On Wed, 4 Nov 2009 09:54:28 -0800 (PST), BradGuth <bradg...@gmail.com> wrote:
>On Nov 4, 9:43 am, amor...@xenon.Stanford.EDU (Alan Morgan) wrote:
>> In article <80v1f5hg1od5qmuumsgu39gtpuh8fmn...@4ax.com>,
>> Henry Wilson DSc <H@..> wrote:

>> >On Wed, 04 Nov 2009 03:47:03 GMT, Sam Wormley <sworml...@mchsi.com> wrote:

>> >>Henry Wilson DSc wrote:
>> >>> On Tue, 03 Nov 2009 22:58:11 GMT, Sam Wormley <sworml...@mchsi.com> wrote:

>> >>>> Henry Wilson DSc wrote:

>> >>>>> Earth is slowly rotating so centrifugal force is insufficiet to obercome
>> >>>>> gratvity near the centre.    But what about a very rapidly spinning neutron
>> >>>>> star?

>> >>>>> It could easily be hollow.
>> >>>>   No Henry, Henri--the centrifugal force from the perspective
>> >>>>   of a rotating coordinate system goes to zero at the core.

>> >>> I know that.

>> >>> It could never become hollow if it was solid....but how do you know it was ever
>> >>> solid?

>> >>   It's a force called gravity--look it up!

>> >What are the required conditions for spinning matter to condense into a HOLLOW
>> >ball rather than a solid one?

>> I can't imagine that it would ever do that.  The equator of the object can
>> be spinning fast enough to resist gravity, but the north and south poles
>> will be subject to gravity and collapse inwards.  A rapidly spinning object
>> will deform into a disk (assuming it doesn't fly apart first), not an
>> empty shell.

>> Alan
>> --
>> Defendit numerus

>How very true.  However the extremely thick and robust crust of our
>Selene/moon has to be quite different than our 98.5% fluid Earth.

> ~ BG