Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape.

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21
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6answers
434 views

How are black holes found?

Black holes have so much gravity that even light can't escape from them. If we can't see them, and the suck up all electromagnetic radiation, then how can we find them?
16
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3answers
348 views

Why can't light escape from a black hole?

I've heard that light can't escape from a black hole. Can it? If not, why?
14
votes
2answers
223 views

What are practical considerations for backyard radio-astronomy detection of black holes?

Evidently, direct observation of a black hole for an amateur astronomer, such as described for what professionals do in the question "How are black holes found?" would be nigh on impossible, so the ...
12
votes
4answers
189 views

What are the differences between a Black Hole and a Supermassive Black Hole

From what I understand, the mass of a black hole should be nearly infinite, how much more massive can something get? Is the name to be literally interpreted such that a Supermassive Black Hole just ...
12
votes
4answers
500 views

Can we (theoretically) spin the black hole so strong that it will be broken apart by centrifugal force?

I can't imagine the forces involved in black holes' lives. So please, help me to find out, if it is possible or not to destroy black hole in this specific way.
11
votes
1answer
108 views

Has Hawking Radiation Ever Been Observed?

I know Hawking Radiation has firm theoretical footing, but has a signal ever actually been observed? What observational research is being done to attempt to see this effect? Is it simply too tall an ...
11
votes
1answer
507 views

How does neutron star collapse into black hole?

We know the spectacular explosions of supernovae, that when heavy enough, form black holes. The explosive emission of both electromagnetic radiation and massive amounts of matter is clearly observable ...
10
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2answers
172 views

Dimensions of a black hole

How big can a black hole become and how small can a black hole become?(minimum and maximum dimensions of a black hole)
10
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2answers
126 views

Will an observer falling into a black hole be able to witness any future events in the universe outside the black hole?

I know someone or something sucked into a black hole could not survive, but is the bending of light so immense that an observer falling into a black hole will be able to witness any future events in ...
9
votes
1answer
99 views

Which came first: black holes or galaxies?

In other terms, did galaxies grow around black holes at their center?
8
votes
5answers
169 views

Orbiting around a black hole

Is it possible (for either a satellite or a planet) to orbit around a black hole? Do they attract everything around themselves into the center? Or they just affect gravitational force just like stars? ...
8
votes
1answer
85 views

Can any information leave a black hole?

Referring to this question, is there any information that can leave black holes? Are they causing a permanent information loss in our universe?
7
votes
3answers
71 views

Are there ways other than the collapse of a star which have been observed to form black holes?

Every time I hear about a black hole, it's always in conjunction with the collapse of a star. Have any other processes been observed to create a black hole?
7
votes
2answers
154 views

How are black holes doors to other universes?

I'm watching MIT OpenCourseWare lectures on general relativity and not too long into the first lecture the professor stated that the Kerr Black Hole solution allowed for travel between universes. How ...
7
votes
1answer
91 views

Is it safer to be near a star or a black hole?

If a star or black hole neared the solar system, which would do the least damage? For the sake of a good comparison, lets assume the candidate star is an "average" 5 solar mass star, and the black ...
7
votes
1answer
99 views

Timeline of falling into a blackhole

For some "average sized" black hole, how long would it take for a distant (spacesuit-wearing!) astronaut to: be able to see the gravitational lensing with the naked eye clearly feel the gravity ...
6
votes
2answers
91 views

If nothing travels at the speed of light, except light, how can a black hole also pull light into itself?

Is it because it has super massive gravity and energy? Or is it some sort of an anti-light component in it because it used to be a star?
6
votes
2answers
143 views

Why don't Neutron Stars form event horizon?

Trying to compare density of Black Holes and Neutron Stars I came up with the following: A typical neutron star has a mass between about 1.4 and 3.2 solar masses1[3] (see Chandrasekhar Limit), ...
6
votes
2answers
165 views

Does matter accumulate just outside the event horizon of a black hole?

My understanding is that time slows and approaches stopping when approaching the event horizon of a black hole. I have seen this explained several places, including a brief explanation in the last ...
5
votes
3answers
134 views

What shape are black holes theorized to be?

I have always been curious about what black holes (or their event horizons) would look like if we could directly observe them. I notice that they tend to be depicted as flat holes in space but it ...
5
votes
3answers
161 views

What is a singularity? What is at the center of a black hole? Specifically regarding space-time

So because I can only really think of space-time in 2-dimensions like a sheet of something, my assumptions might be wrong to begin with. I was watching a YouTube video on black-holes and there was a ...
5
votes
2answers
159 views

What can we expect from the first accurate image of a black hole? (wich will be taken soon)

From recent news from the Max Planck Institute for Radio Astronomy: The European Research Council (ERC) has awarded 14 Million Euros to a team of European astrophysicists to construct the first ...
5
votes
1answer
87 views

Can a black hole reach a limit where it can no longer attract more matter?

Can a black hole reach a limit where it can no longer attract more matter? If so, what happens with that black hole? Does the black hole die? Does the black hole decrease its size?
4
votes
3answers
107 views

Find distance from star to star?

How do you find the distance from a star/planet/black hole to another? I know people can calculate the distance from Earth to a star, but what about from one to another?
4
votes
4answers
394 views

Escaping a black hole

I often hear that nothing can escape a black hole because it's "escape velocity" is greater than c. If that is accurate, what about the following. I know that the following has a lot of most likely ...
4
votes
2answers
136 views

Why do black holes have jets and accretion disks?

If supermassive black holes possess the gravity required to prevent the escape of photons and other mass particles, why do jets and accretion disks form? They seem to indicate that something is ...
4
votes
1answer
110 views

Collision of 2 black holes

There is a large number of visible Supernovas. Each week - about a 20 Supernovas Type 1a around the Universe. Is there collisions of Black Holes? What is this collision called? E.g. 2 black holes ...
4
votes
2answers
104 views

Why one cannot escape from a black hole [duplicate]

The usual explanation is that escape velocity of a black hole is above speed of light, therefore nothing can escape because nothing can move faster than light. This is however a fallacy, because ...
4
votes
1answer
33 views

Why do X-ray binaries such as GRS-1915 have active and quiet states?

X-ray binaries such as GRS-1915 feature a black hole and a regular star. The x-ray luminosity is likely related to the rate of mass flow into the black hole from the star so when there is a lot of ...
4
votes
1answer
83 views

Does gravitational lensing cause a black-hole to be the main 'source' of light in a given area?

Light gets bent around high-gravity sources, such as a black-hole. A source of light, say A, is directly observed in its 'true' position and some of its light is bent around the black-hole, X, which ...
3
votes
2answers
71 views

What is a wormhole?

I have learned that there are white holes and black holes in the universe, but I am confused as to what a wormhole is. Is it a tunnel that connects black and white holes?
3
votes
2answers
114 views

Are black holes orbiting around each other?

Obviously, bodies with low gravity force orbit around another one with higher gravity force, if they are close enough to each other. Is it true also for objects like black holes? Are they even able ...
3
votes
2answers
98 views

Observational Evidence for the Existence of Black Holes

What is the direct observational evidence that black holes exist? I have read that black holes have been detected through X-ray emission. What is some other observational evidence for black holes?
3
votes
1answer
66 views

How many black holes exist?

How many black holes exist and what is their distrubtion over mass? There is a list of black holes, but I'm interested in an estimate of all black holes in the visible universe.
3
votes
2answers
93 views

Why does time get slow near a black hole? [closed]

Why exactly does time get slow around a black hole? And does it provide a way to go into the future?
3
votes
2answers
148 views

Do black holes die?

I know of stars actually dying (exploding as a supernova) but I have never heard of what happen to black holes. Do they continue to live forever, waiting there for more matter to absorb? Do they ...
3
votes
1answer
82 views

Internet Resource which register all Ultra-long Gamma-Ray Bursts

I read in a scientific magazine there was new gamma bursts that last longer than usual. One was detected during december 2010, also known as Christmas Burst: GRB 101225A and another one in 9th of ...
3
votes
1answer
61 views

What does it mean for a black hole to “evaporate”?

It says in this Wikipedia's article: Entropy, however, implies heat and therefore temperature. The loss of energy also suggests that black holes do not last forever, but rather "evaporate" slowly. ...
2
votes
1answer
149 views

Would time go by infinitely fast when crossing the event horizon of a black hole?

If you were to fall into a black hole, my understanding is that from your reference point, time would speed up (looking out to the rest of the universe), approaching infinity when approaching the ...
2
votes
1answer
59 views

What type of energy is escaping from black-hole's poles?

Following this article, it is stated that: As a star drifts too close to a supermassive black hole, intense tidal stresses rip the star to shreds. As this happens, the shredded material will ...
2
votes
1answer
120 views

Black Hole / Hawking Radiation: Why only capture anti-particle?

I may have some specifics wrong here. If so, don't focus on those. Just focus on the general thrust of my question. I "understand" (cough) that particle/anti-particle pairs form spontaneously in ...
2
votes
2answers
128 views

What is Event Horizon of a Black Hole? [closed]

The boundary of a black hole is said to be surrounded by event horizon - the point of no return! What is its significance in terms of general relativity?
2
votes
1answer
66 views

What is the optimal escape trajectory from near a black hole?

Consider a space ship that is being drawn closer to a black hole. The crew begins to notice the effects, and discovers that they are nearing the black hole. They then manage to halt their ...
2
votes
2answers
49 views

how to know the nature of the companion in a neutron star binary?

The companion could be a main sequence star, white dwarf, neutron star or black hole. We detected pulsar-pulsar binaryhere several decades ago. But if one of the pulsar does not radiate towards us, ...
2
votes
1answer
70 views

What does black hole evaporation correspond to in the accelerating universe / black hole analogy?

In the same way, as a black hole emits Hawking radiation corresponding to its temperature $$ T = \frac{\hbar}{r_{BH}} $$ the accelerating universe can be described as all of the stuff falling ...
2
votes
1answer
81 views

Could black holes be creators of dark matter?

At the tremendous forces of gravity inside a black hole, can "matter" be transformed into a more degenerate form; "dark matter" (if that truly what dark matter is)? I know the inside of a black hole ...
2
votes
1answer
75 views

Black Holes emitting Hawking radiation

I've read that even light cannot escape from black holes. The speed of light is theoretically predicted to be the escape velocity of a black hole. I've also read that the general notion that nothing ...
2
votes
1answer
63 views

How is space-time bent by black holes?

I just read When a star becomes a black hole, does its gravitational power become stronger? and it confused me a bit; I always thought black holes are supermassive and that is why they bend ...
2
votes
1answer
111 views

Statistically, what would the average distance of the closest black hole be?

The closest confirmed black hole is several thousand light years away from earth. Our galaxy has about 100 billion stars. I didn't find any reliable information on the black hole count of ratio versus ...
2
votes
1answer
108 views

What if the black hole in the center of the galaxy grew faster?

Imagine that hypothetically the black hole in the center of the milky way gradually increased in mass by for example 50% every year. That is exponential increase in mass. Which visual effects would ...