Scientists have proposed that water can go from being one type of liquid into another in a so-called 'liquid-liquid' phase transition, but it is impossible to test this with today’s laboratory equipment because these things happen so fast. That’s why Kumar and Stanley used computer simulations to check it out.
They found that when they chilled liquid water in their simulation, its propensity to conduct heat decreases, as expected for an ordinary liquid. But, when they lowered the temperature to about 54 degrees below zero Fahrenheit, the liquid water started to conduct heat even better in the simulation.
Their studies suggest that below this temperature, liquid water undergoes sharp but continuous structural changes whereas the local structure of liquid becomes extremely ordered — very much like ice. These structural changes in liquid water lead to increase of heat conduction at lower temperatures. The researchers say that this surprising result supports the idea that water has a liquid-liquid phase transition.