Black Holes

SoundDust

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Mar 17, 2002
Messages
1,678
Reaction score
18
Points
69
Black Hole in the Galaxy

Full Story

Astronomers have spied a black hole that is speeding through our galaxy dragging and feeding on an old star as it goes.
The observation is reported by scientists using the Hubble Space Telescope (HST).

Although the black hole is headed roughly in our direction, it is at a "safe" distance, 6,000 to 9,000 light-years away, in the direction of the constellation Scorpius.

The object's velocity has been measured at more than 400,000 kilometres per hour, good evidence say the astronomers that it is the accelerated "debris" of a stellar explosion, or supernova.
:eek!!!!:
 

rynner2

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Aug 7, 2001
Messages
55,242
Reaction score
9,039
Points
284
Christian Science monitor (Full article)

(I resisted the urge to call this thread "Artificial Black Hole Escapes Laboratory, Eats Chicago"! :D )

After a longish intro, we get this:
In the 1970's, the well-known physicist Stephen Hawking proposed a way in which black holes radiate energy away, eventually "evaporating" completely. Over time, the black hole gradually leaks away all its energy and disappears in a final burst of radiation.

The final death throes of a black hole, scientists suspect, might be very illuminating indeed. Exactly how a black hole dies and what sort of information is carried in the Hawking radiation could tell us quite a bit about what the center of a black hole is really like.

But there are two major problems with observing the last gasp of a black hole. For one thing, the nearest black holes we know of are light-years away, making accurate measurements of Hawking Radiation nearly impossible. Secondly, black holes take a huge amount of time to evaporate, the time being proportional to their mass. Even relatively small stellar black holes would take longer than the current age of the universe to dissipate, and the monster black holes in the middle of galaxies may be the last things to exist in our universe, taking ten thousand trillion trillion trillion trillion trillion trillion trillion trillion years to die away (sorry, I just have to do that sometimes. That is the actual estimate of how long a massive black hole will last).

So what do you do if you can't wait around that long? For the best chance to observe Hawking Radiation and evaporation, you'd want a black hole that was much closer than naturally occurring black holes, and much less massive. It's a common misconception that you have to have a huge amount of mass to create a black hole. Any amount of mass will do, as long as you cram it into a sufficiently small space. A super-massive black hole with the mass of a billion Suns might be the size of our Solar System, but the Earth could be a black hole too if you packed it into the volume of a marble. Even a person will do, although you'd have to cram them into the space occupied by a single electron.

This line of reasoning has led scientists to the inevitable: If we really want to observe black holes and how they radiate, we'll have to whip them up in our own laboratories. And that's exactly what we are on the threshold of being able to do. Now, there is no kind of technology with the ability to physically crush matter to black hole densities, but there's an easy away around that. Einstein showed us that matter and energy are equivalent, so you can also make a black hole by pushing a huge amount of energy into a tiny volume. For those kinds of experiments, there's an obvious choice: particle accelerators. And the next generation is just about to be unveiled.

Amazingly, scientists are becoming increasingly confident that they will be able to create black holes on demand, in quantity, using the new atom-smashers due to come online in the next five years. Some estimates suggest that the new Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN -the acronym is in French) will be able to create an average of one black hole each second. LHC will bombard protons and antiprotons together with such a force that the collision will create temperatures and energy densities not seen since the first trillionth of a second after the Big Bang. This should be enough to pop off numerous tiny black holes, with masses of just a few hundred protons. Black holes of this size will evaporate almost instantly, their existence detectable only by dying bursts of Hawking radiation.

What exactly are scientist looking for in the Hawking radiation? For one thing, it's a big mystery whether Hawking radiation contains any information about the particles that formed the black hole in the first place, or fell in later. Those particles had charge, spin, and other fundamental characteristics that may not have been erased by the black hole. Also, the exact manner in which a black hole dies may give us a view into higher dimensions in space. The most recent theories about the Big Bang and the earliest moments of our universe suggest that there were more than the four (three of space, one of time) we normally experience.

For some reason, the other dimensions didn't expand with our four, and remained "rolled up" at very small scales. These extra dimensions might still be important, and directly felt, in regions right around the central singularity of a black hole. In fact, these higher dimensions might solve the mystery of what a singularity really is. Instead of truly being an infinitively small and dense point, there might suddenly be a whole lot more room provided by extra dimensions that only act on tiny scales. Scientists already have ideas about how these dimensions would affect the temperature and intensity of Hawking radiation. Now all we have to do is power up the acclerator and put those theories to the test.

"But wait", I hear you say, "Has anyone considered that creating artificial black holes might not be the best idea?" The idea of creating black holes in the laboratory has to give one pause. I mean, how can anyone resist the urge to imagine future headlines like "Artificial Black Hole Escapes Laboratory, Eats Chicago" or some such thing? In reality, there is no risk posed by creating artificial black holes, at least not in the manner planned with the LHC. The black holes produced at CERN will be millions of times smaller than the nucleus of an atom; too small to swallow much of anything. And they'll only live for a tiny fraction of a second, too short a time to swallow anything around them even if they wanted to.

If it makes you feel any more comfortable, we're pretty sure that if the LHC can produce black holes, then so can cosmic rays, high-energy particles that smash into our atmosphere every day. There are probably a few tiny black holes forming and dying far above you right now. So I think we should all relax, fire up the Large Hadron Collider, and get ready for a view of the universe that we've never seen before.
 
A

Anonymous

Guest
Fascinating! Also somewhat worrying. Hey, perhaps this solves the Fermi Paradox. All those other civilizations got to the point where they could create ultra-high-energy particle accelerators. They turned them on and promptly created a quantum black hole, which sank, by grativational attraction, to the centre of their planet, and promptly swallowed it. They didn't destroy themselves with nuclear weapons after all.
Of course, I got the point about the life of a black hole being directly proportional to its mass. The life of one of these tinsy-winsy ones would probably be measured in nanoseconds. But what if one manages to reach out and swallow a couple of quarks or something? What sort of receptacle could contain a black hole? Possibly a magnetic bottle or something, but nothing made of hadronic matter obviously.
Still, look on the bright side. If the earth gets eaten, (i) my credit card debt is wiped out at a stroke, and (ii) I wouldn't have to go to the dentist on Wednesday.
There are a couple of good SF stories by Larry Niven on this subject. One of them is called The Borderland of Sol. The other one, whose title escapes me right now, concerns the discovery of an alien artefact on Mars, which contains a quantum black hole in a stasis field. The scientists working on it accidentally release the thing, whereupon it sinks to the centre of Mars and quickly devours it. Whether that helped it to work, rest and play is not stated however.
As for the time stated in the article for a galactic black hole to evaporate, those who frequently travel on Virgin Trains will be familiar with the timescale at least.

Big Bill Robinson
 
A

Anonymous

Guest
Why can't they piss off and do this in a facility in space or something? I don't want to get sucked in a black hole. :(
 

NilesCalder

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Aug 20, 2001
Messages
1,817
Reaction score
16
Points
67
I'll lend you a copy of David Brin's novel "Earth" and you can find out, IJ. Brin suggests that we wouldn't know that a Black Hole was eating the Earth until just a few moments before the end...
 
A

Anonymous

Guest
Inverurie Jones said:
Why can't they piss off and do this in a facility in space or something? I don't want to get sucked in a black hole. :(
Don't worry, just as we all disappear down their artificial cosmic plughole, they'll all be sitting round the Newsnight studio on their arses attempting to convince us that it's all a just an illusion. ;)
 
A

Anonymous

Guest
You see, small black holes are counter intuitive- - a thousand tonne black hole, dropped into a swimming pool of water, wouldn't suck very much water in-
it would be too busy evaporating- it would produce 1000 tonnes equivalent of energy.
ie, more than millions of kilotonnes of TNT...

and it would only last 220 seconds
so it would be like a very extended H-bomb.
Nothing would get sucked in against such radiation pressure.

The quantum black holes produced by these experiments would be much smaller and last a shorter time.
To get a black hole which had a net gain of matter falling in over Hawking radiation, it would have to be nearer a hundred billion tonnes.
cite
 
A

Anonymous

Guest
energy

nice place to chuck all humaities rubbish in return for nice clean energy.
nice!
 
A

Anonymous

Guest
Originally posted by Eburacum45
The quantum black holes produced by these experiments would be much smaller and last a shorter time.
--------------------------------------------------------------------------------
Originally posted by Androman
...Probably.
--------------------------------------------------------------------------------
No- like I said before, little black holes are harmless. It is the strangelets that we have to worry about.
 

tzb57r

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
May 15, 2002
Messages
137
Reaction score
4
Points
49
To get a black hole which had a net gain of matter falling in over Hawking radiation, it would have to be nearer a hundred billion tonnes.


Hawking radiation is a theory only confirmed by inputting the Hawking theory equations into a computer that strangely enough comes back with the answer that the Hawking equations are consistent. No one has ever detected Hawking radiation and had the results published in a peer-reviewed journal that I am aware of. If Charles Fort teaches nothing else to the scientific community it is that there is a vast difference between a right-good-theory and something you can see with your own eyes/detectors. A lot of theories have become fact by repetition and broad publication without a scrap of evidence.

I really would like to apologise to professor Hawking, but as they say “show me the money”.
 
A

Anonymous

Guest
Black holes have never been observed directly-
there are several theoretical alternatives,not involving singularities or event horizons.

Nevertheless the theory types are having fun with the calculations-
they are constructing a marvellous edifice with it in fact, and it would be entertaining to see it all blown away.

This wouldn't however a blow to science or the scientific method at all, quite the reverse.
 
A

Anonymous

Guest
It is a common misconception that black holes are a highly concentrated form of matter generating a huge gravitional field. Not quite true. Black holes bend the fabric of space time to the point where there is actualy a hole in time and space. The four dementions of space and time become one. This is where the term singularity comes from. Single refering to all of the four dementions becoming one. Two dimentional planes are easy to visualise single dimentional planes are not. The correct definition of a singularity is pure energy.
 
A

Anonymous

Guest
black hole

if a singularity is pure energy how is it black?
just what is pure energy ? what kind of energy is pure ?
i realise it is a result of the gravity that no light escapes.
but surely all galaxys are black hole shaped
so are we all living in, and are part of,a black hole?
 

tzb57r

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
May 15, 2002
Messages
137
Reaction score
4
Points
49
I think that Black holes are just the folding of space time. The fact that Black holes have a measurable mass can be thought of as the gradient of the space time curvature at a set distance when compared with other objects, so 0.1 light years from a blue giant will produce a certain gravitational attraction that corresponds to a space-time curvature of a certain gradient. If a black hole produced a similar curvature at a set distance you can say that the mass is identical. Mass and the ability to deform space-time is equivalent. Whether the mass is caused by matter or a tear/hole/singularity in space-time is, from a practical point of view, immaterial.

A balck hole is black only at and beyond the event horizon. Sigularities are rarely naked i.e. without an event horizon.

A black hole is the cause of gravitational potential energy for objects outside the event horizon, but I am unclear as to what type of energy the singularity is.
 
A

Anonymous

Guest
i understand the theory of mass/gravity/space time
just because black holes attract matter dosnt make them heavy?
couldnt they be of a negative matter that draws objects towards them electromagnetily

the singularity is negative energy?or anti matter?
:confused:
 

jarmaniac

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Aug 18, 2003
Messages
118
Reaction score
3
Points
49
Originally posted by prometheus
The correct definition of a singularity is pure energy.


Or, as Mr Spock would put it: "Pure thott."
:)
 
A

Anonymous

Guest
Re: black hole

Tin Finger said:
if a singularity is pure energy how is it black?
just what is pure energy ? what kind of energy is pure ?
i realise it is a result of the gravity that no light escapes.
but surely all galaxys are black hole shaped
so are we all living in, and are part of,a black hole?
1) Because no light can escape it. Blackness is the absence of light. Anything made of energy that draw in all energy would definitely be black, which is what our eyes tell our brain when there is absolutely nothing there.

2) Pure enrgy as in composed only of energy.
 

Yithian

Parish Watch
Staff member
Joined
Oct 29, 2002
Messages
29,371
Reaction score
34,571
Points
309
Location
East of Suez
The final death throes of a black hole, scientists suspect, might be very illuminating indeed.
quite the opposite i'd imagine....
 
A

Anonymous

Guest
The Yithian said:
quite the opposite i'd imagine....
I think it's because when a BH dies, they think it releases all it's energy. Don't wanna be in the same galaxy as that thing :p
 

Yithian

Parish Watch
Staff member
Joined
Oct 29, 2002
Messages
29,371
Reaction score
34,571
Points
309
Location
East of Suez
rigmarole said:
I think it's because when a BH dies, they think it releases all it's energy. Don't wanna be in the same galaxy as that thing :p
:D So 'illuminating' that your eyes melt - great! I'll definitely be watching out for that then!

In seriousness, does the theory that they release energy in death have any empirical support or is it pure speculation? This isn't my subject. Do astronomers suspect that any black holes have actually dies since the start of the universe? I was led to believe that their existence is only inferred from their effects on their locale.
 
A

Anonymous

Guest
The Yithian said:
:D So 'illuminating' that your eyes melt - great! I'll definitely be watching out for that then!

In seriousness, does the theory that they release energy in death have any empirical support or is it pure speculation? This isn't my subject. Do astronomers suspect that any black holes have actually dies since the start of the universe? I was led to believe that their existence is only inferred from their effects on their locale.
It's all theory. However, it sits well with Conservation of Energy. When the Black Hole dies, the energy can't just disappear, it has to go somewhere.

Of course, as someonr hrre once said, the easiest way to piss off Stephen Hawking is to ask him to prove one of his theories, so who knows...
 
A

Anonymous

Guest
Re: black hole

Tin Finger said:
if a singularity is pure energy how is it black?
just what is pure energy ? what kind of energy is pure ?
i realise it is a result of the gravity that no light escapes.
but surely all galaxys are black hole shaped
so are we all living in, and are part of,a black hole?
Black holes are black because they are holes in the timespace continume. They apear to be massive gravitional fields. The force of attraction is so strong that the exceleration of a body can be defined as MC2. Light only travels at 300 000m/s this is not fast enough to escape this masive force of attraction. Light does not come from black holes as not even light can escape this massive force.

Time space matter and light are all forms of energy. Pure energy is where all three become one. We find this hard to visualize as our minds and realities are bound by the laws of time and space. Inside black holes there is no time or space. I believe the corect definition of energy is consiousness.

We are living in a inverted singularity. Before this inversion(big bang) There was no time or space. This concept of No-thing brings us back to God. When one is dealing with a singularity we enter a place that is far removed from our world and enter a place much closer to the creator.

black holes are holes in reality with out such holes we would not be here. There is a very large black hole at the centre of our galixy. With out it we would be just hydrogen floating in the void.

In the understanding of creation there is a place where thought and complexity break down. At this mental event horizon only non thought may pass. Do not think feel!
 

Jerry_B

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Apr 15, 2002
Messages
8,052
Reaction score
50
Points
129
rigmarole said:
It's all theory. However, it sits well with Conservation of Energy. When the Black Hole dies, the energy can't just disappear, it has to go somewhere.
This is one thing that bugs me about black holes - the fact that we don't appear to have found any evidence of those that have 'finished'. I assume that they can only absorb a finite amount before the process stops...? If not, why not?
 
A

Anonymous

Guest
This is all a bit involved, so I'll see if I can go through it without dropping any clangers.
A tiny black hole would evaporate in a fraction of a second; any mass it contained would be liberated in the form of energy.
The smallest size possible would be a black hole 1 planck length in diameter (all diameters are across the event horizon; the singularity is assumed to be a dimensionless point).

if you have a slightly larger one it will still be evaporating, but it will be much smaller than an atom, and the energy coming out would push infalling matter away, so nothing could get in anyway.
A 1000 tonne black hole would last 200 seconds, give off 1000 tonnes worth of pure energy, is smaller than a proton and look a million H-bombs going off.
As Black holes get bigger, the evaporation gets slower, untill you have one the mass of a medium sized asteroid, which is sucking stuff in as fast as it is irradiating energy.
This is about the size of a golf ball.

None of the above black holes have ever been seen, but it is possible the smallest ones may be manufactured one day, but these smallest ones will last just a tiny fraction of a second.

Bigger than that, they are stable, and actually start to increase in size as they suck more mass and energy in from ordinary space;

most of the black holes we know about are EITHER formed from collapsing stars, and are about 3x as massive as the Sun,
but is only ten miles across the event horizon;
there are several objects in the sky which can best be explained as being black holes of this size;
OR formed in the early universe; each one weighs millions or billions of times the mass of the sun, and is perhaps fifteen million kilometers across- the diameter of a large star.

You could fly into a galactic black hole and hardly notice you had crossed the event horizon; but you would never get out again.
 

Jerry_B

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Apr 15, 2002
Messages
8,052
Reaction score
50
Points
129
But do even these larger black holes eventually run out of whatever it takes to keep them going and stop? If so, how would we be able to observe a spent black hole?
 
A

Anonymous

Guest
Any stable black hole will be absorbing more energy from starlight, sunlight or the Cosmic Microwave background radiation to balance the Hawking radiation, and so would continue growing very slowly.
Having said that, big black holes hardly radiate at all, so are fantastically close to absolute blackness-
if no mass is nearby to fall in and emit energy as it does so, you couldn't see them at all.

You would have to look for the optically distorted images of stars round the edge-
like this;
(the black hole is a sphere, so would look like this from every angle)
 

Jerry_B

Gone But Not Forgotten
(ACCOUNT RETIRED)
Joined
Apr 15, 2002
Messages
8,052
Reaction score
50
Points
129
So if there's no matter nearby to be drawn in, or not enough to 'fuel' it , do they run out of the necessary 'fuel' to carry on existing? Can a large black hole theoretically cease to exist if it lacks the necessary 'fuel'?
 
Top