All Questions
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Black Holes and Gravity [duplicate]
We know that nothing including light can escape the gravitational pull of black hole. Now special relativity says that nothing travels faster than speed of light. Then how can effects of gravity due ...
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Counterintuitive effect between event horizons of a 'binary black hole system'
I recently posted a question on my 'mobile phone profile' where I cannot post images and videos so I am trying to use this profile to solve my incomprehension of a gravitational-tidal effect that ...
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2
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730
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Question about light orthogonal to an event horizon
Picture a light wave orthogonal to and just above the event horizon of a black hole, fired directly away from the black hole.
If the black hole is of sufficient mass, the light would be pulled back ...
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2
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135
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A closed laboratory free falls and approaches the event horizon of a Black Hole. Are measurements of physical constants affected?
A closed laboratory is in perfect free fall and hence is an inertial frame. This lab is falling toward the event horizon of a Black Hole. The lab is sufficiently small and the event horizon is ...
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Can someone adjudicate the conflicting answers to "what is the velocity when falling at the event horizon of a black hole"?
I personally like Sarat Kant's answer at Why can an object not reach the speed of light by falling in a gravitational field with constant acceleration?. It makes sense to me. I would just add that ...
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2
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2
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What happens to light in the middle of a BH binary?
A BH binary is a system of two black holes orbiting each other in close orbit.
https://en.wikipedia.org/wiki/Binary_black_hole
Now on this wiki page, there is a simulation of the merging black holes,...
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1
answer
271
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"Black hole spins at $X$% of the speed of light", what does that mean?
I've seen a few news stories recently (example, example) about some black holes spinning at X% of the speed of light. What does that mean? What exactly is moving at that speed, and with respect to ...
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Black Holes without Schwartzschild Radius condition? [duplicate]
Reading this comment makes me ask what does that actually mean that
In fact, if you are close enough to $c$, the mass-equivalent of your kinetic energy may be enough to make you appear as a black ...
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Rotating Black Holes
All stars rotate. And the more they contract the faster the rotation, so is there such a thing as a non-rotating black hole? And as gravity is less at the equator of a rotating star, assuming that ...
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Could harm due to spaghettification be mitigated by entering a black hole at almost the speed of light?
Say that we wanted to send a probe into a black hole, perhaps hoping to see if it's actually a wormhole that might transport the probe elsewhere.
Upon approaching a black hole, the probe would undergo ...
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1
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124
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Escape velocity of Kerr black Hole [duplicate]
Do the event horizon of Kerr black Hole have escape velocity is equal to the speed of light same Schwarzschild black hole?
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2
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What would happen if a planet's escape velocity exceeded the speed of light?
What would happen if a planet's escape velocity exceeded the speed of light? Would it also collapse into a black hole (by Heisenberg's uncertainty principle and Pauli's exclusion principle) or would ...
user220323
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115
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Does space expansion mean the escape velocity at a black hole event horizon is strictly less than $c$?
The title pretty much sums it up.
I could ask this question slightly differently; does the expansion of space cause the effective event horizon to shrink below what it would be for flat space?
If so,...
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3
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318
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Relativistic kinetic energy has no upper bound, so why is there a Schwarzschild radius?
Schwartzschild radius is the distance from the center of a body at which, the escape velocity will be equal to the speed of light, i.e. when $$\frac{2GM}{R} = c^2.$$ However, here it is assumed that ...
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4
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Can you outrun a photon inside the event horizon of a black hole?
I was watching the YouToube video How Time Becomes Space Inside a Black Hole, by PBS Space Time, about how space and time flip within the event horizon.
The way the narrator seems to explain it, the ...
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