Talk:Second law of thermodynamics
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Statement of Law
Could this article please begin with a concise statement of the 2nd law?
Free Lunch
Should it be mentioned that this is often reduced to "There 'aint no such thing as a free lunch"?
microstates and macrostates
the only way i have ever understood this stuff is someone explaining macrostates and microstates. they reduce it to a small game of black and white chits on a board or something. or maybe it was coins, and heads and tails. i cant remember where i saw this, but it sure would help peopel reading wikipedia if someone could do the same here.
Link between heat cycle and entropy ?
I'm trying to explain the 2nd law in simple terms. This is still very much a work in progress. Any help welcome. I have some difficulty making the link between the fact that no heat cycle has a 100 % efficiency, and the fact that disorder is growing: why are those facts equivalent ?? I'll have to do some more research to find out... Pcarbonn 20:41, 22 May 2004 (UTC)
Creationism
I would just like to voice my strong opposition to having creationism stuff on a science page. Objections to scientific ideas should come from scientific sources and the scientific argument should be at least outlined, not just given in links. I'm not demanding anything, just voicing. I know this isn't "PC", and I'll prolly get bashed by all the "PC" appeasers out there, as well as creationists, but sobeit. --DanielCD 13:52, 4 Aug 2004 (UTC)
- No, I put the section in, but basically I'm a biologist and have probably had more experience with this sort of thing. It's in here because its a useful social phenomenon, nothing to do with science, whilst. It's deliberately at the bottom of the article, so the law can be summarised and its history and implications given. If someone bothers to read that far, they might as well know about its misuse by creationists. It is an issue for the whole of science really, though biology gets the brunt of it. See this essay by a physicist (http://www.aps.org/apsnews/1100/110018.cfm). Anyone with any knowledge of science can see that it is patent nonsense, but let them see, there is no need to censor it, let it speak for itself. If there is a particular creationist issue with any topic in biology, I will try to put links in to their POV — let these people speak for themselves — the best advert for science and rationalism is a fundamentalist Christian. Dunc_Harris|☺ 15:28, 4 Aug 2004 (UTC)
- Thanks for the response. Makes me feel a bit better about it. --DanielCD 15:36, 4 Aug 2004 (UTC)
- The argument of the second law and biological evolution, while I don't believe it's a good one, is often misconstrued. That the second law of thermodynamics poses a "direct contradiction" against biological evolution is not an entirely accurate statement of the creationist position. The second law suggests a tendency to go from order to disorder. A number of creationists claim (however incorrectly) that evolution lacks the means to overcome this tendency. Creationists do however claim a "direct contradiction" between the second law and what could be called cosmological evolution. What creationists often claim is that an overall increase in cosmic order is a violation of the second law (since the universe as a whole is taken to be an isolated system). Perhaps this creationist position is flawed also. Nonetheless, misrepresenting the creationist position (however flawed) as it pertains to biological evolution will not do much good. Hence, my attempts to expand the matter in the section. (Wade A. Tisthammer)
Makes it seem like perpetual motion machines are possible
Quote from page: "Any device that violates the second law of thermodynamics would be called a perpetual motion machine of the second kind. One example of this would be a device that can do work such as pumping water, simply by taking energy from the air." Though I'm not sure what the definition of a perpetual motion machine of the second kind is, it seems to me that this paragraph is unclear since readers will think "But that's possible - people have been using windmills for ages - so perpetual motion is possible?" Perhaps change this to "by taking heat energy from the air." --Jomel 15:23, 13 Aug 2004 (UTC)
Hawking
In 1988, Stephen Hawking, in his book A Brief History of Time, used the following line of thought to show the effect of the measurement mechanism : if, contrary to the second law, the entropy of all systems decreased with time, our brain would also go from ordered to disordered over time, and we would not be able to remember the observations we made (because in that case our brain would go from disordered to ordered, which would be a contradiction; see arrow of time). In other words, we would not be able to observe a world where the inverse of the second law would hold everywhere.
I dont remember Brief History well enough, but stated this way it is patent nonsense.
- actual law: entropy of all closed system increases
- logical negation: entropy of some closed system decreases
- "inverted arrow": entropy of all closed systems decreases
- nonsense: entropy of all systems increases/decreases
Entropy of open system can decrease. Example: booting computer, bits in RAM go from disordered to ordered, entropy decreases. (But: it the process electricity is converted to heat and in closed system "power plant+coal+atmospehere+my computer" enropy increases.) Our brain is like computer.
- if the entropy of all systems decreased with time, our brain would also go from ordered to disordered over time
Bad implication - entropy decreases, system go from disordered to ordered.
creationism 2: the return
Okay, there is a suggestion that the creationism section be expanded. Okay, but not the POV rubbish that anons (66.... and 160..... ) have been adding. To start off with "the creationist argument is often misconstrued" is POV; it is not construed it is like all creationism, empty rhetoric, which ironically results from the miscontruing of the second law. Dunc|☺ 20:07, 9 Dec 2004 (UTC)
creationism link
The answersingenesis link says "A closed system exchanges energy but not matter with its surroundings." This is incorrect, right? A closed system is defined as exchanging neither? - Omegatron 18:16, Jan 3, 2005 (UTC)
bad example
"One example of this would be a device that can do work such as pumping water, simply by taking energy from the air."
- I don't understand what this example is trying to show. A hidden source of energy would be something like the potential energy of a water tank being physically above an outlet. Maybe try to think of a real perpetual motion machine claim and how it worked. - Omegatron 17:32, Jan 3, 2005 (UTC)
Creationism stuff
"..entropy can decrease in an open system, but simply applying energy to a system will not decrease entropy." So what, it's impossible for energy to flow anywhere? Nothing can happen and everything is static? It's impossible to throw a ball into the air? Water can't splash? This stuff is complete nonsense and it should be stated that it is wrong since it is. It's not a point of view. --DanielCD 15:27, 25 Apr 2005 (UTC)
I removed a paragraph because it's wrong. Nothing says "disorganized energy" has to increase entropy. The universe has all kinds of "disorganized energy" in it creating forms with massively decreased entropy all the time. What's a star? What's a galaxy? Are we trying to say that no complexity can exist in nature without people creating it? We have to adhere to the scientific definitions not just what something "looks like." There are highly ordered systems everywhere that occur naturally. --DanielCD 15:34, 25 Apr 2005 (UTC)
2nd law question
I've got a question about the 2nd Law. It states heat does not spontaneously flow from cold to hot bodies . What about, say, magnifying solar power here on Earth with lenses/mirrors/whatever -- would the maximum temperature that one could achieve on Earth merely by focusing solar power be at most the surface temperature of the Sun (5800K, which is what the blackbody radiation curve of the Sun corresponds to)? I've heard, unreliably, on a few sites that this is the case, though no one indicates why.
(For example, this (http://www.gstt.org/publications/news/newsletter13/solar%20power.htm) site claims that a large solar magnifier should attain "the surface temperature of the Sun).
This all makes sense from the POV of the 2nd law, but it seems like if you could concentrate, say, 100m^2 of solar energy (at 1kW/m^2) into a tiny area, you'd have an enormous amount of energy in a small area, and I don't understand why it would be limited by the temp. of the Sun. Also, it's obvious that you could convert the same light into electricity, and use that electricity to make temperatures as high as you want.
Could anyone shed some light onto this puzzle? Schmiddy 19:23, May 11, 2005 (UTC)
