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Thread: Backyard Blackholes

  1. #1 Backyard Blackholes 
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    Lab fireball 'may be black hole'
    A fireball created in a US particle accelerator has the characteristics of a black hole, a physicist has said.
    It was generated at the Relativistic Heavy Ion Collider (RHIC) in New York, US, which smashes beams of gold nuclei together at near light speeds.

    Horatiu Nastase says his calculations show that the core of the fireball has a striking similarity to a black hole.

    His work has been published on the pre-print website arxiv.org and is reported in New Scientist magazine.

    When the gold nuclei smash into each other they are broken down into particles called quarks and gluons.

    These form a ball of plasma about 300 times hotter than the surface of the Sun. This fireball, which lasts just 10 million, billion, billionths of a second, can be detected because it absorbs jets of particles produced by the beam collisions.

    But Nastase, of Brown University in Providence, Rhode Island, says there is something unusual about it.

    Ten times as many jets were being absorbed by the fireball as were predicted by calculations.

    The Brown researcher thinks the particles are disappearing into the fireball's core and reappearing as thermal radiation, just as matter is thought to fall into a black hole and come out as "Hawking" radiation.

    However, even if the ball of plasma is a black hole, it is not thought to pose a threat. At these energies and distances, gravity is not the dominant force in a black hole.

    The RHIC is sited at the Brookhaven National Laboratory.
    Story from BBC NEWS:
    http://news.bbc.co.uk/go/pr/fr/-/2/h...re/4357613.stm

    Although any data retrieved from these experiments could greatly increase black hole understanding, one has to wonder what would happen if this got out of hand?


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    Forum Professor Pendragon's Avatar
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    Those particle accellerators really seem to be the edge of science at the moment. Btw, how does such a device work? Is it a big magnet or so?

    I'm allways fascinated by the fact that something can change in such a short time. I mean, you'd think there's a certain inertia in matter, but a billionth of a billionth etc of a second that's nothing!

    but in what way could such an experiment get out of hand? is a black-hole self-sustainable?


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    A particle accelerator uses electric fields to propel charged particles to great energies. Everyday applications are found in TV sets and X-ray generators. The particles are contained in an evacuated tube so that they do not get dispersed by hitting air molecules. In higher-energy accelerators, quadrupole magnets are used to focus the particles into a beam and prevent their mutual electrostatic repulsion from causing them to spread out.

    There are two basic types, circular and linear.

    Circular accelerators

    The accelerated particles move in a circle until they reach sufficient energy. The particle track is bent into a circle using dipole magnets. The advantage of circular accelerators over linacs is that components can be reused to accelerate the particles further, as the particle passes a given point many times. However they suffer a disadvantage in that the particles emit synchrotron radiation.

    Linear accelerators

    The particles are accelerated in a straight line, with the target at the end of it. Low energy accelerators such as cathode ray tubes and X-ray generators use a single pair of electrodes with a dc voltage of a few thousand volts between them. In an X-ray generator, the target itself is one of the electrodes.

    Higher energy accelerators use a linear array of plates to which an alternating high energy field is applied. As the particles approach a plate they are accelerated towards it by an opposite polarity charge applied to the plate. As they pass through a hole in the plate, the polarity is switched so that the plate now repels them and they are now accelerated by it towards the next plate. Normally a stream bunches of particles are accelerated, so a carefully controlled AC voltage is applied to each plate to continuously repeat this for each bunch.

    As the particles approach the speed of light the switching rate of the electric fields becomes so high that they operate at microwave frequencies, and so microwave cavities are used in higher energy machines instead of simple plates.

    High energy linear accelerators are often called linacs.

    Linear accelerators are very widely used - every cathode ray tube contains one, and they are also used to provide an initial low energy kick to particles before they are injected into circular accelerators. They also can produce proton beams, which can produce "proton-heavy" medical or research isotopes as opposed to the "neutron-heavy" ones made in reactors.

    The largest in the world is the Stanford Linear Accelerator, which is 2 miles long
    When any charged particle is accelerated, it emits electromagnetic radiation. As a particle travelling in a circle is always accelerating towards the centre of the circle, it continuously radiates. This has to be compensated for by some of the energy used to power the accelerating electric fields, which makes circular accelerators less efficient than linear ones. Some circular accelerators have been built to deliberately generate this radiation (called synchrotron light) as X-rays - for example the Diamond Light Source being built at the Rutherford Appleton Laboratory in England. High energy X-rays are useful for X-ray spectroscopy of proteins for example.

    Synchrotron radiation is more powerfully emitted by lighter particles, so these accelerators are invariably electron accelerators. Consequently particle physicists are increasingly using heavier particles such as protons in their accelerators to get to higher energies. The downside is that these particles are composites of quarks and gluons which makes analysing the results of their interactions much more complicated.

    The earliest circular accelerators were cyclotrons, invented in 1929 by Ernest O. Lawrence. Cyclotrons have a single pair of hollow 'D'-shaped plates to accelerate the particles and a single dipole magnet to curve the track of the particles. The particles are injected in the centre of the circular machine and spiral outwards towards the circumference.

    Cyclotrons reach an energy limit because of the relativistic effects at high energies whereby particles gain mass rather than speed. Though the special theory of relativity precludes matter from traveling faster than the speed of light in a vacuum, the particles in an accelerator normally travel very close to the speed of light, perhaps 99.99%. In high energy accelerators, there is a diminishing return in speed as the particle approaches the speed of light. The effect of the energy injected using the electric fields is therefore to markedly increase their mass rather than their speed. Doubling the energy might increase the speed a fraction of a percent closer to that of light but the main effect is to increase the relativistic mass of the particle.

    Cyclotrons no longer accelerate an electrons when they have reached an energy of about 10 million electron volts. There are ways for compensating for this to some extent - namely the synchrocyclotron and the isochronous cyclotron. They are nevertheless useful for lower energy applications.

    To push the energies even higher - into billions of electron volts, it is necessary to use a synchrotron. This is an accelerator in which the particles are contained in a donut-shaped tube, called a storage ring. The tube has many magnets distributed around it to focus the particles and curve their track around the tube, and microwave cavities similarly distributed to accelerate them.

    The size of Lawrence's first cyclotron was a mere 4 inches in diameter. Fermilab has a ring with a beam path of 4 miles. The largest ever built was the LEP at CERN with a diameter of 8.5 kilometers (circumference 26.6 km) which was an electron/positron collider. It has been dismantled and the underground tunnel is being reused for a proton/proton collider called the LHC due to start operation in 2007.

    The aborted Superconducting Supercollider in Texas would have had a circumference of 87 km. Construction was started but it was subsequently abandoned well before completion. Very large circular accelerators are invariably built in underground tunnels a few metres wide to minimise the disruption and cost of building such a structure on the surface, and to provide shielding against the intense synchrotron radiation.

    Targets

    Except for syncrotron radiation sources, the purpose of an accelerator is to generate high energy particles for interaction with matter.

    This is usually a fixed target, such as the phosphor coating on the back of the screen in the case of a television tube, or a piece of uranium in an accelerator designed as a neutron source, or a tungsten target for an X-ray generator. In a linac, the target is simply fitted to the at the end of the accelerator. The particle track in a cyclotron is a spiral outwards from the centre of the circular machine, so the accelerated particles emerge from a fixed point as for a linear accelerator.

    For synchrotrons, the situation is more complex. Once the particles have been accelerated to the desired energy, a fast acting dipole magnet is used to switch the particles out of the circular synchrotron tube and towards the target.

    A variation commonly used for particle physics research is a collider. Two circular synchrotons are built in close proximity - usually on top of each other and using the same magnets (which are then of more complicated design to accommodate both beam tubes). Bunches of particles travel in opposite directions around the two accelerators and collide at intersections between them. This doubles the energy of the collision compared to a fixed target accelerator for a small increase in cost.

    Higher Energies

    At present the highest energy accelerators are all circular colliders, but it is likely that limits have been reached in respect of compensating for synchrotron radiation losses, and the next generation will probably be linear accelerators five or ten miles long.
    source: http://en.wikipedia.org/wiki/Particle_accelerator
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    This experiment itself would be pretty much impossible to get out of hand. But further experiments may yield different results.

    It would get out of hand if the matter had enough gravity to pull itself into a singularity. Once this occurs the black hole would become self-sustaining. Then it would begin expanding as it continued to swallow more and more matter, our planet, solar system, and a good chunk of any surrounding matter.
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    The thing about these 'black holes' is that they are so small that gravity isn't a factor. A true black hole is formed from overwhelming gravity. These 'black holes' cannot sustain themselves without it.

    There's no danger.

    There is a guy at the other place, Paul Dixon, who is on a crusade against Fermilab. He thinks that these supercolliders are going to open a rift into de sitter space and cause a type 1a supernova.

    That should be fun.
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    Do not speak of the he who is not to be named, lest you draw his attention here.
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    Quote Originally Posted by Tafkam Aruhpe
    Do not speak of the he who is not to be named, lest you draw his attention here.
    That was an ok movie. Not what I expected, but a good unexpected.

    There is a guy at the other place, Paul Dixon, who is on a crusade against Fermilab. He thinks that these supercolliders are going to open a rift into de sitter space and cause a type 1a supernova.
    Ha, now that would be a quick way to die. I doubt you would even realize it happened.
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  9. #8  
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    Quote Originally Posted by sploit
    It would get out of hand if the matter had enough gravity to pull itself into a singularity. Once this occurs the black hole would become self-sustaining. Then it would begin expanding as it continued to swallow more and more matter, our planet, solar system, and a good chunk of any surrounding matter.
    No, it would just swallow up the earth. Then it would continue to orbit around the sun where the earth used to be. Even if the earth suddenly compressed itself into a black hole, the gravitational attraction between the earth and the sun wouldn’t be any different.
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    Quote Originally Posted by (In)Sanity
    Quote Originally Posted by Tafkam Aruhpe
    Do not speak of the he who is not to be named, lest you draw his attention here.
    That was an ok movie. Not what I expected, but a good unexpected.

    There is a guy at the other place, Paul Dixon, who is on a crusade against Fermilab. He thinks that these supercolliders are going to open a rift into de sitter space and cause a type 1a supernova.
    Ha, now that would be a quick way to die. I doubt you would even realize it happened.
    Possibly you don't know that that guy was maintaining a thread with a spanlife of 4 years, with more than 1000 posts if i remember correctly. I suspect that P. Dixon is as mad as a hatter
    I want to auction off the Universe. Any bid?
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