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phys.org

Scientists discover that water molecules define the materials around us

For decades, the fields of physics and chemistry have maintained that the atoms and molecules that make up the natural world define the char

OKAY THIS ARTICLE IS SO COOL

I'm going to try to explain this in a comprehensible way, because honestly it's wild to wrap your head around even for me, who has a degree in chemistry. But bear with me.

Okay, so. Solids, right? They are rigid enough to hold their shape, but aside from that they are quite variable. Some solids are hard, others are soft, some are brittle or rubbery or malleable. So what determines these qualities? And what creates the rigid structure that makes a solid a solid? Most people would tell you that it depends on the atoms that make up the solid, and the bonds between those atoms. Rubber is flexible because of the polymers it's made of, steel is strong because of the metallic bonds between its atoms. And this applies to all solids. Or so everybody thought.

A paper published in the journal Nature has discovered that biological materials such as wood, fungi, cotton, hair, and anything else that can respond to the humidity in the environment may be composed of a new class of matter dubbed "hydration solids". That's because the rigidity and solidness of the materials doesn't actually come from the atoms and bonds, but from the water molecules hanging out in between.

So basically, try to imagine a hydration solid as a bunch of balloons taped together to form a giant cube, with the actual balloon part representing the atoms and bonds of the material, and the air filling the balloons as the water in the pores of the solid. What makes this "solid" cube shaped? It's not because of the rubber at all, but the air inside. If you took out all the air from inside the balloons, the structure wouldn't be able to hold its shape.

Ozger Sahin, one of the paper's authors, said

"When we take a walk in the woods, we think of the trees and plants around us as typical solids. This research shows that we should really think of those trees and plants as towers of water holding sugars and proteins in place. It's really water's world."

And the great thing about this discovery (and one of the reasons to support its validity) is that thinking about hydration solids this way makes the math so so so much easier. Before this, if you wanted to calculate how water interacts with organic matter, you would need advanced computer simulations. Now, there are simple equations that you can do in your head. Being able to calculate a material's properties using basic physics principles is a really big deal, because so far we have only been able to do that with gasses (PV=nRT anyone?). Expanding that to a group that encompasses 50-90% of the biological world around us is huge.