Charles M. Brown wrote:
Feynman's ratchet used one sprung pawl on a ratchet wheel. The spring
biases the pawl towards the ratchet wheel so mechanical pressure on the
gentle slope of the ratchet wheel drives the wheel the wrong way where
it can rest against the sharp or even overhanging slope. If the pawl is
then lifted by Brownian motion and the ratchet wheel moves a little the
wrong way when the pawl is high, possible 50% of the time, than the
wheel will rotate the wrong way. If the ratchet wheel moves a little the
right way when the pawl is high, possible 50% of the time, then the
pawl will return to a low part of the gentle slope near the sharp slope.
If there are many pawls on one ratchet wheel than they do not have to be
biased by springs because the probability is high, and increases
exponentially with the number of pawls, that at least one pawl of a
similar position group will be in position to block counter rotation of
the ratchet wheel. This type of system should behave like a larger scale
mechanically rectified ratchet wheel at thermal power levels.
I don't think Feynman tried hard enough to break the Second Law.
Fabricating a device that fails with inadequate design doesn't prove
that a better design won't work.
Indeed, you can't prove a theorem with examples, no matter how many
examples you have; using an example can only serve to disprove it (if
the example happens to violate it).
One of my big flops in school was thermo -- I dropped the course at the
point where the textbook presented a "proof" of something or other which
I simply could not follow. As far as I could see the proof didn't prove
anything -- and when I asked about it during the next lecture, well,
that's when I found out the professor was /deaf/. There I was, sitting
in the hall, in a front row seat, with the prof struggling to hear my
question -- he walked over to stand right in front of my chair with his
hand cupped around his ear and had me repeat it, really loud, for about
the fourth time -- with 200 other students sitting in stunned silence in
back of me. Finally the prof went back up to the board and answered the
wrong question 'cause he never had managed to hear what I was asking.
And so I filled out a drop slip and sold the textbook and never did
really learn the subject, beyond Feynman's brief treatment in his
physics lectures.
Classical treatment of Feynman's ratchet:
http://www.eleceng.adelaide.edu.au/Groups/parrondo/ratchet.html
Aloha,
Charlie
