Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Going back in time ?

  1. Apr 15, 2005 #1
    Going back in time.. ??

    Is it ok to say that humans never figure out how to go backwards in time because of the fact that we have never had a visitor from the future?
  2. jcsd
  3. Apr 15, 2005 #2
    as true as to say that you do not exist because I never saw you.
  4. Apr 15, 2005 #3
    Well, every time you think about past events or study some history, it in a sence takes you back through time, of course only in your mind and not physically(Yea this is nothing new dont mean to sound sarcastic im really not trying to be)As far as with acctually bending and manupulating the fabrics of time to be able to control time would indeed be quiet a accomplishment but theres some things in life we will never know at least not in our life span-Heres a question to go along with yours~ If time travel was possible some day are you sure the future would want the past it visits to know they were from the future so in a sence you really cant prove they have come but maybe you also couldnt prove they have not
    Last edited: Apr 15, 2005
  5. Apr 16, 2005 #4
    Mariko has a point; there would be a huge risk of changing the future and not always for the better. For example, it would be great if we could use the information we have about Hitler's whereabouts during the Second World War so we could go back, hunt hinm down and kill him. However, we have no idea what that would do to the future and what effects it would have. It seems like a good idea, but everything happens for a reason. We don't always have to like the reason.

    Attempting to return to the past involves some seriously theoretical physics. Especially since the universe exsists in 11 dimensions and we humans operate in a 4 dimensional place in it; x, y, z, and t. That would be four different types of equations alone before you could even consider combining them to possibly come up with a theory.
  6. Apr 17, 2005 #5


    User Avatar
    Gold Member

    I read somewhere (and don't know it it's true) that Churchill had an opportunity to have Hitler assassinated and decided against it. The fear was that another believer in the cause, who would be a more effective leader, might take his place and win the war.
  7. Apr 19, 2005 #6
    In Michio Kaku's book, Hyperspace, Kaku explains how changing the past, according to relativity, is not possible.

    This would mean that if you happened to go back in time with advanced technologies and the whereabouts of Hitler during WWII, you would not be able to alter the events in history, only fulfill known history. According to this conjecture, despite your greatest efforts to rid history of Hitler's wrath, you would not succeed and Hitler would live. Perhaps something happens to thwart your plans.

    Even so, you should also keep in mind that although relativity is mostly universally accurate in accordance with nature, it's still incomplete. The yet to come Theory of Everything (Grand Unified Field Theory) would provide a much better view as to whether or not time travel is even possible and what happens when you travel.


    Kaku, Michio. Hyperspace. New York: Doubleday, 1994. 238-240.
  8. Apr 19, 2005 #7
    Hmm, that's interesting I have not heard that. Even if you couldn't erase world lines just fulfill them, you might end up altering the future without knowing it. You wouldn't be erasing would lines just changing small parts. I find it rather hard to wrap my mind around not being able to change the past. According to relativity that is. If you were to go back and dilberatly do some things that you had not done, it would change the future because every action has different consequences.
  9. Apr 19, 2005 #8
    At any rate, the TOE will be able to give some more conclusive insight into the matter of time travel once it has been solved. Similar to the relativity point of view, quantum mechanics has another view on the issue:

    Meshing together the quantum standpoint of time travel (that parallel worlds result from inacting superpositions when changing the past) and the relativity standpoint of time travel (that the past cannot be changed or altered but only fulfilled) will undoubtedly give a better depiction of time travel and what it entails once both views have been successfully fused together.

    "The Physics of Time Travel"
    http://www.mkaku.org/articles/phys_time_travel.shtml [Broken]

    "The Theory of Everything"
    Last edited by a moderator: May 2, 2017
  10. Apr 19, 2005 #9
    I tend to lean closer to the quantum theory point of view rather than the relative. Its easier to stretch my brain around it.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook