Posted by
chrisd
on from the infinite-radius-finite-diameter dept.
paradox writes "Reuters is reporting that scientists have found a massive black hole 40,000 light-years away that could change the way scientists think about black holes. The mass of this particular black hole is 14 times the mass of the sun, compared to the typical mass of 3 to 7 suns."
Re:Potential energy source?
by
Anonymous Coward
·
· Score: 5, Funny
Tell you what. You fly out there and do a complete survey of the area. We'll wait for you to come back with your findings and whatever you decide is the best course we'll implement. This is in your hands now.
Thanks for volunteering.
BTW, don't fall in! hahaha... Astronomy joke... *sigh*
It's worth noting that the center of the galaxy is 26,000 lightyears from us, see: space.com. So 40,000 LY is not exactly nearby, as the story seems to imply.
So, don't worry about being sucked into infinitely long strings of goo just yet.
-- Mmmmmmm. Floor pie!
Re:Size IS important.
by
zCyl
·
· Score: 5, Informative
But what about its physical size? I mean, when you are dealing with monstrous astro-physical phenoms beyond human comprehension, isn't it important to be boggled by the density?
Because there IS no size. A black hole by definition is a singularity, and has no conceivable dimensions. The closest thing a black hole has to a size is what's called the Schwarzschild radius, or the event horizon. This radius is the distance from the center at which light can no longer escape (ignoring Hawking radiation, another topic entirely). The Schwarzschild radius is equal to 2GM/c^2, where G is the gravitational constant, c is the speed of light, and M is the mass of the black hole. So the radius is really nothing more than a constant times the mass.
If you know the mass, and you don't have rotation, you know everything that can be known about it.
I think Reuters is being completely irresponsible by reporting this hole before a fix can be completed by all affected parties. The only current known fix for this hole is to make sure less matter falls in than energy is radiated by the hole, and keep it that way for a long time. In the meantime (however many millions and millions of years that takes), script kiddies with FTL drive capabilities will be having a field day.
Slashdot is just contributing to the problem by spreading the news. Sheesh!
-Puk
p.s. This hole is hardly a surprise. We've found that space is riddled with such holes, and to my knowledge, none of them have been closed. If space was open source to begin with, enterprising hackers would have found these holes long ago, and plugged them with Bill Gates' ego.
Re:Size IS important.
by
cascino
·
· Score: 5, Informative
Technically the singularity itself possesses infinte density, and thus it's size cannot be resolved (i.e.: it's a single point, no matter how close you magnify it).
The Schwarzschild radius of such an object, however (better known as the "event horizon"), can be calculated fairly simply using a variation of the escape velocity formula
Rs = 2*G*M / c^2
Where G is the gravitational constant, M is the mass of the object, and c is the speed of light.
Plugging the numbers into the equation yields a radius of 2.95 * 10^6 km. Therefore this black hole has a radius just over four times the size of the sun, and an area 16 times as large. Compared to black holes usually on scales relative to that of the Earth, that's REAL big.
non-watered down story
by
ChazeFroy
·
· Score: 5, Informative
Here's a link to the European Southern Observatory story that's not watered down (gotta love Reuters and AP like that!).
yes you can...
by
efuseekay
·
· Score: 5, Interesting
it's called the Penrose process. You use it on a rotating blackhole.
The idea is that in a rotating blackhole, the minimum point of the potential moves around, so you can actually "slows" the blackhole while getting a nice angular momentum kick.
Much like how you use the rotation of jupiter for slingshot. ("gravity assist" is a bad phrase, reality is that it's "angular momentum assist")
-- Mode (3) smart-aleck mode. Press * to return to main menu.
Re:Size IS important.
by
the_2nd_coming
·
· Score: 5, Informative
no a sigularity is the center of a black hole, it is where space time becomes undefind. a black hole is the defined by the eventhorizon. so it does have a size. if it is just a sigularity it is not a black hole, it is a naked sigularity.
--
I am the Alpha and the Omega-3
Stellar, middle-weight, supermassive
by
michaeldouma
·
· Score: 5, Informative
There are three main classes of black hole. This article relates to the "stellar" type...
Astronomers suspect that most black holes are produced when massive stars (at least 8-10 times the Sun's mass) reach the end of their lifecycle. This is a so-called "stellar black hole." Stellar black holes are the remains of dead stars several times heavier than the Sun, compressed to a diameter of a few miles or less. Supermassive black holes have masses comparable to those of a typical galaxy. These masses range anywhere from a million to 100 billion of our Suns. Supermassive black holes tend to be in the centers of galaxies, creating what are called Active Galactic Nuclei (AGNs). They may have formed in the early universe from giant gas clouds or from the collapse of clusters of immense numbers of stars. Lastly, the field of black holes, formerly dominated by heavyweights packing the gravitational punch of a billion Suns and lightweights just a few times heavier than our Sun, has another contender, the middleweight black holes, weighing in at 100 to 10,000 Suns.
article on the science journal nature,
by
vikool
·
· Score: 5, Informative
here is the article on the science journal nature, it is slightly more detailed than the one on reuters
Re:Size IS important.
by
sigwinch
·
· Score: 5, Informative
A black hole is a singularity.
It's important to remember that a singularity is a mathematical artifact where a physical property has no meaningful definition when measured by a particular metric. For instance, the north pole of the Earth is a longitude singularity, a point where the very concept of longitude ceases to have physical meaning.
It has no size, and therefore its density is infinite.
Actually, that turns out not to be the case, at least not relative to our reference frame. Imagine you're a distant (and indestructible!) observer watching a star collapse into a black hole. The more it collapses, the more it is affected by gravitational time dilation: time appears to run slower for the matter in the star than for the observer. Clocks in the star slow down. Light travelling away from the star is shifted towards the red end of the spectrum.
The more the star shrinks, the more it is affected by gravitational time dilation, and thus the more slowly it collapses as measured by the outside observer. The collapse thus asymptotically approaches infinite time dilation, and appears to freeze in time to the distant observer. Its physical size at the asymptote is the size of the event horizon, a.k.a. the Schwarzchild radius.
One way of measuring the star is to ask how long it would take light to travel from its outside edge to its center, as measured by a distant observer. (Theoretically, of course, as the star would absorb any light.) Think of it as the radius measured in units of literal light years. As the collapse approaches infinite time dilation, the 'light radius' approaches infinity. This is the singularity at the center of the black hole, and is a mathematical construct arising from the distant observer's point of view. It does not mean that density or any local physical parameter is infinite
I'm deliberately ignoring what the collapse looks like to an observer inside the star. Known physics simply cannot make any meaningful predictions, except that it will never be observable from the outside (because it literally takes an eternity to occur).
--
-- Kuro5hin.org: where the good times never end.;-)
Slashdot Mirror
Tell you what. You fly out there and do a complete survey of the area. We'll wait for you to come back with your findings and whatever you decide is the best course we'll implement. This is in your hands now.
Thanks for volunteering.
BTW, don't fall in! hahaha... Astronomy joke... *sigh*
So, don't worry about being sucked into infinitely long strings of goo just yet.
Mmmmmmm. Floor pie!
But what about its physical size? I mean, when you are dealing with monstrous astro-physical phenoms beyond human comprehension, isn't it important to be boggled by the density?
Because there IS no size. A black hole by definition is a singularity, and has no conceivable dimensions. The closest thing a black hole has to a size is what's called the Schwarzschild radius, or the event horizon. This radius is the distance from the center at which light can no longer escape (ignoring Hawking radiation, another topic entirely). The Schwarzschild radius is equal to 2GM/c^2, where G is the gravitational constant, c is the speed of light, and M is the mass of the black hole. So the radius is really nothing more than a constant times the mass.
If you know the mass, and you don't have rotation, you know everything that can be known about it.
I think Reuters is being completely irresponsible by reporting this hole before a fix can be completed by all affected parties. The only current known fix for this hole is to make sure less matter falls in than energy is radiated by the hole, and keep it that way for a long time. In the meantime (however many millions and millions of years that takes), script kiddies with FTL drive capabilities will be having a field day.
Slashdot is just contributing to the problem by spreading the news. Sheesh!
-Puk
p.s. This hole is hardly a surprise. We've found that space is riddled with such holes, and to my knowledge, none of them have been closed. If space was open source to begin with, enterprising hackers would have found these holes long ago, and plugged them with Bill Gates' ego.
Technically the singularity itself possesses infinte density, and thus it's size cannot be resolved (i.e.: it's a single point, no matter how close you magnify it).
The Schwarzschild radius of such an object, however (better known as the "event horizon"), can be calculated fairly simply using a variation of the escape velocity formula
Rs = 2*G*M / c^2
Where G is the gravitational constant, M is the mass of the object, and c is the speed of light.
Plugging the numbers into the equation yields a radius of 2.95 * 10^6 km. Therefore this black hole has a radius just over four times the size of the sun, and an area 16 times as large. Compared to black holes usually on scales relative to that of the Earth, that's REAL big.
Here's a link to the European Southern Observatory story that's not watered down (gotta love Reuters and AP like that!).
it's called the Penrose process. You use it on a rotating blackhole.
The idea is that in a rotating blackhole, the minimum point of the potential moves around, so you can actually "slows" the blackhole while getting a nice angular momentum kick.
Much like how you use the rotation of jupiter for slingshot. ("gravity assist" is a bad phrase, reality is that it's "angular momentum assist")
Mode (3) smart-aleck mode. Press * to return to main menu.
no a sigularity is the center of a black hole, it is where space time becomes undefind. a black hole is the defined by the eventhorizon. so it does have a size. if it is just a sigularity it is not a black hole, it is a naked sigularity.
I am the Alpha and the Omega-3
Astronomers suspect that most black holes are produced when massive stars (at least 8-10 times the Sun's mass) reach the end of their lifecycle. This is a so-called "stellar black hole." Stellar black holes are the remains of dead stars several times heavier than the Sun, compressed to a diameter of a few miles or less. Supermassive black holes have masses comparable to those of a typical galaxy. These masses range anywhere from a million to 100 billion of our Suns. Supermassive black holes tend to be in the centers of galaxies, creating what are called Active Galactic Nuclei (AGNs). They may have formed in the early universe from giant gas clouds or from the collapse of clusters of immense numbers of stars. Lastly, the field of black holes, formerly dominated by heavyweights packing the gravitational punch of a billion Suns and lightweights just a few times heavier than our Sun, has another contender, the middleweight black holes, weighing in at 100 to 10,000 Suns.
http://www.nature.com/nsu/011129/011129-13.html
vikas
The more the star shrinks, the more it is affected by gravitational time dilation, and thus the more slowly it collapses as measured by the outside observer. The collapse thus asymptotically approaches infinite time dilation, and appears to freeze in time to the distant observer. Its physical size at the asymptote is the size of the event horizon, a.k.a. the Schwarzchild radius.
One way of measuring the star is to ask how long it would take light to travel from its outside edge to its center, as measured by a distant observer. (Theoretically, of course, as the star would absorb any light.) Think of it as the radius measured in units of literal light years. As the collapse approaches infinite time dilation, the 'light radius' approaches infinity. This is the singularity at the center of the black hole, and is a mathematical construct arising from the distant observer's point of view. It does not mean that density or any local physical parameter is infinite
I'm deliberately ignoring what the collapse looks like to an observer inside the star. Known physics simply cannot make any meaningful predictions, except that it will never be observable from the outside (because it literally takes an eternity to occur).
-- ;-)
Kuro5hin.org: where the good times never end.