Talk:Second law of thermodynamics

What does "rest heat" mean?

Paul, in the "Discussion of the second law" section, you refer to Q_c as the "rest heat". Did you mean "heat at rest" or did you mean "the rest of the heat" or the "remaining heat"? I made no changes, but I do think that if you meant "remaining heat", then the wording needs to be changed. Perhaps to "remainder heat"?

If, on the other hand, you really meant "heat at rest", then the wording also needs to be changed, because "rest heat" needs to be clarified as to what is meant. Milton Beychok 19:58, 6 November 2009 (UTC)

About the use of DQ

Paul, in the term DQ/T. What is D? is that meant to be Delta? If so, then I think it might be better to use the symbol δ or Δ. I am certainly not the mathematician you are by any stretch of imagination, but I simply have never seen that terminology used to denote a small amount of heat (or anything else). Milton Beychok 20:17, 6 November 2009 (UTC)

How about using this quote somewhere in this article?

The statement by Clausius that "Die entropy der welt strebt einem maximum zu" (The entropy of the universe tends (strives?) to a maximum) is one that that has stuck in my mind ever since I first heard it in a university thermodynamic class over 65 years ago. How about using that quote somewhere in this article? Milton Beychok 20:38, 6 November 2009 (UTC)

Revised Metadata template

Changed the cat "Chemical engineering" to sub "Chemical Engineering", because Chemical Engineering (with a captal E) is a subgroup. Also added the cat "Engineering". Milton Beychok 03:00, 7 November 2009 (UTC)

Populated the Related Articles subpage

I also populated the Related Articles subpage, Paul. If you disagree with any of the links, just revise or delete them. Milton Beychok 03:18, 7 November 2009 (UTC)

Answers

Milt, thank you for reading the article. I really appreciate it.

First a very minor thing: Fig. versus figure/Figure. Different journals use different standards. I leave it as you changed it. Further I used "equation (1)", in some journals this would be Eq. (1) and in others Equation (1).

By rest heat I indeed mean "remaining", "remainder", or "waste" heat, in any case the heat that a power station flushes into a river or a nearby sea (this reminds me of the Manatees that I saw swimming in the warm water near a nuclear reactor at Crystal River on the Florida Gulf coast). What term would you prefer?

About DQ: I don't like δQ because it is used for variation of Q (something different, defined for functions). I don't like ΔQ because it would mean Q(x₂)−Q(x₁) for some parameter x, and the point is that Q is not a function of any x, it is just a small quantity. I've learned it a long time ago as a barred "d" (in some TeX implementations this is \dj), but I couldn't find that character. I've seen several books (among them by T. L. Hill) that use the capital D and that is why I used it. Some texts refer to it as an "inexact" differential, but I avoided that term, in my view it is not a differential, although by the magic of the 2nd law it becomes one if you divide it by T. Would you prefer a barred "d" and do you know where to find it?

I would love to use the Clausius quote, provided I can give the exact source. Would you know where to find it? Further I read in the meantime (in a book by T. S. Kuhn) that Kelvin was the first to realize that the entropy of the universe increases. But still, when you know where Clausius wrote it I'm more than happy to include it.

Cat/related articles is OK, thank you for taking care of that.

--Paul Wormer 09:08, 7 November 2009 (UTC)