From: michael k teehan (miketeehan@worldnet.att.net)
Date: Sat Dec 20 1997 - 04:20:06 MST
----------
> From: John K Clark <johnkc@well.com>
> To: extropians@extropy.com
> Subject: the ultimate refrigerator
> Date: Saturday, December 20, 1997 1:45 AM
>
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>
> >>Me:
> >>I have thought of a problem with the Black Hole refrigerator
idea
> >>however. You're going to have to put your heat radiators pretty
> >>close to the event horizon because Black Holes are small but
they
> >>must fill a large part of the shy. When you get that close the
huge
> >>gravitational field is going to blue shift light, including the
> >>ubiquitous cosmic microwave background radiation, except that
it
> >>wouldn't be microwave radiation anymore, it will be infrared or
> >>beyond.
>
> >Hara Ra <harara@shamanics.com>
> >There's an easy fix to this. Use a telescope. What telescopes do
is
> >enlarge the amount of sky seen by the telescope's magnifying
power.
> >Using a very low f ratio means your radiator can see a lot of
black
> >hole in the sky, at a reasonable distance. Just focus the
telescope
> >on the black hole and put the radiator on the focal point.
>
>
> That won't work. A lens (or curved mirror) can only bring light to a
focus if
> the wave front is parallel or nearly so, and that can only happen if the
lens
> is small and far from the light source. The wave front of the blackbody
> radiation near a heat radiator would be almost spherical and so will not
> focus for the same reason a lage magnifying glass placed right next to a
> light bulb will not focus. To work you'd have to place your telescope at
a
> large distance from the radiator where the wave front has become almost
> parallel, and then only a very small percentage of the heat radiation
would
> intersect with the lens.
>
> Another way to see this is that If it were not true you could make a
> perpetual motion machine, just focus the waste heat from a steam engine
> and run another steam engine with it, then do the same thing with that
steam
> engine.
>
> John K Clark
johnkc@well.com
>
>
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