Re: (TFT) Space travel - galaxy sized dyson spheres.

[Mark Tapley <mtapley@swri.edu>]

At 8:43 -0500 12/7/11, Jim wrote:
> Recent readings from the Voyager craft seem to indicate that the solar
> wind varies quite a bit and spins with the sun.  That could make the
> stresses on an enclosed sphere rather extreme.

	Voyager as well as others; and it varies from equator to pole 
of the sun as well, even over a long-term average.

	However, if the sphere is anything like strong enough to hold 
itself up, it probably could withstand all of those variations as 
well.

	However, I think the same "Shell Theorem" that effectively 
cancels gravity inside the sphere *also* cancels the effect of the 
solar wind on the sphere for centering purposes. That is, for any 
given direction, a closer segment of sphere sees a denser solar wind, 
but a farther away segment sees a greater area of solar wind. 
Equivalently stated, there's just as much solar wind coming out to 
the left as there is to the right (long-term average), so the sphere 
won't be pushed either way.

	So I have to vote with PvK; the "blue ghost" (sic?) of 
"Ringworld Engineers" would be a necessity.
--
						- Mark     210-379-4635
-----------------------------------------------------------------------
Large Asteroids headed toward planets
inhabited by beings that don't have
technology adequate to stop them:

				Think of it as Evolution in Fast-Forward.
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