All Questions
Tagged with black-holes photons
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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 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, $\Delta T=6\pi M$...
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The Calculation of the Volume of a Photon Sphere around a Black Hole
So, I chose this question for my chemistry assignment which is "How many moles of photons will it take to fill up the volume of the photon sphere around Sagittarius A". I realized there is ...
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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 ...
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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 ...
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4
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Do black holes emit no light or does light fall back in black holes?
Black holes have such a strong gravity that escape velocity from it is more than speed of light which basically means nothing could escape it.
Everything in the universe have escape velocity. For ...
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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 ...
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Can photons form a black hole?
Can photons form black holes the same way as other matter? If there happens to be enough of them concentrated in an area of space so that enough energy exists within a radius to form an event horizon, ...
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Photon Sphere Planck Recalibration
Say a black hole's Schwarzchild radius is equal to the Planck length then a horizontal formula can be established as
$A = 4\pi \ell^2$
[1]. I've tried to find an analogue of this set up online but can'...
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1
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What is the formula for the radius of the photon sphere of a charge black hole? [closed]
What is the formula for the radius of the photon sphere of a charge black hole?
I've found the formula for a Schwarzschild black hole and a Kerr black hole but despite some googling but I can't find ...
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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 ...
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If the black hole attracts photons do they do the same with respect the black hole?
If two bodies interact they interchange force carriers and as 3rd Newton law states as the one body influences the other in the same way the other body would be doing the same to the first body. So am ...
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Calculating divergence and flux of geodesic word lines
Given a family of neighbouring geodesic word lines, is there a way of calculating properties such as their divergence or flux? maybe by converting the tangent vectors of the world lines to a vector ...
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Numerical calculation of spherical photon orbits near Kerr black hole
I'm using RK4 method for solving differential equation
$$\frac{d\theta}{d\phi}=\pm(2-2r)\frac{\sqrt{Q-\left(\frac{\Phi^2}{\sin^2\theta}-1\right)\cos^2}\theta}{2r+\left(r^2+\cos^2\theta-2r\right)\frac{\...
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How can a black hole have electromagnetic field? [duplicate]
I know that everything that is shaped from gravity force is rotating, and gravity is a central force, but I want to know how we can understand that a black hole has an angular momentum? By which sign ...
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Do light particles have thrust? [duplicate]
I understand that nothing is faster than light and that it can not escape a black hole. However, light particles may be fast, but perhaps it can't escape a black hole due to it's lack of thrust power? ...
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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 ...
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Would a black hole act as a particle accelerator between the photon sphere and the event horizon?
I'm trying to understand the behavior of photons between the photon sphere and the event horizon. Here is what I think I understand so far :
the radius of the PS is 1.5 times the Schwarzschild radius
...
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The effect black holes have on light
We all know that light loses its energy when it is moving through expanding space and time. And sense a black hole can be summed up to a super compressed space time, shouldn't that mean that a photon ...
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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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In theory (because light can still enter a black hole) if you are inside of the event horizon, could you see outside of it? [duplicate]
To my limited knowledge, it should be possible for you to see from inside of a black hole. Is this true, or am I missing something?
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Radial motion of a photon in Schwarzschild spacetime
For photon worldlines in the equatorial plane of the Schwarzschild coordinate system ($\theta=\frac{\pi}{2}$) in Schwarzschild space-time, the metric equation is given by,
$$-\Big(1-\frac{2GM}{r}\Big)...
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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 ...
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Can black holes move at the speed of light? If so, what would its curvature look like? [closed]
This question has more to do with the curvature of moving bodies but I will first start with this.
If a photon has enough energy, then it could presumably become a black hole (kugelblitz). I see no ...
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Black holes bending light [duplicate]
Ok so I've been watching some videos about black holes but there is one thing I don't get: how can light be bent by black holes since photons don't have any mass?
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Regarding the radial motion of photons
Photons move on null geodesics and the equation of motion on equatorial plane after some algebra can be written as
$$e^{\nu}\dot{t}^2-e^{-\nu}\dot{r}^2-r^2\dot{\phi}^2 = 0$$
$\phi =0$ for the radial ...
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Photons past the event horizon [duplicate]
What would happen if, beneath the event horizon, a photon was emitted outwards along the radius of the black hole? It's speed can't change to any observer in any reference frame, but it surely cannot ...
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Why is a black hole referred to as massive? [duplicate]
I am reading Brief Answers To The Big Questions by Stephen Hawking. In the very first chapter he writes,
A typical black hole is a star so massive it has collapsed on itself. It's so massive that not ...
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If an event horizon never forms for an outside observer, then what do (or don't) we see in the middle area on this real image of an actual black hole?
There are a lot of questions about the m87 image on this site, non of them actually answer my question.
I have read this question:
Does an expanding event horizon "swallow" nearby objects?
...
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Could an infinite number of photons fit into a finite space?
As photons are quantum particles and basically waves in a quantum field, could an infinite number of photons exist in a closed space described by finite numbers? Does the answer to this apply to other ...
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