A new experiment hints at how hot water can freeze faster than cold
A hot object can cool more quickly than a warm one, a new study finds. When chilled, a warmer system cooled off in less time than it took a cooler system to reach the same low temperature. And in some cases, the speedup was even exponential, physicists report in the Aug. 6 Nature.
The experiment was inspired by reports of the Mpemba effect, the counterintuitive observation that hot water sometimes freezes faster than cold. But experiments studying this phenomenon have been muddled by the complexities of water and the freezing process, making results difficult to reproduce and leaving scientists disagreeing over what causes the effect, how to define it and if it is even real (SN: 1/6/17).
To sidestep those complexities, Avinash Kumar and John Bechhoefer, both of Simon Fraser University in Burnaby, Canada, used tiny glass beads, 1.5 micrometers in diameter, in lieu of water. And the researchers defined the Mpemba effect based on cooling instead of the more complicated process of freezing.
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