on the same day and in the same place, and probably not as a result of any conscious decision by Doc Brown.
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What year did Doc warn Marty not to go to?
Doc only insisted Marty not to come back because he was happy. This was not a warning about any specific year... it was just a warning to not go rescue him from the past where he was. There was nothing special or bad about 1885; that just happens to be the year where Doc was.Does Doc remember Marty?
2) The 1955 Doc suffered a memory loss sometime after his adventures with Marty (maybe it was from the drugs he took in the 60's as Reverend Jim!). 3) Doc actually did remember everything, but he still did all the same things he "remembered" because he didn't want to risk disrupting the space-time continuum.Why did Doc Brown invent time?
On November 5, 1955, Doc Brown came up with the idea for the flux capacitor after slipping and bumping his head while standing on his toilet to hang a clock. The idea came to him in a vision he had after being knocked out. This device would be the key towards making time travel possible.1.21 Gigawatts - Back to the Future (6/10) Movie CLIP (1985) HD
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Answer 2
Back to the Future does not seem to operate on a "stable time loop" theory, which is the idea that changes made to the past will always have happened, so the events in the future must lead up to it. The simplest way to see this is the name of the shopping mall. At the start of the movie it's called 'Twin Pines', but during the course of BTTF1 one of the pines is knocked down. When they go back to the future, the mall is now called 'Lone Pine'.
As such, Doc Brown being told of the flux capacitor in 1955 didn't effect 1985 until the precise moment Marty told him about it, which changed history.
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