From: Anders Sandberg (nv91-asa@nada.kth.se)
Date: Sat Dec 21 1996 - 07:13:06 MST
On Fri, 20 Dec 1996, Michael Lorrey wrote:
> One should also be able to travel into the
> past with a simple black hole, according to the latest from Hawking.
How is that supposed to work?
> > > 2) The very rapid rotation would cause the cylinder to fly apart.
>
> Neutronium has such a high gravity gradient that it is self supporting,
> as evidenced by black holes that spin nearly at the speed of light.
Well, black holes doesn't consist of neutronium at all (the matter has
left the picture), rather a self-sustaining curvature of spacetime
(gravitonium?). Neutronium can't withstand too fast rotation since the
pressure drops low enough for it to turn into normal matter; it has an
excellent pressure strength, but no tensile strength. Black holes are
similarly limited, above a certain limit angular momentum and charge the
Kerr solution vanishes and we get something else (unfortunately you cannot
accelerate a black hole beyond this limit according to some theorem, see
_Gravity_ by Misner, Thorne, Wheeler).
-----------------------------------------------------------------------
Anders Sandberg Towards Ascension!
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