All Questions
Tagged with black-holes photons
100
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3
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Photonic black holes
"Can a photon turn into a black hole?" - usually the answer to this question is - it can't, because it has zero rest mass. However, when we derive the Schwarzchild Metric initially the $2M$ ...
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Photon Escape Angle From Black Hole
Consider a photon source emitting photons near the surface of a Schwarzschild black hole.
What angle, as a function of the source's radius from the event horizon, must the photons be emitted at such ...
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Is there a frequency limit for the pendulum near a black hole, and is this related to photons and the UV-cutoff?
I imagine a swinging pendulum being held outside a black hole, supported by the normal force of a rocket. The rocket is hovering the swinging pendulum right above the event horizon in the strong ...
- 6,112
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How close does a photon have to get to a black hole to do a full loop?
How close does a photon have to get to a black hole to do ONE full loop? By full loop I mean it curves once around the black hole, and then it ends up on the same trajectory as it was one before it ...
- 12.2k
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Orbital Photon Speed at the equatorial plane of a rotating black hole
I've been trying to calculate $d\phi/dt$ of photons orbiting a Kerr black hole (Kerr metric in Boyer-Lindquist coordinates) on the equatorial plane, both counter and along with its rotation. So I used ...
- 126
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Photons emitted at the event horizon?
While looking through the questions, a came across a section about black holes. I immediately though; what would happen if an atom is orbiting a black hole and emitted a photon perpendicular to the ...
- 126
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How would a photon act to the gravitational influence of a black hole which is attracting it 180° to it's direction?
With all this situation, it’s also given that the gravitational influence is strong enough to turn the photon back. Now, the photon is being attracted directly from behind the path it is travelling on,...
- 126
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364
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Falling angle of a photon near the event horizon
I have been doing simulations using Mathematica of light and matter paths (plotted in the $r, \phi$ Schwarzschild coordinates) around a black hole, in the Schwarzschild metric. This was in order to ...
- 126
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Why energy matters for light to escape event horizon?
I like to know why photon with sufficient energy can avoid being pulled into the event horizon? Most light will get trapped and forms into photon sphere while some can escape, isn't light supposed to ...
- 126
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Four-momentum of a photon emitted from an accretion disk
Consider a non-rotating compact object surrounded by a revolving accretion disk. A distant observer sees the disk in an edge-on position. The center of the disk may be taken as the origin of $r-\theta-...
- 126
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What is the Critical impact parameter for photons of a black hole?
What is the "Critical impact parameter" for photons of a Black hole with a Radius $r$?
Here I'm defing the Critical impact parameter $C$ as the value such that.
A photon with an impact ...
- 126
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2
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Why is the photon sphere spherical, but the accretion disk not?
As far as I understand, photons are massless, but are still subject to gravity, must follow the distortions of spacetime (including framedragging etc.), period.
Now the only answer on this site ...
- 207k
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Is it possible for the trajectory of a photon in curved time space to be circular?
I am currently working on some work with neutron stars so this led me to calculations of photon trajectories in curved spacetime.
These are the steps I followed to write code that would produce ...
- 126
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239
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Whats the difference between the Photon Sphere and the Marginally bound orbit?
Whats the difference between the Photon Sphere and the Marginally bound orbit?
Why does photon sphere have a radius of 1.5Rs, while the Marginally bound orbit has a radius of 2Rs?
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Photon speed for an observer at the photon sphere [closed]
I am asked to compute the orbital period of a photon, in the Scwarzschild spacetime, at the photon sphere for an observer at the same radius, $r^\star=3M$. I have computed the result, $\Delta T=6\pi M$...
