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Observer's Relative c, am I getting this right?

  1. Mar 7, 2013 #1
    Hello, all. I'm trying to wrap my mind around relativity, and I just wanted to make sure I'm not getting it wrong. I'd really appreciate it if anyone were to take the time to chime in on this hypothetical that I think explains it.

    Say someone was to put two lasers (in a "gravity free" environment) 599,584,916 kilometers apart and fired them at the exact same time. Imagining that the two laser points are observation points and that the person running the experiment was in the center of these two points (299,792,458 km from either laser), we get three relative perspectives. For the observer in the middle, the two points would appear to meet in the center (taking 500 seconds). For either of the laser points they should appear to meet at the opposite laser (taking 1,000 seconds), since the stationary (from the view of the experimenter) lasers would be moving at the speed of light relative to the laser point.

    Do I have this right? I don't really have anyone else to ask... I'm not a student or anything, just curious.
  2. jcsd
  3. Mar 7, 2013 #2


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    Staff: Mentor

    Did you mean 1000 seconds and 2000 seconds? Light takes 1000 seconds to cover 299,792,458 km.

    But even after making that correction, the answer is no, as there is no such thing as the reference frame of light, or the world as viewed by a beam of light. There's some discussion of this in the FAQ at the head of this page.

    Last edited: Mar 7, 2013
  4. Mar 7, 2013 #3


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    I think a lot of us would like to chime in but your scenario is very confusing. Here are some questions you need to answer:
    1) Which direction are the lasers pointed in? Are they aimed at each other or in some other direction?

    2) When you say "fired", do you mean they both emit a short burst of laser light or do you mean they are turned on and stay on?
    3) Are these two laser points moving or stationary?

    4) Are these two laser points the emitted laser light from a burst?

    5) Are these two laser points a place where the laser light is shining, making a bright dot or point?

    6) Are there two observers located wherever these two laser points are?

    7) Is the person running the experiment moving or stationary?

    8) Is the person running the experiment located in line with the two lasers?

    9) Are the two lasers aimed at the person running the experiment?

    10) Does the person running the experiment fire the lasers?
    I can't make any sense of these statements. Maybe after you answer the above 10 questions you will understand how to rephrase the rest of your scenario.
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