Posted by
timothy
on from the that's-an-immense-candy-bar dept.
ChazeFroy writes: "A black hole with a mass of more than 2 million suns has been pinpointed at the center of the Milky Way. Scientists used triangulation based on the acceleration of infrared images of three stars and to find the center. CNN has the story here."
219 comments
Re:Almost Infinite, Literally!
by
Darby
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· Score: 1
I didn't get into the full Gödellian rap because it wasn't relevent
I think you mean the whole "Cantorian" rap.
Georg Cantor is the guy who came up with major portions of the theory of infinite sets. ---CONFLICT!!---
Got news for you dude. Nature doesn't care about mathematics.
I hate to break it to you dude, but Nature cares very deeply about mathematics. This is why she chose to base all of creation on it.
The fact is people didn't invent mathematics, we merely discovered it.
Look at the whole fiasco over the discovery of irrational numbers and "imaginary" numbers.
No one wanted these, they were forced into accepting their existence. ---CONFLICT!!---
Re:It's progress, but it doesn't go far enough
by
Azog
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· Score: 2
You can lower the cable near the horizon to take measurements, but if you lower it into the horizon the cable will snap. Tension will increase without bound if you try to keep it from snapping.
Why? If the tension increases without bound, does that mean there is an infinite gravitational gradient?
Is it impossible for a solid object to be partly within and partly outside the event horizon? Why?
Damn, I have to get a good book on this stuff.
Torrey Hoffman (Azog)
-- Torrey Hoffman (Azog) "HTML needs a rant tag" - Alan Cox
For the love of god man! we're all going to be sucked into a black hole that will negate exsistance as we know it! Panic now! avoid the rush! we've only got a few billion years left!
--
-- There are some people that if they don't know, you can't tell 'em.
i now realize
that we will all simply
boil alive in a horrible,
galactic nuclear
holocost.
Oh, don't worry about that either. As the sun
revs up over the next
billion years, all of the
water on Earth will
evaporate and we'll all
die of dehydration.
T. M. Pederson
"...and so the moral of the story is: Always Make Backups."
-- T. M. Pederson
"Lies, Damn Lies, and Documentation"
For the love of god man! we're all going to be sucked into a black hole that will negate exsistance as we know it! Panic now! avoid the rush! we've only got a few billion years left!
Relax! Our sun will have exploded long before then. --
oh whew, for a minute there i thought we were all going to be ripped apart that the atomic level by a force we could niether understand nor control. i now realize that we will all simply boil alive in a horrible, galactic nuclear holocost. Man i was worried there for a second
--
-- There are some people that if they don't know, you can't tell 'em.
Uhm, you DO know that not only is the universe expanding, it is ALSO accelerating !
Edwin Hubble realized that galaxies were rushing away from each other at a rate proportional to their distance, i.e. the farther away, the faster the recession
The rate is called the "Hubble constant" which you can read about it here:
What I like about these astronomical-black-hole-sun posts, is that you know what to excpect when you look at the forum - first 10 posts (highests scores first) will be *Funny*. Any lame joke will get propagated on top of the list. People, what's up with that? Or is astronomy is way funnier than Napster? hmm..
-- http://dtum.livejournal.com
Re:It's progress, but it doesn't go far enough
by
SIGFPE
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· Score: 2
Check out recent work by Susskind and 't Hooft (the guy who pretty well invented Gauge Theory) - in particular the stuff on the Holographics Hypothesis (this *isn't* the cheesy holographic universe thing in some popular physics book). Susskind had an article in SciAm about a year ago - otherwise, if you have a physics background, try searching xxx.lanl.gov. They, and others, suggest that the event horizon isn't the well behaved place classical general relativists say it is. You may no the classical result that a black hole has no hair. The opposite seems to hold in quantum gravity - the event horizon actually has lots of quantum information concentrated near it. I am sympathetic towards their controversial outlook (I did black holes and strings for a few years before and during my PhD). Who knows though - *none* of this stuff is founded on anything rigorous.
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SIGFPE
Re:Now, I'm No Scientist..
by
lelitsch
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· Score: 1
If you take the Schwartzschild radius, the point where the escape velocity equals the speed of light, it's radius would be about 3000km. Compared to the size of the Milky Way, that's a pinpoint;)
The Schwartzschild Radius is 2 * gravitational constant * mass of sun / (speed of light^2 )
Righty, here is a basic explanation. Some of the bits will pobably be slightly inaccurate but that's okay, you're all understanding people.
Stars are big and hence they have a big gravitational field. What prevents the star from collapsing is basically the heat and light it produces by fusing lighter elements into heavy ones. When the star runs out of available hydrogen to burn it then starts to burn helium and so on up/across the periodic table until it reaches iron which it can't fuse because the released enegy per nucleon is negative.
(non-MS)ie. It don't produce any heat.
The star then begins to collpse. There are various thing that can happen, depending on the mass of the star. If it is big enough, the whole shebang colapses until the core is hyper-compact and reaches the exclusion-principle limit. The outer layers rebound at a fair old fraction of the speed of light (10%???) producing a supernova (I forget which type, IIa???). If it is still above a certain mass, the Chandrasekhar limit IIRC, then it collapses further until the curvature of space around it becomes infinite (as per Gen'l Relativity).
Voilà. Black hole. (All corections welcome:-)
Elgon
Re:Detecting black holes
by
diablovision
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· Score: 1
Let me say this once and for all.
Gravitational lensing has never been and will never be used to detect the presence of a black hole.
The reason? It's not that gravitational lensing does not exist, or even that it's not dramatic enough to detect. The reason is that no black hole is close enough for us to use parallax to know the true positions of stars behind it. The way gravitational lensing works is by being able to detect when stars are out of place (not where they should be) due to their light being bent by a super-massive black hole. We would never know where these background stars should be so we can never figure out if they have moved.
So you just demonstrated how horribly uniformed on the tremendous size of the universe you are, and how that results in us not being able to use gravitational lensing to detect black holes.
yeah, that's not a great choice of comparison for distance. the radius of a one solar mass black hole is about 3 km, and it just scales linearly with mass, so you're looking at no more than 8 million km for a 2.6 million solar-mass BH. By comparison, the radius of our Sun is about 700,000 km, and the Earth orbits at about 150 million km from the Sun.
of course, the above numbers are upper limits on the radius; a BH can always be *smaller* than the Swarzschild radius, but never larger.
We can stop the destruction
by
empesey
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· Score: 1
All we need is an object bigger than the black hole, to plug it up.
As an aside, do things in the northern hemisphere of the universe flush one way down a black hole, while in the southern hemisphere, they flush the other?
To attempt to illustrate it's denseness further, if you could place a cubic inch of this black hole on the floor, it would shoot straight to the earth's core. That's dense!
For those that haven't read it, Stephen Hawking's "A Brief History of Time" is an excellent book that covers black holes.
Typical, but a little on the small side, as supermassive black holes go. A black hole at the center of M87, in Virgo, might have a mass as large as three billion suns, for example.
See this article at space.com for more info.
Re:English as a language
by
diablovision
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· Score: 1
I just wanna know how fast the images were accelerating.
um, that'd just generate an error. I think what you mean is
cat center.galaxy.txt >/dev/null
but even that wouldn't do what you wanted, because center.galaxy.txt would still exist, and doing
cat/dev/null > center.galaxy.txt
wouldn't be the same either, because then it's the black hole going into the galaxy, not the other way around.
I think what you're looking for is
alias 'blackhole=rm -rf'
blackhole center.galaxy.txt
--
My plan is to pimp before they realize I'm a jackass. Hit 'em hard and fast.
A black hole isn't just a homogeneous mass. Theoretically, all the mass collapses to a singularity. The "boundary" of a black hole is the event horizon, or the distance where light can no longer escape the black hole's gravitational pull.
1) how come more negative (un-, if you wish) than positive particles are attracted?
Both particles are equally attracted by the gravity of the hole, but they have different initial velocities. One might exceed escape velocity while the other does not. It takes a lot of luck, but given enough time, it's bound to happen to some particles.
Positive particle do get sucked in just as often as the negative ones. The difference is that normal matter loses potential energy when falling, whereas "negative matter" gains energy as it falls. This is the magic that allows the remaining particle to become "real"... Sounds a little fuzzy, I admit.
1.1) how come gravity works the same on unparticles? Shouldn't they be repelled?
Fair question. I don't know.
2) why does this happen at a faster rate for small black holes (I understand that rate of evaporation is inversely proportional to mass)
The smaller the hole is, the greater the tidal forces at the event horizon. Stronger tidal forces mean that pair of virtual particles is more likely to be ripped apart, just like you'd be ripped apart if you got near the event horizon of small black hole.
1. There is no preferences, and it is not un-particle, but anti-particles.
I made up the word "unparticle". There may be a better term, but I wanted to make it clear that they are not anti-particles. Anti-particles are identical to regular particles, except that they have the "wrong" charge. For example, a positron is an electron with a positive charge. If a positron and an electron were to suddenly appear near a black hole, the universe would object strenuously, because that would violate conservation of energy. However, electrons and "un-electrons", i.e. electrons with negative energy, can come and go as they please, because the sum of their energy is 0.
Does anyone know what the term for a particle with negative energy actually is?
--
MSK
Oh my golly gee. Whitey's at it again.
by
CosmeticLobotamy
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· Score: 1
I can't beleive you guys want to spend more of my hard earned dough on your Wasp Rap devices. I think you white folks need to remember that rap is the language of the people. I'm so tired of you whitees thinking that you can just change all our artforms into your bastardized propaganda for white rule. Power to the people. The revolution will not be televised. Next time you drive around in your $200,000 Chevys, listening to that Warper Eminem, remember that we're taking names and plates, boy. You best watch your back.
Re:centrifugal force (was - Re:Not to be pedantic)
by
KarmaBlackballed
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· Score: 1
The impact of the woman's head on the window is from the acceleration of that window toward her head. (Just another way of phrasing your point about her linear inertia.)
After her body came to rest against the window and the door, she was experiencing centripital acceleration in the literal sense. (Although the car is not a string, and she is not a yo-yo (I dont know her), the factors are the same. The car is keeping her on the arc of a circle.)
[i]Before saying things like it's just Math, you'd better not forget that quantum theory and GR are quite successfull, so if they predict that something happen, well, it has quite a chance to happen "for real".. [/i]
Okay, first off, it's not a matter of chance. Something is real, or it isn't. The theory is either real to the world in this respect or it isn't. There is no way to measure what the "chances" are that it's correct, and as we all know, if you can't measure it, it's not science.:)
And a theory can be completely and totally correct in every respect except one, and still be wrong.
Also, note that I don't thing it's incorrect here, I just don't see how you can get the particle/unparticle explanation from the math of it. Seems like that's a made up explanation for mass comsumption.
---
-- - Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
Black Hole Sued For Copyright Infringement
by
JayBees
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· Score: 3
This just in: Finding that there was a previously undiscovered black hole at the center of our galaxy, the RIAA sued them for copyright infringement. "We thought we had sued everything in the known universe for violating our artists' rights," said a RIAA spokesman. "Thanks to the tireless efforts of NASA and Lars Ulrich though, we have continued to make the universe safe from free music." Reports also indicate the MPAA will sue the Big Bang next week for, "Making the creation of DeCSS possible through its own reckless acts of creation."
It's progress, but it doesn't go far enough
by
Froid
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· Score: 1
So, we're now sure there's a blackhole at the center of the milkyway. But what is there at the center of the blackhole? What are the physics like inside? What's it like to fall in? How many dimensions inside? What would it look like to stand inside and look out at the light falling in? What's it feel like to be a blackhole?
These are the things we still don't know, and I'm afraid we'll never know them within my lifetime.
Re:It's progress, but it doesn't go far enough
by
jafac
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· Score: 2
Anyone remember the URL to that cool site that had the animations of computer simulations of various relations to black holes? orbit around a black hole, falling into the event horizon, watching a star or planet falling into the event horizon, etc.
-- These are my friends, See how they glisten. See this one shine, how he smiles in the light.
Re:It's progress, but it doesn't go far enough
by
Anonymous Coward
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· Score: 1
Re:It's progress, but it doesn't go far enough
by
SIGFPE
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· Score: 2
True. He got quantisation of non-abelian gauge theory to work. As theoretical physics today seems to be nothing but quantising non-abelian gauge theories (at least that's what almost all the theoretical physicists in my mathematics department did!) it makes him a pretty important guy - which is what I really should have said (ie. he's not a crackpot).
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SIGFPE
Re:It's progress, but it doesn't go far enough
by
SIGFPE
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· Score: 2
But what is there at the center of the blackhole?
If you go along with general relativity - ignoring quantum mechanics - we have a fairly good mathematical model of the inside of a black hole - at least in terms of its gravitational field. The problem is at the very centre where the mathematics goes a bit haywire and we have a 'singularity'. That's just a way of saying the solution to the equations goes to infinity and the equations aren't valid at this point.
What are the physics like inside?
In principle. Similar to outside. One twist is that time and radial distance are flipped. What this means is that instead of particles taking an inexorable path into the future from the past they take a path that is confined to travelling towards the singularity. (This is for a non-spinning black hole, spinning black holes are more complex but this is a slashdot post not a book on general relativity).
What's it like to fall in?
As you approach the event horizon you're going to have more and more stuff falling in behind you. Much of that stuff is light that whacks in behind you. That light will have been converted to gamma rays by gravitation blue shift. You'd get frazzled before reaching the event horizon.
How many dimensions inside?
Same as outside according to the theory.
What's it feel like to be a blackhole?
Try 'As She Crawled Across The Table' by Jonathan Lethem:-)
Personally I think there's a lot of evidence that ignoring quantum effects is wrong. There is a lot of evidence that interesting quantum effects take place at the event horizon so that the laws of physics we currently have break down well before the singularity. Connecting quantum mechanics and general relativity is the biggest challenge facing theoretical physics right now but I home we see some glimmer of understanding within your lifetime!
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SIGFPE
Re:It's progress, but it doesn't go far enough
by
Fnkmaster
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· Score: 2
Actually, you're not entirely correct on this one. We can do relatively complete simulations of what it looks and "feels" like to fall in toward and past the event horizon of a black hole. Based on what I remember of these results, your perception of the outside stars and starts to contract behind you until it basically becomes a single pinpoint of light and you are otherwise surrounded entirely by darkness. I.e. your effective horizon of vision of light falling in contracts down to a pinpoint, I believe at a point in time after you've fallen through the event horizon. But my memory of these things has faded somewhat, you can probably pull some of this stuff out of some books on black holes. Of course it's all rather useless since tidal forces will tear you to pieces before you get close enough to enjoy the view (i.e. the delta in gravitational force exerted on your head versus your feet assuming you are falling in lengthwise... depending on the size of the black hole, you could get torn apart long before you get close to the event horizon.
Re:It's progress, but it doesn't go far enough
by
bukys
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· Score: 1
Actually, I thought that you could only
asymptotically approach the event horizon
(time/space would dilate and you'd never actually
get there).
Of course, you'd be torn apart by tidal forces
and horrible stuff flowing around you, so "observation" is somewhat hypothetical (but
interesting).
Re:It's progress, but it doesn't go far enough
by
SIGFPE
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· Score: 2
A third! Where did you find that published? I'm pretty amazed it's that popular given the lack of experimental success. I personally think string (or M) theory isn't a great *physical* theory but I don't care as I think it's the most beautiful thing to come out of physics ever.
Of course you can't make a clean split between gauge theory and string theory and you can quantise strings as a gauge theory.
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SIGFPE
Re:It's progress, but it doesn't go far enough
by
Azog
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· Score: 2
Maybe some of the experts here can answer this random question... a thought experiment, if you will:
Suppose you had a platform or spaceship or something orbiting a small black hole, just above the event horizon. Now, that platform would be moving at just under light speed, but so what.
Now, what if you lowered a cable down towards the event horizon, while simultaneously extending a cable upwards to keep everything balanced out. This is pretty much the standard "space elevator" concept.
Why couldn't you be able to get the bottom end of the lower cable down into the event horizon, and measure the Hawking radiation effects directly? Then, you could pull the cable back out when you were finished the experiment - The end of the cable would then be escaping from the black hole.
I think the only problem (remember, this is a thought experiment) would be making a cable strong enough to withstand the gravitational pull. Would this be fundamentally impossible?
Torrey Hoffman (Azog)
-- Torrey Hoffman (Azog) "HTML needs a rant tag" - Alan Cox
Re:It's progress, but it doesn't go far enough
by
Froid
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· Score: 1
Books have long conjectured there's a black hole at the milkyway's center, but this is the first hard evidence for one. Sure, we have ideas and hypotheses about the answers to my questions, but there's a big difference between "suspecting" and "knowing". I'm awaiting the latter.
Cheers,
Froid
Re:It's progress, but it doesn't go far enough
by
SIGFPE
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· Score: 1
Who's the moron who thinks that 'controversial' means flamebait?
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SIGFPE
Re:2.6 million stars in that space? try 10x that!
by
boarder
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· Score: 1
What calculation are you using?
If (by the greatest of all possible spaces) you are using the min distance Mars-Sun as the diameter of a sphere of space, you can use 4/3*pi*r^3 to get a V of 4.62*10^24 km^3. Sol's V is 1.412*10^18. You can only fit 3.3 million suns in there.
If you just take the linear distance, you can only fit 308 suns in there.
Either way, that is a shit-load of suns in a relatively small space (compared to the normal distance between suns).
-- IANAL, but I play one on/.
Re:2.6 million stars in that space? try 10x that!
by
big.ears
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· Score: 1
I think the original post made that classic geometry error we have probably all made, and substituted radius for diameter. If his calculations are correct, you can fit 26 million inside the sphere measured out by mars, but the quote implied that the _diameter_ of the sphere is about the distance between the sun and mars.
Is that really nougat in a Three Musketeers? I thought nougat was stickier... gooier... and tan. Three Musketeers seems to have kind of a nougat foam in the middle. Weird.
-- It's not enough to bash in heads, you've got to bash in minds. - Captain Hammer
Ok, here's the deal. As far as I know...
Milky Way in Australia "Has it's centre whipped 'til it's nice and fluffy, so it won't fill them up"
In the USA a Milky Way is what we call a Snickers.
A Snickers is peanuts & caramel wrapped in chocolate. It used to be called a Marathon in the UK until the early 90s.
A Milky Way in the UK (and Australia) is just that fluffy stuff wrapped in chocolate. In the USA, a Milky Way also has a layer of caramel over the fluffy stuff. NO peanuts.
I have this on good authority, as an Englishman working in the states - I just asked the guys in the office.
--
--
It's a.88 magnum -- it goes through schools.
-- Danny Vermin
Since when do Milky Ways contain peanuts? Are you sure you don't mean a Snickers?
Don't forget the caramel, either.
If it was just nougat, it would be a Three Musketeers.
Re:We knew the black hole was there..
by
slickwillie
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· Score: 2
That's just a little too close for my comfort. Anyone else care to start up an expedition to move a little farther out in the galaxy before It's too late?
First it was the flouride in the water, then it was the ozone layer, currently it's like "oh no, we'll all be killed by the Asteroid!". Next big thing will be "We're all going to be swallowed up by the black hole!".
Re:2.6 million stars in that space? try 10x that!
by
Bluedove
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· Score: 1
You're right! That is the error I made. I went back and re-read the quote, and although the original quote is not (IMHO) clear, i believe you are correct. Thanks for pointing that out. My misunderstanding arose the comparison of the mass of the black hole relative to the mass of our sun, which put me in a heliocentric frame of mind. Once there, my mind was not prepared to discuss the size of an celestial body as a diameter measured as a radius outward from our sun.
At least i know i was not alone in my mistake...this time.;-)
Rather impossible. If that were so, we'd be inside the event horizon, and therefore we'd be falling into that black hole. Now, even though science fiction has all sorts of time-dilation motifs inside the event horizons of black holes, I tend to doubt that my existence to this point has been a few seconds on the way into a singularity.
Sorry, but that's a little too rough. Particles are not ripped in two. Rather, at the event horizon, just like everywhere else, virtual particle/antiparticle pairs are constantly being formed and annihiliated as allowed by the uncertainty principle (they don't last long enough to be detectable, so they don't violate any conservation laws). However, being at the event horizon, some of these pairs get formed, and then one of the two particles gets trapped by the black hole, and its partner does not annihilate undetectably quickly, but rather sticks around long enough to collide with other matter or decay or both, thus producing Hawking radiation.
... however, Hawking radiation is immeasureably faint, and has nothing to do with how we detect black holes. People spout off about this every time black holes are mentioned on Slashdot, so much so that it makes me wonder if they're just trolling.
Actually, I have one other quibble with your explanation: the virtual particle pairs are not particle/anti-particle pairs. They're more like particle/unparticle pairs. Anti-matter just has a negative charge (relative to normal matter); the stuff that we're talking about actually has negative energy. The difference is that when particles and anti-particles annihilate, they leave a huge amount of energy, whereas when a virtual particle pair annihilates, it leaves absolutely nothing. 1 + (-1) = 0
News flash: The scientists found the black hole in space where it was lost by mistake over twelve billion years ago. The achievement is astonishing if you consider the the hole is only two million times the mass of our parent Sun.
2.6 million stars in that space? try 10x that!
by
Bluedove
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· Score: 5
The CNN article says: The black hole could hold 2.6 million stars the mass of the sun inside a relatively tiny area -- less than the distance from the sun to Mars.
That shouldn't be at all shocking. Even if we take the minimum orbital distance of Mars (~206.7e6 kms), you can fit the equivalent of 26,193,511 Sol volumes within that space. (given the radius of Sol to be 6.96e5 kms)
So, even NOT counting on compression from the incredible amount of mass, you could fit 26 million stars the mass of the sun into the "relatively tiny space".
Given that the numbers match so closely, except for the decimal place, i suspect one of two things:
1) The article writer is amazed you can fit the volume of a marble into the volume of a basketball.
or
2) The article writer put the decimal in the wrong spot, and discovered you can put volume "V" into the space of volume "V"
Yup.
Science in schools, both here in the UK and in the US, has gone down the tubes.
Example: 'Which planet are we sending this (the HST) to?'. Senator Albert Gore.
Elgon
Being a Brit living abroad I was delighted to find that America had Milky Ways and Mars Bars. I was less than delighted to find out they were not the same as the British originals. Same name different product:-(
The black hole at the center of our galaxy is typical for a galaxy like ours. M31, the great galaxy in Andromeda, has a slightly larger one. Both the Milky Way and Andromeda are rather large spiral galaxies.
But neither black hole can hold a candle to the hole at the center of M87, the giant elliptical galaxy at the center of the Virgo cluster. This titan weighs in at several billion suns, and emits relativistic jets of matter from its poles.
Astronomers are very close to demonstrating that the phonemenon known as quasars, are nothing more than an active black hole, swallowing matter at a prodiguous rate in young galaxies that have undergone a burst of star formation. Our galaxy is likely to have shown quasar properties in times past. But as the concentration of matter near the center of a galaxy decreases as it is consumed by the black hole, the quasars turn off.
Astronomers are also gaining new insights into the role of central black holes in the formation of galaxies. It appears that the galaxy and the hole evolved together - the hole provides the gravitational anchor, pulling in nearby gas clouds, which collapse to form stars. We may have never come to exist were it not for the galaxy-forming propensity of massive black holes.
The Next Generation Space Telescope is expected to answer these questions one way or another. It is hoped that it will be able to image very young galaxies in the process of formation, or perhaps even find evidence of naked black holes just beginning to draw in the surrounding primordial gas. That would be quite a find, since it would imply that the black holes came first, and raises the question: from what? Were the created somehow in the maelstrom of the Big Bang, or was there a very early era of star formation that preceeded the era of galaxy formation?
-- Edith Keeler Must Die
Composition of Black Hole is really...
by
ackthpt
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· Score: 1
All the unbought ET cartridges for the Atari 2600. Damn buggers were multiplying so NASA put 'em in a rocket and set 'em flying.
It's all true! ±5%
--
A feeling of having made the same mistake before: Deja Foobar
Re:Detecting black holes
by
re-geeked
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· Score: 5
You said:
"The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission"
Sorry, but that's a little too rough. Particles are not ripped in two. Rather, at the event horizon, just like everywhere else, virtual particle/antiparticle pairs are constantly being formed and annihiliated as allowed by the uncertainty principle (they don't last long enough to be detectable, so they don't violate any conservation laws). However, being at the event horizon, some of these pairs get formed, and then one of the two particles gets trapped by the black hole, and its partner does not annihilate undetectably quickly, but rather sticks around long enough to collide with other matter or decay or both, thus producing Hawking radiation.
Now someone can correct my rough explanation and eventually we'll get this straight...
-- "You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
Just look a any galaxy, they look like suds going down the tub drain. We are going to sucked into a black hole someday, well the atoms that we are made of will.
Well, unlike space, your tub is not a totally frictionless surface. If your tub was made of helium II and your bathtub was in a complete vacuum, then it just might go on for ever. The suds in the tub lose angular velocity because the friction of the air and ground slows them down. We have no such mediums in space.
Re:Probing the inside of a black hole?
by
diablovision
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· Score: 1
Gravitrons? Are you serious?
Gravity is NOT a particle. It is a distortion of space time.
-- 120 characters isn't enough to explain it.
Your speedometer doesn't measure velocity
by
Froid
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· Score: 2
It measures speed. Velocity is a vector, described by speed plus direction. The earth is constantly accelerating towards the sun, but the earth maintains a constant speed (if you treat its orbit as a circular instead of elliptical).
...i think im so funny...
by
gunner800
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· Score: 1
For that matter, velocity and speed are decidedly different concepts, velocity being the combination of both speed and direction...
We knew the black hole was there..
by
Xerithane
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· Score: 2
We didn't find there to be a black hole in the center.. we knew that already
If you read the article you would note that we pinpointed it's location in the milky way
Read the article, then post.
nerdfarm.org
Re:We knew the black hole was there..
by
Hadlock
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· Score: 1
I've always been taught that *all* science is just theories, waiting to be disproven by more true/less false theories in the pursuite of an absolute truth. Many ideas rely on the THEORY of relativity, which many more scientific partial truths are based upon. That we haven't disproven newton's laws doesn't mean that there are exceptions to these rules that we have yet to discover. Black holes are theory.
Re:We knew the black hole was there..
by
Xerithane
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· Score: 1
Hmm.. black holes are theory.
If all science is waiting to be disproven, then it will never advance.
For instance, drive a car for exactly one hour at 60 miles per hour without acceleration (or deceleration). Prove you went 60 miles in that hour.
That's a theory too, sometimes you just have to say this is the way it is and accept it.
Black holes are real
Black holes are more or less the foundation for the universe (the order and such)
If you don't believe me, go ask one. Make sure you get real close so it can hear you. And that event horizon thing, psh.. just a figment of an imagination.
This isn't mean to be a flame at all, my intention is to provide you with a different perspective. nerdfarm.org
Re:We knew the black hole was there..
by
baldeep
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· Score: 2
Well, I think they concluded that the radio source is the same as the black hole.
To quote John Kormendy (quoted in the article) "'And the nice thing is they intersect right on top, almost exactly, of this radio source, Sagittarius A, which people have long suspected is a black hole.'"
AC wrote:
Actually, acceleration is the derivative of velocity over time
Meaning if you are riding your bike at a constant 20 M.P.H. and take a 90 degree turn, maintaining your speed, you have accelerated.
Re:Are we really this dumb?
by
torpor
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· Score: 3
Yup.
Here's a test: On a *snap* basis, figure out what the difference is between acceleration and speed.
Most people won't think about the difference, as most folks think speed=acceleration.
Try it out - go around and ask 5 average folks (you may have a few around) what 'acceleration' means... betcha they all say 'how fast something is going'.
-- ; -- the corruption of government starts with its secrets. a truly free people keep no secrets.
--
Black holes can be detected (in theory of course) by looking for the emissions they give off. The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission. It is these fissions at the edge that make a black hole appear to give off energy, and make it detectable.
That type of radiation is called Hawking Radiation (after Stephen Hawking, naturally). However, this isn't what lets us detect black holes, as Hawking Radiation is ridiculously faint. Black holes can be detected by the X-Rays that they "inadvertantly" produce. When matter is falling into a black hole it is accelerated, heated, and compressed to such a degree that it gives off large amounts of X-Rays. I believe the first black hole we detected (again, assuming black holes exist), was Cygnus X-1 (or cygnus something), and we detected it by the x-rays it gave off.
Another method of detecting black holes is to look for graviational lensing effects. Because black holes are so massive, they bend the fabric of space time. (Imagine a sheet suspended in the air. Place marbles on the sheet. The marbles make depressions on the sheet, like stars make "depressions" in space-time. A black hole is so heavy, it's like dropping something that is the size of a marble but with the weight of a bowling ball onto the sheet. The sheet bends A LOT, and it actually will have a hole where the singularity is.) Light travels in a straight line, so if space-time curves, light also curves with space-time. Gravitational lensing was proved during a solar eclipse. Astronomers observing the eclipse noted that they were able to see stars that should have been blocked by the eclipsed sun. The sun's gravitational field caused enough "lensing" so that stars directly behind the star could be seen to either side of the star. So, if we find something out in space that is causing a LARGE amount of gravitational lensing, but we can't see anything, there's a chance it's a black hole. At that point we normally observe it more to determine if it is or isn't a black hole.
Technically, first, they aren't antiparticles, but particles with negative energy. The difference is, that when particles with negitive energy and regular particles collide, nothing comes out, whereas with a particle and an antiparticle, energy is produced.
Anyway, judging from "A Brief History Of Time", negative particles are more likely to fall in the black hole because they need more energy to escape and not be sucked in(being as their energy's negative and the other's positive).
I never understood the "evaporation" thing. If particle/antiparticle pairs are ripped apart by the event horizon, with one of them going in, aren't half of the "things" going in going to be particles and the other half antiparticles, effectively canceling each other out?
Or is one more likely to fall into a black hole than the other?
For the ones interested, the uncertainty principle variant for this situation is:
dE * dt >= h-bar,
where
dE = the pair's energy, meaning the amount of energy that is "borrowed" from vacuum in order to create it
dt = the amount of time the pair lives
h-bar = Planck's constant divided by 2*pi
Flavio
Re:Detecting black holes
by
Cyberbabe
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· Score: 1
I may be wrong (so all those astophys grads can correct me if they want) but I don't think Hawking radiation works quite like that.
What happens is you have virtual partical pairs (a partical and anti-partical) which blip into existence and then anialate soon after. They have very short lives. However, if a pair form on the event horizon, one half gets drawn into the hole while the other gains the same (but opposite) energy and is ejected out into space.
That was how I understood it, but if I'm talking out of my 'black hole' feel free to correct me.
By the way, always try to reference quotes where the origin isn't obvious, couldn't find your quote on the MAXIM website so I presume you got it from somewhere else.
My tupence.
--
-- Periodically spray diskettes with insecticide to prevent system bugs from spreading.
Re:Detecting black holes
by
jovlinger
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· Score: 1
so presumably the boil off / evaporation of black holes comes from the negative particle being sucked in, and thus causing a net loss in mass.
However, this leaves a few questions
1) how come more negative (un-, if you wish) than positive particles are attracted?
1.1) how come gravity works the same on unparticles? Shouldn't they be repelled?
2) why does this happen at a faster rate for small black holes (I understand that rate of evaporation is inversely proportional to mass)
Umm, what if a massive object moves in front of another object(eg a distant galaxy) and the galaxy appears to be distorted by the object's presence?
I think that lensing would be useful for the detecting of massive object, but it cannot be used for any form of measurement.
And FYI, they were on about lensing on the Sky At Night last Sunday as a way of detecting WIMPs and MACHOs. Not that I am entirely certain what MACHOs are, yet.
Black holes can be detected (in theory of course) by looking for the emissions they give off. The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission. It is these fissions at the edge that make a black hole appear to give off energy, and make it detectable. That type of radiation is called Hawking Radiation (after Stephen Hawking, naturally). However, this isn't what lets us detect black holes,
eh?
as Hawking Radiation is ridiculously faint
doh.
Black holes can be detected by the X-Rays that they "inadvertantly" produce
huh.
When matter is falling into a black hole it is accelerated, heated, and compressed to such a degree that it gives off large amounts of X-Rays. I believe the first black hole we detected (again, assuming black holes exist), was Cygnus X-1 (or cygnus something), and we detected it by the x-rays it gave off.
so why bother with the Hawking Radiation stuff?
Another method of detecting black holes is to look for graviational lensing effects. Because black holes are so massive, they bend the fabric of space time. (Imagine a sheet suspended in the air. Place marbles on the sheet. The marbles make depressions on the sheet, like stars make "depressions" in space-time. A black hole is so heavy, it's like dropping something that is the size of a marble but with the weight of a bowling ball onto the sheet. The sheet bends A LOT, and it actually will have a hole where the singularity is.) Light travels in a straight line, so if space-time curves, light also curves with space-time. Gravitational lensing was proved during a solar eclipse. Astronomers observing the eclipse noted that they were able to see stars that should have been blocked by the eclipsed sun. The sun's gravitational field caused enough "lensing" so that stars directly behind the star could be seen to either side of the star. So, if we find something out in space that is causing a LARGE amount of gravitational lensing, but we can't see anything, there's a chance it's a black hole. At that point we normally observe it more to determine if it is or isn't a black hole.
huh, cool. Why which one do they use, or do they try to sort of "use all of them" and see what the sum of the results are?
[i]However, this leaves a few questions
1) how come more negative (un-, if you wish) than positive particles are attracted?
1.1) how come gravity works the same on unparticles? Shouldn't they be repelled?
2) why does this happen at a faster rate for small black holes (I understand that rate of evaporation is inversely proportional to mass)[/i]
You're taking the particle/un-particle pair too seriously. While that's the conventional explanation, it doesn't quite fit the math. In fact, the math admits of no explanation. It's just mathematics.
Anyway, having looked hard at the math until my head buzzed, I couldn't see how the standard particle/un-particle explanation fit. However, I also couldn't see any 'real world' explanation that fits either.
Virtual particles are tricky bastards. ---
-- - Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
"Black holes are so dense they create gravity so strong that even light cannot escape their surface, making them nearly impossible to see. Kormendy said the black hole at the center of the galaxy is not pulling in other stars.
Even if it's not pulling in other stars yet, I'll bet it'l suck the fillings out of my great,great,great,great,great,great,great,great,gr eat,great,great,great,grandkids teeth... Wonder why it's not eating stars yet, the density there should be high enough for some motion..
Wonder why it's not eating stars yet, the density there should be high enough for some
motion..
For the same reason that the earth hasn't fallen into the sun yet. From a distance, a black hole is just another gravitational body. Any object orbiting that body is safe, provided it stays well away from the event horizon.
Usually those who are at a loss of words, choose to insult and use profanity. Generally speaking, such language is a sign that the individual has a lower level of understanding of rational thought, and as such has to resort to the lowest of all common denominators to express his/her disaproval.
oh man, thats so bad it hurts. thats an intergallactic groaner
--
-- There are some people that if they don't know, you can't tell 'em.
Re:Now, I'm No Scientist..
by
webrunner
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· Score: 1
IT's so dense that it could pass itself off as a Slashdot troll. ----
-- ADVENTURERS! - ANTIHERO FOR HIRE - CARDMASTER CONFLICT
Re:2.6 million stars in that space? try 10x that!
by
Christopher+Thomas
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· Score: 4
So, even NOT counting on compression from the incredible amount of mass, you could fit 26 million stars the mass of the sun into the "relatively tiny space".
Given that the numbers match so closely, except for the decimal place, i suspect one of two things:
1) The article writer is amazed you can fit the volume of a marble into the volume of a basketball.
or
2) The article writer put the decimal in the wrong spot, and discovered you can put volume "V" into the space of volume "V"
I vote for option 3), 4), or a combination of the two:
3) The amount of space is "tiny" compared to the amount of space taken up by stars in the rest of the galaxy. Stars are seldom packed one against the other.
4) The writer is using copy from descriptions of smaller black holes. The even horizon's radius grows in linear proportion to a black hole's mass, if I remember correctly.
This means that volume grows far faster than mass. Black holes with the mass of a mountain are smaller than an atom; a black hole the mass of the sun have a radius of about 3 km. More massive black holes, however, have less density. In fact, if the universe is closed (i.e. returning to a "Big Crunch"), it would be the perfect example of a very sparse black hole - transplant a sufficiently large chunk of it to a reasonably flat space, and an observer outside of the transplanted chunk would see an event horizon surrounding it.
A singularity, which is the very centre of a black hole and in theory a point of infinite gravity, is (once again in theory) infinitely small. So we'd actually be talking about one heck of a small pinpoint here;)
Ooooh. Sorry. But we have a lovely parting gift..
by
Anonymous Coward
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· Score: 1
The odd thing is- I would have expected the acceleration to which they were referring to be the normal force in all circular motion... Big massive stars going in a small circle really fast = a lot of something pullign them towards the middle...
It's not nearly impossible. It's totally impossible. The guy who wrote it has no clue. Black holes suck in everything, including light waves. That's why they are called black holes. You can only observe black hole's effect on other objects. That way you can figure out that there must be a black hole of certain mass at some location. Repeat: you cannot see black holes. ___
-- ___
If you think big enough, you'll never have to do it.
Re:Almost Infinite, Literally!
by
gooser23
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· Score: 1
you are close, but not right one.
there are different sizes of infinity, but you can't just figure out how large the size of infinity that you are dealing with by counting.
an example of this can be seen with the different sets of numbers.
for instance, take the whole numbers (ie anything that's 1 or greater that has no fractional part). there is an infinite amount of them. if you take just the whole numbers that are evenly divisible by 2, do you get a smaller size of infinity? no, you don't. its still the same size (to mathematicians).
now, look at the real numbers. these are the ones that can be represented in decimal form. (so 2.5, -9, 1/3, but not pi, or sqrt(2)) this set of numbers has a larger size of infinity than the whole numbers. why? well, for one, for any two whole numbers, there is an infinite amount of real numbers between them. for example between 1 and 2 you have 1.1, 1.11, 1.111, 1.1111... you get the idea.
i hope i got that right.
-- "Dying tickles!" -- Ralph Wiggum
Re:Probing the inside of a black hole?
by
Elgon
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· Score: 1
I believe that black holes evaporate: the smaller the hole the faster the evaporation. This is a result of 'quantum tunnelling'.
Karma whoring, moi?
Elgon
Re:Behold, the classic Karma Whore
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Anonymous Coward
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· Score: 1
I believe it was copy/pasted from his post to another Slashdot story. He's recycling.:)
Re:Now, I'm No Scientist..
by
MarcoAtWork
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· Score: 1
The mass is equivalent to two million suns, the size, according to the article, IIRC, is approximately the orbit of mars.
-- --
the cake is a lie
Re:Mathematical calculations
by
Froid
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· Score: 1
The sun-to-moon distance refers to the event horizon only, not to the dimensions of the mass contained. If what we know about black holes is correct, then the mass is all concentrated at a singular point at the center. There isn't actually anything at the event horizon's surface.
I thought that a black hole was just a star that collapsed on itself because there was no matter trying to escape, and therefore just started to, uhh, suck.:-)
If that's true, and gravitational forces remain the same, shouldn't things just stay normal? Like, pretend our star was massive enough to become a black hole: if it became one, we would continue to orbit that hole. To distant observers, it would appear that we were obiting nothing. Right?
This is something I read out of a physics book not too long ago... correct me if I'm wrong please. I'd like to know...
I thought that a black hole was just a star that collapsed on itself because there was no matter trying to escape, and therefore just started to,
uhh, suck.:-)
Not exactly. Stars enter other phrases before dying. See The Death of a Star.
Well, we might continue to orbit nothing (I'm not sure... I tend to think that at a minimum the inner few planets would eventually get sucked it), but Earth would still be doomed. Since light cannot escape a black hole, all the plants on Earth would inevitably be doomed, and take most of the animals with them (following the food chain).
Now I have to wonder... do black holes emit heat? They're detected, IIRC, by X-ray emissions, and X-rays can be used to heat metals, at the very least... so would Earth still be "warm"? Or would it be radioactive from higher X-ray bombardment? (The Van Allen belts can only stop so much...)
Actually, the steps leading up to the creation of the black hole would allready signal the end for us. As the sun progresses through it's stellar evolution, it will eventually reach the 'red giant' stage where it's outer layers will reach out over the inner planets. We'll be cooked.
As for black holes, (I'm sure there's countless references in other posts) they only emit Hawking radiation (and not enough of it to be detected with todays technology). It's their interaction with other objects around them that releases the high energy particles like X-rays and what not, and it is really these interactions which we 'see' with our detectors, as well as the effects on other bodies orbits as this article details.
Well, actually I thought that Van Allen belts involved only sequins, to help "be a part" of the atmosphere in Discotech's. The electro-magnetic stuff you speak of truly baffles me; I use the belt as a BABE magnet.
-('course the fro helps too)
-- .sig wanted: Must be concise, funny, and display my cleverness.
Perhaps so, since "acceleration" could equally have described the stars' slowing down, or changing direction while maintaining speed.
--
This next song is very sad. Please clap along. -- Robin Zander
Re:Now, I'm No Scientist..
by
moosemilk
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· Score: 1
Black holes are not a vacuum, they are the opposite. They are similar to neutron stars in that they are very dense, only more so. The state of the matter is unknown, AFAIK, but it is certainly not atomic - i.e. atoms or neutrons. They can have size, but I don't see a way to measure the size - perhaps by the radiation that is emmitted. The surface you refer to is the event horizon.
Just like I've always said,
"This galaxy really does suck."
-- Aah, change is good. -- Rafiki
Yeah, but it ain't easy. -- Simba
centrifugal force (was - Re:Not to be pedantic)
by
Louis_Wu
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· Score: 2
Well, she's right, from a certain point of view. (Luke, I am your father.:)
'Centrifugal force' is a force defined from a non-Newtonian reference frame, and as such, is not a true force. A force can only be defined from within a Newtonian reference frame, so your implication that she is incorrect is correct. (Does that make sense?)
What your wife is actually feeling (aside from the bump) is her linear inertia taking her in a straight line while the car turns away from that line. So, she bumps into the window.
When she asks you what she is feeling ("I'm feeling something, so what is it, Mr. Smary-Pants?"), you can tell her that what people typically call 'centrifugal force' is actually the other side of 'centripetal force'. Centripetal force is the tension in the string when you swing a Yo-Yo over your head; centripetal force keeps an object traveling in a circle.
Try this, Newton's first law of motion says that it takes force to move something or change it's straight line motion at constant speed (in Newton's world being at rest and traveling with a constant velocity are the same thing, the first glimpse of relativity), and you are traveling in your car in a straight line, with constant speed. You turn the wheel and the car starts turning, which means that acceleration is being applied to the car to change it's velocity. This acceleration is called centripetal acceleration.
In conclusion, there is no centrifugal force, although it appears to be a force, but it is measured from the wrong reference.
Louis Wu
"Where do you want to go...
Re:centrifugal force (was - Re:Not to be pedantic)
by
Ella+the+Cat
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· Score: 2
If you're really Louis Wu, why don't you use the puppeteer hyperdrive to have a look at the galactic core like Beowulf Schaeffer did, instead of reading Slashdot?
Re:centrifugal force (was - Re:Not to be pedantic)
by
Louis_Wu
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· Score: 1
Cuz I'm stuck on Ringworld with Speaker to Animals.
Larry Niven predicted this in his Known Space stories... he made it a reason for the puppeteers to leave the galaxy. Lousy puppeteers, with their two heads and their brain in their back...
Re:Now, I'm No Scientist..
by
mOdQuArK!
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· Score: 2
I dunno, wouldn't that cubic inch of 2-million sun black hole actually be more massive than the entire Earth?
So it would be more likely that the Earth would get "eaten" by that cubic inch. Then again, if that chunk of black hole is too small to maintain its integrity, it may just evaporate violently and blow everything in the immediately spacial environment to plasma...
It's not that black holes "suck" in everything; they are just a very compact and massive object, which therefore exerts a huge gravitational force on everything. Much of the gas near the event horizon of a black hole will get sucked in, and by mass there is much more gas than stars near the black hole. The dynamics and orbits of the nearby stars are affected by the black hole, but that doesn't mean they are sucked in. Supermassive black holes at the centers of galaxies rarely pull in another star (about every 10^5, 10^6 years or so). Remember that the Sun is about a million times more massive than the Earth, yet the Earth is not sucked into the Sun. The mass ratio between a star and the black hole is about the same.
This will prove sullen teenagers' assertions that the universe sucks.
-Legion
footnotes:
1. Not only wasn't this funny, but it wasn't original, either. For god's sake, don't mod it up.
2. It's late, I'm on graveyard shift, and I need caffeine.
3. Booze, too.
The rope accelerates and from you point of view 'spagettifies', but because of the relaitve differences in time à la Relativity you will never see it pass the event horizon. The closer it gets, the bigger the time differential so it appears from your point of view to approach the hole asymptotically.
This could of course be total crap, but it's what I remember reading in some book or other with the word 'quantum' in the title.
Elgon
Windows on the event horizon
by
thex23
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· Score: 2
I just thought of a cool experiment.
Take a Windows 2000 server, link it up by some radio connection, and place it near the event horizon of a black hole.
The effect of time dialation would decrease the MTBF dramatically, with only a minor change in processing speed (slow down a Windoze server by a factor of 1E9 and I doubt anyone would notice).
[Unfortunately, there would still need to be a sysAdmin sleeping next to the server to handle the occaisional (every 10,000 years) crash, but then again, that's probably the best use of someone with an MCSE anyway.]
This dramatic improvement in reliability could be a "hole" new marketing angle for MS. Maybe we could put the entire.NET infrastructure INSIDE a black hole to make the Internet REALLY safe...
What I find far more disturbing is that really long distances are now measured in football fields, as football seems to be more common than both kilometers and miles.
Re:Now, I'm No Scientist..
by
DerMarlboro
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· Score: 2
In case you're not kidding: In the same way that a pound of gold is smaller than a pound of feathers, a 2-million-sun black hole is much smaller than 2 million suns. It's dense. Actually, it's more-or-less infinitely dense, since a black hole forms a singularity, a one-dimensional object, a pin-point, like the article said. The thing that confused me was that they also said it was the size of the distance from the sun to mars. Did they mean the event horizon was that size? Seems small to me, not that I would know.
I could be wrong about this, but I'm pretty sure that M & M Mars is an American company. I think you had become accustomed to the export model, not the original, until you arrived in its homeland.
--
This next song is very sad. Please clap along. -- Robin Zander
The black hole could hold 2.6 million stars the mass of the sun inside a relatively tiny area -- less than the distance from the sun to Mars.
Let's see. For purposes of estimation, let's say the sun is 1,000,000 miles in diameter (it is smaller). Let's say the radius of Mars' orbit is 140,000,000 miles. The volume of a sphere is 4/3 r^3. So... In that sphere, 11,488,213 suns would fit at the same density... Even if we assume the article meant the diameter of the sphere was the same as the radius of Mars's orbit, we're still over 1,000,000 solar masses at current solar density. Not very much like a Black Hole at all...
not too relevant in this case
by
mattorb
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· Score: 2
What you say is true, but this isn't what the group mentioned in the article was doing. More germane, maybe, is that another way of "detecting" BHs, and actually quantifying how massive they are, is to look at the motions of objects around them -- if, eg, stars are moving very quickly, then the mass around which they orbit must be quite large. The technique described in the Nature article sorta, kinda, has to do with this, but the goal was (I think) to pinpoint position more than anything else. We were already pretty sure Sag A was a black hole.
Re:Probing the inside of a black hole?
by
Froid
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· Score: 2
Gravity doesn't work that way. It's only a function of mass (and space). Two objects of the same mass and the same vollume will produce the same distortion in the space-time continuum and will appear indistinguishable. It doesn't matter what goes on inside the black box (in this case, the black hole).
Re:Are we really this dumb?
by
PingXao
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· Score: 1
The part that's confusing me about this CNN report is the blandly put statement that "Black holes are so dense they create gravity so strong that even light cannot escape their surface, making them nearly impossible to see. Kormendy said the black hole at the center of the galaxy is not pulling in other stars."
So, how come it's not pulling in stars? Is there some other force out there? My understanding of black holes was that they sucked in everything... even stars. Of course, according to this other article on CNN, that could be because of the winds... anyway, it seems like a cool discovery.
Thalia
So, how come it's not pulling in stars? Is there some other force out there? My understanding of black holes was that they sucked in everything... even stars
Well, no.:) Answer this question: How come the sun is not pulling in the earth?
If something gets thrown into the black hole then it's gone, but things can orbit a black hole like they can orbit anything else with mass.
It is most likely that it doesn't accrete much matter (ie eat stars, gas, etc.) because it has already sucked in everything in its immediate neighborhood. Black holes warp space, causing everything within a certain radius (called the ISCO, or innermost stable circular orbit) to eventually plunge into the black hole. If you are outside the ISCO, then matter is pretty much safe from getting eaten, at least for a while. So, it is most likely that all sorts of stuff is whizzing around right outside the ISCO (and they get the mass by examining the speeds of those objects) but very little is right near the black hole.
I can't believe you all missed this goof!
by
Anonymous Coward
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· Score: 1
Light does *not* travel in a straight line where matter exists because matter is a distortion of space-time. Light therefore travels in a *geodesic*.
Also, the matter falling into a black hole generally forms what is called an "accretion disk" which starts radiating like hell due to friction effects and the conversion of potential energy to black body radiation.
July - Aug 2000 Issue of "American Scientist"
by
dkoyanagi
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· Score: 1
had an interesting article on the structure of the galactic center. An abstract of the article is here.
Lucky for us that couldn't happen, because it either a) couldn't form or b) would've lost so much mass that the pressure pushing outward would be small enough to be contained. Afaik the only way I know to destroy a black hole is to evaporate it completely with the Hawking radiation coming out of it.
umm i thought andromeda was so small it was boredeline galaxy/very large star cluster... that little fact was in one of the Rama Revealed series by arthur c clarke and gentree lee (past director of science and analyasis at NASA), looking at the last book in the series, it's not in there, maybe one of the other 2 by this duo? sombody want to back me up? or am i making this up? anyways, it said that eventually andromeda is quite a bit smaller than our galaxy, and in another 265 million years or so they're supposed to collide, and things'll get really screwy, kinda like two whirlpools colliding, the circular motion is for the most part destroyed. anybody care to comment?
As any math dweeb will tell you, you can't be "almost" infinite. Take any finite value (Dubya's IQ, the mass of the entire universe), subtract it from infinity, and you get infinity. I don't think "infinity" quite counts as "almost".
Perhaps what you were trying to say was "very big"?
Re:Almost Infinite, Literally!
by
cainem
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· Score: 1
You're right that there are more real numbers than integers, but your proof is way off.
There are also an infinite number of rational numbers between any two integers, yet the sets Z(the integers) and R (the rationals) have the same cardinality.
Re:Almost Infinite, Literally!
by
fm6
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· Score: 1
I know about different kinds of infinity. I didn't get into the full Gödellian rap because it wasn't relevent. You can have different degrees of infinity, but the mass of a physical object is still finite -- and thus infinitely (aleph-nullianly?) smaller than "infinite".
Now, the radius of a black hole...
Re:Are we really this dumb?
by
Hadlock
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· Score: 1
yeay! and i was beginning to think my first 6 weeks of physics 101 honors wasn't amounting to anything....this string of posts makes sense
is that "nougascope" is now my favorite word of all time. I think I laughed myself retarded on that one.
Approaching c
by
Anonymous Coward
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· Score: 1
According to the West Hawaii Today (local morning newspaper for the Big Island of Hawaii - where the Keck is housed, and known locally as the West Hawaii Yesterday ) 4 years ago the black hole had orbiting stars traveling at less than 2,000,000 miles an hour. Today the same stars are clocked in excess of 3,000,000 mph.
Unless I'm wrong, that's a change from 1/5th c to nearly 1/3 c in 4 years.
As I understand it, an object's mass increases as it approaches c.
If that's correct, wouldn't there be a chance that a star in a decaying spiral orbit around a bh could be whipped into enough speed that it's mass could hit the critical point and it could collapse on itself to form another black hole?
Then what happens if it's orbital widens and its speed decreases? Could the new black hole decay into a neutron star? Or if the orbit stabilizes - could you end up with a binary black hole configuration?
Enquiring minds want to know...
This may well be the funniest comment I've ever read here at Slashdot.
Thank you, mister david duncan scott, for brightening up my day. Won't someone mod the parent up, dammit? That's how comedy is done.
--
--- Slashdot: News For Zealots. Stuff That's Hypocritical.
Will you guys ever learn?
by
Enoch+Root
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· Score: 1
Another black hole article? You really want to see goatse.cx links florish!
Re:Probing the inside of a black hole?
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Cyclopatra
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· Score: 2
Maybe it's just browsing at 1 that did it, but I was expecting at least 90% of the replies to this post to be jokes based around "probing the inside of a black hole". Instead, people actually gave semi-thought-out answers to the original post! Not a probing joke in sight. Consider this to be in lieu of every bad joke you can think of...
...or alternatively, just imagine a beowulf cluster of those...
-- "We can't all, and some of us don't." -- Eeyore
Re:Behold, the classic Karma Whore
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cwebster
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· Score: 1
i'm glad someone else noticed it too, i was about to go dig up the post myself and check.
it was cut and paste from the last/. article regarding black holes, and the sad part is that all the same corrections we see here were posted to his last attempt, and he didnt even bother to revise his knowingly bad post before reposting it.
not even good karma whoreing.
Probing the inside of a black hole?
by
AdamHaun
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· Score: 1
If electromagnetic energy can't escape a black hole, what can? I had an odd thought -- gravity. Would it be possible to devise some sort of complicated machinery to answer, say, a yes/no question about life inside the event horizon, and by way of an answer produce some sort of gravitational "ripple"(ie produce some sort of critical mass/density)? If we can get gravity out of a black hole, there's hope that we could eventually get some answers about the nature of the beast.
-- Visit the
Re:Probing the inside of a black hole?
by
isorox
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· Score: 1
In my unexperienced youf I thought I could outsmart the world by using gravity instead of light for communications. However no one would tell me how fast a graviton would move.
If the sun suddenly vanished (just say) - the earth would continue orbiting where the sun was for 8 minutes. At least, thats what I've been told.
Gravitons, if they exist, or whatever, move at the speed of light.
I dont understand any of it though.
Re:Probing the inside of a black hole?
by
Mike+Schiraldi
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· Score: 2
Gravity is caused by matter (and energy, but that's usually only in infintesimal amounts - see E=mc^2).. the force of gravity given off by an object is directly proportional to its mass. If we sent an object into a black hole, it couldn't change its gravity (or that of the entire hole) without destroying or creating matter, which is impossible.
I assume your thoughts about ripples are along the lines of having an object split up inside the black hole, so that there would be two little masses instead of one big one.. But outside the event horizon, the black hole acts like a point source of gravity, no matter how split up things were inside. --
Re:Probing the inside of a black hole?
by
re-geeked
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· Score: 2
Assuming that gravity behaves like quantum forces (no sure bet at this time), you could imagine an experiment like those that "detect" quarks without actually separating them from each other.
Assume we can fling massive (order of the black hole itself) objects about at near light speed. No problem:-)
Fling such an object past the black hole at a close distance, and observe the path of the object, plus the gravity waves from it and the black hole.
What I don't know is what current theory would predict about the results of this experiment: would it let you observe the internal structure of the black hole indirectly -- in a sense, would you hear how it rattles, and know what's in the box?
The paradox for me is that the gravitons (again assuming they exist) would travel at the speed of light, and thus not escape the event horizon any better than anything else, but still the existence of the event horizon depends on the effects of the gravitons. Huh?
So, what would this experiment do?
-- "You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
Okay, according to the article, it says that the mass of the black hole is approximately 2.6 million suns in a space smaller than the distance from the sun to the moon. Now the mass of the sun is approximately 2^30 kg, and the distance from the sun to mars is approximately 1.5^11m...
Quick Calculations...
Okay, that's approximately 370 kg/cubic meter. Funny, I figure that a black hole would be more dense than that. I think somebody is making a mistake somewhere. Hopefully it isn't me.
Re:Saving the species.
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Devil+Ducky
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· Score: 2
Well if you deem it important to develop superlightspeed flight in order to save mankind/our replacements, then you would acknowledge a much more pressing need to make a lightsaber.:)
Devil Ducky
--
Devil Ducky MY peers would get out of jury duty.
Re:Are we really this dumb?
by
cookieman
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· Score: 1
I remember reading some articles a while back that talked about how the universe was still expanding (from the big bang) - but how eventually when the expansion halted - the blackholes would slowly over time end up being the cause of its collapse.
Though if there is an especially large one at the center of our galaxy.... it kinda makes you wonder, doesn't it?
Gam
-- I love idealists not because I am one, but because they make life bearable for pragmatists such as myself.
When a star collapses the matter begins to implode upon a point, eventually crossing the point where the escape velocity becomes greater than the speed of light and a black hole is formed. The edge of this black hole is what we call the event horizon - anything passing within the event horizon cannot ever escape. The simple solution is described by the Schwartzchild metric.
The matter however is still collapsing to a point at the centre of the black hole. According to general relativity there is nothing to stop this collapse and we end up with a point of infinite density and zero volume - a singularity.
However when you come to rotating black holes (described by the Kerr metric) there are differences. The angular momentum of a collapsing star is conserved, and this causes the black hole's event horizon to bulge out along the equitorial plane, much like the Earth has a slight bulge around its equator. Indeed, the central singularity itself forms a torus rather than a point when the black hole is rotating.
As angular momentum is increased this bulge gets bigger and the polar size of the event horizon shrinks, until eventually you are left without an event horizon at all, but just a torus-shaped singularity, which is said to be "naked".
Of course, whether a naked singularity can ever exist is an open question. There is something called the "Cosmic Censorship Principle" which states that the laws of physics will never allow a naked singularity to form, but the final answer is "we don't know".
Also of interest is that since the naked singularity would be in the shape of a torus you could theoretically pass through the centre of the torus and find yourself somewhere completely different, possibly even in another universe!
For a fairly technical intro to black holes and singularities, see this article at suite101.
The Hubble Constant (whether it be anything from Sandage's 50 to that French guy's 100) does not say that the expansion is accelerating. Far from it.
It's basically the expansion of a balloon. If galaxies, stars, us, were just flat little blobs on the surface of the balloon, and you blew up the balloon, a spot halfway around the balloon from you would apppear to be moving away very quickly, spots nearby you wouldn't move much at all.
That is not an acceleration of the expansion. If the expansion were accelerating, Hubble's constant wouldn't be a constant, it would be getting larger.
What you are talking about is the Big Bang/Big Crunch theories
If the universe expands like a rubber band type thing, to a point then slowly starts contracting again or
if it will expand infinitely.
It's all relational to the amount of matter and graviational pull to the expansion and what not, unfortunately we don't have enough knowledge of dark matter to definitely say whether we're gonna get crunched or stretched. nerdfarm.org
Anyone consider the temperature?
by
)-(eat
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· Score: 1
I really am not sure about this so thats why i am asking - would the temperature in a black hole be absolute zero (or at least be approaching it as you went farther in)? I would think with the matter so densely compacted there would be no vibration of the particles and this would mean absolute zero.... Hopefully someone has some idea...
-- When the world ends, we'll be burnin' one
-- Dave Matthews Band
The Schwarzchild Radius is the radius that if a mass is compressed to within, the escape velocity exceeds the speed of light. The Event Horizon is the border between the region where an observer can 'observe' 'events' occuring near a black hole and where the observer can no longer 'observe' 'events'. Current theories suggest that these two only coincide for a non-rotating black hole as if the black hole is rotating, the space around the black hole is dragged along with it (Frame dragging) and the Event Horizon decreases in size.
However, the Event Horizon cannot ever reach a size of zero (exposing the Naked Singularity) as that would mean that the Black Hole would have an angular velocity equivalent to an energy of infinity!
How massive is this blackhole compared to others? Is this impressive in any way besides that it's neat that they were able to 'prove' that there's a blackhole at the center of our galaxy?
Re:size?
by
Anonymous Coward
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· Score: 1
Well, it's certainly way huger than any other black holes in our galaxy, being our galaxy's main central hole, but it's probably typical for black holes at the centers of galaxies like ours.
In the same way that a pound of gold is smaller than a pound of feathers, a 2-million-sun black hole is much smaller than 2 million suns.
What's even more interesting is that an ounce of gold is actually heavier than an ounce of feathers.
Gold is divided into Troy ounces, and there are 12 Troy ounces in a pound. As a result, 1/12 of a pound is a Troy ounce, being heavier than 1/16 of a pound, an ounce.
So is the event horizon is the "great barrier" that they talked about in Star Trek V?
Re:Well, here we go . . .
by
Chiasmus_
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· Score: 1
What would have been funny is if you'd somehow made a connection between grits, black holes and mrs. Portman that made some attempt at vernal coherence, while yet maintaining literal impossiblity.
Let me try.
If my pants were in a black hole, Natalie Portman wouldn't even have to pour hot grits in them... they'd eventually end up there all by themselves.
An extension of this logic leads me to conclude that eventually, millions of billions of years into the future, I'll end up getting into Natalie Portman's pants.
-- "Beware he who would deny you access to information, for in his heart he deems himself your master."
The black hole is not more then million suns in size, but *MASS*. That is what makes a black hole: an almost infinite mass in a very small (relatively speaking) radius.
--weenie NT4 user: bite me!
-- --weenie NT4 user: bite me! "Computers are nothing but a perfect illusion of order"
-- Iggy Pop
Between this and the eventual extinction of our sun we better get to work on those faster then light engines sooner rather than later if we plan to save whatever it is humanity is going to evolve into over the next few billion years!
Any where in Space, virtual particles exist. These are pair of particles that are oppositesin all but mass and are created and annihilate each other. Occasionally, one partner is pulled into a black hole. If the other partner escapes, then that particle is promoted to a REAL particle and is said to be produced through Hawking Radiation.
Personally, I think that all these virtual particles have a significant effect on the ?U?niverse and could well be the explanation for Dark Matter.
Occam's Razor - The simplest explanation is usually the correct one.
If people don't know what acceleration is, it is necessary to define it.
If people know what acceleration is, they also know that the definition given is slightly inaccurate. (Acceleration is the derivative of velocity, not speed. You can travel at a constant speed in a circle and still have high acceleration, which is about what these stars are actually doing.)
So people who know that they don't know appreciate the definition.
People who know that they know ignore the simplification of the newsmedia definition.
The only people who complain are those who don't know that they don't know.
Now that we got that out of the way
by
supruzr
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· Score: 1
I personally thought everyone already knew there was a black hole at the center of the galaxy.
But this brings up new questions in my mind...
Since the galaxy spins as a spiral on a single plane, does the black hole spin with us? If so, it's event horizon is largest on the plane of the galaxy, and, if spinning fast enough, nonexistant at it's poles. But if the black hole spins, doesn't the singularity have to be a torus (donut for the laymen)? And if it is a torus, isn't it possible that the inner singularity could be bridging a gateway to another part of the universe, or even another universe?
Or does the black hole not spin, and is that why the center of the galaxy have that huge bulge, it being the demarcation of the event horizon?
Even more interesting, is all the stellar material, including us already within the event horizon? Perhaps that is the only reason such galaxies exist at all, as feed for super massive black holes. After all, we have never found free ranging planets, just sorta floating aimlessly in deep space....
Internet Troll Hole Pinpointed at Slashdot.org
by
Chris+Pimlott
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· Score: 5
A joint team of network specialists, consisting of employees from Cisco Systems, Hewlett-Packard, 3Com and others have located an immensive Troll Hole on the Internet, centered directly on the popular weblog Slashdot. While the presences of the hole has long been suspected, today's announcement has confirmed its status as the largest Troll Hole on the Internet.
Experts say the Slashdot Troll Hole has been continually drawing hundreds of trolls to the site for over three years. "It seems to present an incredible attractive force to individuals with an abundance of spare time," explained Michael Czekjum of the Internet Engineering Task Force. "Once drawn, they find themselves compelled to inundate comments with disguised obscene hyperlinks, single-minded knee-jerk insulting replies and vacuous first post attempts."
While today's pinpointing of the hole represents a great triumph, officials stress there is still much to learn. Early analysis seems to suggest it is expanding. Datapoints from Slashdot's founding in late 1997 show an almost complete lack of trolls. Since then, their numbers have expanded at a geometric rate. The types of individuals being attracted is also being studied. "While traditional text-based trolls are still in the majority, the past six months have seen a great increase in graphical trolls, using primitive ASCII representations," wrote Ari T'teyel of Sun Microsystems in a paper published last week. "In addition, the hole's effect on other individuals, such as karma whores, is as yet unknown."
The Troll Hole draws in
OK, so I love being pedantic. In physics, a can be either positive or negative, so you could call slowing down acceleration. In a news article, and in the context of normal conversational english, slowing down is always "deceleration" and speeding up is always "acceleration".
And no, people aren't that fuckin' stupid. But reporters are.
-- It's rare that you're presented with a knob whose only two positions are Make History and Flee Your Glorious Destiny.
You're right about not changing its effect on distant orbiting bodies.
You're wrong about the mechanism of its formation, though. The way it works is, over its lifetime, the star forms heavier and heavier elements through solar fusion in its core, giving off thermal energy that keeps the star from collapsing. It runs into trouble when it finally works its way up to iron, because you can't derive any energy from fusing iron atoms -- to create any elements heavier than iron actually requires a net input of energy. So, once there's no energy left to be had from fusion, the star can't keep itself from collapsing any longer, and it collapses.
If it's less than about 2.8 solar masses, then it collapses into a neutron star (and most likely causing a super nova in the process). If it's heavier, then the neutron-neutron forces are insufficient to oppose gravity, and it collapses further, into a black hole.
Corrected definition of Hawking Radiation
by
13013dobbs
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· Score: 1
(Sorry for the nit-pick, but I am a recovering Physics Major.) Near the event horizon of a black hole paired particles of matter and anti-matter are being created. these pairs will circle each other for a bit and then destroy each other. Sometimes these particles will have one of their partners sucked into the black hole. Leaving the surviving particle free to wander off into space.
I read about this in a newspaper already. Remember those? A newspaper is that thing you have to unfold to read... those things that never used to get their news to me before/. could...
I don't know what to do! I may have to go to ZDNet or do something equally dumb.
Devil Ducky
--
Devil Ducky MY peers would get out of jury duty.
Precise definition of Hawking radiation
by
Anonymous Coward
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· Score: 2
"event horizon) of the black hole (crossing this line means you never come back" Actually, the event horizon is the point that LIGHT crosses and never comes back. I have a hunch the point that a human in a realistic space craft would have this problem at a much further distance, as that person/spacecraft would have quite a bit more mass than those photons. I.E. Mankind's event horizon happens much further out than light's....(I think, anyways)
Erm, I don't know much about Dyson Spheres, except that they completely contain the energy from the star that they surround, but wouldn't a Dyson Sphere look almost identical to a black hole from a vast distance?
It's not pulling in the other stars because the stars still have plenty of momentum from the Big Bang. Eventually, that'll change.
It's kinda like how 'constant velocity' actually means 'just enough acceleration to offset drag, gravity, and every other force acting on the body in motion'
That'd be my theory. It's just as valid as any scientist's theory, because when you get right down to it, we're all just guessing.:-)
-- Vintage computer games and RPG books available. Email me if you're interested.
I need to read more carefully
by
tycage
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· Score: 1
The first time I read the subject I thought it said "Astronomers Find Black Hole With Milky Way Center"
Maybe I've been working too hard
Well here we are again. Anyways, if you were sucked into a black hole what would happen?
Black holes have immense gravity. As a "matter" of fact the mass of them is so high that the gravity is practically immeasurable. Now, with gravity comes time, as clearly shown in our favorit Einsteinian theory. Yup, the theory of relativity. Now if you all studied and di your homework(did you) then you would know that TIME IS RELATIVE! As a matter of fact time is pretty arbitrary by humans standards, but that is a completely different story.
Anyways, you get sucked into a black hole. Since the gravity IS higher(duh!) then time would slow for you. Things outside would appear to mvoe faster, if there was anything to look at then you would see things going REALLY fast. Since the time is relative you could see the whole universe ending, only because we have not determined how long black holes exist. This poses another question. If the time is slowed down immensely, then black holes must exist long enough so that the universe ends, or the time dialation is not as heavy as theorized and you get sucked in well before the end of the universe. It is also said that you get "stretched" when you go into a black hole because of the difference in gravity between the event horizon and the lip. Well, at a certain point time and space theories as of now are thrown out of the water and well, your fucked. The point of singularity breaks down everything we know about the universe. You would probably also be torn apart atom by atom. The time change would also appear as if you were moving slow to the outside world. This is truly fucked up.
Oh yes, it's also theorized that when black holes reach a certain mass., probably at the end of the universe, they "explode" and realease all the matter they have collected. As amatter of fact eventually blakc holes would suck each other in, possibly creating another big bang.
Astronomers have decided to name the black hole
by
Tony+Hammitt
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· Score: 1
Lewinsky! It goes right to the center of things and sucks like a demon. Its emissions from its job of sucking are widely discussed and clearly visible on the fabric of the dress, er, I mean spacetime...
The velocity, or speed of the stars [...] , had been roughly measured, but the UCLA team took it a step further by using the infrared images of three stars to measure their acceleration -- or how fast the stars were speeding up
Thanks for the definitions. It really helped out those of us who have never owned, driven, or ridden in an automobile before!;) --
You know, I was thinking that they were down the road a piece (I'm in Baltimore), but I didn't want to confuse the poor foreigner.
They're so brave, these Britons, leaving their little villages and their beloved sheep and venturing forth into the hustle and bustle of modern life. Automobiles. airplanes, electric light -- there's so much for them to learn. I didn't want to make it harder with geographic details.
--
This next song is very sad. Please clap along. -- Robin Zander
When the Mars candy company created the Milky Way and Three Musketeers bars, somehow along the way they messed up the packaging. The Milky Way bar was meant to be the bar with a creamy, non-nutty center that eventually became the Three Musketeers bar, and vice-versa. The Milky Way ended up with three main layers (Peanuts, Nougat, and Chocolate). Three layers, Three Musketeers, get it? Yes, I'm sure you do.
Yeah, a life would be in order, but I'm too busy munching down on the Milky Way and filtering the world's Tequila supply with my liver. Oh, well.
A black hole with a mass of more than 2 million suns has been pinpointed at the center of the Milky Way.
.. but if something is the size of more then two million suns, then how exactly is it 'pinpointed?' Wouldn't it make more sense if it was 'two million suns pointed'? Just how big of a pin are you guys using here?!
------------ CitizenC
Re:Now, I'm No Scientist..
by
cwebster
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· Score: 1
i wish i could quote something, and then make up something just to sound good that the article didnt really say. I might get some karma that way.
mass != size
Re:Now, I'm No Scientist..
by
Eeeeegon
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· Score: 1
BTW, a black hole is a zero-dimensional object. A one-dimensional object would only have 'length' as a variable (a line), a two-dimensional object has 'length' and 'width' (a polygon). Since the black hole collapses to a single point, it's zero-dimensional.
Check out the book 'Flatland' for more on dimensions.
THE FACTS: The MilkyWay is often consumed into what may be considered a black hole. However, if this were indeed a black hole, the black hole would not appear to gain mass.
For instance, one 40-year-old male who had taken part in the study, funded by the United States Food and Drug Administration. Where a black hole would compress the matter to a mere geometric point, the black hole referred to in the study actually appeared to expand when the chocolate-malt product was consumed. When enough MilkyWay are regularly consumed, the subject will experience an increased capacity to eat; the capacity increasing with each sitting.
More concerned are the exercise professionals. "Those who consume too much of the product will put personal trainers out of business," suggests Jed Smith, Editor, American Human Body Focus. "People," he adds, "will no longer see a need to keep their bodies fit. Consumers are putting millions of professional trainers at risk of losing their job."
Cynthia Lamon, of the Maximum Performance Association of Athletic trainers (MPAA), has vowed to encourage US Congressional support of the Diet Manipulation Consumption Act (DMCA), currently a bill which was introduced and passed by the House. Pending the approval of the Senate, the President would then be asked for his approval.
The DMCA, if passed, require the millions who consume the MilkyWay chocolate-malt bar to accept the planned licensing agreement displayed on the outside of the packaging. Additionally, if the licensing provisions state so, those who wish to consume the sacred bar will be required to slice the bars only with Mars-KitchenWare utensils. Such sets of tools are alleged to offer technological advantages over traditional fork and knife sets.
The food items will also contain Crafted Structured Starch (CSS) technology, which would make splitting the food fibers impossible without the KitchenWare tools, which are able to unbind the additives which ensure the foods are sanitized.
"the black hole at the center of the galaxy is not pulling in other stars. " Why isn't it? And if it is, what did he mean?
A side note: The event horizon of such a massive black hole would be quite a distance from the surface itself. This would enable us to send a probe literally inches from the Schwarzschild Radii, (because of the cubes and squares and stuff).
Yeah, yeah, flame away.
--
You quitting proves that the karma kap worked. The most annoying of the whores shut up. --CmdrTaco
ah, so that's where all the thoughtful/. posts are going...
-- -=tonyt=-
Before panic sets in...
by
Millennium
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· Score: 2
...oh, great. Even though most Slashdotters are smarter than this, people are probably going to start panicking, if only for a brief time.
The Earth is in no danger whatsoever of being sucked into this black hole. The reason: the black hold has a mass of roughly 26 million suns. That's a finite mass, even if it is of near-infinite density. Expand that into a star with that mass. This star has the same mass as the black hole, and therefore has the same gravitational pull as the black hole. No more, no less.
So then why don't we get sucked into the star? Because gravitational pull is inversely proportional to the square of the distance, not from the surface of an object, but the center of gravity of the object. When the star collapses into the black hole, its center of gravity stays in about the same spot.
What this means is that, once you're further away from the black hole than the radius of the original star, the black hold has no more gravitational pull on you than the original star did. It's when you go inside that radius that the hole's pull gets really strong. So, if our sun were to collapse into a black hole at this very instant (which it can't do, but let's say it does for the sake of argument), we would be in no more danger of falling into the black hole than we were of falling into the sun. We'd be screwed anyway, due to the loss of solar energy and the X-ray bombardment, but we wouldn't fall into the black hole.
This is important, because studies have shown that the solar system is moving further away from the center of the Milky Way, not closer to it. Therefore, the Earth is perfectly safe from this new "threat."
Now if only they could find the black hole in my son's room that keeps moving his stuff around on the floor, slowly attracting it under the bed.
--
Burn Hollywood Burn
So it that what holds us together?
by
affegott
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· Score: 1
Hmm... sounds like a big black hole. Seems like it would be fun to visit... now they need to work on WARP drives.
Seriously, there needs to be more money spent on the space program. It is one of the truely "neat" things humans do. Besides, we have to prepare to one day move off this rock.
Slashdot Mirror
I didn't get into the full Gödellian rap because it wasn't relevent
I think you mean the whole "Cantorian" rap.
Georg Cantor is the guy who came up with major portions of the theory of infinite sets.
---CONFLICT!!---
(nonetheless, they assumed that John Q. Public was already quite comfortable with concepts like triangulation)
--
--
Mod up a post Rob doesn't like and you'll never mod again
Got news for you dude. Nature doesn't care about mathematics.
I hate to break it to you dude, but Nature cares very deeply about mathematics. This is why she chose to base all of creation on it.
The fact is people didn't invent mathematics, we merely discovered it.
Look at the whole fiasco over the discovery of irrational numbers and "imaginary" numbers.
No one wanted these, they were forced into accepting their existence.
---CONFLICT!!---
Is it impossible for a solid object to be partly within and partly outside the event horizon? Why?
Damn, I have to get a good book on this stuff.
Torrey Hoffman (Azog)
Torrey Hoffman (Azog)
"HTML needs a rant tag" - Alan Cox
For the love of god man! we're all going to be sucked into a black hole that will negate exsistance as we know it! Panic now! avoid the rush! we've only got a few billion years left!
--
There are some people that if they don't know, you can't tell 'em.
Maybe you were readin this one?
> but how eventually when the expansion halted
Uhm, you DO know that not only is the universe expanding, it is ALSO accelerating !
The rate is called the "Hubble constant" which you can read about it here:
Cheers
It wasn't funny enough for a 5...I didn't even smile.
Connah
Connah
"Your mouse has moved. Windows NT must be restarted for this change to take effect."
What I like about these astronomical-black-hole-sun posts, is that you know what to excpect when you look at the forum - first 10 posts (highests scores first) will be *Funny*. Any lame joke will get propagated on top of the list. People, what's up with that? Or is astronomy is way funnier than Napster? hmm..
http://dtum.livejournal.com
Check out recent work by Susskind and 't Hooft (the guy who pretty well invented Gauge Theory) - in particular the stuff on the Holographics Hypothesis (this *isn't* the cheesy holographic universe thing in some popular physics book). Susskind had an article in SciAm about a year ago - otherwise, if you have a physics background, try searching xxx.lanl.gov. They, and others, suggest that the event horizon isn't the well behaved place classical general relativists say it is. You may no the classical result that a black hole has no hair. The opposite seems to hold in quantum gravity - the event horizon actually has lots of quantum information concentrated near it. I am sympathetic towards their controversial outlook (I did black holes and strings for a few years before and during my PhD). Who knows though - *none* of this stuff is founded on anything rigorous.
--
-- SIGFPE
If you take the Schwartzschild radius, the point where the escape velocity equals the speed of light, it's radius would be about 3000km. Compared to the size of the Milky Way, that's a pinpoint;) The Schwartzschild Radius is 2 * gravitational constant * mass of sun / (speed of light^2 )
Righty, here is a basic explanation. Some of the bits will pobably be slightly inaccurate but that's okay, you're all understanding people.
Stars are big and hence they have a big gravitational field. What prevents the star from collapsing is basically the heat and light it produces by fusing lighter elements into heavy ones. When the star runs out of available hydrogen to burn it then starts to burn helium and so on up/across the periodic table until it reaches iron which it can't fuse because the released enegy per nucleon is negative.
(non-MS)ie. It don't produce any heat.
The star then begins to collpse. There are various thing that can happen, depending on the mass of the star. If it is big enough, the whole shebang colapses until the core is hyper-compact and reaches the exclusion-principle limit. The outer layers rebound at a fair old fraction of the speed of light (10%???) producing a supernova (I forget which type, IIa???). If it is still above a certain mass, the Chandrasekhar limit IIRC, then it collapses further until the curvature of space around it becomes infinite (as per Gen'l Relativity).
Voilà. Black hole. (All corections welcome:-)
Elgon
Let me say this once and for all.
Gravitational lensing has never been and will never be used to detect the presence of a black hole.
The reason? It's not that gravitational lensing does not exist, or even that it's not dramatic enough to detect. The reason is that no black hole is close enough for us to use parallax to know the true positions of stars behind it. The way gravitational lensing works is by being able to detect when stars are out of place (not where they should be) due to their light being bent by a super-massive black hole. We would never know where these background stars should be so we can never figure out if they have moved.
So you just demonstrated how horribly uniformed on the tremendous size of the universe you are, and how that results in us not being able to use gravitational lensing to detect black holes.
120 characters isn't enough to explain it.
of course, the above numbers are upper limits on the radius; a BH can always be *smaller* than the Swarzschild radius, but never larger.
Actually it'd be Great to the 34999434 power
All we need is an object bigger than the black hole, to plug it up.
As an aside, do things in the northern hemisphere of the universe flush one way down a black hole, while in the southern hemisphere, they flush the other?
--
To attempt to illustrate it's denseness further, if you could place a cubic inch of this black hole on the floor, it would shoot straight to the earth's core. That's dense!
For those that haven't read it, Stephen Hawking's "A Brief History of Time" is an excellent book that covers black holes.
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Typical, but a little on the small side, as supermassive black holes go. A black hole at the center of M87, in Virgo, might have a mass as large as three billion suns, for example. See this article at space.com for more info.
I just wanna know how fast the images were accelerating.
120 characters isn't enough to explain it.
um, that'd just generate an error. I think what you mean is /dev/null
/dev/null > center.galaxy.txt
cat center.galaxy.txt >
but even that wouldn't do what you wanted, because center.galaxy.txt would still exist, and doing
cat
wouldn't be the same either, because then it's the black hole going into the galaxy, not the other way around.
I think what you're looking for is
alias 'blackhole=rm -rf'
blackhole center.galaxy.txt
My plan is to pimp before they realize I'm a jackass. Hit 'em hard and fast.
A black hole isn't just a homogeneous mass. Theoretically, all the mass collapses to a singularity. The "boundary" of a black hole is the event horizon, or the distance where light can no longer escape the black hole's gravitational pull.
Positive particle do get sucked in just as often as the negative ones. The difference is that normal matter loses potential energy when falling, whereas "negative matter" gains energy as it falls. This is the magic that allows the remaining particle to become "real"... Sounds a little fuzzy, I admit.Fair question. I don't know.The smaller the hole is, the greater the tidal forces at the event horizon. Stronger tidal forces mean that pair of virtual particles is more likely to be ripped apart, just like you'd be ripped apart if you got near the event horizon of small black hole.
MSK
Does anyone know what the term for a particle with negative energy actually is?
MSK
I can't beleive you guys want to spend more of my hard earned dough on your Wasp Rap devices. I think you white folks need to remember that rap is the language of the people. I'm so tired of you whitees thinking that you can just change all our artforms into your bastardized propaganda for white rule. Power to the people. The revolution will not be televised. Next time you drive around in your $200,000 Chevys, listening to that Warper Eminem, remember that we're taking names and plates, boy. You best watch your back.
The impact of the woman's head on the window is from the acceleration of that window toward her head. (Just another way of phrasing your point about her linear inertia.)
After her body came to rest against the window and the door, she was experiencing centripital acceleration in the literal sense. (Although the car is not a string, and she is not a yo-yo (I dont know her), the factors are the same. The car is keeping her on the arc of a circle.)
--- -- - -
Give me LIBERTY, or give me a check.
I'm switching to Snickers from now on.
--- Jump!! Fire!! Bullet time!! - Lego version of the Matrix
"illerate" ?
Have no sense.
You tried to be funny with this?
Just another coder...
And jerk (a parameter I've only seen referred to once) is the derivative over time of acceleration
73 de N5VB (ex-KD5BIV) AR SK
it's theorized that lot's of things could happen, there are many theories, stop being so arrogant.
[i]Before saying things like it's just Math, you'd better not forget that quantum theory and GR are quite successfull, so if they predict that something happen, well, it has quite a chance to happen "for real".. [/i]
:)
Okay, first off, it's not a matter of chance. Something is real, or it isn't. The theory is either real to the world in this respect or it isn't. There is no way to measure what the "chances" are that it's correct, and as we all know, if you can't measure it, it's not science.
And a theory can be completely and totally correct in every respect except one, and still be wrong.
Also, note that I don't thing it's incorrect here, I just don't see how you can get the particle/unparticle explanation from the math of it. Seems like that's a made up explanation for mass comsumption.
---
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
This just in: Finding that there was a previously undiscovered black hole at the center of our galaxy, the RIAA sued them for copyright infringement. "We thought we had sued everything in the known universe for violating our artists' rights," said a RIAA spokesman. "Thanks to the tireless efforts of NASA and Lars Ulrich though, we have continued to make the universe safe from free music." Reports also indicate the MPAA will sue the Big Bang next week for, "Making the creation of DeCSS possible through its own reckless acts of creation."
So, we're now sure there's a blackhole at the center of the milkyway. But what is there at the center of the blackhole? What are the physics like inside? What's it like to fall in? How many dimensions inside? What would it look like to stand inside and look out at the light falling in? What's it feel like to be a blackhole?
These are the things we still don't know, and I'm afraid we'll never know them within my lifetime.
If (by the greatest of all possible spaces) you are using the min distance Mars-Sun as the diameter of a sphere of space, you can use 4/3*pi*r^3 to get a V of 4.62*10^24 km^3. Sol's V is 1.412*10^18. You can only fit 3.3 million suns in there.
If you just take the linear distance, you can only fit 308 suns in there.
Either way, that is a shit-load of suns in a relatively small space (compared to the normal distance between suns).
IANAL, but I play one on
I think the original post made that classic geometry error we have probably all made, and substituted radius for diameter. If his calculations are correct, you can fit 26 million inside the sphere measured out by mars, but the quote implied that the _diameter_ of the sphere is about the distance between the sun and mars.
Since when do Milky Ways contain peanuts? Are you sure you don't mean a Snickers?
--
It's a
-- Danny Vermin
That's just a little too close for my comfort. Anyone else care to start up an expedition to move a little farther out in the galaxy before It's too late?
First it was the flouride in the water, then it was the ozone layer, currently it's like "oh no, we'll all be killed by the Asteroid!". Next big thing will be "We're all going to be swallowed up by the black hole!".
At least i know i was not alone in my mistake...this time. ;-)
Demonstrant's Open Source Tools
Rather impossible. If that were so, we'd be inside the event horizon, and therefore we'd be falling into that black hole. Now, even though science fiction has all sorts of time-dilation motifs inside the event horizons of black holes, I tend to doubt that my existence to this point has been a few seconds on the way into a singularity.
Kierthos
Mr. Hu is not a ninja.
Actually, I have one other quibble with your explanation: the virtual particle pairs are not particle/anti-particle pairs. They're more like particle/unparticle pairs. Anti-matter just has a negative charge (relative to normal matter); the stuff that we're talking about actually has negative energy. The difference is that when particles and anti-particles annihilate, they leave a huge amount of energy, whereas when a virtual particle pair annihilates, it leaves absolutely nothing. 1 + (-1) = 0
At least, that's the way I heard it.
MSK
News flash: The scientists found the black hole in space where it was lost by mistake over twelve billion years ago. The achievement is astonishing if you consider the the hole is only two million times the mass of our parent Sun.
You can't handle the truth.
That shouldn't be at all shocking. Even if we take the minimum orbital distance of Mars (~206.7e6 kms), you can fit the equivalent of 26,193,511 Sol volumes within that space. (given the radius of Sol to be 6.96e5 kms)
So, even NOT counting on compression from the incredible amount of mass, you could fit 26 million stars the mass of the sun into the "relatively tiny space".
Given that the numbers match so closely, except for the decimal place, i suspect one of two things:
1) The article writer is amazed you can fit the volume of a marble into the volume of a basketball.
or
2) The article writer put the decimal in the wrong spot, and discovered you can put volume "V" into the space of volume "V"
Demonstrant's Open Source Tools
Yup. Science in schools, both here in the UK and in the US, has gone down the tubes. Example: 'Which planet are we sending this (the HST) to?'. Senator Albert Gore. Elgon
Ahhh two countries divided by a common language.
:-(
Being a Brit living abroad I was delighted to find that America had Milky Ways and Mars Bars. I was less than delighted to find out they were not the same as the British originals. Same name different product
But neither black hole can hold a candle to the hole at the center of M87, the giant elliptical galaxy at the center of the Virgo cluster. This titan weighs in at several billion suns, and emits relativistic jets of matter from its poles.
Astronomers are very close to demonstrating that the phonemenon known as quasars, are nothing more than an active black hole, swallowing matter at a prodiguous rate in young galaxies that have undergone a burst of star formation. Our galaxy is likely to have shown quasar properties in times past. But as the concentration of matter near the center of a galaxy decreases as it is consumed by the black hole, the quasars turn off.
Astronomers are also gaining new insights into the role of central black holes in the formation of galaxies. It appears that the galaxy and the hole evolved together - the hole provides the gravitational anchor, pulling in nearby gas clouds, which collapse to form stars. We may have never come to exist were it not for the galaxy-forming propensity of massive black holes.
The Next Generation Space Telescope is expected to answer these questions one way or another. It is hoped that it will be able to image very young galaxies in the process of formation, or perhaps even find evidence of naked black holes just beginning to draw in the surrounding primordial gas. That would be quite a find, since it would imply that the black holes came first, and raises the question: from what? Were the created somehow in the maelstrom of the Big Bang, or was there a very early era of star formation that preceeded the era of galaxy formation?
Edith Keeler Must Die
All the unbought ET cartridges for the Atari 2600. Damn buggers were multiplying so NASA put 'em in a rocket and set 'em flying.
It's all true! ±5%
A feeling of having made the same mistake before: Deja Foobar
You said:
"The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission"
Sorry, but that's a little too rough. Particles are not ripped in two. Rather, at the event horizon, just like everywhere else, virtual particle/antiparticle pairs are constantly being formed and annihiliated as allowed by the uncertainty principle (they don't last long enough to be detectable, so they don't violate any conservation laws). However, being at the event horizon, some of these pairs get formed, and then one of the two particles gets trapped by the black hole, and its partner does not annihilate undetectably quickly, but rather sticks around long enough to collide with other matter or decay or both, thus producing Hawking radiation.
Now someone can correct my rough explanation and eventually we'll get this straight...
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
Just look a any galaxy, they look like suds going down the tub drain. We are going to sucked into a black hole someday, well the atoms that we are made of will.
Gravitrons? Are you serious?
Gravity is NOT a particle. It is a distortion of space time.
120 characters isn't enough to explain it.
It measures speed. Velocity is a vector, described by speed plus direction. The earth is constantly accelerating towards the sun, but the earth maintains a constant speed (if you treat its orbit as a circular instead of elliptical).
Another layer of chocolate? Genius!
My mom is not a Karma whore!
For that matter, velocity and speed are decidedly different concepts, velocity being the combination of both speed and direction...
We didn't find there to be a black hole in the center.. we knew that already
If you read the article you would note that we pinpointed it's location in the milky way
Read the article, then post.
nerdfarm.org
Dacels Jewelers can't be trusted.
AC wrote:
Actually, acceleration is the derivative of velocity over time
Meaning if you are riding your bike at a constant 20 M.P.H. and take a 90 degree turn, maintaining your speed, you have accelerated.
Yup.
Here's a test: On a *snap* basis, figure out what the difference is between acceleration and speed.
Most people won't think about the difference, as most folks think speed=acceleration.
Try it out - go around and ask 5 average folks (you may have a few around) what 'acceleration' means... betcha they all say 'how fast something is going'.
; -- the corruption of government starts with its secrets. a truly free people keep no secrets. --
Black holes can be detected (in theory of course) by looking for the emissions they give off. The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission. It is these fissions at the edge that make a black hole appear to give off energy, and make it detectable.
That type of radiation is called Hawking Radiation (after Stephen Hawking, naturally). However, this isn't what lets us detect black holes, as Hawking Radiation is ridiculously faint. Black holes can be detected by the X-Rays that they "inadvertantly" produce. When matter is falling into a black hole it is accelerated, heated, and compressed to such a degree that it gives off large amounts of X-Rays. I believe the first black hole we detected (again, assuming black holes exist), was Cygnus X-1 (or cygnus something), and we detected it by the x-rays it gave off.
Another method of detecting black holes is to look for graviational lensing effects. Because black holes are so massive, they bend the fabric of space time. (Imagine a sheet suspended in the air. Place marbles on the sheet. The marbles make depressions on the sheet, like stars make "depressions" in space-time. A black hole is so heavy, it's like dropping something that is the size of a marble but with the weight of a bowling ball onto the sheet. The sheet bends A LOT, and it actually will have a hole where the singularity is.) Light travels in a straight line, so if space-time curves, light also curves with space-time. Gravitational lensing was proved during a solar eclipse. Astronomers observing the eclipse noted that they were able to see stars that should have been blocked by the eclipsed sun. The sun's gravitational field caused enough "lensing" so that stars directly behind the star could be seen to either side of the star. So, if we find something out in space that is causing a LARGE amount of gravitational lensing, but we can't see anything, there's a chance it's a black hole. At that point we normally observe it more to determine if it is or isn't a black hole.
"Black holes are so dense they create gravity so strong that even light cannot escape their surface, making them nearly impossible to see. Kormendy said the black hole at the center of the galaxy is not pulling in other stars.
r eat,great,great,great,grandkids teeth...
Even if it's not pulling in other stars yet, I'll bet it'l suck the fillings out of my great,great,great,great,great,great,great,great,g
Wonder why it's not eating stars yet, the density there should be high enough for some motion..
Dirty Pirate Hooker
In other words, shut up.
Burn Hollywood Burn
Try it again, Timothy. That's it.... Yes... Good boy! Good, good boy!
oh man, thats so bad it hurts. thats an intergallactic groaner
--
There are some people that if they don't know, you can't tell 'em.
IT's so dense that it could pass itself off as a Slashdot troll.
----
ADVENTURERS! - ANTIHERO FOR HIRE - CARDMASTER CONFLICT
So, even NOT counting on compression from the incredible amount of mass, you could fit 26 million stars the mass of the sun into the "relatively tiny space".
Given that the numbers match so closely, except for the decimal place, i suspect one of two things:
1) The article writer is amazed you can fit the volume of a marble into the volume of a basketball.
or
2) The article writer put the decimal in the wrong spot, and discovered you can put volume "V" into the space of volume "V"
I vote for option 3), 4), or a combination of the two:
3) The amount of space is "tiny" compared to the amount of space taken up by stars in the rest of the galaxy. Stars are seldom packed one against the other.
4) The writer is using copy from descriptions of smaller black holes. The even horizon's radius grows in linear proportion to a black hole's mass, if I remember correctly.
This means that volume grows far faster than mass. Black holes with the mass of a mountain are smaller than an atom; a black hole the mass of the sun have a radius of about 3 km. More massive black holes, however, have less density. In fact, if the universe is closed (i.e. returning to a "Big Crunch"), it would be the perfect example of a very sparse black hole - transplant a sufficiently large chunk of it to a reasonably flat space, and an observer outside of the transplanted chunk would see an event horizon surrounding it.
A singularity, which is the very centre of a black hole and in theory a point of infinite gravity, is (once again in theory) infinitely small. So we'd actually be talking about one heck of a small pinpoint here ;)
http://www.asnsw.com/articles/dbh0700.htm
The odd thing is- I would have expected the acceleration to which they were referring to be the normal force in all circular motion... Big massive stars going in a small circle really fast = a lot of something pullign them towards the middle...
It's not nearly impossible. It's totally impossible. The guy who wrote it has no clue. Black holes suck in everything, including light waves. That's why they are called black holes. You can only observe black hole's effect on other objects. That way you can figure out that there must be a black hole of certain mass at some location. Repeat: you cannot see black holes.
___
___
If you think big enough, you'll never have to do it.
you are close, but not right one.
there are different sizes of infinity, but you can't just figure out how large the size of infinity that you are dealing with by counting.
an example of this can be seen with the different sets of numbers.
for instance, take the whole numbers (ie anything that's 1 or greater that has no fractional part). there is an infinite amount of them. if you take just the whole numbers that are evenly divisible by 2, do you get a smaller size of infinity? no, you don't. its still the same size (to mathematicians).
now, look at the real numbers. these are the ones that can be represented in decimal form. (so 2.5, -9, 1/3, but not pi, or sqrt(2)) this set of numbers has a larger size of infinity than the whole numbers. why? well, for one, for any two whole numbers, there is an infinite amount of real numbers between them. for example between 1 and 2 you have 1.1, 1.11, 1.111, 1.1111... you get the idea.
i hope i got that right.
"Dying tickles!" -- Ralph Wiggum
I believe that black holes evaporate: the smaller the hole the faster the evaporation. This is a result of 'quantum tunnelling'.
Karma whoring, moi?
Elgon
I believe it was copy/pasted from his post to another Slashdot story. He's recycling. :)
The mass is equivalent to two million suns, the size, according to the article, IIRC, is approximately the orbit of mars.
-- the cake is a lie
The sun-to-moon distance refers to the event horizon only, not to the dimensions of the mass contained. If what we know about black holes is correct, then the mass is all concentrated at a singular point at the center. There isn't actually anything at the event horizon's surface.
Read what he fixed it up to read now...
If that's true, and gravitational forces remain the same, shouldn't things just stay normal? Like, pretend our star was massive enough to become a black hole: if it became one, we would continue to orbit that hole. To distant observers, it would appear that we were obiting nothing. Right?
This is something I read out of a physics book not too long ago... correct me if I'm wrong please. I'd like to know...
Mike.
--Ask a silly person, get a silly answer.
Black holes are so dense they create gravity so strong that even light cannot escape their surface, making them nearly impossible to see.
Nearly impossible to see... why didn't they call them gray holes?
www.rdex.net
Perhaps so, since "acceleration" could equally have described the stars' slowing down, or changing direction while maintaining speed.
This next song is very sad. Please clap along. -- Robin Zander
Black holes are not a vacuum, they are the opposite. They are similar to neutron stars in that they are very dense, only more so. The state of the matter is unknown, AFAIK, but it is certainly not atomic - i.e. atoms or neutrons. They can have size, but I don't see a way to measure the size - perhaps by the radiation that is emmitted. The surface you refer to is the event horizon.
Just like I've always said,
"This galaxy really does suck."
Aah, change is good. -- Rafiki
Yeah, but it ain't easy. -- Simba
'Centrifugal force' is a force defined from a non-Newtonian reference frame, and as such, is not a true force. A force can only be defined from within a Newtonian reference frame, so your implication that she is incorrect is correct. (Does that make sense?)
What your wife is actually feeling (aside from the bump) is her linear inertia taking her in a straight line while the car turns away from that line. So, she bumps into the window.
When she asks you what she is feeling ("I'm feeling something, so what is it, Mr. Smary-Pants?"), you can tell her that what people typically call 'centrifugal force' is actually the other side of 'centripetal force'. Centripetal force is the tension in the string when you swing a Yo-Yo over your head; centripetal force keeps an object traveling in a circle.
Try this, Newton's first law of motion says that it takes force to move something or change it's straight line motion at constant speed (in Newton's world being at rest and traveling with a constant velocity are the same thing, the first glimpse of relativity), and you are traveling in your car in a straight line, with constant speed. You turn the wheel and the car starts turning, which means that acceleration is being applied to the car to change it's velocity. This acceleration is called centripetal acceleration.
In conclusion, there is no centrifugal force, although it appears to be a force, but it is measured from the wrong reference.
Louis Wu
"Where do you want to go ...
Larry Niven predicted this in his Known Space stories ... he made it a reason for the puppeteers to leave the galaxy. Lousy puppeteers, with their two heads and their brain in their back ...
I dunno, wouldn't that cubic inch of 2-million sun black hole actually be more massive than the entire Earth?
So it would be more likely that the Earth would get "eaten" by that cubic inch. Then again, if that chunk of black hole is too small to maintain its integrity, it may just evaporate violently and blow everything in the immediately spacial environment to plasma...
It's not that black holes "suck" in everything; they are just a very compact and massive object, which therefore exerts a huge gravitational force on everything. Much of the gas near the event horizon of a black hole will get sucked in, and by mass there is much more gas than stars near the black hole. The dynamics and orbits of the nearby stars are affected by the black hole, but that doesn't mean they are sucked in. Supermassive black holes at the centers of galaxies rarely pull in another star (about every 10^5, 10^6 years or so). Remember that the Sun is about a million times more massive than the Earth, yet the Earth is not sucked into the Sun. The mass ratio between a star and the black hole is about the same.
-Legion
footnotes:
1. Not only wasn't this funny, but it wasn't original, either. For god's sake, don't mod it up.
2. It's late, I'm on graveyard shift, and I need caffeine.
3. Booze, too.
The rope accelerates and from you point of view 'spagettifies', but because of the relaitve differences in time à la Relativity you will never see it pass the event horizon. The closer it gets, the bigger the time differential so it appears from your point of view to approach the hole asymptotically. This could of course be total crap, but it's what I remember reading in some book or other with the word 'quantum' in the title. Elgon
I just thought of a cool experiment.
.NET infrastructure INSIDE a black hole to make the Internet REALLY safe...
Take a Windows 2000 server, link it up by some radio connection, and place it near the event horizon of a black hole.
The effect of time dialation would decrease the MTBF dramatically, with only a minor change in processing speed (slow down a Windoze server by a factor of 1E9 and I doubt anyone would notice).
[Unfortunately, there would still need to be a sysAdmin sleeping next to the server to handle the occaisional (every 10,000 years) crash, but then again, that's probably the best use of someone with an MCSE anyway.]
This dramatic improvement in reliability could be a "hole" new marketing angle for MS. Maybe we could put the entire
...we're going to live to see this piece of the galaxy rotate right in front of our eyes."
Anyone know when?
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What I find far more disturbing is that really long distances are now measured in football fields, as football seems to be more common than both kilometers and miles.
--
I dunno either....I was being hypothetical ;-)
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In case you're not kidding: In the same way that a pound of gold is smaller than a pound of feathers, a 2-million-sun black hole is much smaller than 2 million suns. It's dense. Actually, it's more-or-less infinitely dense, since a black hole forms a singularity, a one-dimensional object, a pin-point, like the article said. The thing that confused me was that they also said it was the size of the distance from the sun to mars. Did they mean the event horizon was that size? Seems small to me, not that I would know.
I could be wrong about this, but I'm pretty sure that M & M Mars is an American company. I think you had become accustomed to the export model, not the original, until you arrived in its homeland.
This next song is very sad. Please clap along. -- Robin Zander
it's the thickness.
and i always thought that stuff was caramel!
i will never trust a candy wrapper again
Let's see. For purposes of estimation, let's say the sun is 1,000,000 miles in diameter (it is smaller). Let's say the radius of Mars' orbit is 140,000,000 miles. The volume of a sphere is 4/3 r^3. So... In that sphere, 11,488,213 suns would fit at the same density... Even if we assume the article meant the diameter of the sphere was the same as the radius of Mars's orbit, we're still over 1,000,000 solar masses at current solar density. Not very much like a Black Hole at all...
What you say is true, but this isn't what the group mentioned in the article was doing. More germane, maybe, is that another way of "detecting" BHs, and actually quantifying how massive they are, is to look at the motions of objects around them -- if, eg, stars are moving very quickly, then the mass around which they orbit must be quite large. The technique described in the Nature article sorta, kinda, has to do with this, but the goal was (I think) to pinpoint position more than anything else. We were already pretty sure Sag A was a black hole.
Gravity doesn't work that way. It's only a function of mass (and space). Two objects of the same mass and the same vollume will produce the same distortion in the space-time continuum and will appear indistinguishable. It doesn't matter what goes on inside the black box (in this case, the black hole).
Oh yeah.
The part that's confusing me about this CNN report is the blandly put statement that "Black holes are so dense they create gravity so strong that even light cannot escape their surface, making them nearly impossible to see. Kormendy said the black hole at the center of the galaxy is not pulling in other stars." So, how come it's not pulling in stars? Is there some other force out there? My understanding of black holes was that they sucked in everything... even stars. Of course, according to this other article on CNN, that could be because of the winds... anyway, it seems like a cool discovery. Thalia
It is most likely that it doesn't accrete much matter (ie eat stars, gas, etc.) because it has already sucked in everything in its immediate neighborhood. Black holes warp space, causing everything within a certain radius (called the ISCO, or innermost stable circular orbit) to eventually plunge into the black hole. If you are outside the ISCO, then matter is pretty much safe from getting eaten, at least for a while. So, it is most likely that all sorts of stuff is whizzing around right outside the ISCO (and they get the mass by examining the speeds of those objects) but very little is right near the black hole.
Light does *not* travel in a straight line where matter exists because matter is a distortion of space-time. Light therefore travels in a *geodesic*.
Also, the matter falling into a black hole generally forms what is called an "accretion disk" which starts radiating like hell due to friction effects and the conversion of potential energy to black body radiation.
had an interesting article on the structure of the galactic center. An abstract of the article is here.
Lucky for us that couldn't happen, because it either a) couldn't form or b) would've lost so much mass that the pressure pushing outward would be small enough to be contained. Afaik the only way I know to destroy a black hole is to evaporate it completely with the Hawking radiation coming out of it.
Ewige Blumenkraft.
umm i thought andromeda was so small it was boredeline galaxy/very large star cluster... that little fact was in one of the Rama Revealed series by arthur c clarke and gentree lee (past director of science and analyasis at NASA), looking at the last book in the series, it's not in there, maybe one of the other 2 by this duo? sombody want to back me up? or am i making this up? anyways, it said that eventually andromeda is quite a bit smaller than our galaxy, and in another 265 million years or so they're supposed to collide, and things'll get really screwy, kinda like two whirlpools colliding, the circular motion is for the most part destroyed. anybody care to comment?
moox. for a new generation.
Perhaps what you were trying to say was "very big"?
yeay! and i was beginning to think my first 6 weeks of physics 101 honors wasn't amounting to anything....this string of posts makes sense
moox. for a new generation.
is that "nougascope" is now my favorite word of all time. I think I laughed myself retarded on that one.
According to the West Hawaii Today (local morning newspaper for the Big Island of Hawaii - where the Keck is housed, and known locally as the West Hawaii Yesterday ) 4 years ago the black hole had orbiting stars traveling at less than 2,000,000 miles an hour. Today the same stars are clocked in excess of 3,000,000 mph. Unless I'm wrong, that's a change from 1/5th c to nearly 1/3 c in 4 years. As I understand it, an object's mass increases as it approaches c. If that's correct, wouldn't there be a chance that a star in a decaying spiral orbit around a bh could be whipped into enough speed that it's mass could hit the critical point and it could collapse on itself to form another black hole? Then what happens if it's orbital widens and its speed decreases? Could the new black hole decay into a neutron star? Or if the orbit stabilizes - could you end up with a binary black hole configuration? Enquiring minds want to know...
Thank you, mister david duncan scott, for brightening up my day. Won't someone mod the parent up, dammit? That's how comedy is done.
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Slashdot: News For Zealots. Stuff That's Hypocritical.
Another black hole article? You really want to see goatse.cx links florish!
"We can't all, and some of us don't." -- Eeyore
i'm glad someone else noticed it too, i was about to go dig up the post myself and check.
/. article regarding black holes, and the sad part is that all the same corrections we see here were posted to his last attempt, and he didnt even bother to revise his knowingly bad post before reposting it.
it was cut and paste from the last
not even good karma whoreing.
If electromagnetic energy can't escape a black hole, what can? I had an odd thought -- gravity. Would it be possible to devise some sort of complicated machinery to answer, say, a yes/no question about life inside the event horizon, and by way of an answer produce some sort of gravitational "ripple"(ie produce some sort of critical mass/density)? If we can get gravity out of a black hole, there's hope that we could eventually get some answers about the nature of the beast.
Visit the
It took them this long to find that little hole in the bottom of my toilet? Blargen?
The Voices cannot decide on whose base belongs to whom.
Okay, according to the article, it says that the mass of the black hole is approximately 2.6 million suns in a space smaller than the distance from the sun to the moon. Now the mass of the sun is approximately 2^30 kg, and the distance from the sun to mars is approximately 1.5^11m...
Quick Calculations...
Okay, that's approximately 370 kg/cubic meter. Funny, I figure that a black hole would be more dense than that. I think somebody is making a mistake somewhere. Hopefully it isn't me.
Well if you deem it important to develop superlightspeed flight in order to save mankind/our replacements, then you would acknowledge a much more pressing need to make a lightsaber. :)
Devil Ducky
Devil Ducky
MY peers would get out of jury duty.
Hi!
Illiterate people do not read slashdot, do they?
Just another coder...
I remember reading some articles a while back that talked about how the universe was still expanding (from the big bang) - but how eventually when the expansion halted - the blackholes would slowly over time end up being the cause of its collapse. Though if there is an especially large one at the center of our galaxy.... it kinda makes you wonder, doesn't it? Gam
I love idealists not because I am one, but because they make life bearable for pragmatists such as myself.
When the world ends, we'll be burnin' one
-- Dave Matthews Band
The Schwarzchild Radius is the radius that if a mass is compressed to within, the escape velocity exceeds the speed of light. The Event Horizon is the border between the region where an observer can 'observe' 'events' occuring near a black hole and where the observer can no longer 'observe' 'events'. Current theories suggest that these two only coincide for a non-rotating black hole as if the black hole is rotating, the space around the black hole is dragged along with it (Frame dragging) and the Event Horizon decreases in size. However, the Event Horizon cannot ever reach a size of zero (exposing the Naked Singularity) as that would mean that the Black Hole would have an angular velocity equivalent to an energy of infinity!
What'd they think they'd find there? A tamale? Mmmmm, tamales.
:wq
How massive is this blackhole compared to others? Is this impressive in any way besides that it's neat that they were able to 'prove' that there's a blackhole at the center of our galaxy?
In the same way that a pound of gold is smaller than a pound of feathers, a 2-million-sun black hole is much smaller than 2 million suns.
What's even more interesting is that an ounce of gold is actually heavier than an ounce of feathers.
Gold is divided into Troy ounces, and there are 12 Troy ounces in a pound. As a result, 1/12 of a pound is a Troy ounce, being heavier than 1/16 of a pound, an ounce.
Totally off-topic, but still vaguely interesting.
-Waldo
So is the event horizon is the "great barrier" that they talked about in Star Trek V?
What would have been funny is if you'd somehow made a connection between grits, black holes and mrs. Portman that made some attempt at vernal coherence, while yet maintaining literal impossiblity. Let me try.
If my pants were in a black hole, Natalie Portman wouldn't even have to pour hot grits in them... they'd eventually end up there all by themselves.
An extension of this logic leads me to conclude that eventually, millions of billions of years into the future, I'll end up getting into Natalie Portman's pants.
"Beware he who would deny you access to information, for in his heart he deems himself your master."
The black hole is not more then million suns in size, but *MASS*. That is what makes a black hole: an almost infinite mass in a very small (relatively speaking) radius.
--weenie NT4 user: bite me!
--weenie NT4 user: bite me!
"Computers are nothing but a perfect illusion of order" -- Iggy Pop
Between this and the eventual extinction of our sun we better get to work on those faster then light engines sooner rather than later if we plan to save whatever it is humanity is going to evolve into over the next few billion years!
Any where in Space, virtual particles exist. These are pair of particles that are oppositesin all but mass and are created and annihilate each other. Occasionally, one partner is pulled into a black hole. If the other partner escapes, then that particle is promoted to a REAL particle and is said to be produced through Hawking Radiation. Personally, I think that all these virtual particles have a significant effect on the ?U?niverse and could well be the explanation for Dark Matter. Occam's Razor - The simplest explanation is usually the correct one.
Okay, nice article, interesting stuff. But here's something I noticed:
"images of three stars to measure their acceleration -- or how fast the stars were speeding up--" [emphasis mine]
Was it really necessary to define acceleration? Are people in general really this illiterate?
Zipwow
I don't know which is more depressing, that 2/3 didn't care enough to vote, or that 1/2 of those that did are crazy.
I personally thought everyone already knew there was a black hole at the center of the galaxy.
But this brings up new questions in my mind...
Since the galaxy spins as a spiral on a single plane, does the black hole spin with us? If so, it's event horizon is largest on the plane of the galaxy, and, if spinning fast enough, nonexistant at it's poles. But if the black hole spins, doesn't the singularity have to be a torus (donut for the laymen)? And if it is a torus, isn't it possible that the inner singularity could be bridging a gateway to another part of the universe, or even another universe?
Or does the black hole not spin, and is that why the center of the galaxy have that huge bulge, it being the demarcation of the event horizon?
Even more interesting, is all the stellar material, including us already within the event horizon? Perhaps that is the only reason such galaxies exist at all, as feed for super massive black holes. After all, we have never found free ranging planets, just sorta floating aimlessly in deep space....
-supruzr
http://cha.c2032.net
A joint team of network specialists, consisting of employees from Cisco Systems, Hewlett-Packard, 3Com and others have located an immensive Troll Hole on the Internet, centered directly on the popular weblog Slashdot. While the presences of the hole has long been suspected, today's announcement has confirmed its status as the largest Troll Hole on the Internet.
Experts say the Slashdot Troll Hole has been continually drawing hundreds of trolls to the site for over three years. "It seems to present an incredible attractive force to individuals with an abundance of spare time," explained Michael Czekjum of the Internet Engineering Task Force. "Once drawn, they find themselves compelled to inundate comments with disguised obscene hyperlinks, single-minded knee-jerk insulting replies and vacuous first post attempts."
While today's pinpointing of the hole represents a great triumph, officials stress there is still much to learn. Early analysis seems to suggest it is expanding. Datapoints from Slashdot's founding in late 1997 show an almost complete lack of trolls. Since then, their numbers have expanded at a geometric rate. The types of individuals being attracted is also being studied. "While traditional text-based trolls are still in the majority, the past six months have seen a great increase in graphical trolls, using primitive ASCII representations," wrote Ari T'teyel of Sun Microsystems in a paper published last week. "In addition, the hole's effect on other individuals, such as karma whores, is as yet unknown."
The Troll Hole draws in
And no, people aren't that fuckin' stupid. But reporters are.
It's rare that you're presented with a knob whose only two positions are Make History and Flee Your Glorious Destiny.
You're right about not changing its effect on distant orbiting bodies.
You're wrong about the mechanism of its formation, though. The way it works is, over its lifetime, the star forms heavier and heavier elements through solar fusion in its core, giving off thermal energy that keeps the star from collapsing. It runs into trouble when it finally works its way up to iron, because you can't derive any energy from fusing iron atoms -- to create any elements heavier than iron actually requires a net input of energy. So, once there's no energy left to be had from fusion, the star can't keep itself from collapsing any longer, and it collapses.
If it's less than about 2.8 solar masses, then it collapses into a neutron star (and most likely causing a super nova in the process). If it's heavier, then the neutron-neutron forces are insufficient to oppose gravity, and it collapses further, into a black hole.
(Sorry for the nit-pick, but I am a recovering Physics Major.) Near the event horizon of a black hole paired particles of matter and anti-matter are being created. these pairs will circle each other for a bit and then destroy each other. Sometimes these particles will have one of their partners sucked into the black hole. Leaving the surviving particle free to wander off into space.
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Man, me and the Milky Way are so simalar.
Just this week, Doctors found a black hole at the center of my ass.
Linux - Because Mommy taught me to Share.
I read about this in a newspaper already. Remember those? A newspaper is that thing you have to unfold to read... those things that never used to get their news to me before /. could...
I don't know what to do! I may have to go to ZDNet or do something equally dumb.
Devil Ducky
Devil Ducky
MY peers would get out of jury duty.
FAQ.
"event horizon) of the black hole (crossing this line means you never come back" Actually, the event horizon is the point that LIGHT crosses and never comes back. I have a hunch the point that a human in a realistic space craft would have this problem at a much further distance, as that person/spacecraft would have quite a bit more mass than those photons. I.E. Mankind's event horizon happens much further out than light's....(I think, anyways)
mas cerveza, por favor politically incorrect stu
Good thing it's not an active black hole, eh?
Erm, I don't know much about Dyson Spheres, except that they completely contain the energy from the star that they surround, but wouldn't a Dyson Sphere look almost identical to a black hole from a vast distance?
Most chocolate in America is wose than, well, just about anywhere else.
I gotta say though, at least they don't have deep fried Mars bars like you Brits...
It's not pulling in the other stars because the stars still have plenty of momentum from the Big Bang. Eventually, that'll change. It's kinda like how 'constant velocity' actually means 'just enough acceleration to offset drag, gravity, and every other force acting on the body in motion' That'd be my theory. It's just as valid as any scientist's theory, because when you get right down to it, we're all just guessing. :-)
Vintage computer games and RPG books available. Email me if you're interested.
"Astronomers Find Black Hole With Milky Way Center"
Maybe I've been working too hard
--Ty
Well here we are again. Anyways, if you were sucked into a black hole what would happen? Black holes have immense gravity. As a "matter" of fact the mass of them is so high that the gravity is practically immeasurable. Now, with gravity comes time, as clearly shown in our favorit Einsteinian theory. Yup, the theory of relativity. Now if you all studied and di your homework(did you) then you would know that TIME IS RELATIVE! As a matter of fact time is pretty arbitrary by humans standards, but that is a completely different story. Anyways, you get sucked into a black hole. Since the gravity IS higher(duh!) then time would slow for you. Things outside would appear to mvoe faster, if there was anything to look at then you would see things going REALLY fast. Since the time is relative you could see the whole universe ending, only because we have not determined how long black holes exist. This poses another question. If the time is slowed down immensely, then black holes must exist long enough so that the universe ends, or the time dialation is not as heavy as theorized and you get sucked in well before the end of the universe. It is also said that you get "stretched" when you go into a black hole because of the difference in gravity between the event horizon and the lip. Well, at a certain point time and space theories as of now are thrown out of the water and well, your fucked. The point of singularity breaks down everything we know about the universe. You would probably also be torn apart atom by atom. The time change would also appear as if you were moving slow to the outside world. This is truly fucked up.
Well, just think of the suntan you could get.
Here is the technical article from the Los Alamos preprint server.
Lewinsky! It goes right to the center of things and sucks like a demon. Its emissions from its job of sucking are widely discussed and clearly visible on the fabric of the dress, er, I mean spacetime...
The velocity, or speed of the stars [...] , had been roughly measured, but the UCLA team took it a step further by using the infrared images of three stars to measure their acceleration -- or how fast the stars were speeding up
;)
Thanks for the definitions. It really helped out those of us who have never owned, driven, or ridden in an automobile before!
--
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Mod up a post Rob doesn't like and you'll never mod again
How does this affect Star Trek 5?
After all, didn't they go to the center of the galaxy to find God?
-Vel
the milky way "technically" has a milk chocolate core with chewy nougat and peanuts.
scientists have triangulated it's ooey gooey goodness using several rats and a nougascope.
FluX
After 16 years, MTV has finally completed its deevolution into the shiny things network
"It is seldom that liberty of any kind is lost all at once." -David Hume
Some frekin idiot typed cat center.galaxy.txt | dev/null
i saw that once, during an acid trip. i always wondered what that was.
total Ego loss and sucked into a black hole. it's a hell of a way to go.
- j
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CitizenC
Imagine you're suspended on a really long (and very strong) rope, some distance above the event horizon of a black hole.
You get another really long rope and dangle it towards the surface, and it passes the horizon, so one part of the rope is beyond it.
Now, you're still holding on to it, and we're assuming that your spacecraft has sufficient velocity to be able to orbit above the event horizon.
What happens?
Also, some guy said before that in a black hole "mathematics goes crazy". Got news for you dude. Nature doesn't care about mathematics.
--
NO TOUCH MONKEY!
Once again, the Slashdot moderators have messed up the facts again. As stated (url: http://www.mars.com/facts.asp?op=milkyway ) here, the center of the MilkyWay is not a black hole.
THE FACTS: The MilkyWay is often consumed into what may be considered a black hole. However, if this were indeed a black hole, the black hole would not appear to gain mass.
For instance, one 40-year-old male who had taken part in the study, funded by the United States Food and Drug Administration. Where a black hole would compress the matter to a mere geometric point, the black hole referred to in the study actually appeared to expand when the chocolate-malt product was consumed. When enough MilkyWay are regularly consumed, the subject will experience an increased capacity to eat; the capacity increasing with each sitting.
More concerned are the exercise professionals. "Those who consume too much of the product will put personal trainers out of business," suggests Jed Smith, Editor, American Human Body Focus. "People," he adds, "will no longer see a need to keep their bodies fit. Consumers are putting millions of professional trainers at risk of losing their job."
Cynthia Lamon, of the Maximum Performance Association of Athletic trainers (MPAA), has vowed to encourage US Congressional support of the Diet Manipulation Consumption Act (DMCA), currently a bill which was introduced and passed by the House. Pending the approval of the Senate, the President would then be asked for his approval.
The DMCA, if passed, require the millions who consume the MilkyWay chocolate-malt bar to accept the planned licensing agreement displayed on the outside of the packaging. Additionally, if the licensing provisions state so, those who wish to consume the sacred bar will be required to slice the bars only with Mars-KitchenWare utensils. Such sets of tools are alleged to offer technological advantages over traditional fork and knife sets.
The food items will also contain Crafted Structured Starch (CSS) technology, which would make splitting the food fibers impossible without the KitchenWare tools, which are able to unbind the additives which ensure the foods are sanitized.
"the black hole at the center of the galaxy is not pulling in other stars. " Why isn't it? And if it is, what did he mean?
A side note: The event horizon of such a massive black hole would be quite a distance from the surface itself. This would enable us to send a probe literally inches from the Schwarzschild Radii, (because of the cubes and squares and stuff).
Yeah, yeah, flame away.
You quitting proves that the karma kap worked. The most annoying of the whores shut up. --CmdrTaco
ah, so that's where all the thoughtful /. posts are going...
-=tonyt=-
...oh, great. Even though most Slashdotters are smarter than this, people are probably going to start panicking, if only for a brief time.
The Earth is in no danger whatsoever of being sucked into this black hole. The reason: the black hold has a mass of roughly 26 million suns. That's a finite mass, even if it is of near-infinite density. Expand that into a star with that mass. This star has the same mass as the black hole, and therefore has the same gravitational pull as the black hole. No more, no less.
So then why don't we get sucked into the star? Because gravitational pull is inversely proportional to the square of the distance, not from the surface of an object, but the center of gravity of the object. When the star collapses into the black hole, its center of gravity stays in about the same spot.
What this means is that, once you're further away from the black hole than the radius of the original star, the black hold has no more gravitational pull on you than the original star did. It's when you go inside that radius that the hole's pull gets really strong. So, if our sun were to collapse into a black hole at this very instant (which it can't do, but let's say it does for the sake of argument), we would be in no more danger of falling into the black hole than we were of falling into the sun. We'd be screwed anyway, due to the loss of solar energy and the X-ray bombardment, but we wouldn't fall into the black hole.
This is important, because studies have shown that the solar system is moving further away from the center of the Milky Way, not closer to it. Therefore, the Earth is perfectly safe from this new "threat."
IANAP - I Am Not A Physicist.
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Now if only they could find the black hole in my son's room that keeps moving his stuff around on the floor, slowly attracting it under the bed.
Burn Hollywood Burn
Hmm... sounds like a big black hole. Seems like it would be fun to visit... now they need to work on WARP drives.
Seriously, there needs to be more money spent on the space program. It is one of the truely "neat" things humans do. Besides, we have to prepare to one day move off this rock.
Peace out.
... that just sucks.