Water might secretly be a mix of 2 different liquids, scientists say

Key Points:

• Researchers have found molecular evidence supporting the long-suspected "two-state hypothesis" that water exists as two distinct liquids—a denser and a less-dense form—that continuously switch places.
• Using AI-driven unsupervised deep learning and extensive molecular dynamics simulations, the team identified key variables that describe how water molecules transition between these two states, revealing different energy barrier pathways depending on conditions.
• The study explains water's unique behaviors, such as its density anomaly near 4 degrees Celsius and its unusual viscosity changes, by linking them to the molecular switching between high-density and low-density water.
• Confirming these findings experimentally will require advanced techniques, but the research could ultimately improve understanding of water's role in biological and pharmaceutical processes, impacting how drugs and proteins interact in solution.
• The results, published in Nature Physics, represent a significant step toward unifying various water anomalies under a single molecular model, with future work aimed at refining machine-learning models and connecting them to macroscopic properties.