A black hole is a volume from which photons, or any matter, can not escape. More formally, the coordinate speed of light at the event horizon - the boundary of a black hole - is zero, as measured by a sufficiently separated observer.

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Is there a binary black hole system in the middle of the galaxy? [closed]

We have observed gravity effects from black holes in the center of galaxies, but galactic centers are dusty so we can’t tell if it’s one black hole or two black holes in a binary system in there. A ...
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Why isn't the Bekenstein-Hawking Entropy considered the quantum gravitational unification?

Based on the Bekenstein-Hawking Equation for Entropy, hasn't the relationship between quantum mechanics and gravity already been established.
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What will be the gravitational pull of the Sun if the Sun contracts to a black hole?

What will be the gravitational pull of the Sun if the Sun contracts to a black hole, and would the Sun be a Schwarzschild black hole or not?
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Theoretically, can a black hole collapse until it gets smaller than its Schwarzschild radius?

So, the concept is this: When a supergiant star collapses, its nucleus becomes a black hole. So, what if that black hole collapses again? I don't know if it is possible, but what if it happens?
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Do black holes violate the uncertainty principle?

If black holes have mass but no size, does that imply zero uncertainty in position? If so, what does that imply for uncertainty in momentum?
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What generates such a huge amount of gravitational attraction in a black hole?

I had been fascinated to hear that anything can be swallowed by a black hole. But what causes such a huge amount of gravitational force?
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What is the reasoning behind the idea that light cannot escape from a black hole? [duplicate]

According to the definition, light cannot escape from a black hole. How did scientists deduce that light cannot escape from a black hole?
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If nothing in the universe can travel faster than light, how come light can't escape a black hole? [duplicate]

Possible Duplicate: How does gravity escape a black hole? If nothing in the universe can travel faster than light, how come light can't escape a black hole? I mean, Einstein's relativity says ...
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Are we sure that there are at most x different types of black holes?

If I'm not mistaken, there are a limited different types of black holes. Depending on were I look, the black holes are categorizes according to size, or categorized according to surroundings and ...
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Could the recent evidence of a gravitational force orbiting the solar system indicate not the existence of a ninth planet, but rather a black hole?

In case you haven't heard already, researches at the California Institute of Technology discovered mathematical evidence of large object orbiting the sun at a distance about 20 times further than that ...
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Certain doubts regarding the movie 'Interstellar' [closed]

In the movie, or rather a scientific fiction, Interstellar, we saw in the last part, that the actor falls into the black hole, travels in time, which is a dimension inside the black hole, and then, ...
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What would happen to the Moon if Earth is turned into a black hole?

Assume that all of sudden the Earth is turned into a black hole. And the moon revolves around the Earth (before turning into a black hole). What would happen to the Moon after earth changes to black ...
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Is a blackhole just a neutrino with much more mass?

If there was a blackhole that had a mass similar to that of a neutrino ($0.320 ± 0.081\,\mathrm{eV/c^2}$), would we still be able to differentiate the blackhole from the neutrino? Is there any ...
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How can Maxwell's Demon erase information while a black hole can not?

It is stated, that information can't disappear even in black holes. On the other hand, it is stated, that mystic beings, like Maxwell demons, can easily erase any information if they just pay with ...
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Shape of accretion disk surrounding the black hole in Interstellar (film) [duplicate]

There is a black hole, called Gargantua, featured in the recent blockbuster Interstellar. I understand why the accretion disk is bright (friction), but why does it seem to be flowing in two ...
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Schwarzschild Radius vs Gravitational Pull? Error in Model?

I am a middle-school student who for fun has designed an simulation of gravity that finds the gravitational pull & then the Schwarzschild radius of the object, I have tested the program (coded in ...
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If you flew into a black hole

Would you outlive everyone? I'm coming from the point of view that time would be experienced more slowly (although not from your point of view) the denser the gravity gets.
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How can we detect a black hole? [duplicate]

If black holes are phenomena of very high density (gravitational singularities) which don't emit radiation how can we detect them so far away from us where so much other radiation can hide the black ...
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Where do black holes go?

According to many physicists, any matter near a black hole is obviously gravitated towards it, and transported to a parallel universe. As far as i know, black holes are made up of material particles, ...
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In what other fields of physics does “math break down”? [closed]

I've heard numerous articles and videos state that when it comes to black holes and singularities our "math breaks down". Is there any other areas in physics where math similarly "breaks down", where ...
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Black Hole Matter to Subatomic Exchange

When matter enters a black hole with a singularity the particles smaller than photons released come from within the black hole or do subatomic particles shed from matter just before matter passes the ...
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Spin of black hole?

Black hole have 3 properties Mass, Charge, Angular Momentum. As there is Angular Momentum it's means black hole is spinning. How would we know it is spinning in clockwise or anti-clockwise ? (in x,y,...
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How Can Anything Escape A Supermassive Black Hole?

Some of my questions haven't been well received, because I seem like I'm challenging well respected theories without having done the proper university training and study. I have been studying this ...
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Is the acceleration at the event horizon of a black hole independent of the magnitude of its radius?

Is the acceleration of a free-falling observer at the Schwarzschild radius of a black hole the same regardless of the numerical value of the radius (i.e. outside of a black hole, is the acceleration ...
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Roche Limits and black holes

I am curious due to the course of the idle research that I am doing (my hobby), and I am curious for various reasons as to the answer of this question. Please forgive me in advance for possible ...
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What is the mass required for a star to have the gravity equivalent to a black hole?

At what mass does the light from stars ( I am talking about stars and not black holes) fail to escape the star's gravity? Is it the same (minimum) mass required for an object to be called a black hole?...
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Can negative energy explain black holes?

I think black holes are peculiar and I want to know if there is a relation to negative energy. Does negative energy have positive mass and therefore can explain the nature of black holes? IS there any ...
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Can objects exit a black hole?

I read an article claiming that an object had been observed to be ejected from a black hole. This was the newest article I could find published on it but they still seem uncertain what the object was ...
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What was the frequency of the gravitational wave recently detected, and why?

In one early Internet post there was a graphic that appeared to show the gravitational wave (pulse) at about 30 cps. And another video it was stated that the gravitational wave would be as high as ...
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is the potential energy of a black hole infinity

It appears like black holes posses an escape velocity greater than the velocity of light. It takes an atom infinity energy to travel at speed of light.Do black holes posses that energy to retain light ...
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Black hole accretion disk

Does matter in a black hole's accretion disk eventually fall into the black hole? If no new matter is added to disk, how long does it take or the black hole to consume the entire accretion disk?
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How long does a black hole last after it becomes white hole?

According to Stephen Hawking's theory of black holes, once a sufficient mass has been lost through evaporation, the escape velocity $3 \times 10^8$ meters per second so light is able to escape from ...
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Schwarzschild radius in black hole density

The textbook from which I teach physics at the end of secondary school has a question about the density of a non-rotating black hole. Because the density at the singularity is perhaps infinite or ...
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233 views

How could the “Big Bang” singularity have actually expanded? [duplicate]

We have mountains of evidence about singularities and how they work, and we have mountains of evidence that the "Big Bang" was the origin of the universe as we know it. But if compressing enough ...
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Black Holes and Light [duplicate]

It is said that photons have zero rest mass so how can gravitational force of a black hole affect light? And if photons do have some effective mass while traveling at speed of light then only can a ...
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Charged particle singularity

Is it possible to manipulate magnetic/electric fields, similar to magnetic confinement technologies/penning traps, to compress charged particles into black holes?
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Quantum uncertainty of a singularity: A Black Hole Problem

A black hole in GR seems to have a sharply defined radius. Of zero, that is since all the mass has been compressed into the infinitely dense center point. However, shouldn't the fuzziness of quantum ...
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Temperatures at extreme densities

Cosmology (and astrophysics) talk about the "initial singularity" (IS, became the big bang) and "black hole singularities" (BS, inside black holes), and these appear to be quite different: The IS is ...
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Can we create a small black hole? [duplicate]

Suppose we create very large spherical body by using gamma rays generator and they will concentrate on a single point at the centre of sphere.We will place this spherical body thousands of kms above ...
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Spacetime around a Black Hole

If we consider the sun, then space-time is curve around it. My question is that what is the kind of curvature of space and time around the black hole. Is that space and time more curved around the ...
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Does time and time dilation exist in a black hole?

Since being near stronger gravitational fields causes time dilation, can this be generalized to the region beyond the event horizon? i.e , is it meaningful to say that someone outside the black hole ...
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Exact meaning of radial coordinate of the Schwarzschild metric

In this answer as well as on Wikipedia the radial coordinate of the Schwarzschild metric is described as follows: ...the r co-ordinate is the value you get by dividing the circumference of the ...
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Head on collision of two black holes

LHC was built to collide two atomic particles to study contents within them. There are millions and billions of black holes present throughout galaxies. As collision between the galaxies is common in ...
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What can be the probable escape speed from the event horizon of a black hole?

Is there any approximate escape speed value from the event horizon of a black hole or is it infinite ?
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Would those 'trapped' in a collapsing universe perceive space as expanding?

Let's say we have Uber Massif; a black hole so mindbogglingly huge, if you where to shrink the entire milkyway into a thimble Uber Massif would be the size of the milkyway. Those proportions need not ...
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Why does a black hole grow when it consumes matter? Isn't this a contradiction?

I've been thinking about this for a while but can't get my head around it. A black hole's mass is such that its gravity can overcome light. Its event horizon, as I see it, is the boundary up to which ...
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Black hole surrounding an object?

When a particle crosses the event horizon of a black hole, at one short moment in time would it appear for that particle as if it was surrounded by a black hole? Regardless of which direction you ...
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Do the stellar remnant in a black hole have spatial extent? [duplicate]

I am not talking about event horizons. I am talking about the actual remnant of stellar collapse. Is it just a point, hence the problem with the singularity? Or does it have a finite volume that we ...
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If a super massive black hole captures a very small black hole, would the smaller black hole be immune to spaghettification?

I think to answer this question we would have to fully understand the nature of black holes. It seems to me that the smaller black hole could have a lower density than the larger one. In this case the ...
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Smallest Black hole nessesary to devour Earth?

While looking into black holes I can across the idea of hawking radiation, and the fact that microscopic black holes would near instantaneously evaporate before doing any damage. However larger black ...