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

If time exists , why is it impossible to travel through it ?

  1. Jun 29, 2014 #1
    Forgive my ignorance, but If time exists , why is it impossible to travel through it ? From what I know, it is impossible to travel into the past, and also time dilation doesnt really make one travel into the future cause that would mean satellites would've been long gone since things cant exist both here and in the future right ?
     
  2. jcsd
  3. Jun 29, 2014 #2

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    There is a breakdown in your logic. Where does it say that "exist" must mean being able to "travel through it"? Did you just made up this rule?

    Zz.
     
  4. Jun 29, 2014 #3
    You could say I made it up ... but when we ask why cant we travel into the past wouldnt the simplest answer be "because it doesnt exist" ? Cause surely if it doesnt exist we cant travel through it.
     
  5. Jun 29, 2014 #4

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    Again, there's an issue of logic here.

    If something doesn't exist, then there's a whole list of things it can't have as properties, including "traveling in the past". So not existing is a SUFFICIENT criteria, but not existing is NOT a NECESSARY criteria for not being able to travel into the past!

    But you also need to show the validity of your logic when you reverse it. You simply cannot make a connection between the two when you haven't established the logic.

    Note that we haven't talked about the fault in the PHYSICS yet, because you decided to post this in the GD forum, not in the physics forums. I'm avoiding the physics discussion and simply pointing out the flaw in your train of thought.

    Zz.
     
  6. Jun 29, 2014 #5

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    Sure, and if walls don't exist, then we can't travel through it either. So isn't the simplest answer that walls don't exist either?
     
  7. Jun 29, 2014 #6

    phinds

    User Avatar
    Gold Member
    2016 Award

    HUH ???

    You, personally, exist in that future all the time, just not very far into it. Right now you are in the future of where you were when you started reading this sentence, so I can't imagine what you are talking about in the above
     
  8. Jun 29, 2014 #7
    I've watched a few videos that relate to time travel. Although we don't have the technology to be able to attempt such a huge topic. Since it is impossible to travel at the speed of light but we can get pretty close to it, it consists of how fast you can travel, the faster you are traveling, the slower time becomes. 1 year in real time could only be a few minutes in a vehicle that's almost the speed of light. (although it is only a theory, it does seem to make sense for me).
     
  9. Jun 29, 2014 #8

    phinds

    User Avatar
    Gold Member
    2016 Award

    You speak of "real time" as though that were some absolute thing. It is not. The amount of time that passes in the spaceship is exactly as real as the amount of time that passes on the planet from which the space ship originated. The only SEEMING disparity is that if the space ship turns around and comes back, the person on the space ship will be younger than a person on the planet who was the same age when the traveler left.

    That does NOT happen because either of their times are more "real" than the other, it happens because they have taken different paths through space-time. In this sense, it is possible to travel into the "future" of a person on a planet. I put "future" in quotes because it's NOT the future of the traveler when they meet up and it isn't really the future of the planet either, to the people on the planet, there's just a difference in aging because of different paths through space-time
     
  10. Jun 29, 2014 #9
    I was wrestling with my sister years ago and made her partially travel through a wall.
    It's not just some idea that works mathematically, it's demonstrable.
    Couldn't we consider real time the time experienced by someone standing perfectly still within the universe? Since we're moving through space on our planet, in our solar system, in our galaxy, etc... and someone else may be moving on their planet, solar system, and galaxy at a different speed, then time would be elapsing at different rates for us, right? Is there a way to determine how much slower our time is elapsing than the time experienced by a stationary object in space?
     
  11. Jun 29, 2014 #10
    I'm pretty sure you cant interact with something that doesnt exist.
     
  12. Jun 29, 2014 #11
    If you travel into the past or the future, that means you traveled there, you are there, therefore you arent here in the present anymore.
     
  13. Jun 29, 2014 #12

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    There is no stationary object in space. So it is impossible to stand perfectly still within the universe. The theory of relativity implies that movement is relative and not absolute. So the notions of "standing still" and "moving" are only with respect to a certain observer. They are relative notions, not absolute notions. Everybody will be moving with respect to some observer, while everybody is standing still with respect to himself. Neither the observer nor you is to be prefered.

    This has as curious consequence that the earth is not revolving around the sun, it is only doing so in certain reference frames (such as the frame of the sun). In the reference frame of the earth, the sun is revolving around the earth. Both reference frames are acceptable.
     
  14. Jun 29, 2014 #13

    ZapperZ

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    Please note that all of this is moot if you cannot defend the logical inconsistencies or errors in your original premise.

    People often get lost or too involved in the tail end of the argument without investigating properly the STARTING POINT or the starting premise. If the starting premise is false, then to use the theme of this thread, the rest of your reasoning and argument really doesn't really exist to be debated.

    Zz.
     
    Last edited: Jun 29, 2014
  15. Jun 29, 2014 #14
    You're always traveling into the future at a rate of 1 second per second. I guess that means there is no present, because the moment you identify the present, it's already the past. But you had to exist in the past for you to make the decision to identify the present. So even if the past doesn't exist anymore, it had to exist at some point.
    What if, for example, you were floating in space with absolutely zero matter or energy anywhere else in the universe, can we say you're moving?
    Now I want to see an animation of our solar system moving from the perspective of Earth being a stationary reference frame. That would look funny. The other planets would still be revolving around the sun, but the sun would be revolving around the Earth.
     
    Last edited: Jun 29, 2014
  16. Jun 29, 2014 #15

    micromass

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2016 Award

    There is matter and energy in the universe, so I don't know why your example should be relevant to our universe.

    Well, you live in such a reference frame. But anyway, you can do this with celestia: http://www.shatters.net/celestia/
     
  17. Jun 29, 2014 #16
    Does this not depend on the reliability of the definition of impossible, a lot of things at some time or other have been described as impossible only to turn out to be possible.
    So time exists but we have not found a way yet to travel into the past or future and at sometime in the future this will be proved.
     
  18. Jun 30, 2014 #17

    WWGD

    User Avatar
    Science Advisor
    Gold Member

    IMHO, informal discussions of this sort can be helpful towards understanding things better, but if you want a specific, clear answer, you need to start defining your terms and assumptions carefully, or you risk losing your time in compounded misunderstandings. Unfortunately, there is a tradeoff between the flexibility of informal language and its being inaccurate, and the rigor and precision of formal logic that lacks in flexibility.

    I mean, there is definitely a place to experiment and speculate, in order to explore and understand things better, and, once you can pinpoint the issues more clearly, you try to pin things down using more precise language and making assumptions clear. But it is useful to know which of the two you're trying to do, to avoid jumping back-and-forth between the two.
     
    Last edited: Jun 30, 2014
  19. Jun 30, 2014 #18

    lisab

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    We frequently get challenges to our policy of not discussing philosophy here. It's because we are focused on our mission: to promote understanding of mainstream science, and to help students do well in their studies. We've said it many times: before you can be truly skilled at thinking outside of the box, you must learn how to think razor-sharp inside the box.

    Also, because inevitably it turns into intellectual mush.
     
  20. Jul 1, 2014 #19
    Many many years ago I had a professor who simplified the time travel dilemma. OK so perhaps he oversimplified it. He compared time travel to Jello. Yep Jello. When it is first mixed we can move through it, we can even swim through it, but when it sets up it is not possible.

    The professor's profound belief was that some day, some way, someone would find out how to bring time back into that liquid fluid state, or that we would find an entrance into a place where time is always in the liquid state.

    In some vague mysterious way I still think that he was on to something. Are we scientifically knocking on the door of that entrance? Could it simply be in a place where have never even looked because it didn't fit any theory?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: If time exists , why is it impossible to travel through it ?
Loading...