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Celestial die hards.

  1. Aug 27, 2004 #1
    What is escape velocity at 1 planck length from an event horizon? Or, if it varies with the mass, is there a simple equation for computing the escape velocity? (No rotating black holes please, they hurt my brain).
  2. jcsd
  3. Aug 27, 2004 #2


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    Well, I get that
    [tex] \gamma = \frac{1}{\sqrt{1-(\frac{v}{c})^2}}}=\frac{1}{\sqrt{1-\frac{2GM}{c^2r}}}

    but I could use a double-check. Assuming this is right, if we let R = Rs +d, where Rs is the schwarzxshild radius 2GM/c^2, we can approximate this as

    [tex] \gamma = \sqrt{\frac{2 G M}{d c^2}} = \sqrt{\frac{R_s}{d}} [/tex]

    this can be solved for v

    [tex] v \approx (1 - \frac{d}{2 R_s})c [/tex]

    In planck units, G=c=1
    Last edited: Aug 27, 2004
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