In sci.physics The Ghost In The Machine <ewill@sirius.athghost7038suus.net> wrote:

In sci.physics, Ian Stirling
<root@mauve.demon.co.uk>
wrote
on 02 Oct 2004 12:58:09 GMT
<415ea5e0$0$42246$ed2e19e4@ptn-nntp-reader04.plus.net>:

In sci.physics Uncle Al <UncleAl0@hate.spam.net> wrote:

Skybuck Flying wrote:

Hi,

Seeing all the bullshit in this newsgroup or maybe sci-fi... or maybe
future technology I thought I add some of mine hehehehe.

My idea is to use the SUN as a way to send a message to aliens ;)

We build a big shield around the sun. And then we can turn it on and off
like a lamp.

Won't work.  Shield reaches equilibrium temp and emits.  Who is going
to launch it, NASA?  Ha ha ha.

Do the numbers before you laugh idiotically.
A shield around the sun at the diameter of the earth would reach 
around 0C.

(there are engineering difficulties.)

For starters -- where would the actual mass come from?  Also, the
shield will have to be in orbit around the Sun, at least during
initial construction.

If we were to generate a Dyson sphere out of pure iron -- I've no
idea what thickness would be required to resolve all of the
stresses and strains -- Uncle Al's observation will come true;
the shield will have to (eventually) throw out as much energy as the
Sun generates, lest things get overwarm inside.  Of course the
actual spectrum may be slightly different.  I'm not sure what

Radically different.
If you put it at earth orbit, it's a blackbody of 270K or so, not 2700.
At mercury orbit it's around 400K or so (not done numbers).

Would be a distinctly odd source.
No emission/absorbtion lines, surface temperature under a brown dwarf,
but anomolous luminosity.


If the sun is a black body, and so is the shell, then temperature
goes as the inverse second power of radius.