That mysterious 'second liquid' form of water might not even be a liquid at all—it might just be frozen glass.
April 2, 2026
Original Paper
Glassy Arrest Behind the Apparent Second Liquid in Water
arXiv · 2604.00794
The Takeaway
For decades, scientists have debated whether supercooled water can exist in two different liquid phases. New simulations suggest that what looked like a second liquid is actually water molecules getting 'stuck' in a state of kinetic arrest, fundamentally changing our understanding of the most common substance on Earth.
From the abstract
The origin of water's anomalous behavior remains a central open problem in the physical sciences and is often attributed to a liquid-liquid transition (LLT) between high- and low-density liquid states deep in the supercooled regime. Experimental access to this region has been challenging due to rapid crystallization, leaving atomistic simulations as a major source of supporting evidence. Using extensive machine-learning-accelerated first-principles simulations in direct comparison with spectrosc