change in past = change in future

Discussion in 'Physics & Math' started by Jagdwuf, Jun 19, 2001.

  1. Jagdwuf Registered Member

    I know I may be posting some dumb founed topics, but I am only 15 and Im just now trying to get into the scientific world. Now for my question....

    Base on what is certain,

    If someone was to come back from the future to your time, or, if you went back to the past to someone else time. Would events that take place alter your present?


    I have to be politicly correct about this though cause I may be a pshyco......?????? (extreme sarcasm)

    I go back in time and get rid of my grandma. I then jump back to the present day.

    What would the effects have on my life now?

    Would it alter my timeline, or would my journey back create a seperate alternate timeline where my actual timeline and the new one I have created split? If so, Would I return to my original timeline or to the new alternate time line?

    Im really baffled by this and Time Travel in general. I know there are some very intelligent people out there so will one of you please help me out on this.
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  3. KneD Le Penseur Registered Senior Member


    I think you would come back and be arrested for killin' your grandma

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    But there's a little problem with the present-changing-thing.

    When you travel in time with a sort of machine or at least some help, and in the past you change your present.
    Will your help in the present still be there???

    When you kill your grandma and you get arrested, you won't be able to make your time-machine, so you can't return in your changed present.

    Do I make myself clear or is it too weird?
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  5. rlpete2 Registered Member


    There are speculations that there may be an infinite number of universes, diverging at every instant a decision is made, or an event could have a different outcome. This seems bogus to me, since the number of possibilities in any instant, universe wide, is way beyond imagining. However, if it were true, you simply would return to one (or several) of those alternatives caused by your action in the past. More likely, if you could go back and change the past, you have done it and have caused this present for yourself.
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  7. Shinigami Registered Member

    My theory is that when you go back in time you can't change anything but you are a observer of the past.
  8. KneD Le Penseur Registered Senior Member


    We were talking about time-travel physically, in what kind of circumstances do you think we'll be in the past, when we only can observe???

    If we shoot somebody in the past we just have to change the present don't we? What makes us stop pulling the tricker?
  9. Crisp Gone 4ever Registered Senior Member


    Hi KneD,

    For a mentally sane person, his/her conscience

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  10. KneD Le Penseur Registered Senior Member

    indeed, but is someone who travels through time mentally sane???
    I don't think so......
  11. Crisp Gone 4ever Registered Senior Member


    Hi KneD,

    I first smiled when reading your post, but then I realized there's actually a very good point there. Why would anyone travel back in time anyway ?

    To see yourself get born ? Take the homevideo!
    To witness the crusades ? Take a history book!
    To see the dinosaurs ? Do you really want to be amongst them ?

    Or is it to...
    Take some items there and sell them in this age as antique stuff ?
    Go and get gold/precious metals in the stone age and use them here ?
    Change history by introducing knowledge we have now in 1500 ?

    Would any of these things be a good idea anyway ?


  12. KneD Le Penseur Registered Senior Member

    Scientific view?

    not one of your examples makes any sense to me indeed.
    But maybe from a scientific view???

    I can imagine that people finally want to know how the pyramids are build.

    But go back to a time we know enough about, why should you???

    Selling old stuff makes no sense either, if you want to get rich, just sell your time-machine, it's much easier and it makes much more money.
    Change history is stupid, a big change you can't return. (see my earlier post)
    And about the home-video, who wants to see a birth anyway??? at least I don't

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  13. Yupa Registered Member

    Too much TV physics here!

    I have to assume that conservation of mass/energy does not change when time travel physics is applied. This means that if you "move" chronologically, you'll have to have the same momentum throughout the ordeal.

    Earth rotates, earth orbits around the sun, the sun moves around the galaxy, blah, blah, blah. If time travel really was possible, and you go back to see your grandma, well, you definitely won't appear anywhere near the solar system. (I am assuming that we're not at the center of the universe, and that we have lots of momentum...)

    In order to get anywhere near your grandma as you time travel, the time traveller must have one of those made-for-TV starships to fly back to Earth. The point about shooting anyone seems moot.
  14. KneD Le Penseur Registered Senior Member

    Hey Yupa,

    We should realise that if we are able to travel in space, it must be not so difficult to travel to earth as it seems now.

    (welcome aboard yupa)
  15. Yupa Registered Member

    So you're saying that you see no problem with the point I just made, about how we can't throw out basic principles of physics when time travel ones are developed?

    What I tried to point out in my last posting is the difficulty in knowing where you'll end up when time travelling...To go back 30
    years, it is not improbable that you may end up several light-years away from your target. Then travelling at near-lightspeed to home will result in your arrival many, many years after you started.

    Then, from several lightyears away, Grandma and everyone else you know will die before you could get back.

    Perhaps I erred in posting about "is it possible to do what Jagdwuf suggested", rather than "what happens if it were done..."

    Thanks for the welcome.
  16. KneD Le Penseur Registered Senior Member


    We should be able to travel faster than our milky way, then we can get back on earth before we are in the 21st century again;

    We travel to the year 1950, we travel just a little faster than our mikly way/solar system and we are back on earth in the year 2000.

    The problem is that we can't say the speed we travel through space with our milky way, it is relative.
    We can see how fast we travel inside our cluster, but maybe our whole universe is moving???

    But where you didn't thought of Yupa is that when we go to that place in history and end up at another location (where earth first used to be) then it takes a long time to get there, you can't travel faster then light speed!!!!
    So when we can travel that fast, we can travel that fast back when we indeed end at an elderly location, there is no problem coming back.
  17. Bebelina Valued Senior Member

    Answer to the topic starter

    You would have created an alternative timepath. You have many parallell lives already, alternative yous. So if you die in one of the alternative lives,or kill your grandmother, the rest of them will not see much difference, maybe a slight fluctuation, as a sickness or personal chrisis in the othere lives. You will return to the life you knew as yours before the incident happened. You will not continue to exist in the same reality where you have killed your grandmother, before she gave birth to your mother, or father. Probably a memory of the incident will be left, and you will become more aware of your other existences.
  18. KneD Le Penseur Registered Senior Member

    sorry, but I think your opinion is nonsense, but who am I....??
    everything's possible.

    But I'm just a little to realistic-thinking to believe in this kind of stuff....
  19. Bebelina Valued Senior Member

    Keep an open mind!

    And try not to refer to others opinions as nonsense.

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  20. Chagur .Seeker. Registered Senior Member

    Bebelina ...

    Although KneD may have been a bit less blunt with a lovely scatter-brain such as yourself, I do think he has a good reason to reject what you proposed.

    As I understand you, an 'event' causes an alternate and parallel time line to be created. Were this to be the case, is it only someone from another time period who can trigger such an event? And if not, what are the parameters that must be met?

    Example: If I step on an ant, am I creating a parallel time line in which the ant has not been stepped on?

    Please explain.

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  21. Yupa Registered Member

    Hi KneD,

    In your last post, paragraphs 1,2 does not take into account the possible effects of near-light speeds. I agree with paragraph 3, and you missed the main idea of my first post in your 4th paragraph.

    Let's try an example.

    Suppose Earth rotates around its axis and has no other motion, and that no other celestial object moves. You are standing in a room at the equator when you activate the time machine, set to jump back 12 hours. Where will you be standing?

    What I've suggested is that the room and the time machine must be halfway around the world. You didn't move, and you are on Earth as it was at that time. The only idea in paragraph 4 that I agreed with is the no-faster-than-light (FTL) one. If you ended up in any other location, then not only will you have time-traveled, you would have teleported or gone FTL...Since there are threads on these topics, I won't talk about it here.

    Now let's add in the motion of earth's orbit, and the motion of all celestial objects to my example. You won't be on Earth after a time jump and quite possibly very far away. Get the idea?
  22. KneD Le Penseur Registered Senior Member

    Hi yupa,

    I completely agree with you.

    And I already got the idea, maybe it was a little confusing post from me, but what I was trying to say in the 4th paragraph is:

    The problem of travelling back to earth in space is the same problem as the travelling from earth to that place in time/space.
    That's the speed of light.

    (I think we are on the same point of view yupa...)

    But yesterday when I was trying to get some sleep, another idea came up in my mind:

    When you travel back in time in 2001, and you end up in 1950 but on the location where earth was in 2001.
    And earth will be at his location from 1950.

    That will be great!!! When we consider that earth moves the same way again, and we travel towards it then we don't have to have such a high speed to be on earth before 2001.
    Actually when we don't move, we will be on the same place on earth again in 2001.
    When we travel towards earth then we will be there before 2001!!!!

    And another point: while transporting to the past, we don't have to deal with the speed of light part, we don't move in space!!!
    (but earth does, is that a trouble?? hmmm)
    Last edited: Jul 29, 2001
  23. Bebelina Valued Senior Member

    Alternative realities

    Are created all the time. As in the "ant-incident" and in any incident and event. Everytime there is a choice involved, and that means pretty much all the time.I do agree to being lovely, but certainly not a scatter-brain. I reject such remarks on my personality. Maybe my ideas seem strange and confused for those who have never heard of them before, but If you read with an open mind, then maybe even you will recognize the logical pattern in my reasoning too. Personally I never dismiss anybody as less intelligent, just because I do not agree.

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