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WikiProject Physics (Rated C-class, Mid-importance)
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C-Class article C  This article has been rated as C-Class on the project's quality scale.
 Mid  This article has been rated as Mid-importance on the project's importance scale.
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Start C   This article was improved from Start-Class to C-Class

The above assessments refer the article quality at the time of the TAFI collaboration, and should not be altered to reflect subsequent changes! (Further information)


This article is pretty pathetic. (talk) 18:11, 12 January 2009 (UTC) its cold in here —Preceding unsigned comment added by (talk) 13:48, 31 January 2009 (UTC)

I think the addition of the waiting room was funny. -- (talk) 04:47, 1 March 2009 (UTC)

Nice, interesting and extensible! Why dissolve it within another article? (talk) 12:56, 4 February 2009 (UTC)

  • I agree with the first user above. This article doesn't really say anything, especially of an encyclopedic caliber... Stevenmitchell (talk) 04:43, 4 March 2009 (UTC)

I'm just a non-physicist Dutch speaking guy, but ehm, why does it say that cooling of an object by exposure to ice, dry ice, or liquid nitrogen is done by convection? I'm thinking thermal conductivity, and if done in a fluid or gas (not ice!) convection might just occur, right? I hope some natively English speaking lab guy picks this part up. Rogier —Preceding unsigned comment added by (talk) 09:48, 4 November 2009 (UTC)

The statement “a cold object will contain less thermal energy than a hot object” is not true. It depends on the mass of the objects and the specific heat of the objects.Geweber (talk) 21:14, 5 February 2011 (UTC)

Absolute Zero Theoretically Possible?[edit]

I don't know much about thermodynamics, but I am fairly certain that absolute zero is theoretically impossible. Am I right about this? If I am then the article should be changed to reflect that. Eiad77 (talk) 08:08, 12 July 2010 (UTC)

I don't see why it would be theoretically impossible. They've gotten close, see Bose–Einstein condensate. The problem is how you verify without heating. (talk) 18:44, 24 December 2010 (UTC)
If the substance is at absolute zero, there is no movement of the atoms and hence they have no momentum. If you then measure their position to a high level of accuracy you know both the position and the momentum to a higher level of accuracy than you should be able to. This is a violation of quantum mechanics - specifically the uncertainty principle. —Preceding unsigned comment added by (talk) 00:30, 2 February 2011 (UTC)
This would be a contradiction. The particle to be measured cannot emit positional information itself. It doesn't have the energy. And it has no momentum. The outside observer cannot "pulse" the particle because this would impart energy to it (as editor ...83 has mentioned), raising it above absolute zero. So it seems to me that it is, even in theory, impossible. Never mind that absolute zero cannot practically be achieved. Student7 (talk) 14:08, 4 February 2011 (UTC)
Well, let's see - to cool something you have to remove heat. heat only flows from hot to cold. nothing can be colder than absolute zero. so, how are you going to cool something to absolute zero in the first place? so, don't know if it is theoretically impossible, but from a practical standpoint, it doesn't seem realizable. — Preceding unsigned comment added by (talk) 22:26, 19 July 2013 (UTC)

Opposite of hot?[edit]

Not really the scientific opposite of "hot," but rather the absence of heat. May be grammatically true, but this is not Wiktionary, but an encyclopedia. As pointed out above, while an absolute lack of heat cannot be achieved, we know where that is. We don't really know how hot it can get. Student7 (talk) 02:54, 24 December 2010 (UTC)

Cold and Hot are also touch senses, and in that sense are opposites. Presumably ice is cold whereas steam is hot to the touch. (talk) 18:58, 24 December 2010 (UTC)
Either need to decide whether this is a science article, in which case they are not opposites or a grammar article, in which case it is. Or a dab page with forks to cold (science) and cold (grammar) (sensation). Student7 (talk) 14:10, 27 December 2010 (UTC)

What is the coldest metal element?[edit]

I mean, if say you kept every known elemental metal at -40° and then measured the temperature of the survice of them, which would be the lowest? Robo37 (talk) 17:08, 12 November 2011 (UTC)

Because temperature is the average thermal energy of an object, each metal would be the same temperature. Mind you, some metals have different melting and freezing points, but a similar temperature would indicate that they are at equal amounts of thermal energy. Zoughtbaj (talk) 16:17, 29 June 2012 (UTC)

Order of content[edit]

Looking at this page I am undecided about what works best - a strict chronological flow with divisions based on age (as current), or divide into Research/Theory, Industrial cooling, and Residential cooling. Cas Liber (talk · contribs) 19:28, 16 February 2016 (UTC)

Pardon my confusion, but I don't see any sections on industrial and residential cooling. I'm not sure the emphasis should be on cooling in this article. In my opinion, the physiological sensation of cold and response to cold might be primary among lay folk, along with how the concept of cold was thought of in history. Then the relation of cold to the idea of temperature and the modern view of cold. What makes cold dark matter like a cold beer? Cooling, as a way to make things cold, deserves a place in the article. This is a broad concept article, so should probably leaning a lot on main articles. But these are just my opinions. I don't have a solid secondary source to suggest an ordering. --Mark viking (talk) 22:52, 16 February 2016 (UTC)


I've changed all the dates to yyyy-mm-dd as an editor changed the lot from a combination of MDY & DMY to all MDY,
This isn't an American article so therefore the dates shouldn't of been all converted to mdy and it'd be the same for dmy - Both date formats should be used but seeing as it'd take forever to change some individually I feel this is the only best way of doing it,
Had this been an American topic then I'd happily let one knock themselves out but it's not .... Us British feel the cold as well! Face-sad.svg. –Davey2010Talk 23:07, 21 February 2016 (UTC)

Hi Davey2010. Thanks for updating the dates, I do think that the format you chose is more neutral. Note though that MOS:DATEUNIFY indicates that the date format used in citations should be consistent, as should the format of dates in the article body, so articles should generally not use mixed formats. You're right that this article has no strong national ties, so there is no reason to choose MDY over DMY, but MOS:DATERET states that if an article already has a consistent date format in place, then it should be maintained and there's no reason to make broad changes to format after a standard has been established.
In this case, when the article became the TAFI selection last week, the date formats were mixed. Another user decided to make the formats consistent (MDY) on 15 February, but then subsequent additions to the article used DMY format. My edit on 21 February was only meant to make these newer additions consistent with the previously established format, which I knew had been decided upon by the {{Use MDY dates}} template at the top of the article. The format you chose for citations was certainly appropriate, but the MOS doesn't allow for yyyy-mm-dd format to be used in the article body, and dates currently in the article body use MDY format, so MDY format should probably be retained for the article body. There are a few other dates in citations that were left in MDY format, so I'll go ahead and change them to be consistent with the format you chose. Thanks for your work on the article! Ry's the Guy (talk|contribs) 10:16, 23 February 2016 (UTC)
Hi @Rystheguy and Davey2010: Per the Wikipedia house style MOS:DATES guideline and per other guidelines and WP:essays I set all dates to be consistent at mdy because that was the preponderance at that juncture. If we go by preponderance, then mdy is the correct choice. If we go by the first use of date in the article then the datestyle should be dmy. dmy is used by 90% of the world, so dmy is where we should go. Date consistency throughout the article is the date MoS, including in the references. All-numerical dates are discouraged because day and month are interchanged in various locales. YYYY-DD-MM is never used on the English Wikipedia. YYYY-MM-DD is not to be used in prose. It can be used in tables that need special sorting. There is no strong international tie to "cold" so we are allowed to use mdy or dmy depending on which style was used first. dmy was used first per this diff and per ones that precede it. To that end, since this article lacks tables, we need to change ALL dates back to dmy. Cheers! {{u|Checkingfax}} {Talk} 00:13, 24 February 2016 (UTC)
Hi Checkingfax, I agree YYYY is hardly ever used but I figured instead of everyone edit warring over it I would do the next best thing, I don't mean this in a dickish way but It happens alot when an American will come over and change everything to MDY ... I've noticed it alot and kinda assumed it was the case here, Wait so hang on you believe it should be changed back to DMY ?, Well I have no objections as I agree DMY is used nearly everywhere but anyway if you want to change it I have no objections, Thanks, –Davey2010Talk 00:23, 24 February 2016 (UTC)
I agree with Checkingfax. My only motivation was to make the formats consistent within the guidelines of the MOS, so using DMY is fine with me. Ry's the Guy (talk|contribs) 06:43, 24 February 2016 (UTC)
Hi @Rystheguy and Davey2010: I set them all to dmy. Cheers! {{u|Checkingfax}} {Talk} 07:21, 24 February 2016 (UTC)