Photon Orbit Around a Black Hole: Conservation Law Effects

In summary, the conservation law of angular momentum and the constant speed of light imply that photons can only have circular orbits around a black hole and not elliptical orbits. Additionally, photons cannot accelerate themselves around a black hole, making the idea of a "sling shot" effect impossible.
  • #1
Ontophobe
60
1
Hi. Now that I understand the conservation law of angular momentum, and given the fact that c is constant, I infer that if a photon were to go into orbit around a black hole, it could only take a circular orbit. No elliptical orbits for photons, because if it were to follow an elliptical orbit, it would have to speed up and slow down in order to cover the same amount of space per unit of time. Is this correct?

Related question: Can a photon "sling shot" itself around a black hole and blueshift itself in the process? (since accelerating itself isn't an option for the photon)
 
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  • #2
There are no elliptical orbits for anything around a black hole. Black holes need to be described using general relativity. Already in the simplest case of the Schwarzschild metric, orbits are not ellipses.

Light trajectories around a black hole are not necessarily circular.
 
  • #3
So, parabolas, hyperbolas, and circles are kosher, but no ellipses. Correct?
 
  • #4
Ontophobe said:
So, parabolas, hyperbolas, and circles are kosher, but no ellipses. Correct?
Incorrect. This is also something which applies to Newtonian gravity - except circles, you can always find circular orbits simply because it is a very particular special case.
 

Related to Photon Orbit Around a Black Hole: Conservation Law Effects

1. What is a photon orbit around a black hole?

A photon orbit around a black hole is the path followed by a photon (particle of light) as it travels around a black hole. This is the closest possible orbit that a photon can have around a black hole without falling into it.

2. How is the conservation of energy and angular momentum affected by a photon orbit around a black hole?

The conservation of energy and angular momentum are both fundamental laws in physics. In the case of a photon orbit around a black hole, these laws are still applicable, but the effects of the strong gravitational pull of the black hole can cause some deviations from the expected values.

3. What are some consequences of the conservation law effects in a photon orbit around a black hole?

One consequence of the conservation law effects is that the wavelength of the photon can be stretched or compressed due to the strong gravitational field. This is known as gravitational redshift. Additionally, the orbit of the photon can be influenced by the rotation of the black hole, causing it to precess or spiral in towards the black hole.

4. How do scientists study photon orbits around black holes?

Scientists can study photon orbits around black holes by observing the behavior of light from distant objects that are affected by the gravitational pull of the black hole. They can also use simulations and mathematical models to understand the effects of conservation laws on the photon orbit.

5. What implications does the study of photon orbits around black holes have for our understanding of gravity?

The study of photon orbits around black holes allows scientists to test and validate our current understanding of gravity, specifically in the context of extreme gravitational fields. It also provides insights into the behavior of light in these extreme conditions, which can help us better understand the nature of space and time.

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