Could light find itself in orbit around an object?
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We know light can't escape a black hole but...
Could light find itself in orbit around an object? Say the light is on the cusp of an event horizon. Could it end up in an orbit around the black hole if it was coming in from the perfect angle?
visible-light black-holes
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up vote
4
down vote
favorite
We know light can't escape a black hole but...
Could light find itself in orbit around an object? Say the light is on the cusp of an event horizon. Could it end up in an orbit around the black hole if it was coming in from the perfect angle?
visible-light black-holes
add a comment |Â
up vote
4
down vote
favorite
up vote
4
down vote
favorite
We know light can't escape a black hole but...
Could light find itself in orbit around an object? Say the light is on the cusp of an event horizon. Could it end up in an orbit around the black hole if it was coming in from the perfect angle?
visible-light black-holes
We know light can't escape a black hole but...
Could light find itself in orbit around an object? Say the light is on the cusp of an event horizon. Could it end up in an orbit around the black hole if it was coming in from the perfect angle?
visible-light black-holes
visible-light black-holes
asked 4 hours ago
Tim Lieberman
1282
1282
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1 Answer
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Yes, it is possible in the Schwarzschild solution, but the orbit is not stable. The radius at which this can happen is the photon sphere which lies at $3r_s/2$ where $r_s$ is the Scwharzschild radius. Photons which are at this radius may orbit, but the orbit is unstable in that if the photon moves any closer it will eventually spiral into the black hole and if the photon moves any further it will spiral out and escape.
Apparently there are 2 photon spheres for a rotating black hole, but I am not too familiar with those orbits. I don't believe they are stable orbits either.
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
Yes, it is possible in the Schwarzschild solution, but the orbit is not stable. The radius at which this can happen is the photon sphere which lies at $3r_s/2$ where $r_s$ is the Scwharzschild radius. Photons which are at this radius may orbit, but the orbit is unstable in that if the photon moves any closer it will eventually spiral into the black hole and if the photon moves any further it will spiral out and escape.
Apparently there are 2 photon spheres for a rotating black hole, but I am not too familiar with those orbits. I don't believe they are stable orbits either.
add a comment |Â
up vote
4
down vote
Yes, it is possible in the Schwarzschild solution, but the orbit is not stable. The radius at which this can happen is the photon sphere which lies at $3r_s/2$ where $r_s$ is the Scwharzschild radius. Photons which are at this radius may orbit, but the orbit is unstable in that if the photon moves any closer it will eventually spiral into the black hole and if the photon moves any further it will spiral out and escape.
Apparently there are 2 photon spheres for a rotating black hole, but I am not too familiar with those orbits. I don't believe they are stable orbits either.
add a comment |Â
up vote
4
down vote
up vote
4
down vote
Yes, it is possible in the Schwarzschild solution, but the orbit is not stable. The radius at which this can happen is the photon sphere which lies at $3r_s/2$ where $r_s$ is the Scwharzschild radius. Photons which are at this radius may orbit, but the orbit is unstable in that if the photon moves any closer it will eventually spiral into the black hole and if the photon moves any further it will spiral out and escape.
Apparently there are 2 photon spheres for a rotating black hole, but I am not too familiar with those orbits. I don't believe they are stable orbits either.
Yes, it is possible in the Schwarzschild solution, but the orbit is not stable. The radius at which this can happen is the photon sphere which lies at $3r_s/2$ where $r_s$ is the Scwharzschild radius. Photons which are at this radius may orbit, but the orbit is unstable in that if the photon moves any closer it will eventually spiral into the black hole and if the photon moves any further it will spiral out and escape.
Apparently there are 2 photon spheres for a rotating black hole, but I am not too familiar with those orbits. I don't believe they are stable orbits either.
answered 4 hours ago
enumaris
3,3601520
3,3601520
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