Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: shufeng-zhang on 26/11/2010 19:50:37
-
We define heat engine efficiency η as: η= W/W1, that is, replacing Q1 in the original definition η=W/Q1 with W1, W still is the net work of the heat engine applied to the outside in one cycle, W1 is the work the heat engine applied to the outside in the cycle, then, we use Stirling cycle as the element reversible cycle, if ∮dQ/T =0 is tenable, we can prove ∮dW/T =0 and ∮dE/T =0.
If the formula ∮dQ/T=0,∮dW/T=0 and ∮dE/T=0 can really define new system state variables, it should come to the absurd result of such a definition.
In fact, during the process of obtaining entropy, ∑[(ΔQ)/T)] becoming ∫dQ/T is untenable, therefore, the formula ∮dQ/T=0, ∮dW/T=0 and ∮dE/T=0 are all untenable.
Entropy:A concept that is not Physical Quantity
By shufeng-zhang Email: uhsgnahz@126.com
College of Physics,Central-South University,China
http://wenku.baidu.com/view/cd8704d5b9f3f90f76c61b82.html
http://www.docin.com/p-90203843.html
-
To my mind the problem arises because entropy has two meanings one a precise physical meaning which allows you to calculate precisely how much useful work is obtainable from a heat engine operating between two clearly defined temperatures using clearly defined processes. The other is a much more abstruse concept related to the flow of energy in a system (universe) coupled with an attempt to define a generalised term for the limits that exist. I am afraid in english (and therefore most of science) we use the same word to describe both. Perhaps we should introduce some sort of qualifier to distinguish between them.
-
S remains k ln(w)
-
BC I agree that is the basic model of fundamental entropy but deciding on what all the independent states of the system are to define w is not easy and subject to argument.
-
I accept that it's not easy but there is, in principle, no argument.
You measure the entropy and that tells you w.
It's not a matter of opinion, it's a matter of fact.
No matter how many websites the OP posts his ideas on, as I said, S remains k ln(w).
-
OK consider you were the last person alive as the universe died the heat death and your space suit heater ran out of energy and you froze down to the ambient of absolute zero what then is your entropy?
-
"you froze down to the ambient of absolute zero "
In this house we obey the laws of thermodynamics.
-
LOL!!! I was not suggesting anything against the laws of thermodynamics but pointing out with a satirical thought experiment that the final state of something may be along way from the idealised random structure. So in your deciding of the number of states that anything has (w) to define its numerical entropy the route you take is important and the end points are not all the same Therefore the strict numerical entropy of something is not always single valued.
If you wish to think numbers it is far better to consider the normal differential entropy
-
The point I was making is that it jolly well does exist. It's difficult to calculate or measure in some cases, but it is real whatever shufeng-zhang says about it.
-
shufeng-zhang, this is not the place to promote speculative theories, and posts that consist of nothing but links without discussion will be deleted.
-
In fact, in thermodynamics, P-V figure should be P-V-T figure, that is, Carnot cycle should be drawn in P-V-T chart but not in P-V chart.
Please think the KEY STEP that "deduced" entropy in P-V-T chart, you will know obviously that the KEY STEP is untenable at all.
-
If it's fundamentally wrong, how come it works so well?
BTW, it's still k log (w)
-
it works so well?
You don't know its self-contradiction?
On the other side:
Aristotle free-fall theory worked well for more than two thousand years.
Caloric theory、Phlogiston theory worked well for many years.
And so on.
-
"Aristotle free-fall theory worked well for more than two thousand years."
Nope, it failed as soon as someone thought about it clearly.
"Caloric theory、Phlogiston theory worked well for many years."
Nope it was utterly inadequate to explain the experimental results. As soon as anyone checked on it, it failed.
What experimental evidence is there for a contradiction of entropy in thermodynamics?