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What would you see traveling faster than light?

  1. Jun 9, 2016 #1
    In my universe, the laws of physics are exactly the same, except we've figured out how to create an Alcubierre drive (we discovered how to create negative energy density, how is done through handwaving.)

    So, with that assumption, what would you actually see while traveling in a warp bubble like the one described by Alcubierre.

    I came to the conclusion that it would depend on where you were looking.
    • Directly behind you, you would see absolutely nothing. Light would not be able to reach your eyes from any place outside of the bubble behind you.
    • Directly in front of you, you'd see stars whipping by you, but you'd actually be seeing the far infrared, as they'd be blue-shifted. If the ship is traveling at 3000x the speed of light, light in the 100GHz range would be blue-shifted into the 300THz visible range.
    • To the side of you, you'd see a gradient from heavily blue-shifted stars to heavily redshifted, fading to blackness as you get closer to perpendicular to direction of motion.
     
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  3. Jun 9, 2016 #2

    phinds

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    You have posited a continuous spectrum, so it seems reasonable to me to assume that if EM radiation could reach you then some of it would be shifted into frequencies and intensities that would fry you pretty much instantly, so you wouldn't "see" much because you'd be dead.
     
  4. Jun 9, 2016 #3
    Interesting. I hadn't considered what EM radiation from the rest of the spectrum would do to you. I suppose I'll need some technology to fix that, the ship's force fields should be able to handle the high intensity radiation, humans would have to find a way to deflect the normal space radiation anyway.
     
  5. Jun 9, 2016 #4

    phinds

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    You also need to think about this: if EM radiation can reach you, then why not space dust? Any way you cut it, I think if any of that stuff can reach you at those speeds, you're dead.
     
  6. Jun 10, 2016 #5
    I may be a bit late, but your field of view would increase dramatically- I wish I had a source for this, so I may have to edit this post later. I'd recalled seeing some sort of diagram of going to the sun at near-light speed, and aside from blueshift, that was one of the effects.
     
  7. Jun 11, 2016 #6
    Why is that? The blackness perpendicular.

    For a ship at c, what was once perpendicular (at zero ) is now at a 45 deg angle to the front of you, and what was 45 degrees behind you, is now seen perpendicular to you.
    Any thing ahead of the ship from perpendicular ( at zero ) should now be blue-shifted ( at c ), and anything behind should now be red-shifted. Since all the stars were originally stationary wrt the ship, there should be starlight in 360 degrees all around, except for directly behind.

    By increasing the speed of the ship above c, I would have thought that there would still be a 360 degree view of stars, but that more rotation towards the direction of travel would occur.
     
  8. Jun 13, 2016 #7
    Wouldn't all the stars behind you be moving away from you faster than light? I would think that they would be redshifted to infinity like the galaxies at the edge of the universe?

     
  9. Jun 14, 2016 #8
    So I approximated some geodesic around a positive and negative energy densities and I came up with the conclusion that in front of you you'd see a fisheye view of the universe, like looking out through a peephole in a door. Behind you, you'd see a reverse fisheye view, sort of like trying to look through a peephole backwards. However, both it wouldn't be clear, the entire thing would be out of focus unless you were in an exact sweet spot.

    Does this sound right? In my image, the blue is positive energy density and the red is negative energy density. There are three stars, one green, pink, and brown, the brown on is behind the spacecraft.
     

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  10. Jun 14, 2016 #9
    I thought the idea behind the Alcubierre drive was that the ship is not moving through the space inside of the bubble, and that space outside of the bubble (and the light traveling through it) was moved around the outside of the bubble.

    How big is your bubble? As long as you're bending space, there's no reason to make the outside bigger than the inside, and this could help with that annoying energy flux.
     
  11. Jun 18, 2016 #10

    chasrob

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    Here's a paper discussing exactly that--
    http://arxiv.org/abs/gr-qc/9907019
    The first few pages are a lot of equations; starting about page 10 is an interesting discussion.
     
  12. Jun 19, 2016 #11

    chasrob

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