Alain wrote:
> Anthony D. Baye nous apporta ses lumieres en ce 2005-10-12 20:50:
> 
>> Mike Williams wrote:
>>
>>> Apart from the absence of the plasma tube, I'd say it was Thistledown.
>>>
>>> Where does your hollow asteroid get its light from?
>>>
>> Wow.  Someone else reads what I read.
>>
>> A.D.B.
>>
>> P.S. Alain,  Gravity is based on mass.  A sphere the size of earth's 
>> orbit with a shell thick enough to withstand impacts would naturally 
>> have a reasonable amount of gravity on it's inside surface.
> 
> 
> The gravitational pull from the relatively small but very near region 
> under your feet is exactly countered by that of the extremely large and 
> distant part over your head.
> That leave you with ONLY the gravity from the sun witch is straight 
> up... NOT a good thing.
> 
Far be it from me to dislike being proved wrong.

but an interesting factoid:  Larry Niven's Ringworld, which was 
conceived as an intermediate step toward a dyson sphere, spun at 770 
mi/h.  It was determined that, in order to withstand the shearing forces 
from the spin, the base material which measured 1000' thick would have 
had to have had a tensile strength on the order of the force which holds 
the nucleus of an atom together.

A.D.B.

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