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Can a Singularity Exhibit an Electrostatic Field ? Answered

Picture of

What is wahh.......  a smallblack hole ...........  that's a singularity.
If you bombard  it  with electrons ( which carry a negative charge )
will the tiny Black hole be attracted to your pet cat.  
Cat fur looses electrons easily and acquires a positive charge.

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kelseymhBest Answer (author)2011-08-12

A black hole can have three properties -- momentum (which includes mass), angular momentum (spin), and charge. The no-hair theorems guarantee that they can't have any other observable properties. A black hole with all three is called a Kerr black hole. Astrophysical black holes are presumed to "never" be Kerr-type, because the unbalanced charge would quickly be neutralized from the accretion disk plasma.

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orksecurity (author)kelseymh2011-08-12

As I said in the other thread, thanks for the correction.

(I've always liked the image that "a black hole has no hair". Who says physicists can't be poetic?)

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steveastrouk (author)orksecurity2011-08-13

or that in Russia the term black hole is so rude it isn't used in polite scientific circles.

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iceng (author)steveastrouk2011-08-13

My last only visit to Ireland I was informed an American term the fanny pack
a belted zipper apparel bag favored by some travelers was best avoided
in polite company.
Never got around to asking about dark singularities :•)

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orksecurity (author)steveastrouk2011-08-13

I've heard that claim made. I haven't heard confirmation from a native speaker or a cosmologist.

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Kiteman (author)kelseymh2011-08-13

I've been trawling my memory, but failed to drag up the title of an SF work (1960s? 1970s?) where small black holes were used to power spacecraft. I think they were used as massive flywheels, "tapping" the spin to drive the ship. Yes, I know, but it was fiction.

The point of this ramble is that the black holes were "fed" charge by being zapped with a beam of electrons until there was enough charge on the hole to be able to handle it with powerful magnetic fields.

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Kiteman (author)Kiteman2011-08-13
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steveastrouk (author)Kiteman2011-08-13

Nah, they used "spindizzies"

Steve

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Kiteman (author)steveastrouk2011-08-13

But weren't spindizzies actually black holes being manipulated to generate antigravity?

Still, that's not the right story.

I'll probably remember at about 4am...

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steveastrouk (author)Kiteman2011-08-13

Nope, they manipulated atomic spin.
http://en.wikipedia.org/wiki/Spindizzy

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iceng (author)Kiteman2011-08-13

By the story;
Spindizzie fields were able to lift the island of New York city with subway
and when hooked up ( wired ) Correctly they reduced the coefficient of friction
for machines and people, as memory serves.

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adas10 (author)2011-10-09

black holes are something about which we know very little but according my view- matter is made up of atoms which are made up of protons neutrons and electrons as we all know .Which are further made up of quarks and leptons, hadrons these are nothing but highly stable forms of electromagnetic forces or impure energy these small building blocks make up matter but the forces and conditions inside a black hole are so strong that it is unable for the atom to hold its stability and each and every building block of matter breaks up into simplest form that is electromagnetic forces and ends up in the centre of the black hole in a singularity.

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iceng (author)adas102011-10-09

You need to define impure energy. 
Is that another reason those holes are black ?
End-up, center those are classic Newtonian physics terms
Consider your view may be flawed

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orksecurity (author)2011-08-12

As I understand it, a black hole's gravity is so high that NOTHING escapes, including electomagnetic forces. (With the sole exception of quantum evaporation.)

But there have certainly been science fiction stories that have postulated otherwise. Larry Niven had a story where that idea was used as a way of "handling" a quantum black hole (which is itself an unproven concept).

It should be noted, however, that if a black hole got close enough to you and your cat for you to observe electromagnetic forces, the gravitational force would probably be much, much greater.

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kelseymh (author)orksecurity2011-08-12

Not entirely true. Kerr black holes can have non-zero charge, in addition to mass and angular momentum.

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orksecurity (author)kelseymh2011-08-12

Ah. Thanks; I wasn't certain.

The question that still confuses me: OK, they can have a charge -- but would that have any effects outside the event horizon? Would Niven's idea of applying a massive charge to a quantum black hole and then dragging it around electrostatically actually work?

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kelseymh (author)orksecurity2011-08-12

Yes, indeed. Electrostatics and gravity are the only external effects a black hole can have.

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iceng (author)orksecurity2011-08-12

One of my favorite all time writers Larry Niven. That very story you refer to is
what crossed my mind when wrestling with the magnetic monopole ten
questions back

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orksecurity (author)iceng2011-08-12

I've been trying to remember the name of that story.... Got it. The Borderland of Sol.

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