Most Mysterious Substance on Earth
by Jessica Wapner
Despite our utter dependence on it, water is a mystery. Scientists don't understand why it expands as it cools, why hot water turns to ice faster than cold water or its extraordinary surface tension, which allows it to cling to soil and support insects. "It's almost like water is trying to hide its secrets," says John Russo, a mathematician at the University of Bristol in England, who thinks he may have figured one out.
Their conclusion was as surprising as their subject. "You should really think of water as two separate liquids mixed together," says Russo.