7 within the data analysed in the present study. 5 which is compared to an observation of the Mpemba effect documented as part of a popular science competition organised by the RSC 7 - we include the experimental observations by ref. A model exhibiting a hysteresis in the cooling of water is presented by ref. Such findings therefore offer a route to explaining the Mpemba effect only if they result in a meaningful hysteresis in the thermal or fluid properties of water.
While the findings of these studies are of great interest in their own right, we note that small-scale molecular effects are parameterised within the thermal and fluid properties of water - properties which are known to a reasonable degree of accuracy and do indeed vary with temperature. 6, concern the molecular interactions and hydrogen bonding within liquid water. Moreover, both The Telegraph 2 and The Daily Mail 4 have reported that the scientific work of a group of chemists working in Singapore 5 provides a molecular mechanism to explain the effect. As such the Mpemba effect cannot simply be disregarded. refs 1, 2, 3) and was the focus of a competition organised in 2012 by the Royal Society of Chemistry (RSC) which received substantial publicity, for example a special report on the BBC’s Newsnight programme. Despite the non-specific nature of the effect, the Mpemba effect has been the subject of numerous articles in international broadsheet newspapers (e.g. More precisely, we show that for two samples of water, identical except for a difference in initial temperature, cooled under the same conditions to a prescribed temperature (for example, the freezing temperature of water) the initially hotter sample will take longer to cool - contrary to the assertion of the Mpemba effect.
The statement “hot water does not cool more quickly than cold” is vague and imprecise hot water can be made to cool more quickly than cold by supplying more energy to the cooling of hot water, but it is under such a non-specific premise that the Mpemba effect has become an artefact in popular science.
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