[extropy-chat] Suicide the Green way

[spike]

> Michael M. Butler wrote:
> > On 11/20/06, Anders Sandberg <asa at nada.kth.se> wrote:
> >> A good aluminium sail is supposed to have half wavelength holes
> >
> > Interesting. I hadn't heard that. Source, please?
> 
> I saw it on Wikipedia, http://en.wikipedia.org/wiki/Solar_sail
> I think it follows quite naturally from electromagnetic considerations...
>Anders Sandberg

The Wiki article included this comment which drove me nuts until I heard the
Doppler shift explanation:

..."Another common claim is that the radiation pressure is an unproven
effect that may violate the thermodynamical Carnot rule. This criticism was
raised by Thomas Gold of Cornell, leading to a public debate in the spring
of 2003. [2] The solution is that when reflected by a solar sail, a photon
undergoes a Doppler shift; its wavelength increases (and energy decreases)
by a factor dependent on the velocity of the sail, transferring energy from
the sun-photon system to the sail..."

That Carnot rule sounded solid, but I already knew that stuff does
definitely get pushed away from the sun by light pressure from Amara's PhD
thesis.  Thanks Amara, for writing about such a cool topic!  {8^]

spike