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There's a Hole in the Middle of It All
Apparition writes "CNN is reporting that the star at the center of our galaxy is actually a super-massive black hole. The article then claims that it occupies a volume of space about 3 times that of our solar system. If my math is correct, about 230 million suns could fit into that same volume, so it doesn't impress me that the claimed mass of the black hole is only between 2.6 and 3.7 million times that of the sun. So what is up here? Since when do black holes occupy so much space (I thought they were points)? And how can something with a density only 1/100 of our Sun be called super-massive?" I think the article is talking about a maximum possible size of the object, due to limitations on the resolution of our instruments. Nature has a no-registration story about the research. Update: 10/16 23:44 GMT by M : There's an article with more information on space.com, and a press release from the European Southern Observatory.
RB
--Chag
The size of the black hole isn't the volume taken up by its mass. It's the volume inclosed by the event horizion.
If light enters that volume, it never(ish) gets out.
I am a Karma Library.
The matter in a black hole should be condensed down to a point. The event horizon is what would be many times as large as our solar system.
:)
Such an event horizon would take a whole lot of matter
Sharpies don't just sniff themselves.
The whole idea behind a black hole is that it is a point with the mass of a star. If it was the size of a star with a really large mass, then it would just be a big star. I really don't believe that a black hole can occupy a volume, else it wouldn't work.
SIGFAULT
This reminds me of the hollow earth theory... which is proven to be complete bullshit.
I'm not sure if this article presents a convincing enough argument in favor of the black hole argument.
Thoughts?
The large size is probably the event horizon for the black hole.
The event horizon is the sphere within which not even light can escape from the black hole. It is the dark area the the black hole appears to take up.
The actual size of the object would be much smaller
There should be a moderation category "Dumbest Comment EVER"
the size of the event horizon. What's inside is unknown (and presumably unknowable)
John Roth
"CNN is reporting that the star at the center of our galaxy is actually a super-massive black hole."
I'm no astrophysicist, but really, wtf could hold an entire GALAXY together but a black hole? Seriously, any ideas? I may be naive, but I've always thought this to be a stupid ponderance. Sure, anyone with a scientific mind would want proof of its existence, but to be surprised? *Sighhh*
So, does that mean that in time, the blackhole will swallow up the star?
-Cyc
/.'s 10 Millionth
where Enron's accountants found work.
yeah, i thought black hole's were points too, but they also have event horizon's that extend far out form the actualy black hole point. perhaps that's what they were talking about.
This post was brought to you by the number 584811 and the characters / and .
So what is up here? Since when do black holes occupy so much space (I thought they were points)?
Black holes are points, as best I know. Infinite compression sort of thing. However, their effect reaches beyond "point" status. As their gravity increases, their grip on everything also increases. Here, where they say "that it occupies a volume of space about 3 times that of our solar system" they most likely mean that light can't escape that region.
So, it is a point, but the volume, as they say it, is how far its ultimate effect (capturing light) reaches. At great distances, gravity weakens greatly, so much mass is required to reach large distances.
My clarification.
-DrkShadow
Yes, black holes are a point (that's called the singularity), but they're talking about the size of the event horizon, or point of no return. So this particular black hole has a mass of 2.6 to 3.7 million or whatever suns, but its event horizon is larger than the solar system.
With a black hole this big, you can actually cross the event horizon, and not be torn apart because the change in gravity over a certain distance (6 feet or so for your height) isn't great enough. Smaller black holes will rip you apart quicker though
If my math is correct, about 230 million suns could fit into that same volume, so it doesn't impress me that the claimed mass of the black hole is only between 2.6 and 3.7 million times that of the sun.
As I understand it, all the mass of a black hole is compressed into a singularity at the center of an event horizon with the volume between effectively empty. The impressive thing about a black hole is the incredible density of the compacted mass at the center, not the distance at which the black hole starts taking effect or the actual mass in the middle.
"...until the super-massive black hole eats up our galaxy, and do you think M$ will survive?"
It's nice to see that graduates from the Bob Saget School of Comedy are getting journalism work.
According to my Astronomy course, Super-Massive black holes are less "violent" than their smaller brothers because most of the mass is concentrated at the center in a very very small space. Their event-horizons are very large because of this mass, which makes them seem not as dense as we would assume. With a small black hole, the event horizon is very small, and thus the effects near the point are much more drastic because mass that passes the event horizon is "consumed" immediately. I realize I am simplifying quite a bit, but hopefully you get the point.
I've always thought it was obvious that super-massive blackholes lie at the center of galaxies. The intense gravity at the center should create one, and spiral galaxies are all just pinwheeling "down the drain".
I would bet there are black holes at the center of ALL spiral galaxies like our Milky Way. Other shaped galaxies may just be at earlier stages of evolution (such as elliptical) before their holes have formed.
the scientists in the article seem to assert that this is CONCLUSIVE proof of a black hole's existence. but i remember reading a few months ago about a schism in the physics community - a sizable segment of the community is disputing the theoretical existence of black holes! i wonder how this discovery will affect that debate....
smd4985
The "size" of the black hole refers to the size of its event horizon (a.k.a the Schwarzschild Radius), which is R = GM/2c^2. For a huge value of M ("supermassive"), the event horizon is very large: once you cross this, there's no coming back, and our physics stops at the edge. But since R is so large, the tidal forces are small at the event horizon - much smaller than the tidal forces at the event horizon of a smaller black hole. (Chew on it for a second and it makes sense).
The "actual" naked singularity is in fact a point, but we have no way of probing anything inside the event horizon. So calculating the density of a black hole is misleading...
"I will take the Ring," he said, "though I do not know the way."
However, by size the article is likely referring to the size of the event horizon of the black hole. The event horizon is the bondrary between where light can escape from the black hole and where it cannot. As mentioned in the article, this is not a new idea, only the proof is new. Of course, we could have just sent Beowulf Shaeffer to the center of the galaxy to find this out. (See "At the Core" by Larry Niven)
Would this be the proverbial drain that we're all swirling around to our eventual demise?
Just wondering.
-Goran
Carpe Scrotum - The only way to deal with your competition.
From the very center, this galaxy sucks.
This would seem to imply that, in theory, a very large black hole could have rather low density inside the event horizon. It seems to me that a black hole could spontaneously form around a particularly dense cluster of stars if it was large enough and they all happened to clump together.
But my head starts to hurt thinking about what happens to physics when a region of normal space suddenly finds itself inside a black hole like that. I am definitely not a physicist, so I can't explain what goes on inside a black hole, or if my globular cluster black hole is even possible.
Crispin
----
Crispin Cowan, Ph.D.
Chief Scientist, WireX Communications, Inc.
Immunix: Security Hardened Linux Distribution
Available for purchase
I do not who Bob Saget is, but accroding to this he is God, so I'll take that as a compliment ;)
Rake Free + Mac Poker: CardCrusade
So, would it be possible that whole star systems are intact within the Schwarzchild radius? Could stuff be in stable orbits where tidal forces didn't rip things apart? Cool!
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
As the above reply suggests, the galaxy's own mass should be able to hold it together. Just like the sun holds together the solar system and the Earth holds itself together.
/.-ers might be a recent paper that describes the universe as a cyclical entity (no "big bang"), by representing it as a pair of branes (world sheets, see string theory...). The end result is there's an event (a "bounce) that might look like the Big Bang, but it's really just a collision between the branes.
Black holes are good candidates for causing a galaxy to accumulate. It can be kind of hard to explain what causes galaxies to form.
I'm getting off-topic, but I don't care...
One of the favorite explanation comes from irregularities in mass distribution as evidenced by perturbations in the cosmic microwave background. That's one of the reasons that the CMB became such a hot topic, it offers insight into the origin of large scale order in the universe.
Also of interest to
Like anything else in cosmology, it's all rather speculative (at least as compared to many other physical models).
Find the link on your own (/. might've even covered this topic).
That means our galaxy is one big delicious forbidden dooooughnut.
Seriously who thought that something that exists in nature was the same as a euclidean mathematical construct? A point? I mean really. A point has NO dimention which would give your black hole INFINITE mass. My best guess is, that would give it sufficient grabbity pull the whole universe through to the scientifically documented "negaverse" and we could all hang with bizzaro superman.
Imagine a beowulf cluster of... *DOH!*
This comment is fully compliant with RFC 527.
So how long did it take you to create that webpage just to refute his post? ;)
That's Florida.
.sig last updated Jan. 14, 2000
An object can orbit a black hole just like a planet can orbit the Sun (or a star). The Sun will not swallow or pull in the Earth any time soon. Black Holes are not cosmic vacuum cleaners that "suck" up everything around them. If you're in a stable orbit, it would be just like orbiting a Sun.
That said, there is evidence from general relativity that due to graviton radiation (gravity particles), large orbiting bodies slowly move closer to each other. The gravitons leaving such a system take energy out of the system slowly bringing the orbiting bodies together. This effect is (AFAIK) theoretical, although many people are currently working on ways to detect this graviton radiation and show that it is coming from systems like this. So in this case, yes, eventually (think eons) the star and the black hole would slowly move towards each other (the star would move more since it the least mass of the two) and in this type of collision, the black hole wins.
Who said Freedom was Fair?
Not necessarily. It depends on things started. Celestial objects (stars, planets, black holes, comets, whatever) form orbits around massive objects based upon how they're formed and/or their entry trajectory and speed. It's quite possible for the star to be in a stable orbit around the black hole, just as Earth is in orbit around an object much more massive. The physics at great enough distances (outside the event horizon) is the same.
Well, the door was open...
If you read the earlier post about the kernel patch, you would know that talking about the hole may be a violation of the DMCA!
This comment is fully compliant with RFC 527.
We already know there's a powerful telepath living on a planet there and he needs a space ship. If there had been a black hole in the center of the galaxy, you'd think someone would have mentioned it.
The article is referring to a determination of the orbit of the star closest to the galactic center. The periasteron (closest point in the orbit) is 17 light hours from the galactic center. This implies that the mass necessary to create that orbit is concentrated within that radius. The only thing in our current cosmic zoo that fits 3 million solar masses inside of 17 light hours is a black hole. The event horizon itself should be smaller than that, but not by much.
What is an interesting question is where the Roche limit is for these parameters, and how close this star is to that limit. (In other words, how much closer can the star get before it is ripped apart.) I seem to remember that it is possible to set up conditions so that the Roche limit is inside the event horizon. Obviously, the physics around there are very strange.
I don't know. The whole thing just seems sort of rickety to me.
- r = 2GM/c^2
where G = 6.67e-11 m^3/s^2*kg (the gravitational constant) and c = 3e8 m/s (the speed of light, of course). Plug in 3 million sun-masses (the sun weighs 2e30 kg), and you have- r = 8.9e9 m = 5.5 million miles = 0.06AU
So unfortunately, the event horizon isn't three times as big as the solar system. The earth's orbit is 1AU (that's how the unit is defined). The event horizon barely stretches past the surface of the sun (7e8 meters)!So much for that idea!
at the middle of the galaxy was some calm looking planet with a grey-haired guy that Sybok is looking for. Thanks for bringing up horrible memories of ST:V!
"The objective of securing the safety of Americans from crime and terror has been achieved." -- John Ashcroft
*drooling* Mmm ... donut!
Whoever designed level 61 in Frozen Bubble is a sadistic bastard.
I thought Disney discoverd this in the eighties. http://www.geocities.com/Area51/Shire/6822/
who went to a black hole to measure its radius. never did hear back from him...
They _could_ make out the symbols "/." in a faint gray shade on this monster blackhole.
Slashdot: Failed Car Analogies. Amateur Lawyering. Anecdote Battles.
p.s. I may be wrong about which book mentioned it, but it was one of those uber-cool sci-fact books by a reputable physicist, like Feynman or something. Really. I'm serious.
-Ansel.
G=C800:5
I've been interested in black holes since my last relationship, and I have a few questions. First, could black holes eventually swallow all matter and will there be just one someday? Could such a single singularity explode, as in a big bang? Could this be where some of the missing matter is? How small can a black hole be, could we manufacture one? Since black holes accelerate outside mass to the speed of light, does that stuff freeze in time? Could you use that acceleration to get around? What happens to the stuff at the center, that is the stuff that isn't time locked?
2tec ~ just curious
The sun is about 800,000 miles across. The diameter of pluto is about 7,000,000,000 miles. The volume of a sphere with that diameter is about 4.3e+28 miles. You could fit something on the order of 5e+22 suns in that space.
Imagine a beowulf cluster of black holes like S2...
I hate myself for making a comment like this...
Since when do black holes occupy so much space (I thought they were points)?
They're big points.
RMN
~~~
get it? sucks? rofl.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
Of course this is all based upon classical arguments, and without a theory of quantum gravity we can't be sure. However it hasn't stopped Hawking and Penrose arguing about "cosmic censorship principles" :)
Jon Erikson, IT guru
There's a Supermassive Black Hole in the center of Uranus!
Theoretcially (we'll likely never have building materials struturally sound enough to test this) light should behave in almost exactly this manner close to a black hole. For example, say you've built a circular torus space station around a black hole. If you're within a certain radius to the singularity, but still outside the event horizon, light will bend towards the blackhole, allowing your vision to see 360 degrees around the torus. You can stand in one point and see your back an apparent distance equal to the circumfurence of your imaginary torus away. Closer than that radius means that the torus would appear to bend the wrong way.
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
If my memory serves me, I believe that there is a nearly confirmed black hole at the center of M15 (a globular cluster). However the conditions for it's creation are probably still up for debate. A bunch of semi-simultaneous stellar collisions at the core is not out of the question though.
Shop Smart, Shop S-mart!
Our sun is about 10^30x2 kg while the earth is 10^25x0.6 kg That makes the sun about 10^6 times heavier than the earth([1])
This black hole now is about 2.6 to 3.7 times that heavy when compared to a sun of the size of our own.
Our planet roates around the Sun at about 150,000,000 km at a speed of ca. 29.658 km / s if my math isn't wrong.
That other sun rotates around the black hole at about 17 light hours at a speed of 240.652 km / s (if I am not mistaken here either).
The speed of that sun is more than 8x the speed of the Earth, generating a significantly higher centrifugal force.
Now, that sun is 127.5 times further away from the black hole's event horizon than Earth is from Sun.
At the same time, the increased distance should provide a significantly lower gravitational pull than the 3.6 x relative weight of the sun could provide.
As this sounds completely bogus to me, I'd be happy if someone could enlighten me how this is supposed to work.
... but close ... it's actually r = 2GM / c^2, where G is the Gravitation constant and M the mass for the main contributor to the gravitational field, the black hole. For a more detailed explanation, see here.
"I think the article is talking about a maximum possible size of the object, due to limitations on the resolution of our instruments."
I'm sure this editorial comment was well-intentioned, but the article would have been much better off without it. What the article refers to corresponds closely quite nicely to the Schwarzschild radius of a supermassive black hole.
A very massive black hole will necessarily be much less dense than the Sun, and can even be less dense than the Earth.
The simple reason is that (assuming a static, spherically symmetric mass distribution) the mass of an object is directly proportional to its Schwarzschild radius. But density is proportional to mass divided by radius cubed.
So if you double the mass of a black hole, you must necessarily double its radius. By definition this increases its volume eight-fold, and so its density is decreased by a factor of four.
So as you consider larger and larger black holes, you must see that their densities are smaller and smaller.
If you are in the market for a comparatively easy textbook that will teach you more about general relativity, I recommend Exploring Black Holes by Taylor and Wheeler. If you have a firm grasp of calculus and freshman physics, you will be able to handle it. It is more expensive than a normal book, but cheaper than the average textbook.
Comment removed based on user account deletion
Very much like those things you find at a Krispy Kreme shop, but with a lot less frosting...
Does this mean that the voice we will hear at The End of Time will be saying "OOOhhh... donuts..."
How come Slashdot never gets Slashdotted?
And how can something with a density only 1/100 of our Sun be called super-massive?
:)
It's just not super-dense!
I'm sure he's been a longtime fan well before this thread started. This has only been the first excuse to show it off.
The author's confusion here seems to be regarding the differences between a blackhole and its singularity.
A black hole is just that -- a black hole. It is a region of space from which nothing can escape (approximately; black holes do very slowly radiate heat). In other words, the volume a black hole occupies is defined by the Schwartzchild radius: the point beyond which the escape velocity exceeds c.
A singularity is the "center" of a black hole; it is an infinitely dense point in space, of enormous mass.
Interestingly, black holes may have some useful properties for astronomers. Light heading towards a black hole will be refracted around it and bent; in essence, the black hole acts like a magnifying glass.
social sciences can never use experience to verify their statemen
I don't want to shock anyone, but it is possible that they got the facts wrong. A small black hole (about 2.5 solar masses) has a horizon of a few kilometers (order of magnitude 10km). I am guessing the hole is a few times the size of the SUN not the solar system. That is really huge for a black hole.
Eh? Could you explain what you're talking about here? Because as far as I know, Hawking and Penrose's work has nothing to do with the likelihood of black holes forming. Indeed, one of the things about black hole formation in that no matter how unsymmetrical the initial state the end result is highly symmetrical, possessing no distinguishing features other than mass, charge and angular momentum... the "black holes have no hair" theorem.
Or are you talking about the recent results in M-theory proving Berkentstein's semi-classical formula for black hole entropy? If so, I'm still not sure what that's got to do with black hole formation... it strikes me you've got things confused...
Jon Erikson, IT guru
Black hole? Geez, where have these people been? Everyone knows that the galaxy's core exploded years ago!
End of lesson. You may press the button.
got me :-)
Rake Free + Mac Poker: CardCrusade
you see, Apparition, the article isn't wrong. you're just a tard.
Finally something strong enough to clean up all the AOL disks
Table-ized A.I.
A black hole is just God dividing by zero - Albert Einstein
Cool quote, IMHO.
this is a real stretch, but mabye its relative. mabye if you were looking at it at a certain point of view, it would look like a pinpoint, and from another point of view it would seem super massive, yet all the while it was the same object. who says that what is observed is the truth, because all it really is is perception. mabye there is some sort of wierd dimensional dynamic here...
I can't believe how Milky-Way-centric that Slashdot still is. The bias is incredible. Nowhere in this story does it identify which galaxy, as if we all live in the same galaxy. For chrissake, people, it's the Internet.
Jeez.
-Waldo Jaquith
The orbiting star is at 17 light hours. This does not mean the event horizon is at 17 light minutes, but . . .
The speed of the orbit and the radius gives us the mass of the central object. At 3 million times the mass of the sun it should be VERY bright. Since it is not, and given the very large mass, it can be assumed to be a black hole.
The Swartzchild calculation does indeed give a event horizon radius of about 8.89E+09 meters, or 29.6 light-seconds, certainly not at the orbit of the detected star.
By the way, if you do the Swartzchild calculation using the estimates of the mass of the universe you get a event horizon about the size of the visible universe. We may be living in a black hole.
The size issue: the companion star's orbit tells us the maximum possible size of the central object. If the orbit is 17 light hours across, the primary is at most that large. It can be smaller, just as our Sun's diameter is smaller than the orbit of Mercury.
The proof the central object is a black hole is that nothing else can fit millions of solar masses into a sphere 17 light-hours across. The black hole need not fill that volume. More precisely, the event horizon need not fill that volume.
Singularities, point masses, event horizons: the size of a black hole depends what you mean. The singularity is the postulated point of infinite density: outside observers can't see it because it's inside the event horizon. The event horizon is the point of no return; in classical terms, the escape velocity equals the speed of light at the event horizon. The gravitational force is finite at the event horizon, and need not be extreme if the black hole is very, very large. If the universe is closed, we are all inside a black hole now, and will experience singularity at the Big Crunch.
But it isn't useful to think about the inside of a black hole. Different physics might apply -- lots of smart people think so. From the outside, as another poster wrote, all you get to observe is the black hole's total mass, total charge and total angular momentum -- that's plenty to work with in astronomical observations.
As to matter 'spiralling in', or the entire galaxy being sucked in by 'infinite gravity': Earth isn't being sucked into our Sun, is it? Unless you're quite close to one, the gravitational field of a black hole essentially (asymptotically) follows an inverse square law, like the gravity from any object. (When you get close, in units of the Schwarzchild radius, you do indeed 'spiral in' because the field strength increases faster than inverse square. The precession of Mercury's orbit is used to measure the deviation from inverse-square near our Sun, and is one of the 'proofs' of Einstein's General Relativity.)
The other mechanism for 'spiralling in' is loss of orbital energy due to friction, as in the accretion disk around neutron stars, for example.
That is all. Return to your homes and families. :-)
je ne suis pas un fou
I found this cool earth orbit physics toy and demonstration while reading one of my favorite web logs, Sensible Erection. (I, uh... Read it for the articles.)
/drag the screen to put a satelite in orbit.. see how long it lasts...
"This is the coolest this i have seen all week, click
pull off a moon only orbit for maximum kudos"
The physics for object orbits are incredible. This is a great demonstration of the exact effects you describe, and should apply to the questions and comments about orbits around a black hole.
Enjoy!
P.S.: You have no idea what a breath of fresh air it is to be able to visit cool links that aren't being slashdotted to hell and back.
Average orbital radius of Pluto's orbit is 3660 million miles.
1.2010984306567283*10^7
3 5*10^6
rs=3660000000;
Volume of solar system (based on assumption that the solar system is considered a sphere) in cubic:
vs=(4/3) Pi rs^3
2.0536757052608588*10^29
Mass in the solar system is approximately 2*10^30:
ms=2*10^30
2.*10^30
Density of the solar system is given by the mass divided by the volume:
ds=ms/vs
9.73864
Mass of the unknown object is between 2.6 million and 3.7 million times the mass of the sun (which is 99% of the mass of the solar system):
mo1=2.6 10^6 * ms
5.1999999999999997*10^36
mo2=3.7 10^6 * ms
7.4*10^36
The volume of the object is about three times that of the solar system:
vo=3 vs
6.161027115782576*10^29
The density of the object is given by the mass divided by the volume:
do1=mo1/vo
8.440151134344576*10^6
do2=mo2/vo
The ratio of the density of the object to the density of the solar system:
r1=do1/ds
866667.
r2=do2/ds
1.23333333333333
Thus, this unidentified object is between 8.6*10^5 and 1.23*10^6 times as dense as the solar system. This is very dense, and puts it into the category of a super-massive black hole. These guys are scientists.
Lack of eloquence does not denote lack of intelligence, though they often coincide.
Please mod down all the people who are currently at +5 claiming that the size of the object is really the event horizon, which is very large due to it being a supermassive black hole. This is a true statement, but it still doesn't explain the claimed size of the black hole in the article.
If you work out the schwartzchild radius of the sun using r=2GM/c^2 it comes out to around 3000 m. For the upper limit of 3.7 million solar masses that would mean that the black hole had a schwartzchild radius of around 1 x 10^10 m. This is about a factor of 14 larger than the radius of the sun which is 7 x 10^8 m.
This is no where near as large as the "volume of space around 3 times larger than the solar system" which is in the article. The poster of the article was also correct that the density was way too low. It is correct that supermassive black holes have large event horizons which are larger than the radii of typical stars like the sun. However, the average density inside of that event horizon is still denser than a neutron star.
I wish I had the 5 moderator points I had last week, I'd go to town on this story...
All roads lead to the hole :-)
Don't tell me Pellucidar isn't real!
Who cares about black holes. I want to read more about pink holes and what can fit inside!
I don't.
\begin{vorlon_mode} ...there is a hole in your galaxy...
\end{vorlon_mode}
"huhuhuhuh... hey beavis... like, uhh... stick yer finger in it... uhuhuhuhuh." "no way butt munch! mehehe... you go first, mheheheheh."
Didn't a drunken Homer Simpson once suggest to Steven Hawking that the universe is donut shaped?
I'd prefer naked and petrified celebrities.
Imagine a beowulf galaxy cluster, though.
I've stumbled across NASA's Astronomy Picture of the Day site, and I've become addicted to it. Not a day goes by without me browsing back and back through the archive. Lots of wonderful images there, with explanations by a professional astronomer, in language that even I understand. And ofcourse links for people with more understanding of the stuff they are talking about.
Anyway, it's an amazing site, really worth adding to your daily-visit bookmark group. And yes, black holes in or near "our" galaxy are featured there as well.
(Not karma whoring, I've got plenty. Just wish to share this with you)
karma capped
at the middle of the galaxy was some calm looking planet with a grey-haired guy that Sybok is looking for. Thanks for bringing up horrible memories of ST:V!
And thank you for bringing up horrible memories of ST:V! He was a poor excuse for a Vulcan. Me, I like my Vulcans slim, busty and wearing skin-tight clothing, yes-siree!
GMD
watch this
Some of the more avant guard sting theorists are advancing the notion that black holes are simply really really big (as in high energy) elementary particles (i.e. strings). It'll be interesting to see if this particular theory holds any water, because it might mean high energy physicists may one day be trying to sling black holes at each other ;).
BlackGriffen
This might be a misinterpretation. In the ESO press release they say:
So that puts an upper limit on the scale of the thing, but doesn't imply it takes up all of that space.
This post is strictly my own opinion and not necessarily that of my employer.
I think that's "Schwarzschild", not "Schwartzchild"... unless I'm crazy.
Just being nitpicky in case anybody wanted to look into that further.
If you want to make an apple pie from scratch, you must first create the universe. -- Carl Sagan
My high school physics says that an object falling from far enough away toward a black hole will be going the speed of light when it reaches the event horizon. At the speed of light, things that have mass, have infinite mass? (bad for the universe)? A moment later this object is now going... what? faster than the speed of light?
What am I missing?
Trouble, a mistake or fun, your choice
Regarding discussions about whether the "volume" of the article implied the Event Horizon, that's what I thought it was at first also. But then I came up with some numbers that don't seem to correspond to those of the CNN article. I then checked out the original paper. The paper is formally on the observation of a star that seems to be orbiting the galaxial center, and this radius of orbiting is what they are pinning down as the a putative upper limit of the size of the supermassive object.
It would seem that the original poster's comment was correct in that this was the _Upper Limit_ of the radius of the supermassive object, and not the Event Horizon radius.
Let me clarify,
The Schwarzschild radius (Or Event Horizon) is given by
r_SCH = 2 G M / c^2
where G is gravitational constant, M is mass of object, and c is speed of light. If we use, as per CNN article (yeah, I know, good source)
M = 3 x 10 ^ 6 * mass of sun
mass of sun = 2 x 10 ^ 30 kg
s.t. M = 6 x 10 ^ 36 kg
and G = 6.67 x 10^ -11 Nm^2/kg^2
and c = 3 x 10^8 m/s^2
then r_SCH = 12 x 10 ^ 36 * 6.67 x 10 ^-11/9 x 10^16
r_SCH ~ 1 x 10^10 meters.
I looked up some values of Pluto's radius, and got about 3000 million miles, or 5 x 10^9 km, or about 5 x 10^12 m.
So this galaxial blackhole seems to have a radius 100-1000 times less than the solar system radius.
And indeed, in the final page of the Schodel paper, there is a mention that the observed radius of the orbiting star is ~ 2000 times the Schwarzschild radius, and not the actual Schwarzschild of the star. i.e. the observed radius of orbit is much much larger than the putative Schwarzchild radius.
These researchers are popular here on campus at UCLA. Also, check out some nifty pictures here.
I just wonder what kind:
...
French Cruller
Plain
Sugared
Jelly filled
CNN is reporting that the star at the center of our galaxy is actually a super-massive black hole
I saw a documentary about this over a year ago.
Horizon on the BBC IIRC.
I also seem to remember somebody thinks "our" black hole is "feeding again" (whatever that means).
Do you mind, your karma has just run over my dogma.
The limiting size of 3 times that of our solar system was determined by the orbit of the star around the black hole. They therefore concluded that the object was smaller then 3 times our solar system, and the mass was determined by the orbit of the star around the mystery object. Once the scientists took a look at these values, they realized nothing but a black hole could be located within this space. The maximum size of the Schwarzschild radius is about 2.7 million kilometers, or about 1/50th of the Earth-Sun distance. Also, black holes do emit a magnetic field beyond their event horizon, so you might be able to communicate through it using magnetic pulses.
what sig?
Talking on the z-y-x axis for math. If all are set to zero, there would not be any room for more than a single sub-atomic particle. For them to be a point, would mean that Matter would be destroyed, not converted, but destroyed. This can not happen, this will not happen, matter is forever. It will convert; it will change, but never go away. But then again I may be wrong, it would be the first time, but there is a chance.
Ok, I've heard of there being a singularity in the center of our galaxy for a long time now, and CNN is JUST coming out with this? Isn't CNN a news channel, and isn't new supposed to be current?
Your hair look like poop, Bob! - Wanker.
The diameter of the event horizon of a black hole is proportional to the square root its mass, but the volume is proportional to the cube of the diameter. So mass^1.5 is proportional to volume. Therefore, as the mass of a black hole increases, the density (in terms of mass over event horizon volume) decreases, and a supermassive black hole can actually be much less dense than a star
So, while a black hole with mass equal to the sun would be much smaller than the sun, a black hole with mass 3x10^6 times that of the sun would have an event horizon with ~5x10^9 times the volume of a black hole with the same mass as the sun
Repeal the DMCA!
I thought that was a neat way to look at it, anyway. I don't know if it holds universally...
-Erf C.
Cthulu always calls collect...
When they talk about the 2 or 3 million solar masses sitting within a radius of three solar systems, they mean only that all of that mass must be somewhere within that radius.
They don't mean that the event horizon is that large, because the star orbiting this black hole couldn't possibly orbit right next to the event horizon.
Where is Maximillion?
The article also suggests that (and it is true):
By transitivity:
So *that's* what it is. It's the size of the orbit of the star, not the Schwarzschild radius of the blackhole.
Lots of talk here about event horizons. Since the idea of the event horizon is based on "the" speed of light, does "event horizon" really mean anything now that we know that the speed of light is not a constant?
You could have been pedantic and written "at Milliways". :-)
Wonderful we all live in an accretion disk...
"It's so convenient to have a system where everyone is a criminal" - A. Hitler
Its density. The black hole at the center of the milkyway is a Super Black Hole. This is larger, but also equally more massive than the standard black hold fromed by a single star. The earth would be a black hole in the sense it would have an event horizon if it's mass took up an area the size of a marble. It is actually theoried that you can do computing with minature black holes with event horizons nanometers accross, you could figure out how to make them.
Yeah, but we also only BELIEVE that gravity will continue to function tomorrow. However, there is a wealth of evidence that it will. There is a wealth of evidence for black holes, as black holes in binary systems have been found (of course the black hole could just be a really dim, massive object, but it still is pretty convincing).
Network Security: It always comes down to a big guy with a gun.
There is a hole, and RedHat has a patch out, but we can't explain it to Americans because Bill Gates thinks he owns the copyright on the universe and is threating with the DMCA.
If the thing you fit inside them is thick enough to block light coming from the outside, any hole will become black. Some are tighter than the one at the centre of the galaxy, though.
so how do we know its a point?
If you use Linux, please help development of Autopac
http://archive.ncsa.uiuc.edu/Cyberia/NumRel/BlackH oles.html
t ml
t ml
http://cosmology.berkeley.edu/Education/BHfaq.h
http://image.gsfc.nasa.gov/poetry/ask/abholes.h
The only thing necessary for the triumph of evil is for good men to do nothing. - Edmund Burke
That's why we should throw a party at the event horizon. Everyone arrives at the same time and the party lasts forever.
That or nobody ever gets there and the ride is extremely short.
I can't remember which was the inside observer and which was the outside observer. I think it mixes reference points. The same time reference point is short, and the never arrive takes forever.
Isn't relativity fun?
Network Security: It always comes down to a big guy with a gun.
Vi eta durak yoshe!!
Goatse
So we're being flushed down a giantic cosmic toilet. Great. I know Tool said I should learn to swim, but I guess that won't be enough.
http://en.wikipedia.org/wiki/Signature_bloc
The Spiraling Shape will make you go insane.
From Newtonian mechanics of circular orbits we have:
mrw^2 = GMm/r^2
where m is mass of orbiting body, M is mass of central body,
r is distance between them, w is angular velocity of orbiting
body. Apply this to Earth/Sun system and star/black hole system
and one has:
r_star/r_sun = cuberoot(M_hole/M_sun) * cuberoot(w_earth/w_star)^2
With
M_hole = 3.6 * 10^6 M_sun
w_earth = 15.2 * w_star
this gives
r_star = 940.4 r_sun
= 7520 light minutes
= 125 light hours
According to the website the closest approach
is 17 light hours. So perhaps the orbit is very
eccentric.
By the way, the size of the event horizon is
about 36 light seconds (easy to find if you know
that the Schwarzschild radius of the Sun is about
3 km), or about a 13th of the distance from the Earth to the Sun.
The star can hardly be described as "skirting the hole's event horizon"
as stated in the BBC report.
The world is everything that is the case
If my math is correct, about 230 million suns could fit into that same volume, so it doesn't impress me that the claimed mass of the black hole is only between 2.6 and 3.7 million times that of the sun. More importantly, how many Libraries of Congress can black hole consume?
A cubic foot of lead has much more mass than a cubic foot of styrofoam but they both occupy the same amount of space.
In Science, a "Theory" is "something which is supported by a perponderance of evidence."
The next level down from that is "Hypothesis", and if black hole theory were merely an hypothesis, then you would be more justified in your complaint.
Of course, theories can be wrong. But then again, the next level up, referred to as "Fact", is also found to be wrong from time to time.
The bottom line is that with black holes, they qualify as a theory (ie. something that can be very well trusted), because they are implied by mathematics based on even more strongly established theories, and there is plenty of empirical evidence to support the mathematical implications.
So the likliest thing is that if black hole theory is wrong, then it's probably only partially wrong, because clearly, there have to exist objects with that much mass, and the real thing probably behaves very much like the theory.
Great post. Two basic questions left unanswered in the original article, and a whole host of follow-up questions they've sparked in my imagination...
1) The orbit of this star is described as "eccentric". How eccentric? How close does the star get to the event horizon at its closest point to orbit?
2) Is the star orbiting nearly edge-on to us relative to the black hole (likely, if it's close to the galactic plane), or face-on?
With a period of only 15 years or so, are there points in that orbit at which gravitational lensing effects are significant, and can we get cool data either from lensing or relativistic effects at certain times in its orbit?
Also, how about occlusion events? Can we get data on them? Or is peri"hol"ion (perireallyfsckingbigblackholion!) stuck tantalizingly behind the black hole?
(Oh, the possibilities for a science fiction author. I mean, any species demented enough to try to evolve sentience on such a planet wouldn't need telescopes, would probably call the time their Sun was in the sky "night", and their religious leaders would probably take general relativity for granted until some hereticical freak invented Newtonian mechanics! :-)
There is so much math going on in this topic, I'm very confused. Could someone please tell me, how big is this black hole in terms of football fields?
Thanks.
Forget the whales - save the babies.
Zim: "Hello Friends, I'm a perfectly normal human worm baby, you have nothing absolutely NOTHING to fear from me. Just pay no attention to me and we'll get along just fine"
... Tell me!"
Ms. Bitters: "Take your seat now Zim, today's lecture is about outter space will eventually implode in on itself... Yes Zim?"
Zim: "In say the event of say a full scale alien invasion how prepared do you think this planets planet's defenses would be?
Bitters: As I was saying, the universe is doomed... doomed.. doomed DOOOOOMED"
A black hole is just God dividing by zero
You mean the universe is just a bunch of cosmic core dumps? There goes the neighborhood.
Facts are boring things, because they are all just single observations. Here's an example of a fact: On October 15, 2002, I dropped a pencil. It accelerated toward the ground and stopped on impact.
Theories are a lot more interesting, because they are the generalizations that tie facts together. Here are a couple of examples of theories:
"A dropped objects falls toward the center of the earth"
"There is a universal force attracting particles of matter together that is proportional to mass and inversely proportional to the square of the separation of their centers of mass."
Basically, everything that we think we know about the universe is a theory.
> From the point of view of you (on the train), looking forward, you'll see the entire universe running about 10000 times normal speed - stars evolving in minutes - and the bullet flying away from you at 2% of the speed of light.
Argh. The sped-up universe is what a guy on the back of the train looking backwards (and the guy on the black hole probe looking up) sees.
The guy on the front of the train (and you, lowering the probe and observing the probe) sees a universe running at 1/10000th speed - a 2.0 GHz Athlon will look like it's running at 0.2 kilohertz and what-not.
Roger Penrose talks about it in his book `the emperor's new mind', and here is an excellent link
I believe that Isaac Asomov described the galaxy center as being a black hole in his foundation trilogy, in 1951.
History will be kind to me, for I intend to write it - Sir Winston Churchill
"And how can something with a density only 1/100 of our Sun be called super-massive?"
Because "super-massive" refers to mass and not density nor volume?
They get FUCKED up, not fscked. I ignored the rest of what you said, you fucking bastard.
-- 'The' Lord and Master Bitman On High, Master Of All
When they talk about the volume of space the black hole occupies, they are referring to the event horizon. The event horizon has the same perimeter as the star that gave rise to the black hole. The black hole's event horizon is as far from the hole as the star's surface was from its center.
FYI, the event horizon is the point at which the black hole's gravitational force becomes greater than that of the original star (and exponentially so as one moves closer to the hole). Outside the event horizon, the gravitational pull is the same as the orignal star's.
Also FYI, the largest known star is about one billion times the volume of our Sun.
Finally, who cares about density? Mass means mass, not density. An "object" millions of times as massive as the Sun is indeed super-massive, regardless of its density. Density is merely the ratio of mass to volume. Low density does not mean low mass--a chunk of aerogel the size of the Sun would not be very dense, but would still be massive.
Can't remember exactly.. did Arroway see a blackhole at the center of Milkyway?
I hear that to an outside observer, an object moving towards a black hole will never reach the event horizon. This seems very similary to the "Motion is impossible" problem. What if we fling YOU at a black hole? You will not slow down in relation to yourself, therefor you would reach the event horizon, right?
-- 'The' Lord and Master Bitman On High, Master Of All
You can still make assumptions as to what happens after you cross the horizon. For example would a traveller see the end of the universe, since time passes infinitely fast at the horizon (the answer is no)? How long would a traveller have before actually hitting the singularity in the middle (depends, not long usually)? If the BH is rotating, can the singularity be avoided after all (yes)? if so what happens (various theories there)?
All of these can be computed and their consequences drawn, and these consequences might one day yield a test that can allow to distinguish between a gravastar and a black hole.
if you want to profesize about black holes then try taking a few physics classes first. Otherwise, you can all stop wasting your breath.
So only 3 million suns, eh? Assuming most suns in the galaxy are at least 0.1 suns of mass, and there's about 100 million suns in the galaxy, this would at the very best case amount to 20-30% of the galaxy's mass. I'm going to guestimate that this number is a bit more like 3-5%. Can anyone give a more accurate figure as to the mass of the galaxy not measured in Solar Masses? (dark matter and all)
I had always thought that a super-massive black hole might explain that 90% missing mass/dark matter theory. Or does the rotation of the galaxy suggest the matter is evenly distributed instead of being all at the center? Or is it too soon to tell?
1) the black hole that you "see" is the evento horizon
2) the point in the singularity
3) one cool thing about black holes this large is that they have the property of sucking everything in whole, no spighetification. you fall and fall and fall as light above you moves from a full view to a single point and you actualy never reach the bottom, time aproaches zero as you aproach the singularity and you realy never do reach the singularity (lim as d -> 0 T == Inf)
I am the Alpha and the Omega-3
"And I'll make billions and billions from the book contract and the TV show with the government funding for looking for the nothing in the hole in the middle of it all..." -- Frank Hayes, DON'T ASK
~REZ~ #43301. Who'd fake being me anyway?
http://www.space.com/scienceastronomy/astronomy/ex pansion_001011.html
The Schwartzchild radius is the radius, for a given mass, that will form a singularity. For a ten solar mass star, that is about 30 kilometers.
The Chandrasekhar limit gives the size limit for a star to collapse and produce a white dwarf. Most stars end their lives with a gravitational collapse, but electron degeneracy pressure (from the Pauli exclusion principle) prevents further collapse. However, for stars above ~1.2 solar masses, the gravitational collapse will overcome fermion repulsion, and the collapse will continue. Once the star's density has reached a certain point, it will collapse into a singularity. That density times the star's mass determines the Schwartzchild radius.
The event horizon is delineated by those light rays that will neither fall in nor escape from, the black hole. However, just because you cross the event horizon does not necessarily mean you will strike the singularity. Instead, it depends upon the type of black hole you've encountered.
In actual reality, you'll be fried by the blue shifted radiation coming from the accretion disk around the hole, but let's ignore that quibble.
Black holes have mass, spin, and charge. No other properties are discernable behind the event horizon. The fact that the above properties can be determined without a world-line (that is, information also does not propagate faster than light, and hence cannot escape) says something fundamental about those properties.
An uncharged, unspinning black hole is called a Schwartzchild hole. Once you cross the event horizon, you will unavoidably strike the singularity and perish.
In the other types of black holes, such as the Kerr black hole (uncharged, spinning), Reisnner-Nordstrom (charged, zero angular momentum), and the Kerr-Newman black hole (charged, spinning) it is possible to cross the event horizon without striking the singularity. Instead, you can pass into another universe.
Indeed, it's theoretically possible that you will pass through many universes. This is a one-way trip, however. If you try to get back to where you were, you will encounter the singularity and die.
Actual solution of the Einstein field equations for the holes listed above, however, produce perturbations. These perturbations, so far, cancel out the ability to miss the singularity and enter another universe.
Moving on, Hawking demonstrated that black holes evaporate. Hawking radiation is produced when half of a virtual particle pair appears inside the event horizon. Since both particles are no longer available to disappear under the Heisenberg time limit, the remaining particle acquires real energy. This energy comes from the black hole.
Since the rate of evaporation is proportional to surface area/mass, smaller black holes evaporate explosively. Indeed, no black holes smaller than a proton could exist from the big bang.
Finally, recent research shows that the universe is inflating, due to Einstein's cosmological constant (which, he ironically labelled as his "worst mistake"). That is, Hubble's constant is increasing. There will be no Big Crunch. The universe will expand at a faster and faster rate into nothingness.
There are a lot of good books on cosmology. General Relativity is undergoing a renaissance right now because of all of this important, new information.
"Invincibility is in oneself, vulnerability in the opponent." --Sun Tzu
If this is verified, then maybe it explains the missing dark matter problem.
Perhaps the galaxies we've observed with excessive rotation rates relative to their
observed mass have a lot of such black holes or maybe a single (even larger) one.
Maybe all galaxies have black holes at their centers. I do recall that some researchers
were having a difficult time getting their computer models of galaxies to show stable
behavior.
Just a thought,
-scsg
I bet integral will be perfect for further studies:
http://www.esa.int/export/esaMI/Integral/
3 hours until launch.. now i have to install realplayer *shrug*
Live rm feed at http://esa.capcave.nl/esa/integral/info.html
I have wondered, what happens when two equally sized black holes encounter one another. Do they merge into a single larger black hole? Do they tear each other apart? What would the outcome be?
First of all the sun, or black hole, or the Earth do not "weigh" anything. They have mass. Also, there is no such thing as "centrifugal force" An object released from a circular path will follow a path that is tangential to the circle, not perpendicular. There is, however, centripital force which is in this case provided by the gravitational attraction between the star and the black hole. In any situation where an object is held in a circular path, the centripital force is equal to .5 * the mass of the object * the speed of the object squared. Using your value for the speed of the star and the value given in the space.com article for the mass (15 solar masses) yields:
.5 * 10^30*2*15 * 29.658^2 = 1.3*10^35kN (Kilo-Newtons).
The force of gravity between the two objects must be at least as great as this force to maintain the (not-really) circular orbit. Newton's theory of gravity states that the force of gravity is equal to the gravitational constant, G, times the product of the masses divided by the distance between them squared. Again using the same values, and the most common accepted value for G, we obtain:
6.672*10^-11 * 10^32*2*15 * 2.6*10^6*10^32*2 / 127.5*1.5*10^8 = 5.44*10^50kN
Which is clearly large enough to hold the star in orbit.
I know lots of things. Most of them are wrong.
From Gsu.edu Astrophysics: ... The Schwarzschild radius (event horizon) just marks the radius of a sphere past which we can get no particles, no light, no information.
Any mass can become a black hole if it collapses down to the Schwarzschild radius
R= 2(MG)/ c^2
Therefore at 3.7 million solar masses...
the Schwarzschild radius is
1.0919401548997975x10^10 M
Which is much smaller than our solar system (the earth orbits at 150,000,000 KM).
But I imgine that they would measure the Acreation Disk.....
The Schwarzschild radius calulation is fun. One can plot density verses radius and it becomes clear that something the size of our galaxy with density of water would be a black hole...
Space is an empty place!
DJMD - The fourth man - Planetary
Crap about event horizons aside, the article was talking about the distance enclosing the black hole and a star orbiting the black hole. The mass was deduced from observations of the orbiting star.
god damn, even at 1/100 the density of our sun this is rather heavy for an hole :-)
Overuse of the Pumping Lemma causes blindness
it's 85 and sunny here :)
have a nice day
All together now!
There's a hole in the middle of it all, there's a hole in the middle of it all, there's a hole in the middle, there's a hole in the middle, there's a hole in the middle of it all....
There's a quark in the hole in the middle of it all....
Good judgment comes from experience.
Experience comes from bad judgment.
They were not "incorrect"... they merely fail to describe all reality, as does every other theory we have.
Within the context of what newton and the world around him saw, and the speeds and masses they were working with, and the precision that was noticeable, his theories WERE true, just as einsteins were true until we found quantum behavior that seems to contradict it.
I hate it when people say "relativity is wrong" or "einstein was wrong". To them I say, go figure out how to make GPS work while ignoring the theory of relativity.
is this the reason why the milky way look like a big flushing toilet with starts in it? hope not, because i dont want a drown in water with density of about 1/100 sun's density.... must feel strange! :-)
Overuse of the Pumping Lemma causes blindness
The mentioned size is the size of the event horizon, which is the (spherical) collection of points beyond which even light can not escape.
Others have commented on "singularity" version "non-singularity". The truth is that we do not (and can not) know what is behind the event-horizon, since we can never observe it. We can treat a black hole as though there is a true singularity (a point-mass) in its center. Then, the event-horizon becomes simply the distance from the singularity at which the escape velocity is equal to the speed of light, i.e. the distance at which the gravitational pull of the singularity dips below a certain point.
This is why the mass and size of the black hole seem at odds with each other: the size of the event horizon and the size of whatever is iside it (singularity or not) do not have to be the same, the former can be larger than the latter.
We normally assume that there is in fact a point-mass inside the black hole, since when we do the math, it tells us that the gravitational attraction between the particles is greater than the forces keeping them apart, causing a collapse into a point-mass. What is REALLY inside a black hole will never be known, and is, in fact, irrelevant.
yes, he did
I could have sworn I killed all those people. The tan ghost in my closet said so.
Not really surprised by this news, but a few questions that maybe someone here can answer.
Blackholes are probably just super massive stars that we can't see because even light hasn't the momentum to escape, right? So, does light gravitate toward blackholes (and other masses) because photons have mass or because gravity is a force that attracts all particle energies (in "STATE A" let's say) toward each other? And if the latter is actually the case then wouldn't entropy be an opposite force radiating all particle energies (in "STATE B" let's say) away from each other?
Alos, I've heard that radiation and X-rays escape blackholes. Do any other forms of energy escape their gravitational pull and why?
Maybe we sould just ask the romulans to solve this. They use singularity driven engine and power source systems, don't they? heh... I'm just glad i could be so holpful
... why else do galaxies have a siwrly appearance?
I prefer the term GRAV-STAR myself. The idea that there is a point called a singularity where so and so occurs, whatever.
Ask yourself this: once you pass the Schwarzchild radius going in, is the space contained therein uniform?
I believe in nothing. I just have ideas.
This has been the most educational thread I have ever read on /.
U guys are really nerds.
our galaxy does suck.
The best education consists in immunizing people against systematic attempts at education. - Paul Feyerabend
See this link or read MTW's gravitation (referenced on the linked page).
Are these the same scientists who said the average color of the universe was Bondi Blue, then realized they'd made a miscalculation and it's actually beige?
$x='S24;r)>63/* h@<5+oZ)32"5cz';$me='phroggy'x$];
$x=~y+ -xz+\0-Tx+;print$_^chop$me for split'',$x;
How can the gravitational pull exceed the speed of light (or for that matter, be very large at all) if the black hole is not dense, as people have mentioned. I would surmise that in order to 'produce' enough gravity, you would require density. PROVE ME WRONG.
An observer would be a long strand of speghetti like matter, would he not? I have no degree from cambridge, but I don't think an organism could survive the experience. But if you're talking about a reference frame, thats a different story
According to Einstien, Schwarzchild singularities don't physically exist. Personally I don't subscribe to many of the theories in GR but that's just my opinion (at least for now).
how come both and all observers won't see the same effects? if that train zips past me, won't it seem to the passenger like i'm zipping past them in the opposite direction? so both are moving at the speed of light, no?
Preserve old classics: copy your collection onto all hard drives.
Uh, I think every galaxy has one of these in its center. I further believe that every galaxy will consequently get sucked into its black hole. Once that has been carried out successfully, the now entirely too massive black holes will begin to attract each other, during which the universe will begin collapse in on itself, at which time everything will implode within a matter of mere moments (which will appear to stretch out for billions of years due to time dilation) so that everything becomes an infinitely small and infinitely massive point. At that time, time loops over itself and the big bang happens. (I feel like I've written this before... in another life perhaps.)
Imagine our known universe as a sphere. Not too hard. A universe sized sphere of matter would have quite the event horizon around it.
I can't wait till the day when all of the other similarly sized (as ours) universes come into view.
Maybe a few eyes will be opened. Space is infinite if you ask me. If our 'universe' is 15 billion light years in diameter, and space is mostly empty of course - what is the distance to the nearest neighbor "universe" (Expanding sphere of millions of galaxies.)
http://en.wikipedia.org/wiki/2004_U.S._Election_c
A friend and I worked out a few calculations on the black hole...
Assuming it was 3 million solar masses, the diameter of its Schwartzchild limit (effectively the diameter of the black hole) would be 8.8 million kilometers, or about 6-1/3 times the diameter of our sun.
If the Earth were in orbit around this black hole at the same distance we are from the sun (assuming it wouldn't be torn to shreds by tidal stresses), a year would be 5 hours long.
According to some theories, the Universe itself is a black hole. So, if someone (God maybe?) look at it from the outside, he won't see anything but a big black hole.
Government cannot make man richer, but it can make him poorer. - Ludwig von Mises
Okay, I'm going to give the standard reply, and then my own reply.
The surface area of a sphere is 4pi *r-squared. Except, in a gravitational field, it is less than that.
That is, there is more volume for the surface area than you would think. Or, alternatively, if you calculated the surface area, and then calculated how far you could fall to the center, you would be surprised: in a black hole, you could fall forever.
So you shouldn't be surprised that there is more space (less mass) than you would think. Black holes are nothing but space.
That's the simple answer, anyhow.
For a more complex reply, consider this:
Heisenberg's Energy Uncertainty principle: DEDT=hbar in essence means that a particle can only disappear from the rest of the universe for a short time. Disappearance, though, is defined by a failure to interact. Therefore, particles are forced into interaction in the interests of conservation of energy. [Actually not inherently true, but effectively true.]
Quarks in our neutrons therefore must interact with something. That something is space. By the nature of the possible modes of interaction for quarks, though, we can deduce that the substance of space is an unassociated color-charged and electrically-charged medium.
By the nature of the wavelengths of interaction, and the behavior that we see in light, spatial coordinate systems tend to be defined by higher-energy, more localized particles. So we could infer (not deduce) that the substance of space would be small-radius highly energetic particles.
By the nature of the granularity of time, and by the fact that we cannot detect a spatial ether, we should be able to infer that the particles that comprise the substance of space, when detectable, have extremely short lifetimes.
Now, consider a neutron falling into that star at the center of our galaxy. Well, not star. That black hole. As it falls, the quark nearest it is pulled away from the others, until the energy reaches the energy of creation of a Quark/antiquark pair. That quark/antiquark pair in turn is accelerated away yet farther, and creates another, and another. By the Heisenburg momentum equation, the quark's waveform spreads out flat (perpendicular to acceleration) and thin (in the direction of acceleration), like a pancake. Eventually, these pancake quarks do intersect each other, allowing the quarks to satisfy the zero-color principle.
But these pancakes intersect in an area that is of very high energy, small cross-section, and short lifetime. More than that, by its nature (3 color charges) it is stable in only two modes: tunnel 2-D mode (in black holes) and 3-D mode (in space). That is, you can have particles all going in the same direction, and intersect on a flat plane, or you can have them going in 3 different directions, and intersect in a 3-D space. These particles, in the 3-D mode, would interact with quarks that were not relativistic, and provide cross-communication with the entire universe.
Anyhow, given this line of reasoning, I tend to suspect that black holes are nothing more than the pulling of matter into space. If so, the tunnelling mechanism is inherent -- that is, the black holes are all the time decaying into normal space, which slowly decays via particle-antiparticle creation into matter.
Correct Horse Battery Staple: 72 bits of entropy. Enter "Correct H" into google. When it generates the phrase, that's
Since when has our galaxy been the definition af "It all"?
/. addes another unprecise sensational headline to make it even silly.
The submitter questions the validity of the articles numbers and then
TC - My Photos..
The BBC have a similar story
Enjoy
Eclectic beats from Leeds, UK
handmadehands.co.uk
Has anyone got a graphical simulator for large black holes such as our friend in the middle of the galaxy. Regrettably my relativistic calculus sucks, but a visualisation of the effects would be cool.
See the "picture" at Yeah right Besides being (possibly) bogus, that picture is obviously of a Star Trek planet-eater.
One line blog. I hear that they're called Twitters now.
They discovered it made one elliptical revolution every 15.2 years, during which it came as close as 17 light hours from the centre.
Can you hear me now? Good!
One line blog. I hear that they're called Twitters now.
A black hole is a point, but it is not incorrect to describe one with such huge size as the article does. The "body" of the black hole, such as it is, is a point mass but the event horizon is all that really matters. The even horizon defines the "edge" of the black hole...or more accurately, the point at which the escape velocity exceeds the speed of light.
In Bushworld, they struggle to keep church and state separate in Iraq as they increasingly merge the two in America.
I _do_ remember however that in Larry Niven universe there is an expanding black hole in the center of our galaxy, which will destroy all of it in the next hundred thousand years or so.This is wy the Pierson's Puppeteers ( a very "prudent" alien race) decide to leave immediately this galaxy.
Ciao
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FB
This is just a hypothesis: Now, from the theory of chaos (which is also found in the minds of the scientists who talk about butterflies with the ability to modify the weather with their wings), we very well know that is it impossible to calculate the gravitational relation between more than four (4) planets. With just two, you have Newton's law, in one equation. But with more, things tend to get *very* complex. Now imagine the galaxy which has about a couple of billions of solar systems:
Could this "hole" be just "how much should a black hole be to keep all these rotating around the center of the galaxy, if we want not to calculate all the possible gravitational interactions between them". Or in other word, this huge black hole could just be a mathematical model? An excersise with zero practical interest?
Just asking, in case anybody knows...
Why? Because the massive gravity inside a black hole tends towards the infinite the closer you get to the centre. In turn this slows time down to a virtual stop. If there is no time then nothing can happen and this includes forming a singularity. All that happens is that the matter will get crushed smaller and smaller but on a slower and slower basis until it reaches a size where it effectively has stopped collapsing because time is running so slowly its more or less halted.
No one has mentioned the Wave Front of Deadly Radiation propagating from the center of the galaxy that the 'Pupperteer's' Flying Worlds are fleeing!?
(and definitely not that Ringworld that THEY discovered?)
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(David Bowman, EVA near HUGE Monolithic Win-PC in orbit around Jupiter) "My God - its full of Malware!"
The presence or not of Hawking radiation proves nothing about the nature of a black hole beyond its extreme gravitational field. Hawking Radiation is light emmited when a virtual photon/anti-photon pair emerges from the vacuum right on the event horizon. Usually the pair would mutually anhialate as if they had never existed, however, under extreme gravitational forces they are pulled apart, one into the black hole and one away from it. This is obviously going to be a very rare occurance which is why Hawking radiation is so weak. In fact, Hawking radiation theory states that the virtual anti-particle actually causes the black hole to loose mass, almost as if the black hole were evaporating away. In theory it is even possible for a black hole can attract no more fuel to completely evaporate to nothing simply from the hawking radiation.
You can't win Darth. If you mod me down, I shall become more powerful than you could possibly imagine
What, the core is not exploding? Niven, I'll never trust you again.
It _was_ me, probably. In Larry Niven universe there is a supernova, not a black hole ... I think.
Ciao
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FB
[HUMOUR] There's a Hole in the Middle of It All
You're just begging for the goatse.cx guy to rear his ugly "head", aren't you Michael? [/HUMOUR]
I am a Karma Library.
You can have multiple hypotheses, but not multiple theories. A theory would be a reasonable model that all the available facts and observations did not contradict. If you have so little data that more than one model could still be correct, then they are hypotheses and are not yet mature enough to be theories.
If Slashdot were chemistry it would look like this:Cadaverine
If we think of the matter in the Universe as an expanding sphere, current measurements show the outer parts are accelerating. But how can this be? Consider the forces on a particle at the 'edge' of the Universe... no forces are acting on it, with the exception of gravity, which is pulling it backwards (that's where the rest of the Universe is). So I can understand why it would be still be moving outwards, but not accelerating outwards.
Anyone? Bueller?
I do not understand how a positive acceleration relates to the universe expanding until the end of time, with other variables aside.
The derivative of velocity is acceleration. Take another infinite number of derivatives and if any are negative, the initial acceleration will eventually become deceleration.
Everything comes to a halt.
Also, could you not rule out this 'permanent' acceleration by taking into account that energy for this expansion would have to come from somewhere, which means it would run out eventually.
this is one of the most interesting threads at /. i ever read. thanks to all of you hobby- and junior- and full-grown-astronomers/-physicians to share your knowledge with the unwashed masses. :)
:)
as i'm a fan of this noblest profession myself, i want to place a link here to the online version of one of my favourite fictional short stories. it is titled "The Planck Dive" and is written by Greg Egan. if you are into hard-sf, it's a must-read. it features a nice description of a black-hole-jump...
have fun!
the computer is online
i am not at it
what a waste of ressources
What's in an electron?
Eat at Joe's.
All the advanced physics was interesting and fun to read, but the answer to the comment by the poster, wondering about the mass of the black hole vs the volume of space, is not a matter of black hole physics. Read carefully the sentence from the article:
"The orbital perimeter means that the entire mass of the interior object, between 2.6 million and 3.7 million times more massive than the sun, lurks inside an area three times the size of our solar system."
Get it? It doesn't say the black hole *is* 3 times the size of the solar system, it says the black hole "lurks within" a space that size. It's just a literary turn of phrase.
...you're like saying that black holes are like electrons, neutrons and protons and, like, one of these could be, like, part of an atom in some bigger universe?
That's, like, awesome, Dude.
I have discovered a truly marvelous sig, unfortunately the sig limit is too small to contain i
Go fix it dear Henry, dear Henry, dear Henry
Go fix it dear Henry, dear Henry, fix it.
Sorry, but I just couldn't get that song out of my head after reading that. :)
Perl, cosmology and astrophysics? This has got to be the nerdiest joke ever written on /.
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
If the mass of the black hole is 2.6 x 10^6 times that of our sun, the radius would be closer to 150 million km. (That's a very crude pseudo-calculation, so don't quote me.)
Any sufficiently simple magic can be passed off as mere advanced technology.
Has anyone considered the idea that a black hole, attracting matter around it, would thus increase it mass? :) Anybody know about that one?
IIRC a black hole may be a singularity, but also still has star-like properties. If its mass increases, so its gravitational reach, and by exentsion, its event horizon, right? At which point it would probably begin to attract yet more matter that was previously at teh fringe of the event horizon, and so on?
In that case any black hole surrounded my matter (like one at the centre of a galaxy) would be continuously expanding then?
Nice fate
god it's pathetic when you read a post from someone explaining hawking radiation and they misspell lose