[ExI] Large Hadron Collider

spike spike66 at att.net
Sat Feb 2 01:19:25 UTC 2008


> -----Original Message-----
> From: extropy-chat-bounces at lists.extropy.org 
> [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of 
> Damien Broderick
> Sent: Friday, February 01, 2008 3:24 PM
> To: ExI chat list
> Subject: Re: [ExI] Large Hadron Collider
> At 10:36 PM 2/1/2008 +0000, ben wrote:
> >And wouldn't it take thousands of years, or longer, to start 
> making any 
> >appreciable difference if it did fall to the centre of the earth and 
> >start gobbling it up?
> Apparently. This has been discussed a bit on 
> rec.arts.sf.science; e.g. some random grabs:
> <someone drops a black hole
> onto Earth. It's a billion tonnes, very hot and tiny.
> What happens? The cross section is tiny and material near it 
> will be heated up to a great degree: could it suck up 
> significant amounts of material at all? >
> And that's asteroid mass, not LHC morsel.
> <Plus there's almost no way to keep the hole charged enough 
> to hold onto it with the electromagnet that J.Forward uses in 
> the story.
> If it had that much charge, the immense potential near the 
> horizon would pull in opposite charges quickly, neutralizing 
> the hole. >
> etc.
> Damien Broderick

I have tried to do these calcs but have not been very successful in
convincing myself that they are true or represent reality.

I derive of the event horizon radius of a black hole as a function of its
mass, and get R=2GM/c^2.  G is about 7e-11 and c is about 3e-8, so about
1.5e-27*M.  The radius of a proton is about 1.5e-18, so a black hole would
need a mass of a billion Kg in order to be the size of a proton.  I can be
sure that no collider is going to accidentally create a particle with a mass
of a million tons.  If a black hole is accidentally created, it would be too
small to devour any particle.

Then I theorized that a tiny black hole could absorb electrons since usual
notion of dimension is not necessarily applicable to electrons (the Compton
radius is not directly analogous to what we think of as a radius, at least
not in all applications.)  In any material there are free electrons, but not
free protons.  Therefore the black hole inside a planet would take on a
negative charge and hold it.  Then it would attract surrounding matter, not
with the very weak gravitational force but by electromagnetic force.
Reasoning: it gobbles up the nearby electrons, causing the surrounding
material to become positively charged.  Then the radius of the event horizon
becomes effectively much larger than it would be if everything were neutral.

If that line of reasoning is correct, I suppose a very tiny black hole could
eventually devour a planet.  But I suspect something is very wrong with that
line of reasoning.  I hope so.


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