Questions tagged [black-hole]

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

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134 views

Why does gravity make time go slower and warp light?

I know that objects with lots of gravity are capable of warping light or slowing time (an example being a black hole). I also know this is because of the theory of relativity, but I need someone to ...
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Mini disk of a blackhole meaning

What is meant by the "mini disk" of a blackhole? Is it the same as accretion disk? If not, whats the difference? Eg: In the abstract of this paper https://arxiv.org/abs/1806.05697 it is mentioned "...
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Does matter accelerate to the speed of light as it approaches the singularity?

$$v_\mathrm e=\sqrt{\frac{2GM}r}$$ If we understand the escape velocity to be the speed needed to escape from the 'surface' of a gravitational object described by the above equation. It is equally ...
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Mass of a potential black hole in a binary system

So I've been given the velocity curve, parallax and apparent magnitude of a star in a binary system with what is potentially a black hole. I've calculated from the apparent magnitude and parallax that ...
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Is a black hole a three-dimensional or four-dimensional object? [closed]

Is a black hole a three dimensional or four-dimensional hole?
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Why does the author believe that the central mass that gas cloud HCN-0.009-0.044 orbits is smaller than our solar system?

Phys.org's Hiding black hole found says: A research team led by Shunya Takekawa at the National Astronomical Observatory of Japan noticed HCN-0.009-0.044, a gas cloud moving strangely near the center ...
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Super conductivity of black holes

As we all know that we cannot see black holes due to its strong gravitational force. But I think gravity is not the cause for invisibility of black holes. The temperature of a black hole is 1.4×10^-...
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How did the authors determine both the spatial size of gas cloud HCN-0.009-0.044 and its central mass at the same time?

Phys.org's Hiding black hole found says: A research team led by Shunya Takekawa at the National Astronomical Observatory of Japan noticed HCN-0.009-0.044, a gas cloud moving strangely near the center ...
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Singularities/ringularities and their properties

A black hole contains a singularity at its center. It is a zero-dimensional point, and it's where all its mass is located. So, my first question is: If a singularity contains all a black hole's mass,...
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Smallest mass of star to be a black hole? [duplicate]

It seems to me that I forgot the smallest mass of a star and its angular momentum in order to form a black hole. So I know that electron degeneracy pressure is overcome if the core is 1.4 solar ...
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Can Earth be ejected out of the solar system this way?

I found this image of what maybe a model of our solar system. Without a credible source I'm not sure I am looking at a star or black hole that comes close to our solar system and how it could throw ...
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Possible to use tachyons to explore black hole?

I read on a Wikipedia article lately that tachyons are theoretical particles which always travel at or above the speed of light. That means that when one passes us, we see two images, a blue shifted ...
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What happens if a black hole is produced inside another black hole?

Similar question here. The question I linked got me thinking. It is known that a black hole doesn't let anything escape its event horizon, not even light. Thus, naturally, anything that passes the ...
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Dropping a pebble into a black hole [duplicate]

If one were to drop, say, a pebble, from a sufficient distance, into a black hole. The pebble would continue to accelerate until it were just short of the speed of light. In the next moment it's speed ...
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Binary pairings that haven't been discovered yet?

Question: Are there any kinds of binary pairings that haven't been discovered yet? Any that are particularly significant, or that might shed some light on binary stellar evolution or theories of ...
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Roche Zone of a black hole vs Roche Zone of Neutron Star

Suppose a very unusually small back hole with the mass of about, lets say, 1.5 solar masses(hawking radiation should destroy a lot of mass let's assume). It thus would have a Roche limit smaller than ...
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433 views

Can a photon have a stable orbit around a black hole?

Can a black hole free from an accretion disk collect photons in the photon sphere in a prolonged stable orbit? Could enough photons be in orbit to shade the actual black hole with light? Would a ...
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Is this a black hole?

While researching about galaxies in Google sky, I came upon a strange area. Co-ordinates: 11h 6m 15.0 seconds | -77° 22' 9.8" A lot of space around this body is empty, is there a possibility that ...
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Is an elliptical orbit around a black hole, or an orbit consisting of three bodies (including the black hole) possible?

If this is possible, would it then lead to an object undergoing varying time dilation (predictable variation with elliptical and random variation with three body)?
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Shouldn't we not be able to see some black holes?

Whenever there is a picture of a black hole, (even though they are artist depictions, this is how they are described) most are shown kind of in a flat disk like this. My question is, why do we see ...
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Do falling bodies ever slow down?

I've had some discussions recently about black holes, and the issue of infalling bodies taking forever to reach the event horizon. That's essentially what Einstein said in his 1939 paper on a ...
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Infalling observer could never cross Black Hole event horizon? [duplicate]

I have an interest in cosmology, but I would no way consider myself an expert. It would be great if the more knowledgeable contributors would be able to answer the question I have posed. The intense ...
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Time Dilation and Particle Decay

I am teaching myself astronomy and I'm working on a basic problem regarding time dilation around black holes. The question is basically this: if a neutron were ejected from a nucleus at a distance of ...
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Why doesn't the vertical light beam get out of a black hole?

I'm asking this question as a follow-up to if light has no mass why is it affected by gravity? Imagine you’re standing on a gedanken planet, shining a laser beam straight up into space. The light ...
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How far away was the binary black hole that produced GW170729?

GW170729 was gravitational wave signal's detected by the Virgo and LIGO detectors. I read the following in a news report: Known as GW170729, in accordance with the date of its discovery (in US ...
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preserve information in a black hole

How is information preserved on the surface of a black hole? Is there an compression algorithm for storing the information? What if there is a uniformaly complex object dropped to the black hole? ...
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What is the exact meaning of vicinity of Black hole or a disk? the same as inside?

What is the exact meaning of vicinity of Blackhole or a disk? Is this the same as inside the horizon for black holes? If so, why people don't say inside of BH, simply. What is the difference? I use ...
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Is it possible for particles to be accelerated FTL inside BH travelling towards the singularity? [closed]

Maybe just maybe it is possible for a particle to travel FLT inside of black hole because of the singularity gravitational force This could be due to the fabric of space it self falling towards the ...
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Is the Bondi Radius the Same as the Schwarzschild radius?

$$2MG/c^2$$ This is the expression for both, but some authors use one name and it has confused me. Is there any distinction?
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Can blackholes appear white and black? [closed]

Depending on the angle you view a black hole could it appear white, black or grey? Excluding how the gravitational lensing would make all the light emitted either red or blue shifted creating a ...
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Could a distant black hole (detected due to its mass) be in reality a Dyson sphere?

When the black hole is only detected due to its gravitational effects on other stars and their light, could it be possible that it is in reality a working Dyson sphere? It would still have at least ...
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Need help with a simple Blackhole question

Suppose the amount of mass in a black hole doubles. Does the event horizon change? If so, how much does it change?
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What can be learned from, or noted in this LIGO Orrery video?

The Ars Technica article Physicists detected gravitational waves from four new black-hole mergers notes that This brings the total number of events detected by LIGO and Virgo to 11. It also has a ...
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Can hawking radiation be eaten by another blackhole?

Just a theory, from this video. At last, only the black holes are gonna exist and even they'll decay because of hawkings radiation. As black holes emit hawkings radiation, then if one emits it, ...
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Does a gravitational wave loses energy over distance?

How does a gravitational wave travel over vast distances without losing its energy? Could they go on forever as long as the Space? Thank you
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Black hole, escape velocity, going up?

I do know nothing can escape a black hole, and I understand popsci explanation of geodesics of space-time around and inside the event horizon. I however have some trouble with following thought ...
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How to convert factors of time dilation into something relatable? [duplicate]

On this post, Time according to the gravity of Sagittarius A? They found the factor of time on the varying distances from the SMBH, I am curious on how to turn those factors into relatable terms ...
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How does a blackhole burp?

Recently on the discovery channel I heard that a black hole burps matter out of it when it consumes more than it could process at a time. Given that even light cannot escape from a black hole, how ...
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Do all galaxies have a black hole in the center?

Would I be correct if I stated that all galaxies have a black hole in the center? Since other galaxies orbit around a center point in a galaxy - the barycenter, right? - I would assume at this point ...
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Could Planet Nine be a tiny black hole or an exotic compact object such that it escaped detection? What would its bounds be?

Planet Nine (a variant of the old X-Planet and Tyche-Thelistos hypothesis) proposes a super-earth planet at the edges of the solar system with a mass of around ten Earths. However, given the interest ...
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Since gravity is like an indent on a piece of paper (the space/time matrix) to a marble, can the black hole eventually suck in the matrix?

Can a black hole suck in time? People claim that if you were to put a bowling ball on a trampoline and rolled much smaller balls through the deppression, some would stay in "orbit", some would roll ...
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Could a black hole pass quiescently through the Oort cloud?

Imagine a stellar-mass black hole passing through the Oort cloud, perhaps a quarter to half a light-year from the Sun. How black would the black hole be? That is, any matter that fell into the black ...
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What cosmic disaster is most likely to happen? [closed]

Of all the different ways that the Earth can be destroyed what ways is the most likely that could happen?
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Could Black holes forge heavier elements that have yet to be discovered?

Observations The heaviest elements known in abundance in nature are forged deep within stars. These elements are made possible by the high densities/pressures within the stars. Black holes are known ...
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Once a black hole is formed, is there anything other than Hawking radiation which shortens its life?

Hawking radiation is supposed to very slowly evaporate a black hole (terms and conditions apply :] ). Apart from Hawking radiation, is there any mechanism or effect that can make a black hole cease ...
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How does the center of a black hole can contain so much mass? [duplicate]

We know that "In the center of a black hole is a gravitational singularity, a one-dimensional point which contains a huge mass in an infinitely small space, where density and gravity become ...
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Movement of the Sun in space

Does the Sun undergo any cycles or revolutions approximately every 24,000 years or 8.6 million years? In Hinduism it is believed that the Sun revolves in an elliptical orbit around a large mass at ...
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Astrophysical Jet Size?

I am wondering about what is the estimated size of astrophysical jet that shoots out from a black hole, I don’t know if it is determined by the size of a black hole. What would classify a black hole ...
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What is Propeller Effect exactly?

I find the original reference seems to be here. I still do not understand the mechanism. It is necessarily occur in neutron binaries? Anyone can introduce it in detail? This paper is old.
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What exactly is the accretion disk?

Is it really possible for material such as dust, gas and other stellar debris that come near the black hole, doesn't fall into it, instead forms a flattened band of spinning material?

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