DGDanforth wrote:The second law of thermodynamics is a statistical 'law'. In my opinion, it is not a fundamental law. <snip>
Changing kinetic energy to some other form (such as electric current) doesn't violate energy conservation.
In like manner, I don't view entropy as fundamental. It is only because of the statistical nature of the objects to which it is applied that give it credence.
DGD, thank you for raising the level of this discussion. IMHO you have a robust argument.
This seems to be the same argument, or at least one similar to, the argument that a device which would function as a Maxwell's Demon may actually be possible; that it may be possible to construct a gate which will pass only molecules whose Brownian motion (and therefore temperature) is either greater than or less than a certain limit.
But I've recently read a persuasive argument that the Maxwell's Demon gate would fail, because the control mechanism (a ratchet, for example) of the gate would itself be subject to Brownian motion, defeating the ability of the gate to separate faster-moving molecules from slower-moving ones.
All this is, of course, highly theoretical. The reason I think that we will find it difficult or impossible to take advantage of the statistical nature of thermodynamics-- why we will likely never invent a practical "free energy" device or process, nor a functional analog of a Maxwell's Demon-- is because nature has never invented one. Nature and evolution have had billions of years to invent more efficient biological processes. We are only now beginning to understand how, for example, photosynthesis achieves such an astonishingly high efficiency, on the quantum level, at converting solar energy to chemical energy.
Yet no organism we have discovered runs its metabolism on "free energy"; none has dispensed with the need for a constant input of energy, either chemical energy (food) or sunlight. If Nature had ever invented a quantum method of harvesting useful work from ambient heat, the organism in which it first appeared would have easily out-competed every other type; there would be no life form left in the world except descendents of that one lifeform!
Now, I don't consider this "proof". After all, humans have invented things Nature never did. No organism uses radio for communication; Nature never invented the transistor; no critter's nervous system uses digital information processing or storage.
But for something as basic as finding a quantum method of harvesting energy from ambient heat, or Brownian motion, or any sort of random quantum process-- energy which can be use to perform work, or decrease entropy-- I think if it were possible, Nature would have already found a way.
Again, I don't consider this proof that we'll never be able to take advantage of the statistical nature of thermodynamics to "cheat" entropy-- I just find it highly unlikely that we ever will.
DGDanforth wrote:If the marbles of a Chinese checker game are put into a corner of the board are they in a lower entropy state than if they are randomly spread over the board? Every state is just a state. No one of them is more important or special than another one. It is only when one invokes the time dependent process that governs the motion of the particles that some states stand out more than other ones. Change the process and you change the 'entropy' (probability distribution).
I don't think marbles on a Chinese Checkers board is a good analogy of physical processes on the molecular level. Moving marbles one by one into one corner of the board does not increase the energy necessary to move the next marble to the same corner. Yet if you were to try the same thing with molecules of gas in an enclosed container, trying to move them all into one corner, you'd find that the more molecules you moved into that corner, the higher the temperature in that corner would become. Each molecule moved there would increase the amount of energy necessary to move the next molecule there.
Last edited Sun, 11 Mar 2012, 9:21pm
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