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Baby Black Hole With Big Appetite
kuni ito writes: "'According to the astronomers who detected the object with Japan's Advanced Satellite for Cosmology and Astrophysics (ASCA), the black hole seems to be acting like a supermassive black hole, despite its size. It's sucking up matter at roughly the same rate as its much larger (and seemingly less hungry) relatives, they said.'" This black hole (assuming that black holes exist) seems to be eating a lot more than would otherwise be predicted.
They don't have infinite gravity. They just have to have enough mass-->gravity to overcome neutron pressure, about 2.4-2.8 solar masses or so.
Hate to be a nitpicker, but I'm pretty sure it's 4.7 light years approx.
Infinite mass -> infinite gravity -> nignificant (infinite?) gravity at infinite distance.
Bill - aka taniwha
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Bill - aka taniwha
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Leave others their otherness. -- Aratak
Mmmm.. maybe because normal relativity doesn't like black holes very much?
The Chandrasekhar limit is the mass over which a star's gravity can overcome electron degeneracy pressure. This pressure is a consequence of the exclusion principle, caused when electron waveforms are restricted.
Any star greater than the limit, originally 1.4 suns (later recalculated to 1.2 suns), will collapse past white Dwarf stage to a SuperNova. What happens then depends again on the mass of the star, but that is not the Chandrasekhar Limit.
These people look deep within my soul and assign me a number based on the order in which I joined. -- Homer Simpson
[please moderate this "me-too" into oblivion.]
.02
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Quux26
My
Quux26
www.crashspace.net
They also emit Hawking radiation which emits energy, thus, over time, black holes burn out.
Yes indeed, corpuscular was intended to illustrate a 19th century mentality of the concept of black holes (which originated in the 19th century). The concept was similar...that all 'corpuscles' of light escaping from said massive star strove against gravity so difficult that it turned aside and was rent back into its origin. Thereby, no light could escape such a massive star.
Red shifting to infinity is what does occur to such photons, escaping from a schwarzchild radius as such. Red shifting of a photon increases it's wavelength while reducing the amount of energy that photon contains. Therefore, infinite redshifting means the photon has an infinite wavelength and contains no energy (thereby obeying the law that no information or energy can directly* leave a schwarzchild radius [the technical term used for Black Hole until BH was coined in the 60s]) So, a photon escapes from the black hole, but it doesn't really...exist, technically. Not easy to illustrate in a post here, I'm sorry.
*directly being added after Hawkings theories of BH radiation
"This is where god would go if he wanted to get off blow!"
BOTH, Nerd is a very loosely used term, relateing to anyone who is excesivly skilled or obsessed in a particular area (Especialy those areas that the general public know little to nothing about.) Microft
Sorry, that's nonsense. No accelerator we can build has anywhere near enough energy to create a black hole. Probably would need one the size of the solar system.
Stefan
Just some inline holes in stealth mode. Really, it's a black hole, how do we know if there's a huge black hole behind it or not? I think a black hole is just an ulcer in a huge stomach and once you get in, you wade around in the muck with all the other stuff that's been swallowed.
~Bout Time for another tea party.®~
*dons asbestos suit, welder's mask* Can you imagine a Beowulf cluster of these things? *ducks*
I want the fire back.
Danny
I have written over 900 book reviews
Actually, from what I've read, the time it would take for the black holes to completely consume everything was longer than the time it would take for the Universe to stop expanding and fall back into itself (the so-called Big Crunch).
So, there's no need to fear being eaten alive by black holes billions of years in the future. Just watch out for all of the galaxies coming straight at you from every corner of the Universe. One word of advice: duck!
Tongue-tied and twisted, just an earth-bound misfit, I
Learning to fly, Pink Floyd.
"So, why isn't the "event horizon" (a distance from the actual point of the hole) a sphere extending the same radius in all directions?"
You replied:
"You can't "see" the event horizon. The event horizon is where light can no longer escape and by definition puts out no light. All you would see is a black hole in space -- hence the name "black hole." If you see something fall into a black hole, you would't see it actually hit the event horizon; it would merely keep falling in more and more slowly. In any case, the event horizon tends to be quite small. If you collapsed the Earth, for example, into a black hole, the event horizon would have a radius of just one inch. Only a supermassive black hole of millions or billions of solar masses (the kind you have at the center of big galaxies like the Milky Way) will have large event horizons."
But the question is still a good one if you forgive the incorrect phrase of "see".
Does a black hole exert it's force equally in all directions? I would imagine with such force that peturbations would be minor at best. If it is rotating, does the even horizon have an egg-like curvature as opposed to a beach-ball?
This is stuff I've never thought about but would sure like to know now that someone brought it up.
.02
My
Quux26
My
Quux26
www.crashspace.net
"This black hole (assuming that black holes exist) seems to be eating a lot more than would otherwise be predicted."
Hmmmm... perhaps we should name it Sally Struthers?
Ceci n'est pas une sig.
Maybe more likely then just two passing strangers hooking up, is a galaxy which has two black holes in it's center like twin stars.
With the size of the universe, and the probability of this happening. The chances are good that somewhere there existed, exists, or will exist a twin black hole.
No, I bet the N'Sync's songs would have a STRONGER sucking ability than the blackhole!
Sig it.
The report seems to be that this thing is eating more than a teenage BH should be. But given the way they eat (everything from light on down) wouldn't this just mean that it ran across a particularly dense "meal"?
And because it's fairly fundamental to my Theory of Everything, do BHs grow as they eat?
oh, and Space.com lost about forty points on my credibility scale with this link under the story
"Aliens Among Us -- Which celebrity is really an alien? You decide! "
They trying to muscle in on the Weekly World News?
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+&x
this may be a dumb question, maybe i should just go to bed, but anyway ..... if this small black hole is acting like a big black hole ... remember a while ago people were talking about that accellerator in NY that could possibly cause a small black hole ... if this is true, maybe even a tiny black hole like that one can kill us all... wee
if you find this interesting, good for you, dont moderate me up, i posted a/c so people wont laugh at me, but if i get a score 5 or something ill be pissed, i want the karma damnit!
Bill - aka taniwha
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Bill - aka taniwha
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Leave others their otherness. -- Aratak
I'll help you with this one. Black holes don't have infinite mass, but the do have infinite density. That's probably where that 'infinite' probably wandered into your thinking.
J
Who moderates the meta-moderators?
I can't remember the term for it off the top of my head, but as light is emitted by a massive object, it is redshifted a bit, where the amount of redshift corrolates with how massive the object is. Blackholes are merely massive enough to cause an effectively infinite redshift.
Many physicists believe that a true vacuum cannot exist with any stability, and in the presence of a vacuum the universe gets cranky and (by taking a little local energy) fills the space with pairs of opposite and equal "virtual particles" which, while not quite real, have mass. Usually, these particles attract each other, and annhiliate.
Now, our black hole, which is causing the local space to be subjected to fairly hard vaccum, spawns quite a few of these almost-particles. Some of these pairs are created across the event horizon. The poor particle inside is sucked into the singularity, while its lifemate is flung at extremely high speed out into the nothing. Through some trickery of conservation, this causes the black hole to lose mass, albeit at a rate much less that it is gaining mass.
Here's where my hypothesis kicks in: a black hole that is more massive would have a larger gravity well, and thus a wider event horizon. Basically, it has more surface area. So there's a lot more area in which those v-particles can be torn from each other. Thus, it would evaporate faster. So a really massive black hole's "evaporation" rate would be much higher since surface area increases very quickly with increased volume.
You're probably thinking that the mega-hole would pull mass in faster and would thus offset the evaporation rate. This is where my hypothesis gets a little threadbare, but lets explore a little anyway. First, the gravity well on the mega-hole is so huge that the angular escape velocity will be much lower than a midrange hole, therefore more of the local masses will be above the speed threshold of the gravity well, and ride the slingshot out into deep space, never having gotten near the event horizon. It would, if you are buying this, essentially be throwing its own food away.
A second possibilty that could lower a mega-hole's mass aquisition is that since the mass near and beyonmd the event horizon is going to be getting increasingly dense in any black hole, there may be an upper velocity to how fast the hole can suck in more matter. Much like wind resistance keeps a skydiver from passing the speed of sound. Thus the black holes wouldn't have a linear increase in their rates of "easting" with respect to mass.
So, our friendly neighborhood mega-hole would be evaporating much faster, eating a little faster, and throwing away a significant portion of the local produce. Sounds pretty inefficient. Anyone buy this?
Basically, what I was talking about doesn't have that much to do with the temperature of black holes or the evaporation of black holes.
What you want to know about is Hawking Radiation, as this is actually related to both of your questions. I suggest you grab a copy of Stephen Hawking's A Brief History of Time and read on hawking radiation. If you could get a copy of the illustrated brief history of time, even better, as I've found that book easier to wade through. I'm not going to try to explain hawking radiation, as a physicist friend of mine (not from caltech) yelled at me that what I was saying about hawking radiation would confuse people. Besides, Professor Hawking is far more elegant than I am.
Moller
Yes indeed, corpuscular was intended to illustrate a 19th century mentality of the concept of black holes (which originated in the 19th century). The concept was similar...that all 'corpuscles' of light escaping from said massive star strove against gravity so difficult that it turned aside and was rent back into its origin. Thereby, no light could escape such a massive star.
:-)
;-) )
Ok, thanks, makes sense now
And you did explain the red shifting more than enough for me to figure out what you're talking about. (and I knew who schwarzchild was too,
again, thanks.
Moller
We must measure the size of black holes improperly... For example you can't measure a persons hieght and wieght by how much gas passes through the body. Same goes for black holes... Also don't you find it to be a bit racesist... BLACK hole... why not WHITE hole?????
I understand. The others answered my original question in addition to the question I knew not how to ask without knowing the answer .. anyways .. thanks for the response :-)
Great! Interestingly, I've had this book for a good number of years yet I forgot I had it! Thanks!!! :-)
I think black holes are THEORETICALLY infinitely zero in size and have infinitely high gravity. But, I think that's just because it worked out well in the math. If it had infinitely high gravity, everything would be moving toward it pretty damn fast.
Thank you. In watching the Discovery or Learning Channel, such programs often do a good job of illustrating theory; however, it's not often that they go into greater details to the point where my questions can be answered .. books are good -- an answer.
What he may be talking about is a black hole having infinite density. Zero size, nonzero mass = divide by zero error.
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Okay, I'm gonna admit it - I am a physicist. At least that's what my degree says, anyway. I just though it might be helpful to explain what I got from it. Sadly, it the article was kinda lacking in details, but this is what I gathered.
Basically, a black hole is a big old sucky thing. It pulls in everything around it. Since the stuff can only fall in so quickly, the stuff spends a lot of time whirling around the black hole before it falls in. While it's whirling around, it tends to bump into the other stuff that's similarly whirling.
Now, with all that whirling and bumping, some of the stuff gets turned into x-rays (E=mc^2, remember?).
Now, the stuff that got turned into x-rays doesn't make it into the black hole, which is useful 'cause that's how we detect the things in the first place.
With a bigger black hole, there's a lot more whirling and bumping going on, so less of the stuff that the black hole starts out sucking on makes it into the Sarlac pit - I mean black hole (sorry, just re-watched ROTJ).
That means that with a smaller black hole, a bigger proportion's gonna make it into the black hole itself.
At least, that's what I got from the article. But then, my specialty's nuclear physics...
"If God created us in his own image, we have more than reciprocated"
What's the deal with the event horizon? All the pictures I've seen (admittedly, many from science-fiction) depict a circle, and stuff gets sucked through it like a gate, and funnels downward (so the circle becomes the base of a sort of curvy concave cone shape).
So, why isn't the "event horizon" (a distance from the actual point of the hole) a sphere extending the same radius in all directions?
I'm just guessing here, but could it have something to do with the accretion disk associated with a Kerr (rotating) black hole vs. A Scwartzchild (non-rotating) black hole? Or maybe I have that backwards. In any case, the visible stuff would be the material being sucked in, excited by radiation from the material as it is accelerated. Or something like that. Aren't black holes x-ray sources?
Yes, it was Cygnus X-1, but it's since been absorbed by RedHat V2.
Practice random senselessness and act kind of beautiful.
I don't think we can say that the black hole is rotating. The singularity is a point with (effectively) zero volume, and I would say that this precludes it's ability to rotate.
Since the singularity has zero volume, it must exert its gravitational force equally in all directions. Perturbations in a gravitational field would arise from unevenly distributed mass within a given volume. Since we have no volume, we can't have an uneven distribution of mass.
Moller
How about, "You little asshole!!!!"
"Oblivion is just a click away." -Aazz
Um, that's not correct, is it? I thought that the stuff whirling around is whirling so fast that when it bumps into other stuff, the energy from momentum is what's being given off as x-rays. The stuff itself is not destroyed (converted into energy) but rather slowed down. Unless you're suggesting that there's nuclear fusion happening, which I suppose is possible.
...phil
...phil
"For a list of the ways which technology has failed to improve our quality of life, press 3."
...is it lost forever?
t ions.html
If you drop a copy of the WinNT source code into a black hole, will *all* copies of WinNT source code disappear? Ditto for Linux.
Now, *that's* an OS war.
Ref:
http://math.ucr.edu/home/baez/physics/open_ques
668: Neighbour of the Beast
...that SIZE isn't everything. I've heard that one before, unfortunately from a few of my former girlfriends. Or could it be(here I digress because I just can't resist) that an asshole is an asshole, regardless of size? The fact is (I firmly believe after having subjected myself to a Master's Degree in math and many headaches at the U. of Chicago) that it's not a question of how much black holes "swallow", but how much they "produce"..., or create, if you will. We just don't know WHERE the product of their appetites manifests. There are some interesting theories on that, and I get back later with some Euro-links on the subject if anyone is interested. The question may be posed another way: After the theoritically anticipated "spaghettification" of matter and time that takes place when approaching a black hole, where oh where does the spaghetti go? "Why, it gets converted into energy.", seems to be the accepted and hopeful answer, but personally, I'm not so sure. This might be a phenomenon quite like the dimensional extension of the moebius strip..., the Klein Bottle: the curved "continum" turning in(or out) upon itself. But that's too simplist, I'm sure. And as for TIME itself......That really poses a problem... (I've got to go to work now)
"Oblivion is just a click away." -Aazz
Black Holes & Time Warps: Einstein's Outrageous Legacy by Kip Thorne. It goes into enough detail that you won't be left feeling empty, but it's well within the reach of most amateur enthusiasts.
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All generalizations are false.
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I like to watch.
Now is not the time to be investing in blackhole IPOs, no matter how tempting their prospects for growth are. The market is simply too unstable.
What I find interesting is how they say its a "small" black hole thats gobbling up "lots of stuff". Yet the only way we have of detecting black holes is through the amount of x-ray radiation that escapes at the poles, and heating of dust as it rotates and falls inward.
A black hole that has contradictory data about its size would obviously point to the existence of a seperate unidentified object.
Shouldn't small black holes be MORE massive than big ones? I mean, the more matter a black hole collects, the more gravity is exerted on the matter, the smaller the hole gets. Am I missing something here?
I don't think we could all get more confused than that article left us, but let me try by asking a few questions:
The article is trying to reveal something surprising, but which is it:
That mid-mass black holes are just as INefficient as super-massive black holes, thus bringing an unexpected phenomenon into a new realm of scale?
or
That mid-mass black holes are just as powerful, and thus considerably MORE efficient than, super-massive black holes, thus limiting the odd inefficiency of super-massive black holes to only the highest mass scales?
In any case, I don't think it means that the mid-mass black holes are inexplicably efficient.
Some questions about the low-efficiency super-massive black holes:
Doesn't the mass that gathers around these holes "dilute" the gravitation as you get closer to the black hole, and are surrounded by mass in all directions? Assuming this has been accounted for, how much more inefficient are these holes than expected?
Could the supermassive black holes be decaying, thus weakening the rate at which new mass gathers, while still being surrounded with the mass and radiation to be expected from their large initial mass? Isn't decay a prediction of Hawking's?
Lame-ass speculation is of course perfectly welcome in lieu of real answers...
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
Sorry about that, apparently I was miss guided by myself. Perhapse I should go move to a neutron star somewhere :)
are you some sort of idiot?
-=kellet
this is an interesting article and some very good responses too. but to answer some questions.
a black hole does not have infinite mass. You see mass is the amount of matter in an object. if it had infinite mass we wouldn't have a universe. Black holes have infinite density. it's so dense that 2 quarks end up existing in the same space at the same time. which is an impossibillity thus all matter is destroyed and a singularity where timespace its self does not exist and matter cannot exist occurs.
however since the innitial mass of the black hole no longer exists the black hole does not gain mass even when it sucks up mass. instead all mass and energy entering a black hole is destroyed. now you're probably saying "wait matter and energy can't be destroyed" well the more up to day version is that the sum of matter and energy in the universe remains constant.
and that matter can become energy and vice versa. this throws a big monkey wrench in the theory that the amounts of matter and anti matter chan remain the same. it comes out finally like this.
the sum of matter, antimatter, and energy in the universe must remain constant.
acording to hawking as matter falls into a black hole anti matter comes out. not that the matter is directly converted but rather it's the universe maintaining the ballance. antimatter is created at the point of destruction for matter to compensate for the universes loss of mass.
further notes are thus. gravity is the opposing element to matter,antimatter and energy (we'll call them mass for short)
wherever there is mass there is a directly proportional amount of gravity. it all stems from the beginning. imagin there is nothing.
no mass
no gravity
in order to facillitate the creation of matter the universe borrows agains gravity. thus gravity is the debt which mass owes to creation to be paid back at the end of time in a big crunch. (you can read all about this in Hawking's black holes and baby universes)
now back to black holes
supermassive black holes do generate less gravity at the event horizon. it's even theorized that one could fly a craft into one big enough safely. that is untill you hit the singularity whereupon you're mass is destroyed and an equal amount of countermass is expelled to compensate.
you could consider black holes as the universe's recycling center where all complex mass is replaced by simple mass.
in a further note. all black holes eventually decay. you could call it the universe healing its self. they begin to expell more and more matter untill they've not only compensated for what they sucked in but also the original mass that they were born from and dissapear.
like a giant algebreic equation all things are equal in the end. while I'm not that much of a mathmetition it does make sense.
I really have no explaination as to why this black hole sucks up more than it's size allows for. but perhaps I've offered enough data here for everyone to formylate their own theory. I'll be putting one together too.
because as far as you are concerned, whatever you are watching falling into the black hole never actually falls into the black hole. Because of the time dilation that an object experiences as it falls into a black hole, we never see it actually fall into the black hole.
To use an example from Stephen Hawking's A Brief History of Time:
Suppose that you are watching an astronaut fall into a black hole. Suppose that you can see the watch on the astronaut's wrist. As the astronaut approaches the event horizon, the seconds will start ticking off slower and slower. Actually, each second will take twice as long as the one before, until finally, before the astronaut passes the even horizon, the last second on his watch will take an infinite amount of time to elapse (from your viewpoint). Of course, the astronaut notices none of this, and time passes normally for him as he flies through the event horizon to his death.
This is a consequence of special relativity. In your reference frame (the observer's frame), the astronaut will never actually pass the event horizon. But, since the speed of light is equal in all reference frames, you can still see him because light is still reflecting off of him as far as your concerned.
And the light doesn't grow "Dimmer" as you get closer to the event horizon. The light still has the same intensity, it isn't like the black hole is sucking photons off of their course out of light rays passing by, the event horizon is more like a "curtain", on one side light is passing normally (normally enough, it isn't slowing down, just "curving" because of the warping of space-time around the black hole), and on the other side of the event horizon, light spirals into the singularity, never to escape.
Hope that elucidates things.
Moller
Sorry if I gave the impression it's being destroyed. You're right, it's not and that's not what I meant. It's the bumping that produces X-rays, but that still means less energy for the BH to absorb.
Hope that's clearer.
"If God created us in his own image, we have more than reciprocated"
From what I've read, a black hole is a singularity with mass. That is, it has mass but not size, it is a one-dimensional point. The only measurable property that a black hole has is mass.
Perhaps you should try reading more on the subject, since you seem to be a bit mistaken on black holes' propertiese. For starters, black holes may have a net electric charge and (if magnetic monopoles exist) a net magnetic charge. They may have a net angular momentum as well. All of these, in principle, are observable from outside a black hole's event horizon.
Furthermore, a black hole singularity does not need to be a single point. In the case of a charged, rotating black hole, for instance, the singularity is ring-shaped and has the curious feature that if you were to travel through the center of the ring it's anyone's guess where you would end up. You could, in principle, find yourself in a universe that is on a different "Riemann sheet" than the one we are in now that is connected to our universe through the little bridge of spacetime at the center of the ring singularity. Except for the untidiness of inevitably finding oneself inside a black hole's event horizon in the "parallel universe," this piece of physics seems tailor-made for science fiction.
From a practical standpoint you are correct, however. In 99% of the problems in astrophysics nobody gives a hoot what the esoteric properties of a black hole are. It's just a compact critter that radiates x-rays like crazy when it gobbles up matter. (A notable exception to this is people who study accretion in quasars, where assuming a Kerr geometry instead of a Schwartzchild geometry can affect accretion models by a noticeable amount).
Maybe he means two black holes that just happen to be in the same spot in the sky but at vastly different distances ?
I'm still trying to figure out what people mean by 'social skills' here.
Call Reed Richards... sounds like Galactus is in the area.
You are in a maze of twisty little passages, all alike.
This is nonsense. Perfect Black Holes can't exist, and the event horizon cannot be passed, since for all outside observers, everything that happens near the event horizon happens like infinitely slow, so nothing ever hits the black hole.
I'm still trying to figure out what people mean by 'social skills' here.
Black holes can be detected (in theory of course) by looking for the emissions they give off. The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission. It is these fissions at the edge that make a black hole appear to give off energy, and make it detectable.
That type of radiation is called Hawking Radiation (after Stephen Hawking, naturally). However, this isn't what lets us detect black holes, as Hawking Radiation is ridiculously faint. Black holes can be detected by the X-Rays that they "inadvertantly" produce. When matter is falling into a black hole it is accelerated, heated, and compressed to such a degree that it gives off large amounts of X-Rays. I believe the first black hole we detected (again, assuming black holes exist), was Cygnus X-1 (or cygnus something), and we detected it by the x-rays it gave off.
Another method of detecting black holes is to look for graviational lensing effects. Because black holes are so massive, they bend the fabric of space time. (Imagine a sheet suspended in the air. Place marbles on the sheet. The marbles make depressions on the sheet, like stars make "depressions" in space-time. A black hole is so heavy, it's like dropping something that is the size of a marble but with the weight of a bowling ball onto the sheet. The sheet bends A LOT, and it actually will have a hole where the singularity is.) Light travels in a straight line, so if space-time curves, light also curves with space-time. Gravitational lensing was proved during a solar eclipse. Astronomers observing the eclipse noted that they were able to see stars that should have been blocked by the eclipsed sun. The sun's gravitational field caused enough "lensing" so that stars directly behind the star could be seen to either side of the star. So, if we find something out in space that is causing a LARGE amount of gravitational lensing, but we can't see anything, there's a chance it's a black hole. At that point we normally observe it more to determine if it is or isn't a black hole.
Moller
IANAAstronomer, but I do remember reading that for smaller black holes vs. bigger ones, the gravitational increase after passing the event horizon is curves up much more quickly for small holes vs. big ones (with gravity on the y axis and time on the x, I believe).
Not sure if this has anything to do with how much matter is being consumed by a smaller black hole, however?
When the hell did this happen?
....ok im a dork...
Your Momma's so fat she makes emacs look like nano!
Or... tidal forces are much larger around a smaller black hole, could this have anything to do with it?
That was my first knee-jerk thought, but it's silly if you think about it. Tidal forces don't help you pull the matter in any faster. They just make things more painful for the object being sucked in.
As for the infinite mass comments, remember that the laws of physics no longer apply within the event horizon ("inside" the black hole). That includes concepts like mass. All that matters is that there is SOME gravitational field created by the black hole. It might be infinite mass, it might not. It's a pointless question since physics doesn't work inside it.
A little black hole, Eating all of its neighbors Microsoft is proud.
That experiment up in New England that could have possibly produced a black hole? Great...not only could they possibly create one, but it might be worse that we imagined it ;-)
The Blaster Master Fighting for Truth, Justice, and Evil Pie since 1979
Anyway, it could be that:
My mom is not a Karma whore!
my baby black, baby black, baby black, baby black, baby black, baby black, baby black, baby... baby black hole! Sorry just slipped out. TMH
It oscillates, as do all things.
Anyways, all this article stands to say is that the current interpretation of the mass/size of black holes based on the frequency and luminocity of x-ray radiation is flawed. Since its guesswork and these astrophysical 'revelations' come along once every month or so, I don't see the big deal. Yeah it could be 2 black holes, but the net mass/gravitational force would be the same and its systemic behaviour they are marvelling at...
I just dont see the big deal
"This is where god would go if he wanted to get off blow!"
But then we would see resultant shifting as a result of the closer SR. on the radiation from the farther one; most likely making this observation obvious.
"This is where god would go if he wanted to get off blow!"
Actually, the point of origin can be created with an initial spin which would create an elliptical horizon.
"This is where god would go if he wanted to get off blow!"
1. How do the black holes form? (i.e. Where do babies come from? ;-)
A normal "burning" star is in a state of balance of two forces: 1) the star's gravity, which wants to make it smaller, and 2) the pressure from the nuclear reactions inside which make it want to blow up. Stars eventually run out of fuel; that is, they run out of hydrogen in the core, and start burning helium, and then other elements until eventually you get a bunch of iron. You can't get any more energy out of fusing iron. In fact, it *takes* energy to do it. The pressure from the nuclear reactions drops, gravity wins, and the star collapses. Small stars like the sun become white dwarfs, larger stars become neutron stars, and even larger stars become black holes.
2. Once a black hole is formed, it sucks all nearby matter in. Will it keep growing indefinitely or will it somehow stop at some point?
As long as there is matter around, it should keep growing. Mind you, we think black holes 'evaporate' eventually (Hawking radiation), but it is a very slow process for large black holes.
3. What exactly is meant by the size of the black hole? You can't just go there and measure its size. Heck, you can't even see it. You can only infer its mass by looking at the effects on nearby objects. Right? So what's this talk about small/big black holes?
Usually they are talking about mass, but you can also talk about the radius of the event horizon. The event horizon is the distance you can be from the center of the black hole before you get stuck. As long as you are outside the event horizon, you can still get away (given a big enough rocket :)). The more massive the black hole, the larger the event horizon.
4. (I totally don't get this). When something is being sucked into a black hole it starts accelerating due to the gravitational pull of the black hole. At some point the speed of the sucking object (did I just invent this term? ;-) will approach the speed of light, at which point the time is supposed to slow down...
Well, no. If you throw a ball into the air, it doesn't reach infinite velocity before it reaches the ground, does it? Falling toward a black hole is no different than falling toward anything else with mass. That's not saying that there aren't some odd effects. If someone was watching you fall into a black hole, they would see you move slower and slower as you approached the event horizon, but you would never actually cross it. From your point of view, everything looks normal (apart from being ripped apart by tidal forces) and you cross the event horizon and land on the singularity in a finite amount of time.
There's some good stuff in the black hole section of the Usenet Relativity FAQ
Kip Thorne's "Black Holes and Time Warps" is pretty good, and a really easy read.
If thats too much for you, Hawking's "A Brief History of Time" book can give you a very brief runthrough, but dont expect alot of real theory in there, more general 'vernacular descriptions' to ease the lamen's mind.
"This is where god would go if he wanted to get off blow!"
Add it to the MAPS Realtime Blackhole List!
sulli
RTFJ.
No, a black hole doesn't have infinite mass, so it doesn't have an infinite gravitational field, either.
As mass increases, the escape velocity increases---escape velocity being the velocity necessary to escape the gravity well. When mass increases to the point where the escape velocity is greater than the speed of light, then nothing can escape. Hence, a black hole.
Why is it that everyone drops the word "infinite" in to just about every comment on this topic? Haven't we learned that nothing, except for maybe distance and time (and those two are still subject to debate), are infinite? There are limits to everything, even, especially even if we don't yet have the means to measure them. If we can't measure something does that mean it is either infinite or just plain doesn't exist? no... it just that we as a species haven't refined our ability to measure things that are either that large or that small...
:)
I guess that qualifies as "effectively" infinite. But at this stage in the game to call anything "effectively infinite" just doesn't seem appropriate. How about "a very very very very large"?
IIRC, Hawking radiation deals more with the evaporation of very small black holes. This explains why there are no microscopic black holes, as they should have been formed in the Big Bang, but we dont detect any because they have 'evaporated' over billions of years. Hawking radiation does not appreciably affect the mass of black holes formed by collapsing stars, which is how most black holes are formed.
IANAAP (Astro-Physicist)
Quite frankly, infinities are well justified in this discussion. We're talking about a singularity, for pete's sake. It's an enormous amount of mass squashed into zero volume -- not just approaching zero, but actually zero. Inside it is where Einstein's equations breakdown and generate infinite lengths for objects having fallen into it. It's a truly peculiar beast.
(Besides, as an aside, you can still have different degrees of infinity. The number of integers is infinitely large but it's still infinitely smaller than the number of irrational numbers.)
Black holes, wormholes and time machines, by Jim Al-Khalili
As the name suggests, this isnt strictly black holes, but it is interesting and very readable. A good way to learn more about this is to go the library and look at what they have, they should have a good enough selection that you can find something interesting, just make sure the book isnt loaded with equations if you dont know much about it.
--- Submission is feudal.
What is known about the 'sucking' power of newly created black holes?
Perhaps a 'new' blackhole that just collapsed is still taking in matter quicker..
Jeremy
First, you would see a very funny-looking accretion disk and some very strange radiation patterns.
You'd see massive Doppler shifting from the x-ray spouts, not unlike our observations of the binary pulsar in (I think) 1974.
Black holes wouldn't rotate around each other for long -- in their case, the gravitational radiation would be enormous, causing the system to radiate energy away until they collapsed into one another.
Finally, no wrinkles to special relativity. Gravity's pull would relate to general relativity.
10^70 to eradiate a black hole 3 diameters of our planet. BTW. for all the protons in the Universe to decay it's only 10^30 so we will never see a black hole eradiate since all the matter will decay way before that time
You can't handle the truth.
Thanks for the correction on my misunderstanding of black hole detection
11*43+456^2
In any case, the event horizon tends to be quite small. If you collapsed the Earth, for example, into a black hole, the event horizon would have a radius of just one inch. Only a supermassive black hole of millions or billions of solar masses (the kind you have at the center of big galaxies like the Milky Way) will have large event horizons.
I remember someone told me once that the smaller the black hole, the more of the tidal forces of the black hole reached outside the event horizon. I don't remember why, but it is sort of freaky.
Maybe the state's highest function is to grind out insoluble problems. (Zelazny, Hall of Mirrors)
Momochrome, you're a flippin hoot! I would totally mod this up (+1, Funny) if I could... rock on!
light does, in effect, "spiral down" into the singularity because of the curvature of space-time around the singularity. This is an approximation, since it requires us veiwing 4-dimensional space-time as a 2-dimensional surface.
;-)
Now, this is mainly just from my understanding of black holes having read Hawking's Brief History of Time and taken one astronomy course. But I don't remember ever reading about the light redshifting to infinite (if you could explain that in more detail for me, I'd be grateful).
And I'm not sure how you're using "corpuscular," I've never heard it used that way.
Moller
that's a very good question. And I can't explain it to you in a way that will satisfy you, all I can say it that it stems from special relativity, time dilation and length contraction.
I can tell you that time does not dilate for the astronaut, time flows smoothly for him as he passes the event horizon and flies down to his doom.
Any explanation I give trying to explain the paradox would involve lots of hand-waving on my part, so let's hope someone else can explain it better.
Moller
Black Holes and Beyond
Black Holes: Mystery of the Cosmos
Black Hole: The Death of a Star
Shit Load of Links
Any similarity to a real person is purely coincidental
As a result, some astronomers now think that the total output of X-rays from accreting matter may therefore be more a product of how massive the black hole is, rather than of the luminosity of the region surrounding the black hole, as it once was thought.
What the hell does this mean? That previously a bright x-ray source near a black hole made astronomers think it was surrounded by lots of tungsten filaments, and a not so bright source surrounded by not much damp earth?
Seriously, is this suggesting that the intensity of a black hole x-ray source is independent of the surrounding region? What would be emitting the x-rays in that case?
(this sentence here to provide one not ending in a question mark)
:wq
What's the deal with the event horizon? All the pictures I've seen (admittedly, many from science-fiction) depict a circle, and stuff gets sucked through it like a gate, and funnels downward (so the circle becomes the base of a sort of curvy concave cone shape).
That's the accretion disk that is being depicted. The accretion disk is a vortex of matter that is spiraling into the black hole, getting ionized, energized, and putting out a lot of x-rays along the way. That's why sci-fi artists love to show the accretion disk. You can have a lot of fun and make it look really cool.
So, why isn't the "event horizon" (a distance from the actual point of the hole) a sphere extending the same radius in all directions?
You can't "see" the event horizon. The event horizon is where light can no longer escape and by definition puts out no light. All you would see is a black hole in space -- hence the name "black hole." If you see something fall into a black hole, you would't see it actually hit the event horizon; it would merely keep falling in more and more slowly.
In any case, the event horizon tends to be quite small. If you collapsed the Earth, for example, into a black hole, the event horizon would have a radius of just one inch. Only a supermassive black hole of millions or billions of solar masses (the kind you have at the center of big galaxies like the Milky Way) will have large event horizons.
Does this
Hawking Radiation Explained
Any similarity to a real person is purely coincidental
In that case you should remember to watch out for the mindworms.
simplify things and throw n'suck into the black hole
Any similarity to a real person is purely coincidental
I would start with "A brief history of time" by Stephen Hawking. It covers lot more than just black holes but is well worh the read. No math at all and only 1 equation in all of it.
Carsten Svensgaard
Bill Gates would be a suitable name for it.
Fh
*ducks*
What do I do, when it seems I relate to Judas more than You?
Still not dead.
Who's to say there isn't a black hole behind this one (twin black holes rotating around each other.. Yum!) ?
That being said.. this is interesting because it may mean gravity's pull isn't directly proportional to the mass of an object. This would certainly add a wrinkle to special relativity (if you'll pardon the pun).
Ummm, am I mistaken in remembering that a black hole has infitine mass? So does this black hole have a value of infinite that is greater than other black holes? This humbles me. Every time I think I have most stuff pretty solidly nailed down, something like this comes along.
So somebody answer me this: Do black holes have infitinte gravity, but not an infinite mass? What's the skinny?
- Rev.I'd love to read some stuff on that if you have any links. I haven't seen any of that stuff and I have a slightly-more-than-amateur interest in astrophysics.
Not that I know much about it, but some posters higher up are quoting evaporation times for a hole that size that are 10000000000000000000000000000000000000000000000000 000000000000000 times larger then the time it would take for matter in the universe to evaporate due to proton decay.
-- perl -e'print pack"H*","6e656d6f406d38792e6f7267"'
I'm no astrophysics major, but here it goes...If these things are sucking up so much matter, do they not become more massive, and thus have even more gravitational pull? Basically, are they getting stronger as time passes? Do black holes in general get stronger? I consider myself an astronomy guy, but I'm afraid my knowledge of black hole theory is limited to how we detect them (provided, of course, they are what we think they are).
"The universe seems neither benign nor hostile, merely indifferent." --Carl Sagan
Or maybe Microhole is a better name for it.
And when it grows too much, you can always split it in two pieces.
Fh
Well, the force of gravity would also be stronger right about the surface of a 50k solar mass black hole, as opposed to a 1b solar mass one. At least I think, right?
Grades, Social Life, Sleep....Pick Two.
--Justin Mitchell
"2nd Place is a fancy word for losing" --Bender (Futurama)
A Brief History of Time by Stephen Hawking. This is a very good book. Easy to read. Hawking explains concepts very well. It covers more than just black holes, but if you like this type of reading, the whole book is good. It is not long, either. I read it in one day.
this is a left handed sig
IIRC from Hawking's book, a black hole is defined as a "set of events from which nothing can escape to a large distance." By this definition, the event horizon is the boundary of the black hole. If light is just outside the event horizon, it can escape to a large distance given enough time. That is not to say that the black hole can not grow, but the size of a black hole is definitely not zero. I think Hawking wrote that some black holes grow and some shrink depending on the mass and rate of increase of mass, but I don't remember the exact conditions.
this is a left handed sig
I'd guess you're new around here, but with a userid in the 13k range, you must have just been away or in a coma for awhile.
---
Slashdot: News For Zealots. Stuff That's Hypocritical.
Hope some astrophysicist will answer these (clueless?) questions.
;-)
;-) will approach the speed of light, at which point the time is supposed to slow down. This effectively means that at some point the speed of the object will start to decrease, and, eventually, it will stop moving. Therefore, the object will, in fact, never reach the black hole. Did I just pull this out of my ass or is it at least partially true?
It is my understanding that a black hole is an enourmous amount of matter compressed into some tiny space. It has a gigantic mass, and, due to the small size, its density is effectively infinite (or is it *absolutely* infinite?)
1. How do the black holes form? (i.e. Where do babies come from?
2. Once a black hole is formed, it sucks all nearby matter in. Will it keep growing indefinitely or will it somehow stop at some point?
3. What exactly is meant by the size of the black hole? You can't just go there and measure its size. Heck, you can't even see it. You can only infer its mass by looking at the effects on nearby objects. Right? So what's this talk about small/big black holes?
4. (I totally don't get this). When something is being sucked into a black hole it starts accelerating due to the gravitational pull of the black hole. At some point the speed of the sucking object (did I just invent this term?
___
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If you think big enough, you'll never have to do it.
The sims have noticed the garbage collectors and will soon start correlating disrepencies they cause with the simulated physics of the simulation. Once they realize that they're just a computer simulation, they always commit mass suicide. Oh well. Time to reset the simulation and start a fresh run...
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
11*43+456^2
I would say a good book to read that has information about black holes (as well as alot of other stuff) and is easy to read is "A Brief History of Time - From the Big Bang to Black Holes" by Stephen W. Hawking
Okay, I do not present myself as an expert on astrophysics but I think I can provide answers these questions. 1. Black holes come from the collapse of massive stars. Only stars of a certain mass can generate the immense gravity needed to create a black hole (I think it's about several times the mass of the sun). 2. As far as we (scientists) know, black holes do not "grow" in size, they just keep sucking in more matter. 3. The "size" of the black hole is known as the Event Horizon and is the point at which you start getting sucked into the black hole. 4. When something is getting pulled into a black hole it stretches as gravity pulls on it (called "spaghettification") until you're pulled apart. After which, what's left of you floats to the singularity where it is crushed until oblivion. Great. From the outside, people can only see you because light is reflected off you. As you get deeper into the black hole, the light has a hard time getting out until it can't. From the outside, you appear to slow down indefinitely so it only *looks* like you'll never reach the black hole. Hope this helps...
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When the pin is pulled, Mr. Grenade is no longer our friend.
-leoglas
i've looked at love from both sides now. from win and lose, and still somehow...
I by even further means would be an astrophysicist, but if a blackhole had infinite mass let's say. Then any gain of gravity associated with it would be inconcievably small, as to have the 'pull' not to change over time. "to be lost you must first be found, therefore you do not exist" (philosophical tech support)
I thought the size/mass of a black hole (or any celestial body) can be determined by the observation of its affect on nearby mass.
If this small black hole is attracting matter the same as a much larger black hole, where is this extra pull coming from? That might not be an easy question but it can be alternatively stated why is the black hole "small" if it has such a large gravitational pull? If it looks, feels, smells and tastes like a supermassive black hole, it must be a supermassive black hole... right?
Ok, I suppose a lot of good questions offer more than a lot of poorly researched replies to the original article.. So here's to being productive!
Let me know if i am correct: Why is it that black holes cannot be detected? Is it because any light that would otherwise escape indicating its presence is consumed?
Also: What are some good books on black holes that one of a mind uneducated as far as black holes are concerned might be able to read wiht little trouble?
Is the spectrum obtained through string theory a continuous black-body, or are there discrete levels? I saw Abhay Ashtekar speak on his theory of "area quantization" last year (somewhat related). Very interesting ideas.
As a matter of interest, you referred to the concept of a "value of infinite that is greater than other black holes". This has little to do with black holes, but it's worth noting that in number theory, there are indeed infinities that are bigger than other infinities. The proof of this is fairly easy to understand - if you're interested, try this page for a very accessible explanation.
This is the limit at which a star is too massive to form a neutron star and instead collapses to a black hole. IIRC, it is equal to about 2.4 solar masses.
Just so ya know. ;-)
Re: formation. When a star is in the happy, go-lucky stages of its life (the Main Sequence, when its burning Hydrogen into Helium in its core), and even a little later, its structure is set largely by the balance of gravity against ordinary gas pressure. (Take the term "ordinary" loosely here.) Later on, as material in the core of the star becomes very tightly packed, etc, that core becomes electron degenerate -- what's holding it up is the tendency of electrons to dislike rather intensely being crammed next to other electrons. (Again, I'm grossly simplifying things here, but what the hell.) This, in turn, leads to all kinds of interesting things -- for one, the conductivity of electron-degenerate matter is extremely high, so it tends to be largely isothermal; for another, degenerate matter is just plain weird : when you pile more mass onto the degenerate core, the damn thing gets smaller! So you see the normal cycle of compression-expansion is screwed up, and strange things can happen. The degeneracy will actually be broken multiple times in the life of the star, as the core eventually reaches its ignition temperate (in massive enough stars : and remember, because its isothermal, the whole thing reaches the ignition temp. more or less at the same time -- which is why you get the so-called "Helium flash" or "carbon flash").
I've veering wildly off-topic here, so back to the point: eventually, if the star is massive enough, even electron degeneracy pressure isn't enough to hold up the star against the crushing pull of gravity. The core collapses -- the electrons fuse with protons to form a big soup of neutrons, which can exert an even more impressive form of degeneracy pressure. (The core-collapse process, as you might imagine, is pretty dramatic: remember that this is an awful lot of mass we're talking about here. There is a rebound off the neutron-degenerate core, plus an outgoing flood of neutrinos which were produced in the p-e fusion into neutrons -- a truly stupendous amount of energy is released, and we call it a Supernova.) And (you can probably see this coming) if the remnant core is massive enough, even neutron degeneracy pressure isn't enough. But we know of no force in the universe that can stop the collapse after that : the object collapses indefinitely, to a singularity.
But the Black Hole, it should be mentioned, comes into being long before all the mass is concentrated in a single point : a BH can be said to exist the moment an event horizon exists -- that is, the instant the density of matter in a region is so great that the escape velocity from that region is greater than the speed of light.
God, that was a long answer to a short question. To top it all off, the supermassive BHs in the cores of galaxies may be totally different beasts -- nobody is entirely sure how they form, though certainly there is a long process of merging and growing before they attain their current (billion-M_sun) masses.
2.3.4 : I don't really have the energy to answer these very completely anymore. :-) But very "briefly." 2: black holes don't suck, any more than normal matter does. If our sun were magically replaced by a black hole, our orbit wouldn't change one bit. (Of course, we wouldn't have too long to appreciate that fact, since we would miss rather dearly the lack of sunlight.) A BH is "different" from a normal object, attraction-wise, only once you get pretty darn close to the thing. So yes, they will eventually stop growing. 3: people use "size" sloppily, but I usually mean the radius of the event horizon. This is really the only definable radius for a BH; it is related to the mass by a well-known formula. Some people also use "size" interchangeably with "mass" -- there are certainly more or less massive BHs. 4: no. :-) but you're actually hitting on some real points here -- to an outside observer, and supposing certain other things, it would like someone falling into a BH was taking an infinite amount of time to do so; in fact the Russian term for BHs was, IIRC, "frozen star," for precisely this reason. read Kip Thorne's book, called -- I think -- "Black Holes and Time Warps," for a good discussion of this sort of thing.
Hope this helps.
The force of gravity at the surface of the more massive one would be greater. What would be smaller, however, is the difference in gravity between at the surface and, say, two feet above the surface. That's what tidal forces are about: the slope of the gradient, not the values along the way.
let me get this right... eventually all our universes black holes will eat all the matter in the universe, eventually eating each other until there is only ultra massive black hole - at that point, all the matter in the universe will be compressed into just one singularity. Sound familiar? what happens to a black hole once there is nothing left to consume? also, wouldn't a black hole have zero effiencity once it has consumed all the matter in the universe, assuming efficiency is expressed as amount of matter consumed/mass?
M period. Fresh, comma
Many low luminosity galaxies, although showing evidence of having very massive black holes at their center, appear less bright than expected given the calculated size of their black holes. This has been explained by models which assume that the black holes in question are "underfed", i.e. that there's no longer enough matter close enough to the holes to create larger amounts of radiation.
However, the galaxy described in this paper, NGC4395, is an exception to this scenario, which is why it is interesting. Although it is of similar low luminosity to the galaxies described above, according to this paper, it shows evidence of containing a much smaller black hole than other low-luminosity galaxies. This smaller hole is from 10,000 to 100,000 solar masses, which is small for a galactic-core black hole.
The paper concludes that NGC4395 behaves more like a brighter galaxy with a larger hole, but because its hole is small, it appears dimmer. Attempting to apply the massive-underfed-hole model to this galaxy, based on it having low luminosity, gives incorrect results; instead, the model that applies is that of brighter galaxies with larger holes, except that in this case, the hole is smaller and thus the galaxy dimmer.
The space.com article actually did manage to say something along these lines, but you have to completely ignore the first half of the article, which is confused nonsense, and read the following paragraphs:
Until now, scientists had speculated that black holes residing in galaxies with dim cores - such as NGC 4395 - were either too old or too small to quickly eat up lots of material, as more massive black holes do on a regular basis. But now it seems that "mid-mass" black holes (a new nickname for the smallest type of supermassive black holes) may simply be more efficient matter-eaters.
"We now see that the nuclear source in NGC 4395 is a scaled-down version of black holes found in the most luminous of galaxies," said, Andrew Fabian, another Institute of Astronomy researcher who worked on the discovery. "Everything is the same, only it is smaller."
As a result, some astronomers now think that the total output of X-rays from accreting matter may therefore be more a product of how massive the black hole is, rather than of the luminosity of the region surrounding the black hole, as it once was thought.
Hawking and Berkenstein came up with this concept in the 70s. Since Hawking radiation implies that black holes have a temperature it follows that they have an entropy as well, and the relationship is S=A/4h, where A is the surface area in appropriate units.
This theory has recently been proved using string theory. Since entropy has its basis in the number of available quantum states of a system, Strominger and Vafa showed this relationship to be true by counting the degeneracy of configurations for strings and D-branes corresponding to black holes in string theory. This is a real result for string theory, since up till then the theory only had a semiclassical derivation.
For more information, see here for more information on the superstring proof or here for the semiclassical derivation.
There'd be an enormous observable doppler effect. Two blackholes rotating around each other (besides being improbable) would have to revolve at an enormous speed in order to avoid collapsing from their enormous gravitational pulls.
And why are you mentioning special relativity? Special relativity is all about not taking gravity into account, and blackholes are all about gravity.