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Optic and velocity

  1. May 9, 2005 #1
    there's a question which is confusing me a little bit;
    it is known and verified that the speed of light is about 300000km/s
    well, as we look through the stars
    which are very distant from us in thousands light-years
    we notice that we can view them spontaneously.
    thus, it doesn't take much time even though the distant is largly very great.

    does this imply that our vision's velocity is greater than the speed of light,
    or is it just an explanation for a light propagation like diffraction and diffusion, etc...?

  2. jcsd
  3. May 9, 2005 #2


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    Actually, we view them as they were in the past. We see a star that's ten light years away as it was ten years ago.
  4. May 9, 2005 #3
    Seems you have misconceptions on how light works. When you look at the stars you are seeing light that was emitted long ago. You can not "see" something until the light from that object enters your eye and is processed by your brain. If today a star 100 light years away blew up, or disappeared for some reason, we would not see it happen for 100 years.

    The statement about your "visions velocity" is incorrect. Your vision is triggered by light entering your eye from some source. Imagine a ball being thrown in your direction. Your eyes are closed so you don't see it. The ball next hits you in the chest and you "feel" it. The same thing happens with light. The light is coming at you just like the ball but you never really "see" it, but instead your eye "feels" the impacts of photons hitting the retnia and the brain creates an image from the information.
  5. May 9, 2005 #4
    thanks for clarifying the subject for me,
    i was hesistating and i knew there was a mistake in my thoughts.
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