Experiments use positive and negative electric forces to tweak ice formation
A watched pot never boils, but an electrically charged pot sometimes freezes.
A study in the Feb. 5 Science reports that water can freeze at different temperatures depending on whether the surface it rests on is positively or negatively charged. Under certain conditions, water can even freeze as it heats up.
“We are very, very surprised by this result,” says study coauthor Igor Lubomirsky of the Weizmann Institute of Science in Rehovot, Israel. “It means that by controlling surface charge, either positive or negative, you can either suppress ice formation or enhance ice formation.”
Water usually begins freezing by forming an ice crystal around a particle of dust or some other impurity. Without that starting point, water can stay liquid well below its freezing point, down to about -42º Celsius. This supercooled water is useful in nature and in the lab, from frogs and fish surviving long winters to cryogenic preservation of b