From: Anders Sandberg (asa@nada.kth.se)
Date: Thu Dec 04 1997 - 03:12:34 MST
Keith Elis <hagbard@ix.netcom.com> writes:
> I was under the impression that such travel would be impossible due
> to the fact that wormholes tend to collapse as soon as they form.
"Traditional" (Einstein-Rosen bridges) wormholes do collapse almost
immediately, before anything can traverse them. But Thorne showed that
in principle it is possible to stabilize wormholes by threading them
with negative energy densities (for example from electric fields,
negative matter or the Casimir effect). Later papers have shown that
stable wormholes may be possible, but most involve violations of the
energy conditions (which say there are no negative energy densities;
they are however somewhat doubted) or dynamic wormholes that change
"radius" (some do this so slowly they are traversable).
>However, I was speaking with a friend a while back, and he brought up
>the subject of Kerr (sp?) black holes. It seems that these are
>theoretical black holes in which the singularity is larger than a
>mathematical point, elongated perpendicular to an axis of
>rotation. Some physicists seem to think that that this singularity
>may be ring-shaped. If so, this would mean that one could follow the
>axis of rotation into the very center, supposedly "passing through"
>the singularity (which if I am not mistaken would have the properties
>of a wormhole/gravity well).
Yes, the Kerr-Newman solution to the equations (which is a rotating,
charged hole) has many interesting properties, including a
ring-singularity inside the black hole and the possibility of a
wormhole through it. Unfortunately there seems to be results that
suggests that natural black holes will not work, the wormhole
connection is broken when the hole is formed.
> If it were possible to begin a normal (Schwarzchild) black hole
> rotating, would one be able to create such a ring-shaped
> singularity?
Maybe. Making a Schwartzschild hole rotate is simple, just throw in
mass with angular momentum. But I'm not sure we can control where the
"wormhole" leads, and it might be very hard to get out of the wormhole
opening if that is another black hole. I think I prefer classic
womholes...
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