Re: ESO: A Black Hole's Dinner is Fast Approaching

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Psnarf
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Re: ESO: A Black Hole's Dinner is Fast Approaching

Post by Psnarf » Thu Dec 15, 2011 4:39 pm

The message over in Breaking Space News, ESO: A Black Hole's Dinner is Fast Approaching, reminded me of a couple of questions regarding supermassive black holes. Recent astrophysics theory is that near the event horizon, space-time gets wacky and inside the event horizon, time becomes dominant, so all forward time vectors from the event horizon sphere point to the singularity. It's not like stuff can't escape because the gravitational pull is so great, as time ticks on, the stuff inevitably ends up at the center (along with all the rest of the Higgs bosons?).
Meanwhile, that gas cloud becomes more compressed as it approaches the event horizon. Is there a radius outside the event horizon with sufficient gravitational pressure to induce fusion? Would such fusion reactions explain the radiation events we detect?
Regarding the accretion disc, why is it always depicted as a ring around the middle? Do particles falling toward the upper latitudes somehow get into orbit around the equator? The greatest gravitational pull on objects approaching from above would be along a line from the singularity to the object, or does the existing accretion disk present a greater gravitation attraction?

With all the forward time gradients meeting at the singularity, things must be very strange in there.

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Psnarf
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Re: Re: ESO: A Black Hole's Dinner is Fast Approaching

Post by Psnarf » Fri Dec 16, 2011 4:04 pm

This, from NASA: http://www.nasa.gov/topics/universe/fea ... tbeat.html

In order for a magnetic field to exist, there must be a flow of electrons somewhere, probably from the innermost part of the accretion disc. The distance between the innermost ring of the accretion disc periodically increases, something pushes it away. Could that force come from fusion? The electrons seem to get stripped off, which would form the magnetic field. A ring of particle fusion close to the event horizon could explain both the radiation and the periodic jets? Then the pushed-away part of the ring that was far from the fusion zone falls into that zone and the process begins again. All bets are off if the compressed gas doesn't get hot enough to allow spontaneous proton-proton fusion, somewhere around 14 million degrees Kelvin.

http://svs.gsfc.nasa.gov/vis/a010000/a0 ... index.html
http://www.nasa.gov/topics/universe/fea ... -jets.html

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Chris Peterson
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Re: Re: ESO: A Black Hole's Dinner is Fast Approaching

Post by Chris Peterson » Fri Dec 16, 2011 4:41 pm

Psnarf wrote:In order for a magnetic field to exist, there must be a flow of electrons somewhere, probably from the innermost part of the accretion disc.
A magnetic field does not require a flow of electrons. Many elementary particles have intrinsic magnetic moments, which is why many materials produce magnetic fields in the absence of electron flow.

It is possible that black holes can have a magnetic charge (that remains an open question); if so, we can expect to find magnetic fields even when there is no accretion disc. That said, where there is an accretion disc, dynamo mechanisms seem inevitable. The material in the disc is heated to a plasma, and now you have rapidly moving, charged particles- and thus, a magnetic field.
The distance between the innermost ring of the accretion disc periodically increases, something pushes it away. Could that force come from fusion? The electrons seem to get stripped off, which would form the magnetic field.
Maybe, but there's no requirement for fusion. All you need is a slight increase in pressure towards the center, which could occur simply because the disc isn't perfectly homogeneous. The disc itself is heated to a plasma, which is all that is required to produce a magnetic field by dynamo processes. It doesn't need to be anywhere near hot enough for fusion.
Chris

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Psnarf
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Re: ESO: A Black Hole's Dinner is Fast Approaching

Post by Psnarf » Sat Dec 17, 2011 3:35 pm

Thank you for explaining things in a way such that even a feeble-minded goof like me can understand.

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Psnarf
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Re: ESO: A Black Hole's Dinner is Fast Approaching

Post by Psnarf » Fri Jan 13, 2012 4:10 pm

I stumbled upon this bit of information while exploring IBM's 12-atom magnetic memory http://www.ibm.com/smarterplanet/us/en/ ... emory.html

"An electron has a standing-electric field and magnetic field in right angle regardless of any kind of its motions and act as a tiny bar magnet with a negative charge. In an atom, the electric fields of its electrons will be directed to the nucleus and magnetic fields will be horizontal to the nucleus. Arrangement of electrons in a molecular magnet: If the magnetic fields of two or more electrons in the atoms of a molecule are parallel, then that molecule becomes magnetic."
Click to play embedded YouTube video.
The text is from the "Show More" script below the movie. The last time I spoke with the director of the electron ring at Cornell, he did not tell me that a single electron has a magnetic field in addition to the electric field that I studied in undergrad physics. I guess it takes the research dollars of a corporation like IBM to build the tools needed to view and manipulate single atoms. I know a stream of electrons is affected by a magnet by watching a beam in CRT follow a bar magnet around the tube, and from my days repairing computer monitors some 25 years ago. Time to go back to school to figure out how an isolated electron generates its magnetic field. I haven't a clue why electrons generate an electric field. Professors told me in engineering classes that you don't have to know what's the deal with that, just that on the macroscopic scale the formulas work (Kirchoff, Maxwell, Faraday - http://academicearth.org/lectures/basic ... cl-mmethod) and you can make useful stuff using them.

Related: http://www.youtube.com/watch?v=18zR31JwxLY

Thank you for your kind nudging, Dr. Peterson!
--
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and quid pro quo.
So little time,
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Re: ESO: A Black Hole's Dinner is Fast Approaching

Post by Markus Schwarz » Mon Jan 16, 2012 9:06 am

Psnarf wrote: Time to go back to school to figure out how an isolated electron generates its magnetic field. I haven't a clue why electrons generate an electric field.
An electron has an electric charge and spin. Both are intrinsic fundamental properties. The electric charge is the source of its electric field. Its spin leads to its magnetic moment. The magnetic moment is not a source of a magnetic field, but describes how a system (in our case the electron) reacts to an external magnetic field.

Keep in mind that the spin of the electron is a quantum mechanical property. As the name spin suggests, it can be pictured classically by a rotating charged sphere, leading to a dipole moment. This is why the electron can be said to act like a dipole magnet. But this analogy can bring you only so far.