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How does the principle of Reference Frames work?

  1. Dec 17, 2009 #1
    How does the principle of "Reference Frames" work?

    What would be an appropriate answer for that statement? I can't think of anything fitting, also I'm not too educated in that subject. Any help is greatly appreciated. :)
    Last edited: Dec 17, 2009
  2. jcsd
  3. Dec 17, 2009 #2


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    Re: How does the principle of "Reference Frames" work?

    Apparently, it means something different to an actual physicist than it does to me. I was corrected in a thread a couple of years ago. From my layman's perspective (which itself is relative), it simply means that an event of any sort is not the same for someone observing from a different location.
    Take as an example a ball thrown 'forward' by someone on a moving train. Someone on the train sees the ball as traveling at 20 metres per second (made-up number). An observer on the ground, however, sees the ball as traveling at 20 metres per second plus the speed of the train, so let's say 35 metres per second. Someone on an overtaking aircraft would see both the train and the ball as moving backward, but the ball more slowly than the train.
  4. Dec 18, 2009 #3
    Re: How does the principle of "Reference Frames" work?

    The problem with our instinct is that it makes us believe that space is a sort of "stage" that events take place on. Our instincts mislead us.

    There is true independence from both space and time with regard to the reference frame. In other words, if you're riding your bicycle down a path, then every stationary object you see (trees, river, etc) is actually independent from you on the most fundamental levels. That means that the trees and the river are aging slower than you are, and the airplane overhead is aging more quickly than you are.

    How can this be? This sounds like nonsense, I know, but it's true. You age slower than the passengers in the aircraft above you, but the age differrence is so small that there's really no way you can measure this difference (read about the Lorentz Transformations for more info regarding this interesting fact)

    Therefore, space is not a stage by which events take place on, but everything in space has it's own reference frame. The reference frame of the aircraft flying above is aging quicker than you, just as you--being a completely separate reference frame--are aging quicker than the bushes and river that lie along your bicycle path.

    In closing I can sum it up like this: a reference frame is just that frame that has its own measurement of time and space. That's it.
    Any reference frame that does not share your 'rate of time' (any reference frame that is aging slower or quicker than your frame) or 'measure of space' (any frame that has a 12" ruler that's either shorter or longer than your 12" ruler), is a separate and distinct reference frame from your own.
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