Water's Hidden Side Revealed - It Can Exist in Two Liquid Forms at Once

By Michelle Franklin, University of California - San Diego
March 12, 2025



Researchers at UC San Diego used machine learning and supercomputers to simulate a long-suspected, yet never observed, liquid-liquid transition in water. Their findings could lead to groundbreaking applications, but experimental proof remains elusive. Credit: SciTechDaily.com

Scientists have found that water, under extreme pressure and cold temperatures, can split into two different liquid phases. This was theorized decades ago but never proven—until now.


The Unique Nature of Water

Water is a truly unique substance. It is one of the few materials that can naturally exist as a solid, liquid, and gas at the same time under normal conditions—for example, think of ice floating on a pond, liquid water beneath it, and water vapor forming clouds above. It is also unusual because its solid form, ice, is less dense than its liquid form, which is why it floats.

Now, researchers at the University of California San Diego have uncovered another remarkable property of water. Under extreme pressure and low temperatures, liquid water can separate into two distinct liquid phases—one denser than the other. This discovery, published in Nature Physics, provides new insight into water’s complex behavior.

Molecular Modeling: A New Approach

Francesco Paesani, a professor of chemistry and biochemistry at UC San Diego, leads a team that combines chemistry, physics, and computer science to develop advanced models of molecular behavior. Using machine learning and computational algorithms, his group creates highly realistic simulations that closely match experimental observations.

“Our water model is so realistic you can almost drink it,” Paesani said.

More:
https://scitechdaily.com/waters-hidden-side-revealed-it-can-exist-in-two-liquid-forms-at-once/