From: Michael S. Lorrey (mlorrey@datamann.com)
Date: Fri Dec 01 2000 - 13:43:12 MST
Adrian Tymes wrote:
>
> Jeff Davis wrote:
>
> > The star may have a magnetic field. The field lines may extend out into
> > space. How far out do they extend? They may interact with the dyson
> > sphere. They may be conducted through the dyson sphere. What is the
> > sphere made of? If it were made metallic and isotropic, would the star and
> > sphere be magnetically drawn together, or held stably concentric? Could a
> > non-isotropic or non-metallic sphere design take advantage of or circumvent
> > magnetic effects to passively achieve spherical concentricity?
>
> Modern technology, believe it or not. The keywords you want are
> "intertially contained fusion": basically, keeping a plasma contained at
> the center of a (spherical, usually) shell. They're still working on
> the "fusion" part, granted, but people have contained plasmas this way
> before. This would appear to be that, just on a much larger scale.
Actually, Daimler-Chrysler is involved in inertial electrostatic
containment fusion research, and there are functioning desktop reactors
that DO, in fact, have fusion reactions. Just not an over unity level of
reactions, so all they are good for is for neutron sources, not as an
energy source. This method was pioneered 30+ years ago by one of the
inventors of TV.
Since a dyson sphere or niven ring would orbit at a velocity higher than
orbital velocity, in order to produce a 1 g centrifugal gravity
simulation, it is likely that the radial velocity differential between
it and the solar corona would create its own magnetic field that might
be used to stabilize the ring or sphere much as a magnetic bearing.
>
> > One last note. Though the 800 lb gorilla appears neutral in this matter,
> > that's only first order effects. Second order gravitational effects may
> > come into play. If the non-uniform heating of one side of the sphere
> > causes it to distort, or tidal forces cause it to distort, then
> > gravitational forces may again come into play. The devil's in the details.
>
> Even with an undistorted sphere, would the pull of gravity not be larger
> on the point of the sphere closest to the star's center than on the
> opposite point? This would seem to be the biggest argument for keeping
> the star centered (so there is no poin substantially closer to the
> center). Also, in practice, it may be desirable to support spheres with
> non-uniform mass distribution - say, for docking large spaceships, or
> for manufacturing, or for sentients residing in a similar fashion as
> sentients on the surface of the Earth today (that is, clustering in
> cities, migrating, et cetera) - though this may be best handled by
> figuring the current center of mass and moving the star there with
> respect to the sphere.
So long as this instability can be kept resonant as a standing wave, I
should think it would not be a real problem. The problem is if the wave
continuously builds on itself, like the Tacoma Narrows bridge. Solar
flares would cause perturbations, of course, and no other planets could
be allowed in the system either. Note that such a ring or sphere would
in fact need some type of active system to make corrections, which even
the cloud methodology requires to minimize fragmentation.
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