Super cool discovery: Shining an ultrafast laser on supercooled water enabled the team to identify the new liquid-liquid critical point. (Courtesy: POSTECH University, South Korea) Researchers at Stockholm University in Sweden have found experimental evidence of a long-predicted critical point in water at -63 °C. The result, which they obtained by supercooling liquid water and probing it with ultrafast laser pulses before it could freeze, provides further evidence that liquid water exists in two distinct phases. Water is a strange substance. Unlike most other materials, its liquid form is denser at ambient pressures than the ice it forms when it freezes. It also expands, rather than contracting, as it cools, and it becomes less viscous when compressed. All told, water exhibits around 60 different anomalous behaviours, and it is especially atypical when cooled below its usual freezing point.…