[extropy-chat] Suicide the Green way

[Robert Bradbury]

On 11/20/06, Anders Sandberg <asa at nada.kth.se> wrote:

> 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?


This makes sense to me but manipulating the amount of material required for
a useful solar sail with holes in it is presumably a rather dicey task.
(Anders jumping off the diving board into the deep end of the pool which has
had the water drained from it when he wasn't looking...)

Of course as a piece of trivia one might want to read [1]...
  Design of a high performance solar sail system.
  Drexler, Kim Eric
  1979, MIT Masters Thesis

I've only read parts of it but as I recall Eric was doing the calculations
based on thin films, not thin films with holes.  Of course this entire
corpus of scientific thought needs to be rewritten once you have nanorobots
which can do nanoassembly in free space.  Completely unexplored -- the best
sail driven by a free electron laser tuned to the optimal wavelength to
accelerate the sail (a) as fast as possible; (b) as efficiently as
possible.  (The optimal wavelength for energy conversion may not be the same
as the optimal wavelength for sail construction).

Offhand, does anyone know why boron doesn't reflect light?  Or whether we
can have hydrogen mirrors?  Why do we have to constrain ourselves to
aluminum?

Robert

1. https://dspace.mit.edu/handle/1721.1/16234
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