Light Around Black Holes: Can It Orbit?

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In summary, light around a black hole follows the curvature of spacetime, causing it to bend and appear distorted. It cannot orbit a black hole, but instead follows a curved path around it. The distance at which light can get to a black hole before being pulled in is known as the event horizon, and once light crosses it, it cannot escape. The speed of light is constant, but may appear distorted or slowed down when observed due to the effects of gravity.
  • #1
turin
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I just wanted a quick affirmation. Can light orbit a black hole? That is, can light remain between two well-defined distances from the event horizon (or at a single well-defined distance, which I am leaning towards) indefinitely?
 
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  • #2
For a Schwarzschild hole it can orbit at the photon sphere [tex]r_{ps}[/tex] which is at
[tex]r_{ps} = \frac{3GM}{c^{2}}[/tex].
It is an unstable orbit though.
 
  • #3
Thanks, DW. That's exactly what I was looking for.
 

Related to Light Around Black Holes: Can It Orbit?

1. How does light behave around a black hole?

Light around a black hole follows the curvature of spacetime created by the immense gravitational pull of the black hole. This can cause light to bend and appear distorted, as well as create an effect known as gravitational lensing.

2. Can light orbit a black hole?

No, light cannot orbit a black hole in the traditional sense. Since light has no mass, it is not affected by gravitational forces in the same way that objects with mass are. Instead, light follows a curved path around the black hole, similar to how a planet orbits a star.

3. How close can light get to a black hole before being pulled in?

The distance at which light can get to a black hole before being pulled in is known as the event horizon. This distance varies depending on the mass of the black hole, with larger black holes having a larger event horizon. However, no matter the size of the black hole, once light crosses the event horizon, it cannot escape.

4. Can light escape a black hole once it has crossed the event horizon?

No, once light has crossed the event horizon of a black hole, it cannot escape. This is because the gravitational pull of the black hole is so strong that even light, which travels at the fastest speed possible, cannot escape its grasp.

5. How does the speed of light affect its orbit around a black hole?

The speed of light is constant, regardless of the gravitational pull of a black hole. However, the path of light may appear to be distorted or slowed down when observed from a distant point due to the effects of gravity. This is known as gravitational time dilation.

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