Talk:Second Law of Thermodynamics

Wrong! Wrong! Wrong!

I am getting a little tired of the (pardon the immoderate language) stupid edits in relation to the second law of thermodynamics. As has been stated by a number of people on the Talk:Theory of Evolution page, the second law of thermodynamics does not disprove the theory of evolution. You are just making this site look stupid by stating that it does. I see that the person who committed the muddleheaded reversion has now protected the page. Might I respectfully suggest that the protection be removed and some scholarship prevail. --Horace 22:01, 3 March 2007 (EST)

Protection and other issues

The trend towards protecting articles by users in edit conflicts is worrisome. Furthermore, the protected version is simply wrong. One of the Conservapedia Commandments is that everything should be sourced. I therefore would very much like to know if there is any source for the claim that "he Second Law of Thermodynamics states that the entropy of the universe tends towards a maximum" This statement is wrong at multiple levels- the 2nd Law is about closed systems (or can be stated about open systems with a some tweaking of the consequent), it says nothing about the universe. Furthermore, tending towards a maximum doesn't even mean that the entropy levels can't decrease. For example, the sequence, 1,3,2,5,4,7,6,9,8... tends towards infinity but is not an increasing sequence. JoshuaZ 04:05, 4 March 2007 (EST)

Second law also says nothing about an upper bound to the entropy of a system; the entropy of the Universe could increase without limit, in principle, making the 'maximum' part wrong too.

To be fair to Philip, the increase of the Universe's entropy is a tendency, not an absolute. The total entropy of an isolated system can decrease; it's just hugely improbable on the scales we're used to dealing with. Quantum effects can lead to a decrease in entropy; one has to deal with a very small system over short periods of time to actually notice this, however. Arbitrarily large decreases in entropy are also possible, given sufficient time. This is true whether one is discussing the fluctuation theorems of QM, or good old-fashioned classical systems.

But these are not, strictly speaking, parts of the second law. Second law doesn't say anything about tendency. The rest of physics just says that second law is not absolute. So I don't think using the word 'tends' in the definition is very useful.

The main problem with the article is, of course, the part about evolution, which as Horace says is just wrong, and painfully so. It's a seductive argument to the layman; after all, entropy is all about order and disorder, and evolution clearly requires the production of order. Right?

Wrong, of course. The second law of thermodynamics is a statement about thermodynamic quantities; 'order' is not one. One can choose to define the term 'order' in thermodynamic terms, in which case the statement that the Universe must become, on net, more disordered over time is true, for certain definitions. But the price for that is rejecting one's intuitive understanding of what constitutes 'order' and 'disorder,' and going with the maths. By a thermodynamic definition of order, my hot chocolate is self-organizing as we speak. Therein lies the danger of describing esoteric physics in terms which carry the baggage of their lay definition. Better to stick with entropy, and check one's prejudices at the door.

Perhaps the simplest way to illustrate this is with a different statement of the second law; the Clausius statement, which reads:

It is impossible to construct a heat engine which, operating in a cycle, produces no effect other than the transfer of a quantity of heat from a colder to a hotter body.

Now, precisely which part of evolution violates that? This version of the second law makes it abundantly clear that we're talking about a specific, mathematically rigorous statement about heat flow, not some general philosophical statement about order and chaos. Tsumetai 07:51, 4 March 2007 (EST)

Oh, yes, I forgot to weigh in on the page protection issue. Tonya Harding strategy, right?

A while ago, I suggested to ASchlafly that a written policy on when page protection should be used, and for how long it should last would be helpful. Anyone else agree? Tsumetai 07:58, 4 March 2007 (EST)

The following is incorrect

From the article:

"It is impossible for the total entropy of an isolated system to decrease, therefore the universe is becoming more and more disordered. In this way the Second Law of Thermodynamics disproves evolution."

The first sentence is true, but the second is false. Evolution does not cause the total entropy in the universe to decrease, only local variations. By analogy, a fridge does not cool the universe, only a small part of it at the expense of the rest. Please correct this clear error to avoid the increasing levels of criticisms being levelled at this wiki. Nematocyte 07:45, 5 March 2007 (EST)

To add my thoughts on this: there are two errors in this article. First, the second law only applies to isolated systems, not to systems that are merely closed, let alone open. Then it becomes clear that the "disproving" of evolution by referring to the second law is severely flawed. There is nothing against a local decrease in entropy, as long as it is balanced by at least as large an increase elsewhere. Moreover, the assumption that evolution is directly linked to a decrease in thermodynamic entropy is not immediately obvious. I agree with Nematocyte that in its present state, this article will just serve to invite more criticism. PaulB 09:16, 13 March 2007 (EDT)

Time to unprotect

OK, it's been over a week now, and no one has attempted to defend the inclusion of such rubbish. Might we have the article unprotected so that those of us who actually understand elementary thermodynamics can fix it? Tsumetai 07:50, 12 March 2007 (EDT)