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Question on a visual

  1. Aug 17, 2013 #1
    If you were in a ship, traveling very close to the speed of light, what would it look like? Would the universe look like a bright dot out in front of the ship or would it just be really bright any direction you looked?
  2. jcsd
  3. Aug 17, 2013 #2


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    What you'll see is influenced by two effects: aberration and Doppler shift. All the stars in front of you will be Doppler shifted towards the blue, while those in back of you will be shifted to the red.

    Aberration changes the stars' apparent location. Stars anywhere to your side will have their apparent position moved forward, with the result that the forward hemisphere of your vision will have the light from more stars and they will appear closer together. The backward hemisphere just the opposite. This is also known as the headlight effect. Both of these effects will make the forward hemisphere appear brighter.
  4. Aug 17, 2013 #3

    Thank you for the consideration and reply.

    I guess red light from the front would be more intense and blue light from the back less intense with green and yellow on the sides being medium intensity. So the aberration might be some kind of orange color between red and yellow.

    I wonder what the view and color of the sky would be in a black hole. Maybe black since it has already seen the stars from its outside run out of fuel.

    From inside a proton.. There is the shell to consider. It reflects the outside light but there is energy in there somewhere. Maybe like looking at the inside of a curved mirror.
    Last edited: Aug 17, 2013
  5. Aug 17, 2013 #4
    what about

    The EM spectrum covers a lot of frequencies. Wouldn't that turn light from the front to cosmic rays and light from the back to ultra low radio waves and leave visible light spectrums somewhere on the sides? Since all visible frequencies are seen at the aberration point I'd think it would have to be white. Scale back the speed some so that the aberration point gets larger and it might look like a circle rainbow with the colors backwards.
  6. Aug 17, 2013 #5


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    Last edited by a moderator: Sep 25, 2014
  7. Aug 20, 2013 #6


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    What about length contraction? In the stars' frame your eyeballs are contracted, while in your frame the entire universe is contracted.
  8. Aug 21, 2013 #7


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    If you use the relativistic velocity addition, you get a different aberration than classically (for high relative velocities):

    Does this account for length contraction?
  9. Aug 21, 2013 #8
    As I am right now working on illustrations for my book concerning exactly this topic, here is the graphics I have just made:


    It shows how the standard spherical coordinate system on the sky is deformed as a result of the boost described by the following SL(2,C) matrix


    This particular matrix comes out from the polar decomposition of


    The boost corresponds to the velocity v=0.745356 c in the direction of the black dot. Only (relativistic) aberration effects are shown. Colors are accidental.
    Last edited: Aug 21, 2013
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