Talk:Mpemba effect

message: "containers at 35 and 5 °C (95 and 41 °F) to maximize the effect"
This 5 °C is roughly (as if rounded) where liquid water is at maximum density. Freezing from the higher temperature would require less expansion. The density change should also have an effect on entropy.  — Preceding unsigned comment added by 97.104.88.146 (talk) 08:26, 22 May 2016 (UTC)
thread_title:  interesting temperature 

message: The article several times refers to the 'quantity' of water without specifying how this is defined.  The Mpemba/Osborne experiments appear to have used volume as the measure of quantity.  The other obvious measure would be mass (usually measured by weighing in standard conditions).  Since the density (mass per unit volume) of water varies with temperature, the two measures are not equivalent, as a unit volume of water at a higher temperature will generally have less mass than the same volume at a lower temperature.  Quantitatively the difference is probably too small to explain the alleged phenomena, but it seems desirable to avoid the ambiguity.86.132.140.164 (talk) 13:56, 7 December 2016 (UTC)
thread_title:  What is 'quantity'? 

message: Batholomeo or Bartholomeo ?  — Preceding unsigned comment added by 188.238.242.155 (talk) 16:49, 18 December 2016 (UTC)
replies: text: Probably with an r.  For more information and external sources such as pp 7 and 11 of an FAO report see an old Wikipedia biography of Mpemba--Rumping (talk) 13:29, 16 February 2017 (UTC)
thread_title:  Name 

message: There are achieves of previous talk at Talk:Mpemba effect/Archives/ 1 and Talk:Mpemba effect/Archives/ 2 but I cannot see a link on these pages --Rumping (talk) 13:29, 16 February 2017 (UTC)
replies: text: Added this in manually at the top of the talk page, as the usual template wasn't working with the non-standard archive naming (in the past)  Klbrain (talk) 16:39, 2 April 2018 (UTC)
thread_title: Talk archives

message: How mpemba effect operates
 Nkungwej (talk) 14:52, 24 August 2017 (UTC)
thread_title:  History 

message: This is just an armchair observation, but wouldn't greater temperature differential and thermal gradients that are further from equilibrium be responsible for creating thermal eddies, flows and momentum in either or both fluid turbulence and thermic turbulence?  With a greater momentum, we see a flywheel effect of thermal distribution even as temperatures nearer equilibrium.  See Turbulent Prandtl number. - 75.173.66.142 (talk) 20:27, 1 January 2018 (UTC)
thread_title:  Thermal eddy momentum and diffusivity via [[Turbulent Prandtl number]]? 

message: There are two photos, purporting to lend evidence to this effect. The caption on one states "Mpemba effect experiment: the hot water contained in a thermos, if thrown into the air in a very cold environment, freezes instantly before touching the ground." 
This is not a very helpful caption for two reasons: 1) water cannot freeze "instantly," and 2) where's the evidence that it freezes before it hits the ground? Photos or videos of throwing hot water into very cold air show a lot of condensation, and a lot of droplets so it can look very spectacular, especially when backlit. But they never show that the droplets are frozen. 
Is there evidence that the water freezes before it hits the ground?
Hermanoere (talk) 18:43, 24 October 2018 (UTC)
thread_title:  Photos 

message: Suggested explanations
The following explanations have been proposed: 
when electrons are moving faster the it is easier to form a optimal atomic orbit shape
having longer time to release and gather eletro energy makes the shell thinner 
sharing is easier The Beautiful Captain Lightning (talk) 21:53, 26 January 2019 (UTC)
replies: text: Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format and provide a reliable source if appropriate. ‑‑ElHef (Meep?) 23:05, 26 January 2019 (UTC)
thread_title:  Semi-protected edit request on 26 January 2019 

message: Please remove the two pictures of people throwing boiling water into the cold air as they do not seem to relate to the Mpemba Effect.
The Mpemba Effect relates to hot water freezing faster than cold water in certain circumstances, none of which is identified as having been thrown up in the air. Also, while the Mpemba Effect is not well understood, the trick of throwing hot water into very cold air so that it quickly vaporizes and then condenses into small droplets and freezes into a cloud of crystals is well understood. There is a good explanation of it at https://news.nationalgeographic.com/2018/01/frozen-bubbles-boiling-water-freezing-explained-bomb-cyclone-bombogenesis-winter-weather-viral-videos-spd/ https://news.nationalgeographic.com/2018/01/frozen-bubbles-boiling-water-freezing-explained-bomb-cyclone-bombogenesis-winter-weather-viral-videos-spd/. Other sources across the internet also cite the Mpemba Effect for this demonstration, but this is a case of two similar-seeming effects being attributed to the same cause without reason.
thanks! MeeToney (talk) 20:36, 1 February 2019 (UTC)
replies: text: Done – Jonesey95 (talk) 05:34, 2 February 2019 (UTC)
thread_title:  Semi-protected edit request on 1 February 2019 

message: Is there any information documenting whether this supposed affect has been tested with other liquids?  Watching the BBC Facebook video brought me here; they claimed that this is one of the unique properties of water alone. RobP (talk) 14:10, 9 February 2019 (UTC)
replies: text: We know that it works for ice cream. Mpemba was a Tanzanian student who noticed that hot ice cream mix freezes faster than cold ice cream. But of course ice cream contains water. I did a google search to see if anyone had tried it with wax, oil, iron, aluminum, etc. but didn't find anything. If it turns out that the the Mpemba effect works with iron, that would be the death of the hydrogen-oxygen bond theory. --Guy Macon (talk) 17:41, 9 February 2019 (UTC)
replies: text: It has been reported to work for ice cream. Are there any reliable sources stating that it has been measured for ice cream? · · · Peter Southwood (talk): 07:21, 28 January 2021 (UTC)
thread_title:  Unique to water? 

message: To consider integrating:
Why Hot Water Freezes Faster Than Cold—Physicists Solve the Mpemba Effect
O:H-O Bond Anomalous Relaxation Resolving Mpemba Paradox
Peter Kaminski (talk) 17:10, 8 May 2019 (UTC)
thread_title:  O:H-O Bond Anomalous Relaxation Resolving Mpemba Paradox (2013) 

message: In the Commons there are some uncategorized images related to this effect? These images are:
*:File:Mpemba-3182934 1280.jpg
*:File:Mpemba effect (30653381280).jpg
*:File:Mpemba-3138995 1280.jpg
--Estopedist1 (talk) 06:44, 6 October 2019 (UTC)
replies: text: Pretty pictures but no evidence that they are relevant. · · · Peter Southwood (talk): 07:16, 28 January 2021 (UTC)
thread_title:  Photos 2 

message: I've edited the page to change Mpemba's appellation from 'scientist' to 'schoolboy'. I hope that's not too controversial! Yes, he was a 'scientist' in the amateur sense, publishing an observation on science; but he was never a professional scientist, did not gain a degree in science, and spent his adult life as a game warden. And it's probably of more relevance and interest to the reader that he was a schoolboy when he made his observation.
Drjamesaustin (talk) 22:50, 18 July 2020 (UTC)
thread_title:  Is Mpemba a 'scientist'? 

message: The article makes a claim about an experimental observation: hot water freezes faster than cold water (in certain circumstances). However in the literature there is a lot of discussion about the validity of this experimental observation and its poor reproducibility. Most careful experimental work conclude that the effect is due to confounding factors such as (quoting) " (a) evaporation, (b) dissolved gases, (c) mixing by convective currents, and (d) supercooling" https://arxiv.org/ftp/arxiv/papers/2010/2010.07287.pdf Another experimental paper concludes that the effect can entirely be explained by nucleation and supercooling (d) http://afanporsaber.com/wp-content/uploads/2012/11/When-does-hot-water-freeze-faster-then-cold-water-A-search-for-the-Mpemba-effect.pdf. These factors are already mentioned in the article, however against this high quality experimental evidence theoretical evidence for the Mpemba effect is brought. However these theoretical papers atre highly idealized and can not prove in any way that this effect occurs in water (or any liquid at all). Ofcourse they open interesting avenues for realizing the Mpemba-like effects, and speculate about potential mechanisms driving it, but they do not lend credibility to the Mpemba effect actually occuring. I propose moving all theoretical references to their own section. I want to stress that I make no statements about the quality of the theoretical work, just stating that theoretical evidence in general is much weaker than experimental evidence.Nomenenus nescio (talk) 07:59, 16 October 2020 (UTC)
replies: text: I went ahead and split experiments and theory in their own separate sections. Content and wording is left wholly intact. Nomenenus nescio (talk) 08:30, 19 October 2020 (UTC)
thread_title:  Theoretical evidence should be given low priority 

message: Having looked at some of the references here, I can see little evidence that this effect is reproducible and has any scientific validity rather than being an urban myth.
Are there any clear descriptions of how the effect can be reliably created in water? Belinda479 (talk) 10:35, 7 November 2020 (UTC)
replies: text: Fluid dynamics and thermodynamics are not uncommonly counterintuitive. It's a bit burried in the current version of the article, but in my view, the best theoretical explanation is from 2021. To quote from the abstract of that paper, . My point here is that simple thought experiments aren't sufficient to refute experimental findings observing such an effect, as more sophisticated theory is consistent with the Mpemba effect. I do agree, though, that it would be nice to have more experimental evidence? A challenge to any applied physicists out there? Klbrain (talk) 20:01, 15 July 2021 (UTC)
thread_title:  Urban Myth? 

message: Having read the references, I’m in the camp that the Mpemba effect is bogus, pseudo science.  Or call it “Urban Myth”.  Or maybe it’s real.  Regardless, I added this possible theory mostly as a joke.  I understand that this is inconsistent with the guidelines for Wikipedia, and accordingly invite its removal.
That said, I also wrote it hoping that readers might follow the phlogiston link, learn about it, and consider the evolution from today’s credible theories to yesterday’s debunked ones.
At least combustion is real.  ;-)
Slgaiser (talk) 23:23, 12 June 2021 (UTC)
replies: text: Not at all amusing; fortunately, someone quickly reversed your unconstructive edits. Klbrain (talk) 14:38, 22 August 2021 (UTC)
thread_title:  Phlogiston 

message: The lead says that "this so-called “effect” is not reproducible" then has a graph reproducing it, showing hot water reaching zero before cold water. Should the graph be there, or is the sentence incorrect? --Lord Belbury (talk) 15:41, 18 August 2021 (UTC)
replies: text: The sentence, using the pejorative "so-called" and scare quotes around "effect" is definitely not neutral, and doesn't reflect what the cited source actually says. I have modified the sentence. ~Anachronist (talk) 18:43, 22 August 2021 (UTC)
thread_title:  Graph in lead 

message: The topic is poorly defined. What do you mean «in some circumstances it can happen»? Until the circumstances are properly described, theres no substance to be dicussed. The lack of rigorous description of the experiment that produces this observation it is meaningless to say «all other factors constant». 
and this is just the very first step of desribing what would be descussed. Then come the reference to aristotle and others, while theres still nothing clarified. 
at best this would be a fun paradox for teaching physics, if it were described to any level. But it isnt. In its current form its pseudoscience that is not even wrong, just waste of time.
to be clear, this isnt the fault of the schoolboy who made the first observation. But neither is his obaervation amount to a “physics effect”, instead it is an effect in the sensationalist journalism reporting sense. 
the first perspn who reported it should have made a better job, but that is also not to find a fault with the reporter. Reporters are not expected to only make scientifically meaningful statements. 
this shifts the burden to the next in line, which is wikipedia: this article should either give a scientifically rigorous description of the effect, that is refer to a publication where these details are included, or begin the lede with a clear statement that no such experiment is to be found and therefore refer the topic to the heresay, beer science, word-play category which may say that there is a hitherto unexplayed phenomena but, fails to describe the phenomena in a way that would be the prerequisite of any methodological inquiry into its explanation. 2A02:2121:62B:5A3C:94B8:62C4:138E:62A4 (talk) 10:43, 26 May 2024 (UTC)
thread_title:  Attention seeking unscience 

message: A has said a great many things on many topics, but ref.3. gives no account as to what relevant statement A has made and how that relates to the alleged observation. This reference is of as much use as another reference to what Puss in Boots has said would have been.2A02:2121:62B:5A3C:94B8:62C4:138E:62A4 (talk) 10:53, 26 May 2024 (UTC)
thread_title:  Aristotle said