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Month Index: August, 1994

From:     Michael Sandy <mehawk@?????.?????.com>
Date:     Mon, 22 Aug 1994 05:11:58 -0400
Subject:  Re: What is a ringworld?
Niven made a large number of astrophysical errors in creating Ringworld,
only some of which he corrected in the second book.

While a uniform sphere exerts no gravitational force on the interior, the
reverse is not true, if the star is not perfectly centered the structure
will be subjected to massive, rapidly changing stress loads, especially
if it spins to maintain surface gravity.

Ok, so the structure is an engineering nightmare, as the rigid structure
isn't.  What about some of the structures that exist to ensure livability?

The spill mountains are completely unnecessary.  And the reason why leads
to another major flaw.  The ring is a mountain, 1/4 million miles high, but
only a mile thick.  That is enough to generate a gravity which produces a
noticable well over, say, 10 thousand miles, a mere bump.

>--->---->----->-----|-----<-----<----<---<  Arrows indicate gravity level.

This is a problem.  100,000 km into a micro gravity well is likely to be
equivalent to kilometers in a normal gravity well, and the gravity
effect of the edge is similar to the gravity on a 1/4 million km sq,
1 mile thick.  Or, 125,000 km from a spherical mass about 4,000 km in
diameter.  That is very high in the micro-gees.  Things aren't in danger
of going over the edge, their in danger of falling towards the middle, and
the more stuff that falls that way, the greater the pull.

If you want a wonder world that doesn't require too active a creator/maintenance
squad, I reccommend a Toroidal world.  A spinning, massive Torus can 
maintain a uniform surface gravity over its entire surface.  Give it a
decent axial tilt and it is habitable in four Temperate bands, inner
north, outer north, inner south and outer south.  Except for solar tides
instead of lunar, the climate would be fairly Earth like.  Well, the inner
zones experience a Total eclipse that lasts a couple of days to a week,
depending on the ratio of width to diameter of the ring, but Crossover
storms should be pretty neat.

Crossing the Arctic zones would transport adventurers to a whole new world
for them.


For more flaws in Dyson Sphere, Ringworld design, send e-mail to


Michael Sandy

Previous Message: What is a ringworld?
Next Message: Ringworlds & Dyson Spheres
Month Index: August, 1994

SubjectFromDate (UTC)
What is a ringworld?    Stephen Burton Mann    22 Aug 1994 05:52:47
Re: What is a ringworld?    Michael Sandy    22 Aug 1994 09:11:58

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