Re: Why can't we beat 2nd Thermo with low f-ratio?
- From: "Michael" <mbush@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Thu, 13 Apr 2006 16:02:44 GMT
Not to dispute your larger point, but Archimedes legend isn't impossible....
see http://web.mit.edu/2.009/www/lectures/10_ArchimedesFAQ.html for an
interesting experimental demonstration
"Andy Resnick" <andy.resnick@xxxxxxxxxxx> wrote in message
news:e1lms1$fg$1@xxxxxxxxxxxxxxxxxxxxxx
Neil wrote:
I've heard that limitations in principle (?) of optical focusing won't<snip>
let
us form an image with a brightness greater than the source itself, even
though it *seems* that in principle we could squeeze down f-ratio enough
to
do that. (I forget which Sci. Am. or etc. article discussed this issue in
reference to solar collectors.) If we could, that enables violation of
the
2nd Law of Thermodynamics. Just let the lens focus thermal radiation from
one surface onto another, which would reach a higher equilibrium
temperature
than the first. (? - Although the radiation would go both ways, we can
have
the source at enough distance that it receives a narrow pencil of rays
from
the target.)
Some time ago, someone posted the following reference:
G. G. Slyusarev, "On the Possible and Impossible in Optics",
FTD-TT-62-175/1+2 (19 July, 1962)
Which I recommed you read. The first 11 pages specifically discuss the
legend of Archimedes setting ships on fire using mirrors. This legend,
and your idea, requires the existence of energy-carrying parallel beams
(which do not exist) and concentrating cones (which also do not exist).
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University
.
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