Re: Hole in a box

From: Mike Lorrey (mlorrey@datamann.com)
Date: Thu Feb 14 2002 - 10:47:13 MST


Anders Sandberg wrote:
>
> On Thu, Feb 14, 2002 at 02:46:03PM +0100, Eugene Leitl wrote:
> >
> > Problem with small holes is that there's a tradeoff between luminosity and
> > blackbody wavelength. E.g. a 10 kK hole would radiate less than a 10 MK
> > hole, but 10 kK radiation sans attenuation would be a lot easier to use
> > with solid state photovoltaic devices.
>
> Thermodynamically speaking, wouldn't higher frequencies be more
> efficient? We have spent most work on photovoltaics at wavelengths close
> to solar radiation, but I don't see why similar ideas can't be used for
> higher frequencies. Hmm, beyond a certain range molecular matter of
> course becomes rather fragile, but there might be some interesting
> nuclear photovoltaics that catch gammas and use them to do charge
> separation.

Well, I'd have to say that higher frequencies would penetrate materials
deeper (i.e. x-rays, etc) so that a given receiver would necessarily
have a lower energy density to efficiency ratio. Microwaves, which are
longer wavelengths than visible light, can be rectified into electricity
at a much higher efficiency than visible light can, etc..

So you have this curve of wavelength conversion efficiency to deal with,
plus a curve of wavelength versus total flux. Where these two meet
should be the wavelength you want your black hole to produce the most
of.



This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:12:22 MST