Talk:Mpemba effect/Archive 1

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Archive 1

Possible solution

Not sure if this is a solution - I don't understand it enough to add or edit the main article https://medium.com/the-physics-arxiv-blog/why-hot-water-freezes-faster-than-cold-physicists-solve-the-mpemba-effect-d8a2f611e853#.khu4xov6s [[[Special:Contributions/80.4.165.202|80.4.165.202]] (talk) 04:53, 5 May 2016 (UTC)]

The English is so poor in the arxiv article that I find it impossible to evaluate the claims fairly, as it's unclear what they are. My BS detectors go off often.--Elvey^(t•c) 20:42, 26 August 2016 (UTC)

I am pleasant to present you the new version of my explanation academia Warmed up and recooled water contains more entropy than cold water El662009 (talk) 12:23, 23 February 2018 (UTC)

Improvements

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The article would be improved by a free copy of the chart at http://www.sciencebuddies.org/science-fair-projects/project_ideas/Phys_p032.shtml#background - [1]. (In the US, facts (the main content of the chart) aren't copyrightable.)

Perhaps the article should go into more of the things that would make for a good or bad experiment, and or more or less likely to produce he effect. One of the latter would be assuming that the freezer temperature is stable, while a good experiment might address this by doing the tests at the same time, so any temperature variation would tend to effect the results equally.

I tried to reproduce the effect and didn't find it. Used quarter cups of tap-hot and tap-cold water, in plastic cups in a home freezer. To minimize conduction, I leaned the the cups so they were in contact with the freezer shelf at only a point. I tested all samples at the same time. The cool water froze much sooner than the warm water. Likewise, when professor Osborne first confirmed Mpempa's claim, he minimized conduction, but by placing the samples on a sheet of polystyrene foam. The effect as described implies steps have been taken to minimize conduction, but some efforts to reproduce the effect don't take such steps. (One YouTube video shows beakers being placed directly on a bed of ice cubes!) Looking at the chart noted above, there's no clear optimal set of temperatures to maximize the effect, but it looks like a temperator for the 'cold' water is fairly warm: somewhere around 60 to 80 Celsius is likely optimal.

It's claimed that "the effect has been noted by many scientists throughout history including Aristotle, Francis Bacon and René Descartes." so this should be added if solid sources confirm it. The Aristotle quote is readily verifiable, at least.

This is definitely a case where we should be careful what we say in wikipedia's voice. Extraordinary claims require extraordinary evidence. We've got the 2012 Royal Society of Chemistry competition making it seem quite real, and yet it seems quite fleeting in 2014 - most are saying it's not reproducible --Elvey^(t•c) 20:42, 26 August 2016 (UTC)