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I How much Gravity is needed to bend light?

  1. Apr 12, 2016 #1
    By gravity I mean the mass of a object capable of bending light. I don't want a explanation too say about how or why it will bend, just want the mass in numbers or equation please.
  2. jcsd
  3. Apr 12, 2016 #2
    Any mass at all will bend light. Gm/(r*c^2) where G is the gravitational constant, m is the mass you're considering, r is the radius from the center of mass to the light path, c is the speed of light. The result is in radians. I saw a rough calculation that says the mass of the Earth can bend a beam about 10^-9 radians.
  4. Apr 12, 2016 #3


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    From what I've read, things with zero mass can bend light.

    It's beyond my comprehension how it works. But since @pervect is staff emeritus, I'm inclined to go with their answer. :smile:
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