- #1
Sigie
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I posted a similar question under cosmology but the question was unable to be answered. I thought I would try a reframe the question.
When approaching a black holes event horizon, the exit cone for light become smaller until it is eliminated at the event horizon itself. But how can gravity bend light that is directed exactly away from the line of force?
Employing the principle of equivalence, no matter how fast I accelerate in flat space, a beam of light directed in the same direction as I accelerate will never bend. Therefore, it seems to me that the event horizon breaks the principle of equivalence.
For example, I am in an elevator with a laser pointer. If the elevator is accelerated upwards in flat space, from my perspective, the light bends, except if I direct the laser pointer directly upwards of downwards. If I direct the laser pointer directly upwards, no matter how fast I accelerate, the light beam will always be traveling away from me at speed c.
If I use the equivalent situation of a mass below me, then, no matter how massive the object, the laser should never bend.
If I am in an elevator that is crossing an event horizon (assuming a huge black hole where tidal forces won't tear me apart at the vent horizon), and I direct the laser pointer exactly away from the line of the force of gravity, at a point where the laser emiter is inside the event horizon, yet the top of the elevator is beyond it, the laser cannot by definition reach the ceiling. Yet the light cannot be slowed, and it cannot be bent if it is line with the force of gravity.
Thus, it seems to be that gravity cannot completely close off light's exit cone and thus an event horizon (and a black hole) cannot truly form, no matter how massive an object. I would be very appreciative if someone could explain this paradox to me.
Thanks
When approaching a black holes event horizon, the exit cone for light become smaller until it is eliminated at the event horizon itself. But how can gravity bend light that is directed exactly away from the line of force?
Employing the principle of equivalence, no matter how fast I accelerate in flat space, a beam of light directed in the same direction as I accelerate will never bend. Therefore, it seems to me that the event horizon breaks the principle of equivalence.
For example, I am in an elevator with a laser pointer. If the elevator is accelerated upwards in flat space, from my perspective, the light bends, except if I direct the laser pointer directly upwards of downwards. If I direct the laser pointer directly upwards, no matter how fast I accelerate, the light beam will always be traveling away from me at speed c.
If I use the equivalent situation of a mass below me, then, no matter how massive the object, the laser should never bend.
If I am in an elevator that is crossing an event horizon (assuming a huge black hole where tidal forces won't tear me apart at the vent horizon), and I direct the laser pointer exactly away from the line of the force of gravity, at a point where the laser emiter is inside the event horizon, yet the top of the elevator is beyond it, the laser cannot by definition reach the ceiling. Yet the light cannot be slowed, and it cannot be bent if it is line with the force of gravity.
Thus, it seems to be that gravity cannot completely close off light's exit cone and thus an event horizon (and a black hole) cannot truly form, no matter how massive an object. I would be very appreciative if someone could explain this paradox to me.
Thanks