Astronomy Stack Exchange
Astronomy Stack Exchange

Questions tagged [black-hole]

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

Questions regarding points of extremely high mass density, which creates an extremely strong gravitational field from which light cannot escape. Black holes are formed when a massive star ($>10M_\odot$) goes supernova and collapses into one.

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How do we know that black holes are spinning?

How is it possible to know if a black hole is spinning or not? If a planet is spinning, you can see it clearly but you can't really see a black hole. Next thing would be that matter interacts with adjacent matter and we could see in which direction…
sirzento
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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?
user19
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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.
Pavel Voronin
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Escaping a black hole

I often hear that nothing can escape a black hole because its "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 impossible assumptions, but I'm trying to understand…
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Do Schwarzschild black holes exist in reality?

Do Schwarzschild black holes exist in reality? I have searched answer for this question but am not fully satisfied. Everything in the universe, including planets, stars, and galaxies, is spinning. How can something nonrotating/non-spinning exist in…
apk
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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)
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Is there a maximum size for a black hole?

As far as I understand it black holes radiate Hawking radiation and probably gravity waves, which over time causes them to lose mass and eventually evaporate after almost unfathomable amounts of time. I've also read that black holes eventually have…
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Does blackhole merging break their event horizon segregation?

So far as I know, if we have 2 blackholes A and B, both having their own event horizons, then what's inside the event horizon of A remains completely unknown to us, and same for what's inside the event horizon of B. Now, suppose A and B coalesce…
Xenos
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Infalling observer could never cross Black Hole event horizon?

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 gravitational field near a black hole causes time…
John Davies
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M87 Black hole. Why can we see the blackness?

So, as the title states, why are we able to actually see the 'blackness' of the black hole? I get that what we are actually seeing is the event horizon, or accretion disk. But should this not extend all the way round? Surely the black hole is not a…
MCG
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Can I make a black hole with one or two atoms?

So I was watching something that said if we compressed Earth into the size of a peanut: we would get a black hole; if we compressed Mount Everest into a few nano-meters; we would get a black hole. Can I make a black hole with one or two atoms? If…
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Is it possible that some stars are already black holes yet we see light emitted from before becoming a black hole?

For stars we see that are burning fuel at a fast rate, that are very bright, (or any star for that matter sufficiently far away from us) could it be that they are already black holes (the sufficiently large ones) and we are just seeing the light…
gigatexal
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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?
Timtech
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Do black holes have energy?

So black holes are created by certain dying stars and when the star runs out of nuclear energy gravity wins out and the star implodes. An entire star’s mass collapses down into a smaller and smaller volume of space. Which then creates a black hole,…
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Is the initial gravity of the black hole the same as the mass of the object that created it?

Is the gravity of a black hole the same or more than the original star that created it, before the black hole gets more matter? Is the gravity proportional to the initial mass?
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