14 DAY TRIAL // Water is the most important life-sustaining chemical on the planet, and yet it also remains one of the greatest mysteries. While we do have a fairly good understanding of how it works, some of its behaviors cannot readily be explained. Researchers took a closer look at these in a new study.
The study team – from the Massachusetts Institute of Technology (MIT), in Cambridge – focused on behaviors such as water expanding when it freezes, rather than shrinking. This ability is what allows the stuff to float on liquid water.
According to scientists, the factors that enable this fundamental property remain elusive. But the mystery attracted MIT PhD student Yang Zhang to investigate the issue. The findings he and his team made support a controversial theory related to the behavior of water.
Details of the new analysis appear in a recent issue of the esteemed journal Proceedings of the National Academy of Sciences (PNAS). Given the fact that the behavior of water influences so many processes, the findings could have applications in areas ranging from biology to engineering.
This chemical is “probably the most weird substance on Earth. It behaves very differently from other materials,” say Zhang. He is the lead author of the new research paper, which is heavily based on his PhD thesis research.
MIT Department of Nuclear Science and Engineering professor Sow-Hsin Chen was the expert's doctoral supervisor. Six other researchers at the Institute are listed as coauthors for the new research.
In a nutshell, the controversial theory holds that water undergoes two phase transitions while in liquid form. A phase transition occurs when a material switches from being a solid, a gas or a liquid, into another state of matter. Water is commonly understood to exist in just three states.
If the new findings are correct, then there are actually two separate states in which water is liquid. These states are mainly characterized by different densities. This may help explain some of the weirdest behaviors water displays.
If the study is confirmed, then this would be the first time that liquid-liquid transition is demonstrated in water. However, evidence accumulated up to this point are still circumstantial, and do not constitute proof in a scientific sense.
In order to conduct this type of research, experts need to maintain water liquid at temperatures far lower than 0 degrees Celsius. In the new experiments, they went as low as minus 60 degrees Celsius.
These experiments address “one of the most interesting open questions on the liquid state of matter, and in particular on water: the possible existence of a phase transition between two distinct phases of liquid water,” Princeton University professor of engineering and applied science Pablo Debenedetti says.
Researchers at MIT plan to conduct more investigations into this issue. They hope to gather enough evidence to demonstrate that liquid-liquid phase transition actually occurs in water.