All Questions
Tagged with black-holes event-horizon
1,182
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What happens if we throw the observer in a black hole?
Sorry if this sounds like a silly question, but what would happen if a scientist observes Schrodinger's cat alive, but is then thrown into a black hole before he has leaked any information to the ...
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Does a geodesic exist that will take someone across the event horizon?
I saw the movie "Interstellar" a few years back, and was amazed that Cooper was able to fall from 1 AU into a black hole before his daughter turned 110. Intuitively, I would think that there ...
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Is entropy dependent on mass alone?
The entropy of a non-rotating, non-charged black hole is only proportional to the surface area of its event horizon (Bekenstein, 1973).
The area of the event horizon of a spherical black hole is only ...
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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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Why isn't there an event horizon in the negative mass Schwarzschild metric?
The negative mass Schwarzschild metric has no event horizon.
Why isnt there a particular radius in which spactime flows outwards at the speed of light? This would imply a region of the solution for ...
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Can light "phase through" a small black hole?
Suppose we have a small black hole, maybe $1\ \mathrm{cm}$ in diameter, and a ray of light with a wavelength of $10\ \mathrm{m}$ (or more, if necessary) is exactly aligned with it.
Suppose the black ...
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Penrose diagrams and Holographic Principle
What would the Penrose Diagram look like that represented a black hole (call it Black Hole-B), inside of a massive black hole (Black Hole-A), in our universe?
and, as inside of the Penrose diagram for ...
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Why do we defer to GR when describing black holes rather than rely on QM?
This is a broad question but it's well documented that GR and QM are very well tested in their own domains but they conflict around black holes.
Picture a neutron star slowly accreting matter until it'...
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If it's a common myth that a black hole contains a singularity, what does a black hole actually (likely) contain?
It's a common myth (especially in popsci) that a black hole contains a singularity. However, I cannot find an explanation for what we think a black hole actually does contain. The best I've seen is &...
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Why negative energy particles not created near a black hole? [duplicate]
If you take empty space right next to a black hole once in awhile, you will get a positive particle being admitted in the opposite direction of the black hole. In the creation of the photon this ...
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Mass distribution of a black hole
One of my references states that the moment of inertia of a black hole (as might be deduced from a safe distance outside the event horizon) is I(bh) = mr^2 where r is the radius of the event horizon. ...
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Closest possible flyby to a nonrotating supermassive black hole
Imagine you think Laplace is the last word on black holes. That is, you are aware of the radius for which the escape velocity is $c$, but you think gravity is Newtonian. You set your spacecraft on a ...
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Is the Newtonian Darkstar event horizon half that of Schwarzschild? [duplicate]
Idk where, but at some point i heared the Event Horizons of a Schwarzschild black hole and Darkstar coincidentally are the same size. I have since then done a lot of stuff in GR, including Kerr black ...
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How to derive the surface gravity in terms of redshift factor in static spacetime?
I am following Carroll's book "Spacetime and Geometry" p. 245-247. I have the following expression for the surface gravity of a Killing horizon:
$$\kappa^2=-\frac{1}{2}(\nabla_{\mu}K_{\nu})(\...
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Can a body escape a black hole by being thrusted? [duplicate]
I am told many time that nothing can escape black-hole because black-holes escape velocity is more than speed of light. But we know object don't necessarily have to exceed speed of light to escape a ...
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