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How does space-time curvature affect light?

  1. Feb 12, 2016 #1
    If space is warped around heavy objects in space, i feel that space would be FUBAR around black holes. So, my question is, Does light get sucked in by gravity, or does it just get caught in the warped space around a black hole?
  2. jcsd
  3. Feb 13, 2016 #2


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    Gravity IS the "warped spacetime".
  4. Feb 13, 2016 #3
    Well, I understand that gravity is space pushing on you (Thanks to Relativity). My problem is, Light travels in a straight line. Warped space will bend light, but not make it disappear. I know that a black hole funnels space to the center or singularity, but i also know that warped space can't hold light. When the solar eclipse that proved Relativity happened, light traveled through warped space, then came out of it so we could see it. It should have wrapped around the sun, but it didn't. So, i wonder.
  5. Feb 13, 2016 #4


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    "around"? The path of the light and the mass / diameter of the Sun would only produce a slight warping effect, which is what was seen. These effects are all a matter of degree and mostly cannot be seen at all because the conditions are not extreme enough.
  6. Feb 13, 2016 #5


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    Yes, light travels in a "straight" line, and curvature can mean these straight lines aren't really straight (rather as a straight line on the curved surface of the earth will bend as it follows that curved surface).

    The sun is not a black hole; its gravitational field is just strong enough to bend the path off to one side a bit. That's what Eddington's group observed in the solar eclipse (and we have since seen many more spectacular examples - google for "gravitational lensing").

    The spacetime curvature near a black hole is so strong that at the event horizon all the straight-line paths that light can follow ("light-like geodesics" or "null geodesics" in the lingo) lead inwards. At the event horizon light cannot escape because there is no path out; move at the speed of light in any direction and you'll still end up inside the black hole.
  7. Feb 16, 2016 #6
    Thank you for the replies.
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