[extropy-chat] Suicide the Green way

[Robert Bradbury]

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

> > Offhand, does anyone know why boron doesn't reflect light?
>
> Isn't this due to the pi bonds in the atom sheets? A EM wave arrives, sets
> the mobile electrons in movement and is absorbed. But this would only work
> for the sheet allotrope, the rhomboedral ought to have other optical
> effects. Does anybody know what color it is?


Not I.  But questions could involve why Be is reflective while B is not?
And why is Al which is right above B in the PTE reflective but B is not?
And then why are Ag and Au the best reflectors and why are they different in
their reflectivity? (Ag is better than Au at most visible wavelengths).

As for non-aluminium, according to Landis people looked at beryllioum but
> it wasn't so good. And it is hard to get many stable metals on the top of
> the periodic table. Landis also points out that for the laserdriven sail
> low resistance may actually beat lightness. Maybe we will go to the stars
> on gold foil?


The mirror on the JWST is Be so it can't be that bad.  I would be curious to
know why low resistance beats lightness -- do the photons charge the sail?

Robert
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