1. lordofhats
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    lordofhats Contributing Member

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    Time Dilation Effect?

    Discussion in 'Research' started by lordofhats, Feb 18, 2008.

    Can anyone here explain in lammens terms (If that is actually possible :confused:) the methodology behind Time Dialation and space flight?

    Reason for asking. 003 is finished but I have expanded my interest in the universe and am developing the universe a little bit. I remember this from Enders Game and am interested in possibly using it myself, if I can ever understand it well enough to actually represent it in the storyline.

    Anyone know anything?
     
  2. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    From the standpoint of an external observer, time passes more slowly on board a ship that is travelling closer to the speed of light. For example, an hour may pass on board the ship between two events, and the clocks and the crew will all experience a normal hour of time. However, the observer at the launch time may experience 3 or four hours time pass between the events.

    Time dilation also occurs with ships that don't even come close to the speed of light, but the effects are extrremely difficult to measure except at very high speeds. However, measurable time dilation effects have been detected in manned apce miissions using extremelt accurate timekeeping equipment.

    The situation is really a lot more complex that that though, because space is also compressed along the direction of travel, and because there is no such thing as simultaneous separate events (which one occurs first depends on the frame of reference you measure the events from). But the simple answer is, the faster you travel, the slower time passes for you relative to the point you measure speed relative to.

    I hope this helps more than confuses.
     
  3. lordofhats
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    lordofhats Contributing Member

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    That helps alot Cogito thanks. Thats a much better explaination than wikipedia gave. I don't need to get it 100%, just enough to represent it in the story with some level of looking like I know what Im saying :p.

    Thanks
     
  4. TWErvin2
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    There is a forumula, which I used when writing my first SF Novel. Once the values are understood, plugging them in to find a result isn't that much of an issue.

    Basically, however, what I think you're looking to understand is that as one group in a space vessel increase speed, time for them "slows down" as compared to those who are stationary, or not moving. However, it takes nearing the speed of light for the effect to become reasonably measureable (have an impact), but the closer one gets...say 90% the speed of light or more, it becomes much more stretched out, so to speak.

    Here is a link at wikipedia that discusses it in pretty general terms: Talk:Time dilation - Wikipedia, the free encyclopedia
    and here is the Lorenz formula which can be used to calculate time dialation (which can be due to/applied both speed of travel or even strong gravitational effects--such as a black hole). Lorentz factor - Wikipedia, the free encyclopedia

    You can google search, but much of what you will find are physics heavy discussions and formulas. If you're really interested, it is not beyond you, but will take some careful reading, note taking and time to sort out.

    Hope that helps.

    Terry
     
  5. MumblingSage
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    MumblingSage Contributing Member

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    So time dilation really does work the way they show it in sci fi? Like, I'm going near the speed of light and though only five weeks passes for me, it's five years for the people back on Earth?
     
  6. Banzai
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    Banzai One-time Mod, but on the road to recovery Contributor

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    In theory. It happens normally (theoretically) but the effect is so minute (as with most of quantum physics) that you don't notice it until you're approaching the speed of light.
     
  7. MumblingSage
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    Okay. *nods*

    So say a friend and I are both traveling to planet Google across the galaxy at near-light speed. And I send my friend ahead to prepare a hotel room.

    Let's say my friend's ahead of me by 5 days.

    So does she land on Google 5 days ahead of me, or, because I'm still traveling at near-light speed when she lands, by the time I arrive will she be days or weeks more head of me?
     
  8. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Both you and your friend are cruising in congruent inertial frames, so I'm assuming 5 days apart is in terms of your shared inertial frame. Otherwise, the question becomes even more complicated, because there is no such thing as simultaneity in separated spacetime events in relativity.

    As soon as your friend begins to decellerate (ah! there's the catch!), your clock, relative to hers, appear to slow down. Depending on the decelleration curves, from her perspective, she will have arrived weeks, months, or years later. From your perspective, you arrived less than 5 days after you observed her landing.

    As for your age differences after it all, you were on different accelleration profiles as you came up to cruising speed as well.
     
  9. lordofhats
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    lordofhats Contributing Member

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    In short, Quantum Physics are baffling... :confused:
     
  10. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Oh, that's not even Quantum Physics, it's only Relativity. :)
     
  11. Banzai
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    Banzai One-time Mod, but on the road to recovery Contributor

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    Quantum physics makes even less sense.
     
  12. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Well, it both does and does not, depending on how you observe it ;)
     
  13. MumblingSage
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    MumblingSage Contributing Member

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    Okay.

    And how much time debt could we accumulate? I mean, assuming planet Google was really far away, could my friend arrive only to find me decrepit or dead?
     
  14. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    The greater the peak velocity difference between the most different inertial frames, the greater the possible time dilation effects. The speed of light is, of course, a limit that can be approached but never reached by a massive object, according to Einsteinian physics, but the closer you approach it, the greater the magnitude of the time paradoxes, and the more energy that must be expended to attain a velocity closer to C.
     
  15. MumblingSage
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    MumblingSage Contributing Member

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    So the faster we go, the more likely it is that things will get screwed up?
     
  16. Banzai
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    Banzai One-time Mod, but on the road to recovery Contributor

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    Pretty much. Certainly the effect is greater the faster you go.
     
  17. MumblingSage
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    MumblingSage Contributing Member

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    Okay. Thanks, all. I think this will show up as a plot point in the thing I'm writing.

    We can hope, anyway.
     
  18. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    Reminds me of the old joke bumper sticker: The faster I go, the behinder I get.
     
  19. Banzai
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    Banzai One-time Mod, but on the road to recovery Contributor

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    Hehe. Does it show that I'm a geek, that I laughed at that?
     
  20. Neo
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    So, given the relative effects of time dilation on different congurent frames of inertia, and the relativistic effects of decelloration on the actor-observer effect in relation to the passage of time measured by a stationary observer...

    ...who will win I'd Do Anything?
     
  21. Al B
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    Is that an obscure reference to the talkie toaster scene on Red Dwarf I see there?

    Al
     
  22. Banzai
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    Banzai One-time Mod, but on the road to recovery Contributor

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    That sounds like one of the questions from my physics exam...
     
  23. Neo
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    So, no two events can take place at exactly the same time? So, the experience of time at home is different to the experience I have when I pop to the shops? Because each is an indiviual frame of reference?
     
  24. Al B
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    Yup, basically that's it. If I have to travel for five days at warp factor 8 (or whatever) to get to a different place in time, it makes no difference to anyone who hasn't also done that, because I'm so far away it has no relevance to them, hence the relativity part (although that's not the only thing it is referring to).

    You might be interested to know that NASA actually did some research into that, try googling for 'project looking glass'. The basic idea was to put a telescope so far out into space that it would observe events from the past on Earth, because the light from those past events had yet to reach a certain place in space. So in theory, you could go fifty light years out into space, train a telescope on the grassy knoll in Dallas, and see what actually went on when Kennedy was assassinated. Trouble is, you've got to get the telescope there, and then get it back, so while in theory it would work, in practical terms it's a no go unless you get into using wormholes and other theoretical ways to sidestep the actual transit times. There's also the problem of an expanding universe and the movement of objects in space (not to mention having a lens big enough to be able to see the details), you'd have to know exactly where in space the Earth was on the day you wanted to observe an event, this is something which screws up 'time machine' stories, since if a time machine was not also some sort of craft that could change its location, you'd go back three days in time and find yourself floating in space with the Earth several thousand miles away, which would be a bit of a bummer for Rod Taylor in the movie, as an Edwardian smoking jacket is not the ideal attire for doing a space walk.

    Al
     
  25. Cogito
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    Cogito Former Mod, Retired Supporter Contributor

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    The amount of possible skew between two events in spacetime is determined by the total distance between them in all four dimensions, but that distance depends on the velocity of the observer's frame of reference relative to each of the events.

    It's not completely arbitrary how much time can separate events that appear simultaneous to one observer, but you will always be able to find an observer to whom the events are not simultaneous unless the events coincide exactly (i.e. are the identical event at the same time and place.).
     

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