×

Welcome to the Slashdot Beta site -- learn more here. Use the link in the footer or click here to return to the Classic version of Slashdot.

Thank you!

Before you choose to head back to the Classic look of the site, we'd appreciate it if you share your thoughts on the Beta; your feedback is what drives our ongoing development.

Beta is different and we value you taking the time to try it out. Please take a look at the changes we've made in Beta and  learn more about it. Thanks for reading, and for making the site better!

Black Holes May Not Grow Beyond Certain Limit

ScuttleMonkey posted more than 5 years ago | from the stand-back-I-don't-know-how-big-it's-gonna-get dept.

Space 201

xyz writes "Do black holes increase in size indefinitely? According to an analysis by astronomers at Yale and the European Southern Observatory, the maximum size a black hole may reach is only few tens of billion of solar masses. The limit was calculated using an analysis of what may happen to the gas surrounding a black hole which has reached few tens of billions of solar masses. It is thought that black holes of such size heat the surrounding gas to a temperature where the radiation pressure begins blowing outer layers into space."

cancel ×
This is a preview of your comment

No Comment Title Entered

Anonymous Coward 1 minute ago

No Comment Entered

201 comments

Interesting repercussions (4, Interesting)

AKAImBatman (238306) | more than 5 years ago | (#25530927)

I am not an astrophysicist (IANAAP?), but this would seem to have some interesting implications for galactic mechanics. For one, does this means that stars are continously recycled by the black hole believed to be at the center of each galaxy? i.e. They get sucked in, crushed, then ejected as gassous emmisions which then collect and reform as a new star.

Wouldn't this also create a "galactic wind" similar to the solar wind experienced inside a solar system? Could such a wind (as weak as it may be on a micro scale) be responsible for the universe's apparent anti-gravity effect? It seems to me that if a galactic wind did exist, it would cause the galaxies to repel each other as the particles communicate back the forces of the particle collisions over billions of years.

Speaking of Black Holes, I was just listening to an interview with Brian Greene on NPR this morning. It seems that he has released a children's book designed to help children understand Relativity. Specifically, the link between gravity and time. Amazon has a nice video* [amazon.com] where Mr. Greene explains the story and how he attempts to create an emotional connection between readers and the physics of Relativity.

* Full Disclosure: I did NOT include a referral code. This is a clean link
** Someone should really make a joke out of LHC doomsday and how we're all saved. I couldn't come up with anything funny.

Agreed, Very Interesting repercussions (4, Interesting)

eldavojohn (898314) | more than 5 years ago | (#25531031)

It is thought that black holes of such size heat the surrounding gas to a temperature where the radiation pressure begins blowing outer layers into space.

Well, I'll admit this sounds intuitive with the Penrose-Hawking singularity theorems applied to the Big Bang [wikipedia.org]. Now, I'm not a physicist either but I have read a lot that speculates the Big Bang was a singularity that created a hot unstable mess. All the mass of the universe in a singularity suddenly starts blowing out and producing massive heat. Although what was around this singularity is nothing--not even space.

As always, it brings up interesting questions about what was before that epoch [wikipedia.org] since it is kind of clear that such a singularity could not be possibly be stable for any amount of time (as this research indicates).

** Someone should really make a joke out of LHC doomsday and how we're all saved. I couldn't come up with anything funny.

I was trying to relay what I had read about the micro black holes the LHC is trying to create to a female coworker. I failed. She told me someone in India committed suicide facing the LHC being turned on. All I could think of was that I really wish they called micro black holes that exist for minute fractions of a second something other than "black holes." It scares people unnaturally.

Re:Agreed, Very Interesting repercussions (-1, Offtopic)

Creepy Crawler (680178) | more than 5 years ago | (#25531189)

The fact that somebody committed suicide over a trivial happening indicates that they were suffering from a disease of the mind.

Suicide in terms of protecting a loved one is bravery, as is the solder who does the same for their comrades. It is questionable if it is acceptable to do so if they are end-term on a horrific disease, due to the chance of recovery.

Re:Agreed, Very Interesting repercussions (2, Funny)

Clandestine_Blaze (1019274) | more than 5 years ago | (#25531277)

All I could think of was that I really wish they called micro black holes that exist for minute fractions of a second something other than "black holes." It scares people unnaturally

What scares me unnaturally is the uncanny resemblance. [kuvaton.com] We're doomed!

Re:Agreed, Very Interesting repercussions (1, Funny)

Anonymous Coward | more than 5 years ago | (#25531433)

I was trying to relay what I had read about the micro black holes the LHC is trying to create to a female coworker.

For some reason I read this as "LHC is trying to create a female coworker", and I thought that was a pretty funny joke, until I realized that wasn't what you meant to say at all.

Re:Agreed, Very Interesting repercussions (1, Funny)

sexconker (1179573) | more than 5 years ago | (#25531615)

Seems to me that that Large Hardon Collider would be seeking to create male coworkers.

Just Like MRIs (5, Interesting)

Anonymous Coward | more than 5 years ago | (#25531495)

What we today call MRI (Magnetic Resonance Imaging) used to be called NMRI (Nuclear Magnetic Resonance Imaging). As with "Black Holes", people were afraid of anything "nuclear"; hence the name change.

Re:Agreed, Very Interesting repercussions (4, Funny)

psychicninja (1150351) | more than 5 years ago | (#25531659)

As always, it brings up interesting questions about what was before that epoch...

The Sixties?

Re:Agreed, Very Interesting repercussions (3, Insightful)

mcgrew (92797) | more than 5 years ago | (#25531729)

All I could think of was that I really wish they called micro black holes that exist for minute fractions of a second something other than "black holes."

Microscopic singularities. Of course, the press wouldn't eat that up; newspapers don't exist to educate the public, they exist to generate revenue.

Re:Agreed, Very Interesting repercussions (0)

Anonymous Coward | more than 5 years ago | (#25532075)

such a singularity could not be possibly be stable for any amount of time/quote>

That's fine, since "before" the Big Bang, there not only was no space, there was no time, either.

Not that I'm saying the question what came before the Big Bang isn't an interesting one, but I don't think one can just say "the singularity can't have been stable, therefore, there must've been something before it". It may well be that there simply wasn't a before.

Re:Agreed, Very Interesting repercussions (0)

Nimey (114278) | more than 5 years ago | (#25532103)

If fools kill themselves over stupid shit like that, the gene pool's better off without them.

Re:Interesting repercussions (1)

Ethanol-fueled (1125189) | more than 5 years ago | (#25531079)

They get sucked in, crushed, then ejected as gassous emmisions which then collect and reform as a new star.

That sounds a lot like the big bounce [wikipedia.org] theory, which is like the big bang except that the bounces are periodic. It depends on the theory that space begins to behave repulsively as the amount of mass packed into it reaches a critical point.

Side note: makes much more sense then the big bang theory, which reeks of creationism.

Re:Interesting repercussions (4, Interesting)

KillerBob (217953) | more than 5 years ago | (#25531233)

Side note: makes much more sense then the big bang theory, which reeks of creationism.

Until somebody asks where it all came from in the first place. Then you're back at square one, with the same problem that the Big Bang theory has.

Unless you adopt the Hindu/Buddhist take on the cosmology... it wasn't created, it didn't magically poof into existence out of nothing: it just is. Always has been, always will be, and goes through periodic cycles of growth and destruction, without end.

Re:Interesting repercussions (4, Funny)

Ethanol-fueled (1125189) | more than 5 years ago | (#25531329)

Unless you adopt the Hindu/Buddhist take on the cosmology... it wasn't created, it didn't magically poof into existence out of nothing: it just is. Always has been, always will be, and goes through periodic cycles of growth and destruction, without end.

...and that's the explanation which makes the most sense to me. I like science to be mundane and predictable. If I want drama then I'll go see a movie and entertain the thought of some big magical guy in a toga who made the Earth with snot and space rocks.

Re:Interesting repercussions (1)

sanosuke001 (640243) | more than 5 years ago | (#25531393)

Well, if you think of it as time being a loop, then there is no time outside of time (er...) and once it ends, it is back at the beginning again and starts over.

Now, ask me to prove that and I'll just laugh. But, there are possible outcomes/beginnings that might be plausible. I think time being a loop is a lot more realistic than some twat in the sky creating us, but that's my opinion.

Re:Interesting repercussions (1)

cream wobbly (1102689) | more than 5 years ago | (#25532165)

If you think of the dimensions as being loopy as well, it makes even more sense. Like being on the surface of a sphere, only with more dimensions, and no "in" or "out". But it would be more fun if it were a Möbius pitcher.

Sorry for giving you a headache.

Re:Interesting repercussions (1, Funny)

Anonymous Coward | more than 5 years ago | (#25532167)

...some twat in the sky creating us..

All hail the Magic Celestial Vagina!

We need to find the ANCIENT TIME-LOOP DEVICE (2, Funny)

Joe The Dragon (967727) | more than 5 years ago | (#25532185)

To control the loop.

Re:We need to find the ANCIENT TIME-LOOP DEVICE (0)

Anonymous Coward | more than 5 years ago | (#25532479)

Loop control found:

for (i = 0; i < MAX_UNIVERSE_SIZE; i++) { universe.expand(); }

Re:Interesting repercussions (5, Interesting)

SBacks (1286786) | more than 5 years ago | (#25531593)

Why does everyone assume that nothingness is the default? From everything we've observed of the universe, it tends towards chaos and disorder (entropy). Nothingness is the complete lack of entropy, so why would should that be considered stable?

And, by the way, there are branches of cosmology that contend that the universe, has, in fact, always been and will always be. It comes from the idea that as you measure time further and further backwards, you find yourself measuring time forwards again. It has something to do with string theory, but the math is way beyond me.

Re:Interesting repercussions (3, Insightful)

sexconker (1179573) | more than 5 years ago | (#25531629)

Don't feel bad, the physics is way beyond the string theorists, so they just make up the math as they go along.

Re:Interesting repercussions (0)

Anonymous Coward | more than 5 years ago | (#25532177)

And, by the way, there are branches of cosmology that contend that the universe, has, in fact, always been and will always be. It comes from the idea that as you measure time further and further backwards, you find yourself measuring time forwards again.

It's a really popular concept, but not with the people you'd expect:

http://en.wikipedia.org/wiki/Wheel_of_time

Re:Interesting repercussions (3, Insightful)

Mr. McGibby (41471) | more than 5 years ago | (#25531541)

Side note: makes much more sense then the big bang theory, which reeks of creationism.

So, instead of using rational thought and evidence to decide what theory is correct, you're going to use your "gut" feeling to make the determination? Sounds a little like what the relgionists, that you're so quick to deride, like to do.

Re:Interesting repercussions (0, Flamebait)

Ethanol-fueled (1125189) | more than 5 years ago | (#25531635)

Fail. Read my post any try again. I have already decided, based on my understanding(which includes having done my homework) of the two theories, that the big bounce makes much more sense to me than the big bang does. The reference to creationism was just an afterthought.

Re:Interesting repercussions (3, Insightful)

Mr. McGibby (41471) | more than 5 years ago | (#25531751)

OK, read again. You still sound foolish.

Doesn't sound like an afterthought. Sounds like the whole point.

Re:Interesting repercussions (1)

Missing_dc (1074809) | more than 5 years ago | (#25531679)

So, instead of using rational thought and evidence to decide what theory is correct, you're going to use your "gut" feeling to make the determination? Sounds a little like what the relgionists, that you're so quick to deride, like to do.

The 100 trillion life forms that reside in my gut have faith in my ability to provide for them, why should I not listen to their prayers?

More than 500 different species of bacteria exist in our bodies, making up more than 100 trillion cells.
http://www.brainsturbator.com/articles/networks_bacteria_and_the_illusion_of_control [brainsturbator.com]

Re:Interesting repercussions (4, Insightful)

Zenaku (821866) | more than 5 years ago | (#25531131)

I'm not an astrophysicist either, but as far as I can tell nothing about this hypothesis contradicts the idea that once matter crosses the event horizon it doesn't come out again, except as radiation. They aren't saying that the black hole begins "ejecting" gas, just that at that mass it gives off enough radiation to prevent any more gas from falling in.

I'm not sure I buy that as setting an upper limit on the size of a black hole. It just means the rate of growth would slow, and potentially reach equilibrium with regards to the surrounding gas. If something denser, like a star were to fall in, I doubt that the radiation pressure would push it away.

But who knows. I don't.

Re:Interesting repercussions (2, Informative)

Colonel Korn (1258968) | more than 5 years ago | (#25531287)

I'm not an astrophysicist either, but as far as I can tell nothing about this hypothesis contradicts the idea that once matter crosses the event horizon it doesn't come out again, except as radiation. They aren't saying that the black hole begins "ejecting" gas, just that at that mass it gives off enough radiation to prevent any more gas from falling in.

I'm not sure I buy that as setting an upper limit on the size of a black hole. It just means the rate of growth would slow, and potentially reach equilibrium with regards to the surrounding gas. If something denser, like a star were to fall in, I doubt that the radiation pressure would push it away.

But who knows. I don't.

You are completely correct. Good work.

Re:Interesting repercussions (1, Informative)

Anonymous Coward | more than 5 years ago | (#25532203)

Not quite right either. Nothing escapes a black hole except gravity. The radiation produced by a quasar comes from the super-heating of the gases as they are compressed rushing into the black hole.

What this article is saying is that the radiation (light/x-ray, etc.) pressure from this glowing super-heated gas is pushing away other incoming gases at a rate that "chokes off" the process.

Re:Interesting repercussions (0)

Anonymous Coward | more than 5 years ago | (#25531619)

I'm not an astrophysicist as well. Just thought you'd like to know.

Re:Interesting repercussions (2, Interesting)

interiot (50685) | more than 5 years ago | (#25531849)

If something denser, like a star were to fall in, I doubt that the radiation pressure would push it away.

It's not just that it pushes gas away, it also gets to the point where it prevents star formation in its vicinity:

Furthermore, it appears that black holes can keep the gas too hot to settle in large quantities back to the galaxy's nucleus or to form stars through most of the galaxy's bulk. ... "So galaxies reach the point where you don't make stars."

But stars can still form elsewhere and be pulled in, yes. These black holes would be ~one tenth the mass of our galaxy, so they should be able to capture other galaxies [wikipedia.org] that orbit it and eventually fall in.

Re:Interesting repercussions (2, Insightful)

Visaris (553352) | more than 5 years ago | (#25531895)

I came here to post almost the exact same thing. The story is about a limit to the size of black holes with respect to the ways the universe is expected to have developed. This is not a hard limit on the size but more of an equilibrium thing as the parent mentioned.

Think about this thought experiment:
One finds a black hole and shoots energy into it in the form of light in discrete sized packets or quanta. If the packets are put in faster than the natural blackbody radiation of the black whole releases energy through Hawking radiation, it will grow in size. Since the black body temperature of the hole decreases as it gets larger, it can grow in this way indefinitely. The larger it is, the softer it pushes outwards (w.r.t HR)...

The story is only really talking about matter/gas clouds, EM energy is an entirely different beast.

Re:Interesting repercussions (3, Informative)

jbeaupre (752124) | more than 5 years ago | (#25531227)

Not quite sucking them in and spitting them out. Rather it's when the inflowing matter creates so much heat it clears out all the remaining matter in the area. Creates a "dry galaxy" (their term, not mine). So nothing left nearby for it to suck in and thereby grow.

An analogy would be how when a star forms it coalesces to a point that it produces enough energy to clear the area (T Tauri wind?). The star growth is then capped.

Re:Interesting repercussions (3, Funny)

cthulu_mt (1124113) | more than 5 years ago | (#25531971)

I have enough trouble with "dry counties"; the thought of a dry galaxy makes we want to weep.

Re:Interesting repercussions (1)

mfh (56) | more than 5 years ago | (#25531255)

For one, does this means that stars are continously recycled by the black hole believed to be at the center of each galaxy? i.e. They get sucked in, crushed, then ejected as gassous emmisions which then collect and reform as a new star.

Well it could mean they are continuously recycled, and then ejected as gaseous emissions, but only if a spell-check was involved. :P

Either way, this SPELLS trouble for us all because it could potentially support arguments against the big bang. :S

Re:Interesting repercussions (0)

Anonymous Coward | more than 5 years ago | (#25531683)

And you are an idiot with a two digit number. Wow.

The big bang isn't a religious theory. It may be wrong and in fact, you have to accept that possibility in science.

Re:Interesting repercussions (1)

mfh (56) | more than 5 years ago | (#25532179)

And you are an idiot with a two digit number. Wow.

The big bang isn't a religious theory. It may be wrong and in fact, you have to accept that possibility in science.

You misunderstood me. I was suggesting that this finding could result in the Big Bang theory being turned on its ear, which is an upset for science that the creationists would feed on, and we all know that it's a bad idea to feed creationists unless they are threatening to eat your young (and they do from time to time, just ask Sarah Palin).

I don't recall suggesting the big bang was a religious theory. But if you misread my comment, perhaps it was the terrible spelling in the grandparent that misdirected you? Oh wait... you are AKABatman!!! So you are calling me an idiot because I embarrassed you. Dude don't worry about it, I've forgotten to spell check before SUBMIT, too. It happens. Nietzsche was right! It's worse to publicly offend someone who has created an insignificant error than it is to condemn someone for acts they deserved. To hell! (that was a toast)

Re:Interesting repercussions (1)

AKAImBatman (238306) | more than 5 years ago | (#25532527)

Um, dude. I'm right here. (*waves hand*) And I thought that post was rather unfair to your comment. My response would have been some sort of grumbling about the fact that Chrome didn't catch the spelling mistake when I copied and pasted it. (I did check! Worst. Spell. Checker. Ever.)

On his second point, I have no idea why anyone is trying to drag religion into this. As I recall, the original theory of the Big Bang was not acceptable to the Catholic church either. Funny thing, though. It wasn't acceptable to science, either. Until it was refined, many of the issues worked out, and the Pope stopped by to say "God created the Universe with a Big Bang". There. Settled on both sides.

Perhaps we'll prove tomorrow that both the scientists supporting the theory and the Pope were wrong. Maybe the next Pope will declare that God created the universe with a series of pops after science disproves the big ol' bang. Personally, I'm not really vested either way. :-)

As for the identity of the AC? Looks like Yet Another Slashdot Troll(TM).

Re:Interesting repercussions (4, Informative)

Bemopolis (698691) | more than 5 years ago | (#25531403)

or one, does this means that stars are continously recycled by the black hole believed to be at the center of each galaxy? i.e. They get sucked in, crushed, then ejected as gassous emmisions which then collect and reform as a new star.

What happens, roughly, is that stars that stray too close to the black hole are torn apart by the tidal forces, their constituent gas adding to a large torus of gas orbiting the black hole. Some fraction of this torus loses enough angular momentum to either fall into the event horizon of the black hole, lost "forever" (astronomically speaking), or a grazing collision that gives it enough energy to avoid being sucked in. This gas can form a galactic wind of sorts: that flow becomes collimated by the high spin rate of the black hole and the torus of gas around it. This produces jets like those seen emanating from the core of M87 [nasa.gov]. That gas, with its high temperature and flow rate, will not cool to a low enough temperature to coalesce into new stars any time "soon" (astronomically speaking.)

Now, there are flows that involve gas being ejected from the disk of the galaxy with less energy, which can rain back down onto the disk and contribute to newly-formed stars. But these "champagne flows" are usully caused not by the energetics of the central black holes, but rather the collective stellar winds from the stars in the disk; for example, the galactic superwind of M82 [nasa.gov]

In both cases, the thermal energy of the ejecta is insufficient to explain the gravitational anomalies you mention.

LHC doomsday (0)

Anonymous Coward | more than 5 years ago | (#25531479)

As an optimistic observer-moment, I'm sure it won't occur. Every universe in which the LHC fired up successfully has been destroyed already.

We'll see a few more spectacularly random failures before our scientists realize that the safe bet is to permanently deactivate the thing.

No matter ejected from inside the hole (4, Interesting)

iamlucky13 (795185) | more than 5 years ago | (#25531935)

They're not saying that matter is ejected from inside the hole, so no, stars wouldn't be recycled. Also, they are not saying black holes at galactic cores are at this limit. Sagittarius A*, for example, which lies at the center of the Milky Way, is estimated to be only 3.7 million solar masses...orders of magnitude below this theoretical maximum. Also, such a wind as you suggest should be observable as it interacts with free gas and dust in the Milky Way. This may sound hard to believe, but it is in fact regularly observed in supernova remnants and massive stars like in the Crescent Nebula [nasa.gov].

So what they're actually decribing is gas, dust, etc in the accretion disc orbiting near but not yet swallowed by the black hole. As stated, this gas becomes superheated and expands as it swirls ever closer to the hole. They claim that at some point the heat grows so intense that like a Wolf-Rayet star at the Eddington limit, it just blows all of the remaining gas away from itself to form a big bubble of relative emptiness. The article fairly descriptively labels this as a "dry" black hole. Actually, going back to the star recycling concept, this effect may be so dramatic as to actually prevent star formation in the host galaxy for the predictable future.

At this point I think the description is a little sloppy, since the black hole would then be devoid of material to compress and heat, and therefore the "black hole wind" (AC's insert crude fart joke here) effect is now gone. Theoretically then, feeding is able to occur at slow rates, and reading between the lines of the article, it sounds like the researchers agree about that. However, it would not allow the super-fast feeding behavior that results in the distant strobes known as quasars, which are believed to be such super-massive black holes below this limit.

Ultimately what they're suggesting is that quasars can't last forever because eventually their growth slows down to practically nothing, and then you have a relatively quiet, but huge black hole. Please keep in mind, however, that the end of the article disclaims this as being speculative physics. It makes sense, and it seems to fit the data, but it hasn't been thoroughly validated yet.

Re:No matter ejected from inside the hole (0)

Anonymous Coward | more than 5 years ago | (#25532517)

You asked, so I must deliver:

At this point I think the description is a little sloppy, since the black hole would then be devoid of material to compress and heat, and therefore the "black hole wind" (wouldn't this be more of a brown hole wind?) effect is now gone.

I feel cheap for doing that, hence the AC post.

Re:Interesting repercussions (2, Insightful)

Anonymous Coward | more than 5 years ago | (#25531985)

Lets see if we can clear some of this up for everyone...

When you have a black hole sucking in matter, that matter will start to get denser as it gets closer to the black hole. The larger the black hole the farther its gravitational influence and the more matter it can attract. As the matter falls in and gets denser its rotational momentum causes it to orbit. As this happens it starts to get quite close together and due to friction begins to heat up. Eventually it gets really really hot and expands as well as emitting high energy radiation. Once this reaches a critical point it overpowers the gravity of the black hole attracting said matter and starts blowing it back out.

Eventually this wind will be dissapated and will be inconsequencial on the scale of 100s of light years. Since galaxies are tens of thousands of LY across the intergalactic medium is not affected by this.

Again, this is not due to anything being emitted directly from the black hole, only the superheated matter falling into it.

Tens of billion? (2, Funny)

courteaudotbiz (1191083) | more than 5 years ago | (#25530949)

few tens of billion of solar masses

Since when "tens of billion" is "few"?

Re:Tens of billion? (4, Funny)

OglinTatas (710589) | more than 5 years ago | (#25530975)

When your national debt is in the tens of trillions

Re:Tens of billion? (5, Funny)

Hatta (162192) | more than 5 years ago | (#25531063)

So the phrase "astronomical numbers" is now superseded by "economical numbers".

Re:Tens of billion? (1)

SpeedyDX (1014595) | more than 5 years ago | (#25531259)

Or "economic numbers".

Trying not to be a grammar nazi (and obv failing), but the generally accepted definition of "economical" is to the effect of "thrifty" or "prudent", ant., "wasteful". "Economic", on the other hand, refers to that which pertains to the economy, or science of economics, etc.

He's quoting Feynman- (2, Interesting)

Petskull (650178) | more than 5 years ago | (#25531773)

He's quoting Feynman:

"There are 10^11 stars in the galaxy. That used to be a huge number. But it's only a hundred billion. It's less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers." -- Richard Feynman

Also: Economical Number
A number n is called an economical number if the number of digits in the prime factorization of n (including powers) uses fewer digits than the number of digits in n. The first few economical numbers are 125, 128, 243, 256, 343, 512, 625, 729, ... (Sloane's A046759). Pinch shows that, under a plausible hypothesis related to the twin prime conjecture, there are arbitrarily long sequences of consecutive economical numbers, and exhibits such a sequence of length nine starting at 1034429177995381247.
http://mathworld.wolfram.com/EconomicalNumber.html [wolfram.com]

Re:Tens of billion? (5, Informative)

gv250 (897841) | more than 5 years ago | (#25531483)

There are 10^11 stars in the galaxy. That used to be a huge number. But it's only a hundred billion. It's less than the national deficit! We used to call them astronomical numbers. Now we should call them economical numbers.
Richard Feynman, US educator & physicist (1918 - 1988)
http://www.quotationspage.com/quote/26930.html [quotationspage.com]

Re:Tens of billion? (4, Funny)

eldavojohn (898314) | more than 5 years ago | (#25531067)

When your national debt is in the tens of trillions

Stop spreading FUD, it's only a single ten of trillion.

Watch out for that Event Horizon Tsunami! (1)

PolygamousRanchKid (1290638) | more than 5 years ago | (#25531207)

When your national debt is in the tens of trillions

Stop spreading FUD, it's only a single ten of trillion.

That was true when you posted, but in the meantime ... that national debt grows like crazy ... he must be eating his "Wheaties" ...

Re:Watch out for that Event Horizon Tsunami! (1)

genner (694963) | more than 5 years ago | (#25531355)

That was true when you posted, but in the meantime ... that national debt grows like crazy ... he must be eating his "Wheaties" ...

We should stop making pennies then......*rim-shot*.....*crickets*.......so ashamed.

Re:Tens of billion? (0)

Anonymous Coward | more than 5 years ago | (#25531301)

I don't know, 20 billion solar masses of gold would cost $1.029 times 10 to the 45 dollars, and 20 billion solar masses of light sweet crude would be 284.131 times 10 to the 36 barrels and would cost about $17.937 times 10 to the 39 dollars. At today's prices. So the national debt is really nothing against that.

At least if my calculations are correct.

Re:Tens of billion? (0)

Anonymous Coward | more than 5 years ago | (#25531369)

... Or when you throw around $810 billion around at the strippers

Re:Tens of billion? (1)

dreamchaser (49529) | more than 5 years ago | (#25531201)

It just means more than 1x10 billion but not many multiples thereof. Yes, it's a fuzzy definition.

Re:Tens of billion? (1)

PyroFred (1279992) | more than 5 years ago | (#25531241)

I would think the that "tens of billion" is realativly "few" when regarding thing on such a grand scale. It would be the same scale if it was say, cells in a human body. The number is large, but realativly it is only a few.

Re:Tens of billion? (1)

shawb (16347) | more than 5 years ago | (#25531825)

I think that phrase was slightly mistyped. I parsed it as a few (tens of billions.) I assume they are using English units, in which a few is about a half a handful, which is somewhere around 10-12. So they are saying about 50-60 billion solar masses.

What if our universe were one big black hole? (1, Funny)

PrescriptionWarning (932687) | more than 5 years ago | (#25531093)

I either just blew your mind, or sucked it.

Re:What if our universe were one big black hole? (1)

Rayeth (1335201) | more than 5 years ago | (#25531279)

science never sucks, it can only blow.

Re:What if our universe were one big black hole? (1)

hierophanta (1345511) | more than 5 years ago | (#25531707)

science never sucks, it can only blow.

unless you work for Dyson - in which case science never loses its sucking power

Re:What if our universe were one big black hole? (2, Informative)

elFarto the 2nd (709099) | more than 5 years ago | (#25531469)

I saw an interesting interview with Michio Kaku here [youtube.com], and he talks about just this.

Re:What if our universe were one big black hole? (0)

Anonymous Coward | more than 5 years ago | (#25532041)

see a Spaceballs quote coming...

"Oh, my God. It's Mega Maid. She's gone from suck to blow. "

Consistent with interracial porno. (0, Troll)

bloodninja (1291306) | more than 5 years ago | (#25531199)

While I've noticed that white chicks' holes grow in a linear fashion to their, um, workload, the black chicks' holes grow in a logarithmic fashion. So at first they grow fast, but then they tapper off and after some time there is barely any noticable growth.

Thai chicks, on the other hand, seems to vary by a sine wave. God, I've got to get to Thailand.

Re:Consistent with interracial porno. (1)

mfh (56) | more than 5 years ago | (#25531339)

Thai chicks, on the other hand, seems to vary by a sine wave. God, I've got to get to Thailand.

First, get out of your parents basement, then explore THE WORLD. Go, outside!

Re:Consistent with interracial porno. (0)

sanosuke001 (640243) | more than 5 years ago | (#25531423)

So, white chicks progressively get sluttier as tehy get older, black chicks start out slutty and can't really get sluttier from there, and thai chicks have cycles?

Re:Consistent with interracial porno. (1)

bloodninja (1291306) | more than 5 years ago | (#25531899)

So, white chicks progressively get sluttier as tehy get older, black chicks start out slutty and can't really get sluttier from there, and thai chicks have cycles?

That's what us basement dwellers have been led to believe.

Re:Consistent with interracial porno. (1)

mcgrew (92797) | more than 5 years ago | (#25531923)

OT but I have been to Thailand. Considering your comment, I think you might be interested in this ole K5 diary [kuro5hin.org].

I've heard that "once you do black you never go back" but that's not been my experience.

Colliding black holes (5, Interesting)

CubicleView (910143) | more than 5 years ago | (#25531415)

I'm sure I'm basing this on some bad sci fi movie or other, but can't two of these maxed out black holes merge together (in theory at least) to form a larger one?

Re:Colliding black holes (1)

AstroWeenie (937631) | more than 5 years ago | (#25532477)

I'm sure I'm basing this on some bad sci fi movie or other, but can't two of these maxed out black holes merge together (in theory at least) to form a larger one?

Actually this is a very good question and was the first thought I had too. (And I am an astrophysicist.)

It looks like the answer that the paper [arxiv.org] offers is that to have two extremely massive black holes in the same galaxy would require that galaxy to be more massive than any we have found. There's a close correlation between the mass of the central black hole and the mass of the galaxy.

I consider this a slightly weaker explanation though, compared with the argument that the black hole can't continue to grow because gas can't accrete to it.

Stable Structure? (2, Interesting)

corsec67 (627446) | more than 5 years ago | (#25531515)

What if there was a black hole, at this size limit, inside of a very dense cloud of gas?

Would it look like an enormous gas planet to an outside observer?
If the gas cloud was dense enough, could fusion start, creating a star with a hollow region between the "star" part and the black hole, held in place by this "radiation pressure"?

Hmm, what if the external part started becoming solid? Would it be like a planet, but inside out with "gravity" provided by the pressure from the black hole? Of course the radiation on the inside would be huge. Would the outside have tolerable gravity levels, due to the empty space inside?

Heh, I think I have one sentence there that isn't a question.

Re:Stable Structure? (1)

ceoyoyo (59147) | more than 5 years ago | (#25532589)

It would look like a very dense cloud of gas first being turned into a rapidly rotating disc, heating up enormously, then being shot out in jets, from the poles.

Wait a second (0)

Anonymous Coward | more than 5 years ago | (#25531719)

only few tens of billion of solar masses?

not so fast! (1, Interesting)

Lord Ender (156273) | more than 5 years ago | (#25531829)

You can test these theories like you test software. Consider an edge case.

Suppose there exist two of these "maximum" density black holes on a collision course. Sure, the "radiation pressure" may exceed gravity at some point for low-momentum gas particles, but that doesn't mean the pressure would be so much greater than gravity that it would halt an oncoming super black hole (with corresponding super momentum!).

It seems in such a scenario it would be possible to form a black hole with double the "maximum" mass.

Re:not so fast! (1)

kungfugleek (1314949) | more than 5 years ago | (#25532197)

It seems in such a scenario it would be possible to form a black hole with double the "maximum" mass.

I call it a "Hawking Hole".

Re:not so fast! (1)

ceoyoyo (59147) | more than 5 years ago | (#25532533)

The paper (not the summary) doesn't suggest that you can't have bigger black holes, just that you generally won't because the normal way black holes grow has limits.

Note that anything that's not actually another black hole will get torn apart by tidal effects, and two 30 billion sun mass black holes colliding is likely to be a fairly uncommon event.

slashdot editor fail... (1)

g0dsp33d (849253) | more than 5 years ago | (#25532037)

the maximum size a black hole may reach is only few tens of billion of solar masses

Physics understanding fail! Volume != Mass

Re:slashdot editor fail... (3, Informative)

kosack (155278) | more than 5 years ago | (#25532353)

It's not totally crazy - when talking about black holes, the "size" of the black hole refers to it's Schwarzschild radius, which is directly proportional to its mass. Though you're probably right that in this case it's just a mistake!

Re:slashdot editor fail... (1)

ceoyoyo (59147) | more than 5 years ago | (#25532561)

For black holes "volume" (as far as that term applies) is strictly related to mass. Note also that "size" does not necessarily imply "volume," particularly for objects like black holes.

Where does the energy come from? Hmmm? (1, Insightful)

argent (18001) | more than 5 years ago | (#25532181)

The energy to blow away the dust and gas from the black hole comes from infalling dust and gas. In the absence of infalling dust and gas the black hole doesn't emit any energy at all. So once it reaches this limit, and clears out the nearby vicinity of the hole, what keeps its neighborhood clear? It's no longer taking in matter, the radiation pressure drops, and the expelled matter eventually returns to start te growth again, no?

This all sounds like the T-Tauri stage in stellar evolution... except that the star continues to radiate, and the black hole doesn't.

Re:Where does the energy come from? Hmmm? (2, Interesting)

Dan Ost (415913) | more than 5 years ago | (#25532423)

Black holes do radiate particles (search for "hawking radiation" on Wikipedia), but that's not what they're talking about here. As matter falls into the black hole, it gets superheated and radiates lots of EM. Thus, it isn't radiation from the black hole that clears out the surrounding space, but radiation from the matter falling into the black hole.

Re:Where does the energy come from? Hmmm? (1)

argent (18001) | more than 5 years ago | (#25532481)

Black holes do radiate particles (search for "hawking radiation" on Wikipedia)

The hawking radiation from a galactic sized black hole is negligible.

As matter falls into the black hole, it gets superheated and radiates lots of EM.

Indeed, that's my point. One the black hole has cleared its surroundings to the point where it's no longer growing, then the radiation emitted from this source will drop until it starts growing again.

Growth not forbidden, merely altered (1)

SleptThroughClass (1127287) | more than 5 years ago | (#25532607)

The proposed situation does not forbid the growth of black holes, it merely suspects that the usual supply of material may be lost. Basically, the infalling material may become so energetic that it explodes outward and pushes away the interstellar dust and gas. However, anything which gets close enough to the black hole will still be pulled in. Growth of the black hole is not forbidden. Gas and dust which escapes "nearby" stars will still fall in, as will any stars which pass too near. The proposed mechanism would only block growth if any particle or photon which approaches the black hole will be so excited by the approach that it gains enough energy to escape before reaching the event horizon. This also requires that when an accelerating particle heats up and emits radiation, any infalling radiation also is accelerated and escapes. Nothing in the summary of the process indicates that the process affects all infalling material, only an effect upon some surrounding material.

Real limits on black holes (2, Funny)

ziani (255157) | more than 5 years ago | (#25532677)

Personal experience has shown that black holes expand to about the size of a corporate accounting department.

They may actually be one and the same thing.

Load More Comments
Slashdot Account

Need an Account?

Forgot your password?

Don't worry, we never post anything without your permission.

Submission Text Formatting Tips

We support a small subset of HTML, namely these tags:

  • b
  • i
  • p
  • br
  • a
  • ol
  • ul
  • li
  • dl
  • dt
  • dd
  • em
  • strong
  • tt
  • blockquote
  • div
  • quote
  • ecode

"ecode" can be used for code snippets, for example:

<ecode>    while(1) { do_something(); } </ecode>
Sign up for Slashdot Newsletters
Create a Slashdot Account

Loading...