Physicists Create Coldest Liquid Water Ever, Reaching Bizarre Mathematical Singularity

Scientists still haven't found the limit for just how cold liquid water can get. Wikipedia

Water acts familiarly at familiar temperatures. It freezes into ice at 32 degrees Fahrenheit, which corresponds to 0 degrees Celsius and 272 Kelvin. But “supercooled,” water can remain liquid even at temperatures as low as minus 40 degrees Fahrenheit. Now, recent back-to-back breakthroughs are revealing the bizarre behavior liquid water adopts at the coldest temperatures ever achieved, Gizmodo reported.

A new technique created by an international team of European researchers recently helped break the record for coldest liquid water by measuring a temperature of minus 44.59 degrees Fahrenheit (minus 42.55 degrees Celsius, 230.6 Kelvin for anyone wondering), according to the American Physical Society. By tracking the diameters of microscopic water droplets in an evacuated chamber (meaning, vacuum-sealed with nothing inside, not even air) and illuminating them with lasers, the scientists were able to record measurements of unprecedented precision. A paper describing the research was published in the scientific journal Physical Review Letters.

water1 llustration showing fluctuations between regions of two different local structures (high density as red and low density liquid as blue) of water that depend on the temperature. Stockholm University

Meanwhile, a new technique has allowed a separate team led by physicists at Stockholm University to map the unique way supercooled liquid water fluctuates between two states—both of them liquid, just different kinds. Using X-ray lasers, the researchers demonstrated that at such extreme temperatures, water acts like it can't make up its mind about what to be, shifting back and forth from a high density to a lower one. The strange behavior is what's known in mathematics as a singularity, according to Gizmodo—a point at which the exact state of something can't be defined. A paper describing the research was published in the journal Science.

"What was special was that we were able to X-ray unimaginably fast before the ice froze and could observe how it fluctuated between the two states," Anders Nilsson, a professor of Chemical Physics at Stockholm University and a corresponding author of the Science paper, said in a university press release. "For decades there has been speculations and different theories to explain these remarkable properties and why they got stronger when water becomes colder. Now we have found such a maximum, which means that there should also be a critical point at higher pressures."

Supercooled water droplets can exist naturally in the upper regions of the planet's atmosphere, but physicists still don’t know just how cold liquid water can get. The more they learn, the more they might be able to improve climate models of atmospheric phenomena like ice formation, according to the American Physical Society.

"There has been an intense debate about the origin of the strange properties of water for over a century since the early work of Wolfgang Röntgen," Nilsson said in the press release. "Researchers studying the physics of water can now settle on the model that water has a critical point in the supercooled regime. The next stage is to find the location of the critical in terms of pressure and temperature. A big challenge in the next few years."