What do you think a Black Hole looks like?

[Lunar Echo 10,334]

So in a couple of year from now we should be getting imagery of what a black hole looks like. I wanted to ask the question on what are current thoughts are on just how a black holes look. So, what is it you think a black hole looks like? Do you believe it will be the same as what we've been exposed to so far?

 

I believe it looks something like this:

 

 

For all we know it could look like something we've never seen before.

Edited September 21, 2015 by Lunar Echo

[Scrubbed user 3,415]

I do believe that a black hole is exactly what it says on the the tin: a mass of extreme gravitational pull that nothing can escape from, not even light.

[Untitled Goose Q 5,136]

Technically, a black hole doesn't look like anything, due to vision being caused by reflected light. and not being able to reflect light off something with such an intense gravitational pull.

 

You might be able to see something once you get past the event horizon, but good luck getting back and telling us.

[PROJECT: Simon 3,953]

A black hole? A black hole~! xD But seriously, I think it looks like that some hole in Transformers 3~ xDDD <3 <3  

[Starshine 16,330]

Pretty sure we can say what a shadow looks like even if there's isn't exactly anything inside that particular area, we can trace around the lack of reflected light and figures out what it looks like. Does it looks like something made by a deer, a bull, or a chainsaw-wielding maniac? We can tell

 

I think a black hole would just look like a sphere, or a circle. Everything in it is crushed by the sheer gravity down to a single point, I don't think there would be any room of variations into it, just a smooth sphere of starstuff.

*bored*

[Raritas 6,820]

Science tells us that a black hole looks like... Well... Nothing. Not even light escapes it. If we do see one, we'll do well to spot it. Although, it depends on the surroundings, if it is mid way through eating up a star system, I think we'll have a good idea of whether there's one there, and what it looks like

[Chaton 3,765]

A black hole doesn't look like anything. It sucks everything in, even light. It is literally the absence of everything apart from immense gravity. The only way we can "see" them is either seeing a bunch of matter and energy being sucked into nothing and the high amounts of gravity.

[SasQ 1,355]

First of all, the question implicitly assumes that such thing as a black hole exists.

For me, it is still an open question, since I don't know of any verified observation of any black hole in the Universe. There are only speculations about nearly every weird gravitational effect found in distant galaxies. Even if many scientists try to convince us that they found evidence for black holes, I've seen no convincing evidence so far, just speculations, simulations, and other unverified theories. But it seems that everyone forgot about that implicit assumption, because it is, well, implicit: each question about black holes asks about something else, like their features, how do they work etc., but I see no questions anymore about whether they exist at all. I think I might be only one in doubt

 

Second, if such a thing as a black hole exists anyway, it definitely won't look like most of the images of black holes you can find on Google, e.g. this one:

 

 

Those images are PURE FANTASY!

Why?

Because a black hole is not just a simple bathtub sink hole where everything rotates around until it goes to its middle, where it sinks down to form a whirling stream of water. There's no 2-dimensional "surface" in space. Space is 3-dimensional, as well as black holes. Matter goes towards them from every direction, and every line of sight ends up in it on the event horizon, no matter what direction you look at it. Their centres are pretty much spherical. So there is a "ball" in the middle which doesn't let any light to escape its surface (the event horizon), so it will appear as a totally black round spot. A black sun, if you like.

 

Sure, there can be a spiral disk around it if there was some matter around (e.g. a twin star), because the angular momentum is conserved and the net angular momentum of the entire star dust and gases spiralling towards the "black sun" would be just one axis, so the overall shape of that dust would be a disk, similar to a spiral galaxy. (Some scientists claim that in the centre of every galaxy there is a humongous black hole, but no one ever been there, so how can we even trust them? )

 

But there's something more: The black hole has a very strong gravitational field around it, farther from the centre than the event horizon, and this gravity field would bend the rays of light around it, sometimes even into close orbits. So you would see a warp / lens effect around the black hole. Here are some example images from physics simulations (keep in mind, though: they are just simulations! not pictures of real objects!):

 

 

http://i.stack.imgur.com/67mCp.jpg [warning: a big image]

 

And here's a video which demonstrates how would it look like if a black hole formed in a class room:

 

 

Notice how the space seems to bend and warp at first, in full 3D. The moment where the black hole forms in the middle is when the image turns over to its upside-down mirror image (that is, pretty much reversing all the directions in 3D space). The event horizon is then the border line between the "normal" image and the "perverted" image. It will start getting more and more black with time, when it traps more and more light rays (that is, when they world lines go through the event horizon). If a black hole existed from the beginning of the Universe, its centre would appear black all the time.

[ThatOneComrade 1,091]

I imagine a huge hole in the middle of space that stars are attracted to, and once they get too close they disappear in the darkness

[Justin_Case001 4,860]

I think it looks like Link's mouth after he at that edible cake ink.

https://www.youtube.com/watch?v=evNGHI669DE#t=12m40s

[Kyoshi Frost Wolf 40,439]

As others have pointed out, we cannot actually view black holes directly, we can only see the effects that they have on surrounding matter. Not sure how often we see such a thing but it is a very fascinating thing, in an eerie way. A gravitational pull that annihilates stars and even light itself? *shivers* Needless to say, I would not want to see one honestly.

 

 

I think it looks like Link's mouth after he at that edible cake ink.

https://www.youtube.com/watch?v=evNGHI669DE#t=12m40s

Best GMM moment ever. XD

[Steel Accord 6,658]

Well they don't "look" like anything. They're invisible. It's not a matter of "what do you think." We know this scientifically. Light can't escape it's gravitational pull, a black hole is imperceptible to the eye.

 

You can see where one IS because you can see space warping around it but the hole itself is just that, a hole. Not a lot TO make of it visually.

[SquipyCheetah 449]

Seeing as how a black hole cannot really be seen, I normally would just say that if you did see a black hole, it would look a lot like death. Meaning you'd be dead.

[xX_PinkDragon_Xx 417]

What do I think a black hole looks like? Kind of like this!

[Windseeker 546]

Would my toilet count?

 

Seriously, that thing can flush a towel.

[Guest]

 

He'll answer your question. 

[SCS 7,445]

I would be extremely surprised if a black hole could be observed by the human eye. It would be interesting to see if there would be any way for us to analyze its structure. If it really does suck in everything, including light, then that might extend to light not visible to the human eye. So, in essence, there might not be any way using our current technology to perceive or analyze a black hole on any kind of visual or structural level. Which is frustrating, because it would be fascinating to study whether or not black holes are hyperdimensional.

 

It seems more likely to me that we could perceive the existence of a black hole through measurement of physical properties in its general neighborhood.

[Espada12 17]

Like bread thats soft so not bagels from NY/NJ/PN

[SasQ 1,355]

Regarding the video above:

 

I did never buy that story about compressing matter to create a black hole. What does density have to do with anything? Density doesn't change the amount of mass and therefore doesn't influence gravitational field. From Gauss' Law it follows that the central field of a spherical massive object is the same as if all its mass were located at the centre anyway (as long as you're at the outside of that mass), so it doesn't really matter (huh) what its size is and how close-packed it is, because the gravitational field doesn't depend on that – it depends only on the amount of mass which produces it.

The problem isn't really about density, but about the Newton's equation for the law of gravitational attraction force:

F = -G m M / r² which, as we can see, is inversely proportional to the square of the distance from the source of gravitation (that is, from the centre of mass). So pretty much all that matters in this formula is this: F ∝ 1/r². If you graph it, you will see a hyperbola symmetric with respect to the F axis (vertical). For large distance it is low, but the closer to the centre, the faster it grows, because the number in the denominator gets very small; smaller than unity. And the inverse of very small is very big!

Now look what happens when r = 0: you get F = 1/0, that is, a division by zero! If it is true what mathematicians say that you cannot divide by zero, then there is an enormous flaw in the theory of gravity no one seems to complain about! So either the formula gets trickier as we come closer to the centre of mass (any mass!), or the theory is wrong altogether, because there are no paradoxes in Nature! They could be only in our theories when these theories are wrong. A paradox is something that cannot exist. And everything we encounter in Nature obviously exists

So let's suppose we are not at the centre yet, but very, veeery close; a smidgemeter from it, as Pinkie Pie would put it. How big is the force of gravity at that place? It's ENORMOUS! (Because if you divide something into tiny little pieces, the number of these pieces gets very big.) It's ALMOST INFINITE! You don't need Einstein and his Relativity theory to see that something fishy is going on here, because this would mean that there is a black hole inside EVERY piece of matter, located exactly at its centre! (Some scientists, such as Nassim Haramein, already claim that.) And the closer you are to that centre, the more you get sucked towards it. So it's not really about density. The "black hole" is a result of the classical Newtonian formula for gravity itself!

But there is a problem of practical nature, which makes that theory quite impossible in practice: suppose we have a 1 kg metal ball. It has this "black hole" at the centre, but the surface of that ball doesn't allow us to get close enough to that centre to feel that enormous force. If we sunk into the ball, the radius of the Gaussian surface gets smaller as well. In other words: not all mass is influencing us in that case – only the part of the ball which is closer to the centre than us, because the remaining part is "outside" for us and it doesn't attract us to the centre, but rather towards the outside, making the gravitational pull weaker. Because of that, the force of gravity starts to decay as we get closer to the centre, and drops to zero when we're at the centre. That's how Nature solves this paradox. No black holes, sorry

But there's that thing called Schwarzchild's radius. It can be calculated for EVERY gravitational field and for EVERY mass, even for an apple. It is a radius at which the gravitational force is so strong that you would have to be faster than light to be able to overcome the gravitational pull. R = 2 M G / c². For a 1 kg mass the Schwarzschild's radius is 1.485×10^-27 of a meter. So tiny So you would have to fit all that mass into such a small radius, because it is only when you observe that mass from the outside and you are that far from its centre, you feel that much pull that wouldn't let you escape even if you were light.

Even for billion of kilograms, the Schwarzschild's radius is still very small: 1.485×10^-18 m.

But for a mass of our Sun, the Schwarzschild's radius is pretty big already: around 3 kilometers. So if the Sun's mass could somehow fit inside a radius of 3 kilometers, the gravitational pull at its surface would stop light from escaping and the Sun would be a black hole.

"Aha!" – you may say – "So it IS about density! You had to squish the sun to a more dense state to produce a black hole out of it!"
Well, not quite.
The density for a 1 kg black hole is around 0.7×10⁸⁰ kg/m³. That's ENORMOUS!
But the density for a Sun's mass black hole is around 0.8×10²⁰ kg/m³. Still huge, but much smaller (and, most importantly, DIFFERENT!) than the previous one!
We can actually find a Schwarzschild's radius for ANY mass density whatsoever. The black hole condition is just that all that mass fits inside the Schwarzschild's radius. The radius and the mass would have to be very big if we wanted to have small density, e.g a density of a cloud, but it is still possible. For example, if my calculations are correct, in order to get a

1 kg/m³-dense black hole we would have to take around 4.2×10⁹ (or 4.2 billion) times our Sun's mass and fit it inside a sphere of a radius of 1.24×10¹⁰ km (or around 0.0013 of a light-year). The density of mass inside such a black hole would be just 1 kg/m³ which is a density of an Aerogel or almost the density of air at the sea level.

Pretty much a black hole out of thin air

 

I hope that this convinces you that it has nothing to do with density. It's about the strength of the gravitational force produced by a mass at some distance when you observe all that mass from the outside.

 

There's an interesting calculation involving our entire Universe as well: when you estimate its mass from Hubble's constant and Hubble's time, you can calculate the critical conditions for the Universe to become a black hole. And it turns out that the Universe fulfils these conditions! Which means that we're already living inside a black hole!

Doesn't feel like it, eh?

Just a food for thought.

 

---

 

As to the Numberphile channel the guy recommended at the end of his video, I would rather discourage that channel to you. They can seem as if they knew what they're doing when seen by a layman, but when you're interested in Mathematics a bit deeper than just some popular hodgepodge, you will spot many errors in their videos and flat out bullshit. Once I watched their video where they claimed that 1+2+3+4+5+... = -1/12 (sic!) and tried to justify it first with some "unusual properties of infinite series" and then with some "quantum effects", i facepalmed four-dimensionally inside my head and stopped watching their videos altogether ;P  There is NO WAY in which ANY series of POSITIVE numbers added together, no matter how many, could ever result in a NEGATIVE number. If their theories say that, they're simply WRONG and they need to rethink their assumptions and calculations. Their claim contradicts all the basic axioms of mathematics at so many levels that if they claim they're PhDs, someone should take their titles off as soon as possible until they do more damage to their clueless viewers.

Edited September 24, 2015 by SasQ

[ConcorDisparate 385]

I am not an expert, but I think the question should rather be : How does it look like around a black hole ? You wouldn't see light coming right from it, but the interesting part is how it bends the light around it.

 

I Heard about a movie recently, which was "approved" because they used the help of scientists to represent how a black hole would look like. In fact, they didn't really follow what they were told (I guess it would have been less impressive otherwise). Black holes really affect the light, creating mirror-like effects around them, which means you would see the exact same thing no matter the angle. But I was told about that, so I don't have precise information about it. I may be wrong I didn't check and, again, I'm not an expert.

[Codelyy 1,286]

Most people would think that it just looks like a very dark hole in space and it most likely is but we will never be able to see it unless we create something that can see without light...somehow.

 

You can only see things that light reflects off of and since a black holes gravitational pull is so strong it can pull in light, no light is reflecting off the black hole meaning you can't see it.

[SasQ 1,355]

@@Code, when I'm looking at your avatar, I wonder why you didn't say that a black hole looks like a wibbly-wobbly timy-wimey stuff BTW Tennant = best Doctor

 

 

 

You can only see things that light reflects off

 

Or which it is being emitted from (like from a Sun, for example). Just a minor nitpick

 

 

 

and since a black holes gravitational pull is so strong it can pull in light, no light is reflecting off the black hole meaning you can't see it.

 

What about the light that passes around it farther than the photon sphere? It just bends or wraps around, so in a way we can see around a black hole something that is behind it. (Gravity lensing.)

 

It could be interesting to bend light around an object in such a way that it would just pass around it and then restore to its original direction. This way we wouldn't see that particular object, but something that is behind it (just a bit farther than it really is). And if you think it is impossible, I once stumbled upon a presentation slides from some scientific conference where such experiments with bending light rays to cause invisibility/cloaking has been discussed and a couple computer simulations has been made. There are devices (some special waveguides) which can do it already with microwaves. So I guess that optical cloaking is not that far off in the future.

[Invincible 2,090]

Allow me to cover my own butt here by saying astrophysics and optics is not my field, far from it. But, i believe that the question is flawed.

 

Our vision is based on the light returned to our eyes from other objects (either from producing light or reflecting it).

 

A black hole is an object that absorbs light, and therefore cannot be directly seen.

 

What could be noticed is the gravitational lens effect, basically the light that isn't absorbed will cause the area around the black hole to appear distorted to us because of the pull on it. Still not the actual black hole, though.

 

All in theory, of course.

[Side Bird 565]

I believe it looks like the one from the movie Interstellar.

 

Lots of space missions and things happening in the next few years, very excited.

[Wayzer 1,418]

I was about to say something I thought was smart... then I read all the formulas people posted and was like.. nevermind XD I'm happy I understood what those posts meant though!