The more we learn about the world around us, the more it keeps surprising us with how little we actually know. Case in point: water. The vital, life-sustaining liquid is everywhere. It covers most of our home planet, it makes up about 60 percent of the human body, and it's even in the air we breathe. Yet no one completely understands this fundamental compound.
Water is intriguing for a number of reasons. It's one of the few substances whose solid state floats on its liquid state, and unlike most other substances, it expands when it freezes. While boiling point temperatures usually increase with increasing molecular size, water has a surprisingly high boiling point given its low molecular weight.
Now, it's about to get weirder. In a new study detailed in the International Journal of Nanotechnology, physicists note that liquid water has a whole new set of properties when it hits temperatures between 40°C and 60°C (104°F and 140°F). In that range, water goes into a "crossover" phase, essentially a second liquid state.
A research group led by University of Oxford physicist Laura Maestro investigated the unique properties of this second liquid state. They examined how characteristics such as thermal conductivity, refractive index, conductivity, surface tension, and the dielectric constant responded to temperature changes in water. They noticed that each of the characteristics began to shift into this second-state at a different temperature in the 40-60°C (104-140°F) range. For example, the surface tension of water was different at temperatures below 57°C (134.6°F) than it was at temperatures above it.
What does this mean for the universe around us? As mentioned, water is everywhere, but it's also unusual. Is this second liquid state the cause of water's weird properties? If water has two liquid states and our bodies are two-thirds water, have these states been impacting our biology all along without us knowing?
The researchers point out in their publication that finding out if and how these structural changes in water affect proteins, the building blocks of living cells, is one of the many questions for biological and nano systems raised by their research. In the meantime, more independent studies need to be done before any conclusions can be reached, and no doubt as we delve further into this mystery of the universe, we'll find just as many new questions as we do answers.