Re: CERN Atom Smasher May End the World

On 2008-04-16, Eivind Kjorstad <eivindorama@[EMAIL PROTECTED]
> wrote:
> Hmm. I'd think that as the hole grows, the mass-input would -stop-
> being pro****tional to the area of the event-horizon, because by the
> time the hole has earth mass (and thus earths gravity) the gravity
> -is- rather significant.

At first I thought so too.  But then I realized that it should be
pro****tional to area for any size black hole moving through a medium
of a given average density.

At any non-quantum size, for a fixed velocity the minimum impact
parameter for absorption will be pro****tional to the radius of the
hole.  (For quantum sizes I expect we can only talk about
probabilities of absorption).  Therefore the cross-sectional area of
absorption should still be pro****tional to event horizon area.

The main place where the model is likely to break down would be the
assumption of constant average velocity.  As it absorbs matter, it
will acquire its momentum and hence slow.  That process would be
essentially complete long before it reaches even 1 gram in mass.

So any matter-consuming micro black hole will esentially come to rest
long before it has any meaningful effect on anything, and will be
surrounded by a micro accretion disk of extreme density.  How fast
will matter in that disk radiate away angular momentum, so that it can
fall into the hole?  At what rate would the radiation and particle
pressure from the hole match that of the surrounding solar core
matter?

That seems to be an extremly messy problem to solve, but one that will
in the end determine how fast the black hole can eat matter.


- Tim