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Cuneiformist
The Imperfectionist
USA
4955 Posts |
 Posted - 03/30/2005 : 18:10:34
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I read this story in today's NY Times (free membership required). It's really interesting stuff, but one line in the story made me laugh, and then freaked me out. For a second. Really:quote:
Before Brookhaven began its gold collision experiments in 2000, it issued assurances that the experiment could not accidentally create a black hole that would destroy the earth. Laboratory officials say that is still the case.
OK-- two seconds.
This was a topic brought up several times in Posner's Catastrophe (see this link). Something to think about...
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beskeptigal
SFN Die Hard
USA
3834 Posts |
Posted - 03/31/2005 : 00:28:19 [Permalink]
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I don't have a clue about how they would create a black hole but my guess is no matter how condensed the particles of matter are, one needs enough of them to have the gravity that the interstellar black holes have that make them hazardous. In other words it is the gravity not the density, stupid. Not addressing anyone here mind you. |
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Plyss
Skeptic Friend
Netherlands
231 Posts |
Posted - 03/31/2005 : 08:13:09 [Permalink]
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quote:
Originally posted by beskeptigal
I don't have a clue about how they would create a black hole...
According to New Scientist it works by colliding gold particles with near-lightspeed energies
quote:
At the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York, US, beams of gold nuclei travelling at close to the speed of light are smashed into each other. The intense heat of the collision breaks down the nuclei into quarks and gluons, the most basic building blocks of all normal matter. These particles form a ball of plasma about 300 million times hotter than the surface of the sun (New Scientist print edition, 16 October 2004).
The fireball, which lasts a mere 10-23 seconds, can be detected because it absorbs jets of particles produced by the collision. But 10 times as many jets were being absorbed by the fireball as were predicted by calculations using quantum chromodynamics (QCD), the theory that describes quarks and the forces that hold them together.
quote:
Originally posted by beskeptigal
but my guess is no matter how condensed the particles of matter are, one needs enough of them to have the gravity that the interstellar black holes have that make them hazardous. In other words it is the gravity not the density, stupid. Not addressing anyone here mind you.
I seem to recall that to form a stable black hole you need a certain minimum amount of mass. If they contain less they spontanously explode. At least, that's what i understood from my reading of Kip Thorne's Black Holes and Time Warps: Einstein's Outrageous Legacy.
Good reading too, pity it's way over my head. |
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Dr. Mabuse
Septic Fiend
Sweden
9688 Posts |
Posted - 03/31/2005 : 08:46:24 [Permalink]
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I agree with beskeptigal on this.
In order to create a singularity one need a pretty good dent in the space-time continuum. Thinking about the extremely small dimentions that is involved at quantum level, if someone really managed to create a singularity with just a few particles, the radius of the event horizon will be so small it wouldn't be able to swallow anything.
The more I think about it, the more unlikely I think it is.
Let's take out the calculator and make some layman's calculations.
Calculating generously, a singularity can form from a Neutron Star of mass ~3 times the mass of the Sun.
6x10^30 kg.
The radius of the event horizon is roughly 1km per sun mass.
radius --> 3x10^3 m
If the mass can be compelled to form a singularity below the Chandrasekhar-limit, and the radius remain linear we can calculate how much mass has to be compressed into a small space in order to create a singulatity.
To create an event horizon the size of a lithium atom we need a mass of 3x10^17 kg...
The Bohr-radius of a neutron is about 1,1x10^-15.
That would require a mass of 2,2x10^12 kg.
Two billion metric tonnes will have to be suffinciently compressed in order to create an event horizon the size of a neutron.
The shortest length, Planck lenth is according to this site 1,6x10^-35
An event horizon of that size needs 3,2x10^-8 kg, or 32ug.
32ug would seem like a very little mass, but then I'd like to remind you that it's still an awful lot of atoms that has to be compressed into a space that is 10^-20 times the size of a proton. Packing quarks back to back just don't seem enough...
Disclaimer: These calculations are made from a relativistic point of view. I have no idea how quantum effects will interfere with this. |
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Valiant Dancer
Forum Goalie
USA
4826 Posts |
Posted - 03/31/2005 : 10:23:17 [Permalink]
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quote:
Originally posted by Plyss
quote:
Originally posted by beskeptigal
I don't have a clue about how they would create a black hole...
According to New Scientist it works by colliding gold particles with near-lightspeed energies
quote:
At the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, New York, US, beams of gold nuclei travelling at close to the speed of light are smashed into each other. The intense heat of the collision breaks down the nuclei into quarks and gluons, the most basic building blocks of all normal matter. These particles form a ball of plasma about 300 million times hotter than the surface of the sun (New Scientist print edition, 16 October 2004).
The fireball, which lasts a mere 10-23 seconds, can be detected because it absorbs jets of particles produced by the collision. But 10 times as many jets were being absorbed by the fireball as were predicted by calculations using quantum chromodynamics (QCD), the theory that describes quarks and the forces that hold them together.
quote:
Originally posted by beskeptigal
but my guess is no matter how condensed the particles of matter are, one needs enough of them to have the gravity that the interstellar black holes have that make them hazardous. In other words it is the gravity not the density, stupid. Not addressing anyone here mind you.
I seem to recall that to form a stable black hole you need a certain minimum amount of mass. If they contain less they spontanously explode. At least, that's what i understood from my reading of Kip Thorne's Black Holes and Time Warps: Einstein's Outrageous Legacy.
Good reading too, pity it's way over my head.
It's what I understood from reading some of Hawking's work. |
Cthulhu/Asmodeus when you're tired of voting for the lesser of two evils
Brother Cutlass of Reasoned Discussion |
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