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Scientists Discover Teeny Tiny Black Hole
Posted by
Zonk
on Wed Apr 02, 2008 06:04 PM
from the for-relative-terms-of-teeny-and-tiny dept.
from the for-relative-terms-of-teeny-and-tiny dept.
AbsoluteXyro writes "According to a Space.com article, NASA scientists have discovered the smallest known black hole to date. The object is known as 'XTE J1650-500'. Weighing in at a scant 3.8 solar masses and measuring only 15 miles across, this finding sheds new light on the lower limit of black hole sizes and the critical threshold at which a star will become a black hole upon its death, rather than a neutron star. XTE J1650-500 beats out the previous record holder, GRO 1655-40, by about 2.5 solar masses."
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That's nothing... (Score:5, Funny)
(But who will be there to measure...?)
Re:That's nothing... (Score:5, Funny)
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Re:That's nothing... (Score:5, Funny)
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Re:That's nothing... (Score:5, Funny)
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Quantum Foam (Score:4, Informative)
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Re:Quantum Foam (Score:5, Insightful)
The value of the Chandrasekhar limit depends on how one performs the calculation, but typically it comes out to around 1.4 solar masses (not 2.5). But actually, this is not so much the interesting question, because the Chandrasekhar limit applies only to white dwarfs, whose mass is supported by electron degeneracy pressure [wikipedia.org]. This is only one type of a much broader concept called fermion degeneracy pressure.
For example, a neutron star is much denser than a white dwarf, and is supported by neutron degeneracy pressure instead of electron degeneracy pressure and hence the Chandrasekhar limit does not apply to neutron stars. The equivalent limit for neutron degenerate matter is called the Tolman-Oppenheimer-Volkoff limit [wikipedia.org]. Like the Chandrasekhar limit, this calculation is very dependent on the behavior of the degenerate matter, but UNlike the Chandrasekhar limit, we know very little about the properties of neutron degenerate matter, and so the uncertainty of the T-O-V limit is quite large; it is usually placed (as you can see in the wikipedia article that I link to) between 1.5 and 3.0 solar masses. And there are even denser objects that have been proposed (though not observed) made of quark degenerate matter, and the limit on the mass of these things is even more uncertain.
So the point is, there is still a good deal of physics that can come from the observation of a 3.8 solar mass black hole, as it can constrain various models of fermion degenerate matter.
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Re:That's nothing... (Score:4, Funny)
But... it needs more string theory.
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Re:That's nothing... (Score:5, Informative)
001 = First black hole created by LHC
Some people are afraid the LHC-001 is going to destroy the Earth.
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Oh shit... (Score:5, Funny)
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Re:Oh shit... (Score:5, Funny)
Not to worry, the Enterprise is speeding around the Sun as we speak... Space-whales told them to.
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Relax (Score:4, Funny)
Besides never apply a Star Trek solution to a Babylon Five problem. [starwreck.com]
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What the article fails to pont out is ... (Score:5, Funny)
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Re:That's nothing... (Score:4, Funny)
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Re:That's nothing... (Score:5, Funny)
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Re:That's nothing... (Score:5, Funny)
Actually, nm, don't say it, it's too obvious....
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I dunno, but... (Score:4, Funny)
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Is it smaller than this one? (Score:4, Funny)
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Black-hole... sheds new light... (Score:5, Funny)
We weren't the first (Score:5, Funny)
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Re:We weren't the first (Score:4, Funny)
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Re:We weren't the first (Score:4, Funny)
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Awwww, little baby one (Score:5, Funny)
Size vs Age (Score:5, Interesting)
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At least, if I were a scientist and not someone pulling this directly out of my ass, that might be what is happening here.
Re:Size vs Age (Score:5, Informative)
But!
The temperature of a black hole can be defined by the rate at which Hawking photons are streaming away from it. In the case of a black hole of a few solar masses, this temperature will be in the nano-Kelvin (I think -- don't hurt me if I'm wrong by a few orders of magnitude). Now remember everything in the Universe is sitting in a bath of cold photons from the Big Bang (i.e. the microwave background). These photons have a temperature of ~4 Kelvin.
Therefore, black holes whose Hawking temperature is above the microwave background will be net *gaining* mass.
Which is all a long way of saying, no, this isn't a normal size black hole that has decayed over time. It must have been created at this mass (or smaller).
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Goldilocks (Score:5, Funny)
When we find the most average, space bears will come and blast us into porridge.
Astronomy kicks ass.
untrue statement (Score:5, Interesting)
Theoretical limit is 1.4 Solar Masses (Score:3, Informative)
http://en.wikipedia.org/wiki/Chandrasekhar_limit [wikipedia.org]
"this finding sheds new light" (Score:5, Funny)
Re:Probably Something Stupid (Score:5, Informative)
The mass of the black hole is the most defining characteristic.
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Re:Probably Something Stupid (Score:5, Informative)
A black hole, conventionally, consists of an event horizon surrounding a region of space from which you can't send information to the external world. This region of space is not a point, it has a well-defined circumference. (Because of the non-euclidean nature of general relativity, it doesn't actually have a well-defined radius (since you can't measure across the middle!) but people usually just consider the radius as if it were defined as the circumference divided by 2 pi, and don't worry about the fact that you can't actually measure it.)
At the center of the black hole is, according to general relativity, a point singularity, which indeed has no dimensions.
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Re:Probably Something Stupid (Score:5, Informative)
It was this tear that lead, if I recall, to the original conjectures of a white hole, and the Einstein-Rosen bridge.
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Rotating black holes [Re:Probably Something S...] (Score:5, Interesting)
Well, maybe. Actually, rotating black holes radiate away angular momentum, and they also preferentially eat material that reduces their angular momentum, so it's an open question as to whether real black holes will be rotating. Probably, because the accretion disk is likely to be rotating, and it swallows up the accretion disk and gains the momentum from it, but I'm not sure you can necessarily say that all natural black holes will rotate.
It was this tear that lead, if I recall, to the original conjectures of a white hole, and the Einstein-Rosen bridge.
Actually, the Einstein-Rosen bridge comes from the maximum analytical extension of the Flamm embedding, way predating the Kerr solution. (It's a very trivial embedding, z = sqrt(r). The extension is z = plus or minus sqrt(r).) Turns out that the extended Flamm embedding is misleading, and a Schwartzschild black hole isn't a wormhole after all. But that wasn't obvious.
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Re:Probably Something Stupid (Score:4, Interesting)
No, actually it doesn't. What is usually called the Schwartzschild "radius" is not actually a radius by the definition of the word, "distance to the center".
Exactly. You can calculate the area (which is well defined) and divide it by 4 pi, and you are free to call that the radius if you like. Or, equivalently, divide the circumference by two pi. But you can't measure the distance to the center.
Finite... and timelike. It would be a little like trying to define the radius of a circle if you're standing on the circumference, and the center is next Tuesday at noon.
Within the event horizon, any choice of coordinates is rather badly behaved, because there is no well-behaved stationary coordinate system.
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Re: (Score:3, Interesting)
it doesn't actually have a well-defined radius (since you can't measure across the middle!)
Why do you need to measure *across* the middle to measure the radius?
Is there a (theoretical) problem with using some kind of high tech space calipers to measure the radius without going anywhere near the 'middle'?
You could, but the result wouldn't really be right. A black hole is like that blessed +2 bag of holding that has much more room inside it than the space that it actually encompasses. I never really studied general relativity, but I think that when an object is in a strong gravity field, it becomes shorter (or everything else becomes longer). This means that the notion of length gets a bit weird. Similarly, if you used calipers to measure the diameter of a block hole, the sides of the calipers would no long
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Yes that's what astronomers mean when they say how "big" a black hole is.
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About 10^68 yr. Bring a book.
Bemopolis
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A black hole of any stelar size will only radiate like a body in the femto-kelvin range.
This means that galactic background radiation will "refill" it more than it could ever lose.
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Re:The Earth in danger from microscopic black hole (Score:4, Interesting)
"If they were able to make a small blackhole, and it got "loose" and fell to the center of the Earth, the pressures at the Earths core would force material into it so fast that even a very small one would gobble us up very fast. I am not sure what the exact pressure is at the Earths core but it could force material through even a very small "hole" very quickly. I do agree that once it gobbled up the Earth, it would just continue to orbit the Sun, and the Moon would still orbit the blackhole as if it were the Earth..."
No, you should read this thread.
First of all, a black hole that falls to the center of the earth, wouldn't stop there, but would continue falling up on the other side, just to plunge in again, and on and on, because there's no "friction" on the black hole.
Second, there have been posted in this thread a lot of calculations of the speed at which it would gobble up matter.
Don't forget that the black hole we're talking about here IS MUCH MUCH SMALLER THAN A PROTON. As such, pressures on *atomic* level (such as in the center of the earth) matter little: the black hole travels most of the time in the empty space between nucleae.
A way to calculate the probability of hitting a nucleus (and somehow imagining that it would gobble up the entire nucleus, which is MUCH MUCH bigger than the black hole itself - which is a worst-case scenario) is done by calculating the "cross section" of the black hole and its probability to cross a nucleus on its voyages through the earth. We know its speed (just falling), and knowing the cross section and the density of nucleae, we can estimate how many nucleae it could eat per unit of time.
For a classical black hole, the calculation is done in the link provided by Pervect in this post:
http://www.physicsforums.com/showpos...4&postcount=12 [physicsforums.com]
for a MUCH LARGER black hole, about the size of a proton, weighting a billion tons (figure that! A black hole *the size of a proton* weights a billion tonnes ; we're talking here about black holes that weight 10 TeV or 10^(-24) kg - go figure how small it is !)
For more exotic calculations which are more severe, orion made some, and arrived at a time to eat the earth ~ 10^46 years.
All this in the following rather un-natural hypotheses:
- no Hawking radiation (which would make the black hole evaporate almost immediately)
- production of black hole EXACTLY IN THE CENTER OF GRAVITY of the collision (no remnant particles)
- very high production rate, producing billions of black holes per second.
I am not a physicist, but from what little physics I have had, and from reading threw the thread/flamewar, I dont think we have to worry about the LHC
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