k.e..
Posts: 5432
Joined: May 2007
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| Quote (olegt @ Sep. 07 2012,15:02) | PaV chimes in with some weapons-grade po-mo bullshit:
| Quote | | I think, for the sake of simplicity (and, hopefully, clarity) we should take a very simplistic view of what entropy is: it’s basically directionless-ness. It is a ‘loss’ of ‘direction’. |
Alas, clarity is nowhere to be found. He begins with explaining how he understands Clausius's version of the second law:
| Quote | No cyclic process is possible whose sole outcome is transfer of heat from a cooler body to a hotter body
This statement presupposes: (1) that the bodies are either separate from one another, or, that there are separate areas of one body–a ‘hotter’ and a ‘cooler’ area, and (2) that the ‘flow’ of energy/heat goes in only ONE ‘direction’: from hot to cold. Flow itself is likewise a vector quantity and, hence, itself implies a ‘direction’.
What we seem to go round and round on here at UD is this notion of ‘directionality,’ and it seems that what we loose sight of is this minimal amount of ‘directionality’ that entropy requires. |
Round and round he goes and then comes to this gem:
| Quote | (N.B. Again, this irreducible ‘directionality’ that entropy requires can be lost sight of even in a classical thermodynamic equations like dU = TdS – pdV. On the r.h.s., the first term amounts to dQ, which is the already present ‘internal energy’ of the system. On the l.h.s., dU is the change in ‘internal energy’. Finally, the second term on the r.h.s. is pressure x volume. What is perhaps hidden here is that pressure equals Force/Area. And, again, force is a vector quantity, and, so, has ‘direction.’ To change the heat content of something, ‘work’ has to be done, and pdV is what accomplishes it. Now, if you heat up a pressure cooker, the pressure will always be at right angles to the container’s walls–i.e., it is a NON-RANDOM orientation of forces!
This is the critical point: an entropy change always has a direction. This is exactly what the 2LofT tells us, but, we usually lose track of it. Nevertheless, it’s there. |
I hate to break it to you, PaV, but dQ is NOT dQ, "the already present ‘internal energy’ of the system." It is the amount of heat received by the system. And although force indeed is a vector quantity, its direction has nothing whatsoever to do with the direction of heat transfer. It's hard to sound any more clueless that this!
It goes downhill from there as PaV channels his long-lost knowledge of calculus:
| Quote | Let’s look at an example that Sal uses in the second part of his recent post on entropy.
He tells us that the change in entropy, S, is equal to the integral (sum) over the initial and final values of dQ/T. (N.B. the ‘initial’ value of dQ/T is always higher than the final value of dQ/T, revealing again, this hidden directionality. Normally, in any given mathematical expression, there is no need for the initial value to be ‘less’ than the final–they just need to be different) |
PaV clearly used to be able to do integrals, but he does not understand them now, so all he can do is wax poetic about them. Not surprisingly, he looks at Sal's calculation of entropy and says thanks, but no thanks:
| Quote | But let’s move on.
Sal then adds:
Perhaps to make the formula more accessible, let us suppose we have a 1000 watt heater running for 100 seconds that contributes to the boiling of water (already at 373.2?K). What is the entropy contribution due this burst of energy from the heater?
Well, let’s turn this around (change it’s ‘direction’): what would happen if we had a 1000 watt (electric) heater surrounded by water that was boiling, and then we added steam to the system that was generated by a nuclear reactor. Would this produce electricity? Of course not! This energy-producing system only works in one direction!
Nevertheless, it is possible to take the steam that a nuclear reactor produces and then produce electricity! But this is an entirely different process/system, and, it is a process/system that is given its ‘directionality’ via intelligent design of engineers.
And, here we have it. This is the nub of the issue, I believe. Darwinists want to convince us that if ‘steam’ is available (analogously, the energy of the sun), then ‘electricity’ can be produced (analogously, the ‘direction’ of entropy can be reversed). |
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PaV is pushing warm shit uphill.
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