[EMAIL PROTECTED] wrote:
Michel Jullian wrote:
> I think you're right on this Paul, however you're unnecessarily rude
as usual.
That's just your interpretation according to a POV of common social
behavior. That's a result of being programmed by society. What you
refer to as rudeness I refer to as bluntness with very little attached
emotions. On occasion I practice the art of tiptoeing around ones
emotions, which is what society refers to as common social skills, but
it requires unnecessary time and energy.
> Anyway I don't think that rectifying the hot resistor noise with a
diode breaks 2LoT. Does a photovoltaic cell (which is a diode too) break
2LoT when converting the thermal energy radiated by a 6000°C black body
to electricity? In both cases there is a cold source somewhere, not
everything is at the temperature of the hot source.
You can't just hypothesize that there's a cold reservoir somewhere --
the cold must be necessary to the effect, of course, or it's irrelevant!
And in the case of a resistor and diode, it's not obvious how a "cold
place" is necessary. What, exactly, must be kept cool in order to
obtain energy from the resistor?
Is it the diode? If so, why?
In general Maxwell's demon tends to run a fever in fall down on the job.
In this case it's the diode which is the demon, and I'd guess it's
heat in the diode that kills the effect. But I certainly can't prove it.
Come to think of it, considering that a thermocouple is really only
three back to back diodes with the center diode at a different
temperature from the outer two, I actually feel pretty confident that
it's heat in the diode which kills it in this case. (If you thought
there was only 1 diode in a thermocouple, ask yourself how the
dissimilar materials of the two sides of the thermocouple are attached
to the rest of the system.)
Michel, once again there is a vast difference between a law and an
interpretation of such a law. If you adhere to a stricter
interpretation of the 2nd law then yes, the solar cell breaks such a
law.
At 300 K a flat 1 x 1 m^2 of material emits 203 nW of radiation
between 1600 nm and 400 nm on one side. New technology allows
photovoltaic cells to efficiently capture up to 1600 nm wavelengths.
The 203 nW is a conservative figure since I did not include ultraviolet
photovoltaic cells. How much of that 203 nW depends on the efficiency
of the cell. As to how much such a cell will capture is irrelevant.
Fact remains that a photovoltaic cell will convert room temperature
black body radiation to DC, which could charge a capacitor.
And how much electrical noise energy is the cell converting back into
radiation, eh? If everything's at the same temperature you'll most
likely find the amount of radiation the cell is generating, as a result
of "running backwards", is equal to the amount of radiation it's
converting to electricity. You should at least check that possibility
carefully before you invest any money in a scheme based on this effect! ;-)
That is
storing ambient temperature energy to a capacitor, which will indeed
drop the net temperature in the closed system. Understandably even
present leading edge photovoltaic cells are highly inefficient at such
low radiation levels, but by laws of probability such a photovoltaic
cell will generate DC electricity.
The "laws of probability" predict that if you wait long enough you'll
fly up into the air because the molecules under your chair will all get
together and bump the bottom of your seat at once. That's a violation
of the second law, too, and in exactly the same sense.
For that matter you can dispense with the diode, photocell, and
everything _except_ the capacitor and a wire, and just wait for random
jiggling of the electrons in the wire to charge the capacitor. (You may
need to wait quite a while, of course.)
These examples may be hard to reconcile with the second law of
thermodynamics but that doesn't make them any less irrelevant.
Rectifying Brownian motion has been an "impossible dream" ever since
someone first noticed its existence.
Therefore, you'll have to ask yourself if the photovoltaic cell breaks
the 2nd law in accordance to your interpretation of such a law. Here's
a quote from Wikipedia,
Quote,
http://en.wikipedia.org/wiki/Brownian_ratchet
---
"This is against the principle of the second law of thermodynamics,
which can be stated as 'It is impossible for any device that operates on
a cycle to receive heat from a single reservoir and produce a net amount
of work."'
---
A charged capacitor is a source for usable work and can generate heat.
[snip]
Regards,
Paul Lowrance
