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Time travel

  1. Aug 21, 2015 #1
    I asked myself, "what did I have for breakfast tomorrow morning", my answer, " I don't know, haven't ate breakfast tomorrow yet", so, how can forward time travel be at all possible if future events have not happened yet?
  2. jcsd
  3. Aug 21, 2015 #2

    Simon Bridge

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    If you can have backwards time travel.... you can eat breakfast then travel back in time to when the question makes sense.

    Time travel involves causality violation... ergo: it is generally held to be impossible in Nature.
    However, there is nothing in our best models of space-time to absolutely rule it out.
  4. Aug 21, 2015 #3


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    I don't get what your question is. This is the science fiction forum. Are there any specific works of fiction involving time travel you have in mind? Planning the future is not equivalent to the future.
  5. Aug 22, 2015 #4
    What if time was not linear? In other words, just the act of going forward or back in time alters the time line, creating a whole new time line, or a new reality. Then there would be no violation of causality or paradoxes. Simply going forward or backward in time might irrevocably alter time like creating a new tributary to a river, or a new junction on a highway. Then you could go back in time, kill your grandfather, and continue to exist because in the new time line you created by going into the past you never would have existed in the future, and therefore there is no paradox. Or, using the question asked by the original poster, you could go forward in time one day and eat an oatmeal breakfast, then go back in time one day and know that you will have an oatmeal breakfast tomorrow, yet still be able to choose to eat something other than an oatmeal breakfast the next day. If time was not linear, then neither the past nor the future would be fixed and repeatable. Just the act of time travel would permanently alter the time line the time traveler experiences.
    Last edited: Aug 22, 2015
  6. Aug 29, 2015 #5

    Simon Bridge

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    ... this is a common SF fudge, that is correct.
    OP question remains confused because, to specify a date/time uniquiely requires specifying the timeline also. This was not done so the question is poorly posed.
    "What I had for breakfast tomorrow" referrs to tomorrows date in the other timeline.
  7. Aug 29, 2015 #6
    Yes, but the premise is still the same, how can you travel to an event that has not happened yet in any timeline? Backward time travel is only possible to the point at which the machine was built, so we build a backward time travel unit, launch it to go to the exoplanet of our choice, say it takes 10,000 years to get there, when it does it turns itself on and connects to the second unit we built in our time. Just a thought passing through the vacuum of space in my mind.
  8. Aug 30, 2015 #7

    Simon Bridge

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    This is something you'd have to account for in your story.
    Benford managed it by sending a message back to a machine that was slready built for another purpose for example, while Crichton's time travel was limited to those timelines where the time machine's receiver had bern invented earlier and Dick had time travel in a manner similar to "The Butterfly Effect". You can probably come up with your own variation... please remember which forum you are posting in.

    Dr Who style time travel involves teleportation... so the issue of getting the time machine someplace where it hadnt been invented is the same as normal teleportation... as far as the story goes, the machine is a bit of tech that you use and your question is s bit like worrying how you can get little pIctures through the air to peoples TV sets.... its something the society has solved already: lets get on with the story.

    In 4D thinking, time is another dimension of space. The time machine allows travel in time the same way we travel in space... in the "preferred history" framework, the characters do not travrl to the past, they are travelling to the future... the future in one wich looks identical to some bit of history except it has a time traveller in it.
    Last edited: Aug 30, 2015
  9. Aug 30, 2015 #8


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    You often see this statement in sci fic but I'm not aware of any actual such limitation on an actual magical device that could travel backwards in time, I think it's just another sci fic statement based in making your own rules for the magic (after all, you can't use physics rules so you might as well make up your own).
  10. Aug 30, 2015 #9


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    This topic is not appropriate here. If you wish to say it's for writing, then you need to follow the rules for that forum and post in that forum. This forum is for reviewing books and movies, not for speculation outside of our forum guidelines.

    Members (and mentors) please pay attention to which forum this is and report, not reply.
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