What really goes on in black holes?

[GrassDragon]

I dont know much about this subject so i would like to hear all the theories out there. the few that ive heard include: black holes hold other universes, they serve as worm holes to other parts of our universe, and the ever popular, giant vacuum cleaner. Whats really goin on there?

[Mattimeo]

I like to think of black holes as actual holes in the space-time continuum and anything that passes the event horizon falls into the "hole" and ceases to exist.

[TranquilNightElf]

Black holes are like a whirlpool.
If you orbit around the circumference of the hole and at the speed of light then you won;t get sucked in.
Anything else thatn down you go.
Your molecules will disaasociate and will eventually be concentrated at singularity.

Now many people thuoght that black holes just suck things in and don;t actually exude anything.
this is not true...whenever it engulfs a large quantity of matter then a large plume of energies going to the top and bottom from the center can be isible.
Also in space matter and anti matter are always being produced except for a VERY short time and they annihilate themselves as soon as they are produced.
However at the edge of a blackhole it is possible for one of the antiparticles to be sucked in but its counterpart wuold be radiated out.This is called Hawking Radiation..

Also Wormholes "known" to connect blackholes, constantly expand and contract back to singularity.
The only hope of travelling via a wormhole would be to use exotic matter.
Normal matter has an inward trend of energy ie +ve energy,It pulls things into it self by way of gravity .
"Exotic Matter" on the other hand has -ve energies and has an outward flow of energy.This would prevent the worm from collapsing.

[WeekendLazyness]

Now where did you copy and paste that out of?

[OboeGuru]

I wouldn't say it's copy-pasted, there's too many typing errors. ;) Time to take a looksee in a few books.

[MacG]

I thought even Light cannot escape the black hole. Isn't the black hole a gravity well from a exploded star?

[Demon_Child]

This is one of those questions that no one can really figure out since Black holes have such a high gravimetric pressure that it is so great at the event horizon that it could even devour the biggest stars and solar systems as an snack.

[OboeGuru]

I thought even Light cannot escape the black hole. Isn't the black hole a gravity well from a exploded star?
One, it's an imploded star. Two, a lot of the "emitted light" is really the energy released from the inevitible collisons among particles and metter swirling into the singularity.

[WeekendLazyness]

This is one of those questions that no one can really figure out since Black holes have such a high gravimetric pressure that it is so great at the event horizon that it could even devour the biggest stars and solar systems as an snack.
It would actually have quite a hard time doing that. Since a black hole is not much than a superdense star that collapsed upon itself, it cannot have more mass than the original protostar had (including planetary material). Therefore, since the mass is the same, the gravity is the same and the black hole cannot pull anything new closer to it. And if it were to be able to pull all of this mass towards it, it would take a long time to suck this new mass in because of the accretion disk around the hole. It would swirl around the hole, and as it got closer, gain energy, thereby keeping it out of the black hole.

[OboeGuru]

It's been observed that some galaxies actually have a black hole at their center. o.O Keep in mind, WL, that a singularity is hypercompressed matter, making the black hole have a greater gravitational pull than the protostar.

[MacG]

One, it's an imploded star. Two, a lot of the "emitted light" is really the energy released from the inevitible collisons among particles and metter swirling into the singularity.Yeah, that makes more sense. Everything I have no idea.

I would enjoy reading about this if it was more lay man's terms, but not idiot's terms.

[OboeGuru]

Get the book Stephen Hawking's Universe: The Cosmos Explained. It's written expressly to explain that kind of stuff in layman's terms. :D

[TranquilNightElf]

Now where did you copy and paste that out of?
*looks shocked* :eek:
*gives hurtful glance* :(


Therefore, since the mass is the same, the gravity is the same and the black hole cannot pull anything new closer to it.

Actually The mass is way way more than the original like OboeGuru (and yes i know,I have to work on getting rid of my typos when I type fast :p) said.
Also black holes DO pull new matter closer to themselves ..it's just that only after the event horizon is point of no return.
There is supposed to be a massive blackhole at the centers of our galaxy.And it's been known from time to time to give out massive energy plumes several hundred of light years in length.

[OboeGuru]

Actually The mass is way way more than the original like OboeGuru (and yes i know,I have to work on getting rid of my typos when I type fast :p) said.
I wasn't saying that the mass is greater, that isn't true, the mass is the same. The gravitational pull is greater because of the immense density of the singularity dramatically increasing the specific gravity, or whatever it's called (for those physics buffs out there). :D

[TranquilNightElf]

whoops my bad..yes quite right....same mass but in a very much smaller area.

[Fenguin]

It would actually have quite a hard time doing that. Since a black hole is not much than a superdense star that collapsed upon itself, it cannot have more mass than the original protostar had (including planetary material). Therefore, since the mass is the same, the gravity is the same and the black hole cannot pull anything new closer to it. And if it were to be able to pull all of this mass towards it, it would take a long time to suck this new mass in because of the accretion disk around the hole. It would swirl around the hole, and as it got closer, gain energy, thereby keeping it out of the black hole.

It's not mass. It's density. Think of it in terms of general relativity [stuff with gravity make depressions in space-time]. Humongous density = huge depression = lots of suckage.

[OboeGuru]

...Which is basically what I was saying.

[WeekendLazyness]

But at several light years away, it doesn't really make a difference, does it? The net effect of the gravity would still be about the same on all other stars, wouldn't it?

[Fenguin]

That's like saying a vacuum cleaner doesn't work because when the Cheerios are a mile away from the vacuum cleaner, they don't get sucked in. o.O

[OboeGuru]

That's like saying a vacuum cleaner doesn't work because when the Cheerios are a mile away from the vacuum cleaner, they don't get sucked in. o.O
Right, it's simple physics. When calculating the force of gravity between two objects, the product of the two masses and the coefficient of gravitation is divided by the square of the distance, so at several light years' distance, the effect of the black hole's gravity is indeed negligible, but that's not to say it isn't enormously great at close proximity.

[Fenguin]

Physics nerd. :) I don't even want to think about physics right now... ;)

[OboeGuru]

Heh, I'm only a physics nerd about stuff that I understand, which isn't that much. And it's just one equation, forum slacker Fengy, so what if you've just had a whole sciency tournament...

I never heard of the whole wormhole thing before.

[TranquilNightElf]

I never heard of the whole wormhole thing before.

Really?..Chek it out in a book by Stephen Hawking called " A Brief History of Time".
It has a brief explanations of them.For more detailed explanations though it won't do.

[OboeGuru]

Okay, so it's in the Big Brother of the book I read... I swear, with anything related to our universe, one need only page through a Hawking book to find the answer.

[WeekendLazyness]

Right, it's simple physics. When calculating the force of gravity between two objects, the product of the two masses and the coefficient of gravitation is divided by the square of the distance, so at several light years' distance, the effect of the black hole's gravity is indeed negligible, but that's not to say it isn't enormously great at close proximity.
True. My teacher calls that the Grimm equation, the "i" being the division line. But that's besides the point. What I'm trying to say is that black holes don't suck up everything within the galaxy, only in closer proximity, such as in the case of a binary system.

[Fenguin]

But stars being sucked in have their gravity too. So they suck stars close to them, which suck stars close to them, etc etc etc :)

[Kahuzal]

I still don't like how my science department doesn't treat time as a vector quantity...
a+bi
gg no re.

[JamesDavis]

My understanding, which could be wrong of course, was that black holes can and do move around the universe, so what would happen if two black holes ran into each other?

[Fenguin]

The bigger black hole would eat the smaller black hole. Since the small back hole is nothing but a very dense piece of crap, and the big black whole is more massive/dense, it would suck the small black hole inside. ;)

[T-Dawg]

and the net result? a super uber black hole?

that make's too much sense for physicss.

[OboeGuru]

I don't see how black holes could move around the universe except by the general expansion of the universe, which would not be very likely to bring any black holes in proximity to each other, in fact just the opposite. A black hole is a gravity well, not an actual object. One could argue that the singularity is an object in a way, but I would argue that it most likely exists outside the realm of normal space-time and isn't affected by the rules of space-time.

[MacG]

and the net result? a super uber black hole?

that make's too much sense for physicss.
I completely agree with you on that point T-Dawg. :bigsmile:

[OboeGuru]

Since when does physics have to not make sense?

[Demon_Child]

http://space.com/scienceastronomy/star_destroyed_040218.html

For all of your needs on facts about Black Holes.

[Fenguin]

I don't see how black holes could move around the universe except by the general expansion of the universe, which would not be very likely to bring any black holes in proximity to each other, in fact just the opposite. A black hole is a gravity well, not an actual object. One could argue that the singularity is an object in a way, but I would argue that it most likely exists outside the realm of normal space-time and isn't affected by the rules of space-time.

Why can't they move? What if they were moving in the first place? Would they stop moving?

[Modred]

From my understanding, the pressure of being under such great gravitational pull would crush almost anything into near nothingness.

Obviously, this mass must go somewhere. The logical explanation is that the absorbed mass is added to the black hole, so if enough matter is "absorbed" by a black hole, the hole will gain an even stronger gravitational pull.

The compression of any matter, be it gas, solid, or liquid, at a rate that would occur when brought too close to such a gravitational force would cause large quantities of energy to be released due to collision of particles in the matter.

A black hole is a gravity well, not an actual object.

I think you might should explain exactly what you mean by "gravity well." I could construe that to say that to mean that black holes have no mass. And without mass there is no gravitational force. Now if a black hole could have little or no mass but could still produce large amounts of gravity, that is physics that doesn't make sense.

[TranquilNightElf]

Obviously, this mass must go somewhere.

It does.From time to time known black holes have been known to release massive plumes of energy from all the matterl they have been gobbling up.

[GrassDragon]

when you say gravity well, that makes me think... could a black hole just be a rip in space-time? its gravitational force is attributed to the fact that space-time is being pulled and stretched in a weird way around the black *hole*. and everything that were to be sucked in would just cease to exist in this dimension as it would be outside of sapce-time.

[Fenguin]

Like, something got so dense/massive that it ripped a hole in space-time? Omg, that would be so awesome! :D

[TranquilNightElf]

Yeah :D..
But i think most of the discussions we have had here poitns to that :)

[Semi]

It does.From time to time known black holes have been known to release massive plumes of energy from all the matterl they have been gobbling up.
I've never heard of that, but maybe im just uneducated. Any sources for that?

I think black holes can move, cuz what if you have 2 black holes within a certain distance of each other? Obviously the gravitational pull would be great, and they would move.

When black holes collide, i think they combine to form a black hole with an event horizon that was the sum of both of their previous event horizons. (or something like that)

[Fenguin]

I've never heard of that, but maybe im just uneducated. Any sources for that?

I think black holes can move, cuz what if you have 2 black holes within a certain distance of each other? Obviously the gravitational pull would be great, and they would move.

When black holes collide, i think they combine to form a black hole with an event horizon that was the sum of both of their previous event horizons. (or something like that)
Haven't you ever heard of a "pulsar"? :annoy;:

And you can use math to determine the event horizon. I don't think it's the sum, but I might be wrong ;) Or if a black hole is a hole in spacetime, the other black hole would just fall in. ;)

[Battlecruiser]

I don't know if this is right but isn't a black hole sort of like a super huge star that shunk in size while having the same mass. and the super huge star shrinks to almost the size of a dot and it is invisible. and because it has so much mass it also has such a high gravity that light cannot escape it.

[GrassDragon]

but if it were just a rip in space-time, would it move at all? if there were two black holes in close proximity wouldnt they just "stretch" space-time between them?

[Fenguin]

Yeah, that's exactly what a black hole is. :D

But maybe if a black hole got so small that it cut through the space-time supporting it, it might fall through and make a hole in space-time :D

[Battlecruiser]

man I still don't understand the concept of spacetime. It probably is hard to explain so you can give me a website to look at because this whole space time stuff confuses me. Wonder if I have to learn this stuff in high school. I am only in 8th grade so I probably don't know a lot of stuff.

[Fenguin]

Think of space-time as a huge sheet of cloth spread across the universe. Then, heavy stuff make dents. Then, planets and such just go around and around the heavy stuff because they're trapped in the dents. :D

Black holes make huge dents. :D

[Semi]

But maybe if a black hole got so small that it cut through the space-time supporting it, it might fall through and make a hole in space-time :D
Unless im mistaken, that would be the generally accepted theory, although not as animated (e.g. it doesnt "fall" :) )

Pulsars are black holes?? :eek: How come i was unaware of this :(

Edit:
Think of space-time as a huge sheet of cloth spread across the universe. Then, heavy stuff make dents. Then, planets and such just go around and around the heavy stuff because they're trapped in the dents. :D
And this cloth is 3 dimensional, further complicating the visualization of this. I kinda got it down though.

[Fenguin]

Haha, I'm not sure that they are; it was hypothetical :D
And by "fall through" I mean "make a hole in the sheet of space-time" :D

[Battlecruiser]

Think of space-time as a huge sheet of cloth spread across the universe. Then, heavy stuff make dents. Then, planets and such just go around and around the heavy stuff because they're trapped in the dents. :D

Black holes make huge dents. :D

where is the time part of the model

[Semi]

where is the time part of the model
Spacetime is in 4 dimensions (At least for now. String theory might make that 10 or more). You have your standard x, y, z position coordinates and a time coordinate.

If we limit the position coordinates to just x and y, it becomes a plane/cloth type of thing. Now lets say we have a planet. We drop it on the plane, and what does it do, it "sags" underneath the planet. This sagging causes gravity, because if another planet strolls along near it, it could fall down into the dent and never escape. The hard part is visualizing this in 3d, where its not dented into the 3rd dimension (as with the 2d model), but instead dented into the 4th dimension.

I say you should just stick to 2d just cuz i cant really explain 3d too well.

[GrassDragon]

time is the fourth dimension through which all of the universe passes through, so space-time is really like a 4D piece of cloth

having said that, i wonder if ripping space-time would have an affect on the things surrounding the rip as far as time goes. if stuff is pulled physically toward the rip, shouldnt it be pulled chronologically also? i dont know what kind of an effect that would have, maybe a relative time slow down or speed up?

[Semi]

time is the fourth dimension through which all of the universe passes through, so space-time is really like a 4D piece of cloth

having said that, i wonder if ripping space-time would have an affect on the things surrounding the rip as far as time goes. if stuff is pulled physically toward the rip, shouldnt it be pulled chronologically also? i dont know what kind of an effect that would have, maybe a relative time slow down or speed up?
Im not sure whether or not time is inherently altered. I would think it woudl be, if the cloth is 4d. But ive always thought of it as 3d for some reason.

But either way, when things get close enough, they will accelerate pretty fast, and high speed causes a slow-down in time (dunno how significant it gets in the scenario though).

[Fenguin]

I think that time is altered near a black hole :) Remember that gravity does have an effect on time :D

[GrassDragon]

hmm i hadnt thought about the speed up=time slow down thing. and the only reason i said it would affect time is because i read the words "space-time" one more time and the "time" part of it made me think... ive always thought of it as 3d too with the "depressions" or holes as being into the 4th dimension, but that could be because its basically impossible to envision anything in 4 dimensions.

having said that though, that would have to mean there were 5 dimenions at least, because the dents would have to pass in another direction. or maybe there are only 4 dimensions and time is just the dimension that everything "dents" into.

[Battlecruiser]

another thing I don't understand is how time is slowed down by a black hole. It just doesn't make sense.
that is why newtonian principles are much more easy to understand then Albert Einstein principles

[GrassDragon]

who said black holes slowed down time?

[Semi]

if stuff is pulled physically toward the rip, shouldnt it be pulled chronologically also? i dont know what kind of an effect that would have, maybe a relative time slow down or speed up?
I believe you proposed it :bigsmile:

[GrassDragon]

whoops :bigsmile: guess i did... sorry its getting a little late, memories just drift away...

well then if i did propose it i might as well try to explain it... the rips (as far as weve discussed it, i think) are in either the 4th or another dimension. so if a black hole pulls stuff towards it physically, and it exists in at least 4 dimensions, should it pull stuff towards it through time also?

dont you just love italics? :)

[OboeGuru]

My explanation of time slowing down is this: the gravity well would reduce the natural vibration of particles, which would make time appear to slow down (the converse of what was proposed in the "things moving really fast" thread). Thusly, the closer you are to the gravity well, the slower time seems to be, so basically, time could be a function of gravity. The reason that there's likely no major difference between the perception of time on Earth and in space is that the difference in gravity isn't that significant, whereas a black hole has the enormous gravity well that well exceeds the gravity of the Earth. Heck knows what the gravity around a black hole is like anyways, it's not like we can just send a probe to measure it. ;)

[TranquilNightElf]

Actually that's fairly accurate ...light is also bent (and slowed?) by gravity..
An example of this I read is that say if you were directly above a massive dense body and light would be coming up to you from that body.Becuase of the huge gravitational pull of that body , light would come to you in a relatievly slower speed.Thus if anything /anyone would be living on the surface they would seem to you in a different time dimensions casue they would be doing things very very slowly.
Hence you would be in a different (faster) time zone thatn the people on the surface of the massive body ..and that too because of gravity .

[TranquilNightElf]

Think of space-time as a huge sheet of cloth spread across the universe. Then, heavy stuff make dents. Then, planets and such just go around and around the heavy stuff because they're trapped in the dents. :D

Black holes make huge dents. :D

That is also the reason that earth actually travels in a straight line around the sun. But because of the gravity of the sun , space time has curved that line into an ellipse and the earth travels along that straight line/ellipse.

[TranquilNightElf]

Haven't you ever heard of a "pulsar"? :annoy;:

Weren't Pulsars very fast spinning Neutron stars emanating radio signals?..?

(Yes I know i made three speparate posts but i got mixed up with three different windows i had opened. :tu: ...how do I delete my posts? )

[Semi]

Weren't Pulsars very fast spinning Neutron stars emanating radio signals?..?
Thats what I remembered them to be, so I was kind of confused. Magnetars are still much cooler than them though.

[Fenguin]

Magnetars sound like pokemon. Please enlighten us to what they really are.

[Modred]

It does.From time to time known black holes have been known to release massive plumes of energy from all the matterl they have been gobbling up.

I think you missed my point. Read the link DC posted. Unless I misread it, it would seem that your massive plumes of energy are the remains of matter that has not been "gobbled up" by the black hole. These plumes of energy and matter are what is not absorbed by the black hole. My point was that what wasn't scattered across the cosmos by explosions (your plumes of energy), had to go somewhere, and logically it would be absorbed into the black hole, making its mass greater.

And perhaps someone should explain how more density creates a stronger gravitational force.

Gravitational force between two objects is equal to the gravitational constant multiplied by the masses of the two objects all divided by the radius between the objects squared. Hence gravitational force is determined by mass and proximity, not density, meaning that either 1)when a star collapses into a black hole, it pulls in large amounts of nearby matter to increase its mass or 2)this principle does not apply to black holes.

[Fenguin]

If we look at the effect of black holes on space-time [assuming that the "space-time can be looked at as a sheet" theory is true], the amount that it "sinks" into the "fabric" would be due to the pressure exerted on the "fabric". And since pressure is force divided by area, as the black hole gets smaller in cross-section area, the pressure would increase, the "deeper" it would go, and the more gravity it would exert. :)

[Modred]

Um, compression doesn't increase gravitational pull. ;)

When things are compressed, more mass is in a smaller area, and the more mass there is, the more gravitation there will be. But say you have a limited amount of mass, then compression will not increase gravitational force, but your object will get much smaller.

[Semi]

Lets say we have a sheet of metal weighing 5 pounds. When placed upon a piece of fabric, it will dent it a certain amount. Now if this same 5 pounds was applied to a needle's tip, would it not be strong enough to puncture the fabric? A similar thing happens with gravity (assuming im not wrong). Smaller volume makes it cause a more powerful dent in the fabric, sometimes powerful enough to cause a puncture (singularity). This would be a black hole.

[Fenguin]

Um, compression doesn't increase gravitational pull. ;)

When things are compressed, more mass is in a smaller area, and the more mass there is, the more gravitation there will be. But say you have a limited amount of mass, then compression will not increase gravitational force, but your object will get much smaller.
Stop thinking of that Physics formula! Think of it in terms of space-time! More density = more force per area = more pressure = more push-downage of space-time = more gravity!

[TranquilNightElf]

I think you missed my point. Read the link DC posted. Unless I misread it, it would seem that your massive plumes of energy are the remains of matter that has not been "gobbled up" by the black hole.
.

Actually the plumes of energy are given off from the black holes themselves.It's not as if a BH takes in half a planet and we see the other half as the energy plume.The BH would take in the entire thing without question.
They have been able to take infrared hubble images to support this.


Gravitational force between two objects is equal to the gravitational constant multiplied by the masses of the two objects all divided by the radius between the objects squared.

I don't think applies to black holes, cause for one thing normal laws of physics are disrupted at singularity.

Fenguin and Semi's explanation seems more viable

[Modred]

Actually the plumes of energy are given off from the black holes themselves.It's not as if a BH takes in half a planet and we see the other half as the energy plume.The BH would take in the entire thing without question.

If you would just read that link DC put up, you would realize that of the star (in the article) being devoured by a black hole, only approximately 1% of the star's mass was ever absorbed into the black hole. Explain that.

[TranquilNightElf]

Firstly, In binary systems when a star orbits a black hole, the BH sometimes continuously draws matter and energy from the star and that gas and matter heat up to release the energies.

Secondly, The energy plumes (though of lesser intensity)also come from the matter that has gone into a black hole and has been disassociated into radiation and the like.

Thirdly .Yes(and i was mistaken about this..thanx) if a star gets close enough it will be torn apart like the article says and the energy plumes will be released that way.

Basicaly the point I was aiming was for that the matter does go flying out into space due to the action of the black holes eating up celestial bodies in either of the ways listed above.

But as for your theory about the absorbed mass adding to that of the BH ..I don;t think that would add very much to it.
How much more can you increase infinity?

[Semi]

First off, there are different magnitudes of infinity, a few being aleph-null, aleph-1, etc. Fenguin can tell you all about those. (think integers and real numbers)

And the mass would add to the black hole, since the black hole's mass isnt infinity. Its just very dense, causing massive spacetime warps. Also, if it did have inifinte mass, it would attract all other matter with infinite force, and just the thought of that is absurd (unless so-called dark energy also has equally infinite repulsion ;))

It might be true that the absorbed mass might not be a huge contributing factor, but you cant say that it wont add to it.

[TranquilNightElf]

When I say infinity I mean infinite density (considering of course the essence of a black hole is matter concentrated at a single point) and not infinite mass.So though the mass absorbed would contribute to the mass of the BH , i doubt it would greatly affect the density inside.

[Fenguin]

Ooo... singularities singularities! :) That's assuming black holes are singularities, of course. There's a high chance that they might be, but there's also a chance that they might not be. They might just be very very very heavily compressed, but still not infinitely small.

[TranquilNightElf]

Yeah...so much in science depends heavily on assumptions that have to proved otherwise to be wrong.