Physicists confirm two distinct liquid states of water

Scientists have made a breakthrough discovery: water can exist in two different liquid forms that merge into one under certain conditions. This confirms the long-suspected existence of a hidden critical point in supercooled water. The discovery helps explain water's exceptional behaviour compared to other liquids.

International physicists have achieved a rare breakthrough in the scientific world, experimentally confirming that water can exist in two distinct liquid states. This is a discovery that scientists have sought for decades, but whose experimental proof has been virtually impossible until now.

The hidden critical point

Scientists have long theoretically suspected that in heavily supercooled water lies a so-called hidden critical point—a boundary around which water behaves unexpectedly. Now this suspicion has received experimental confirmation: water indeed exists in two different liquid forms that, under certain physical conditions, are capable of merging into one homogeneous liquid.

This discovery is exceptional because under normal circumstances, studying supercooled water is extremely difficult-water tends to freeze into ice rapidly before scientists can achieve the critical conditions.

Why does water behave differently?

Water is known for its many anomalous properties: it expands when freezing, has high specific heat capacity, and behaves differently under pressure than most other liquids. The existence of two distinct liquid phases may be the key that explains why water differs so significantly from all other liquids found in nature.

The new discovery opens the way to a deeper understanding of water's molecular properties and may in the future influence materials science, biology, and chemistry-fields where water's behaviour under extreme conditions is of critical importance.