Fifth State of Matter Probably Found in Sand

Sand is, perhaps, the single best material in the world. Millions of people live in it, and billions others interact with it as children or during holiday. And it's in this seemingly common, uninteresting, and sometimes deadly material that physicists believe they may have discovered hints about the fifth state of matter. Researchers from the University of Chicago collected some sand, and started playing with it in the lab, under a very powerful, high-definition camera. The goal of their investigation was to analyze exactly why droplets were formed in a flow of falling sand.

Granular materials have had scientists scratching their heads for quite some time now. They are very peculiar because they behave very differently from other materials, and can exhibit traits usually associated with liquids, gases, or solids in some circumstances. “Here we have a material right underneath our noses, that everybody grows up playing with in a sandbox, yet it’s full of surprises for scientists,” UC expert and Physicist Heinrich Jaeger said.

When sand falls, it exhibits some pretty amazing properties. For starters, it forms droplets, which are not really droplets, because they are not liquids. However, as far as appearances go, there can be no doubt about it. Scientists proposed some time ago that the formations appeared because of instabilities in the subtle atomic forces that usually made sand grains stick to each other. It's the same type of anomaly that can be found in a water stream flowing from a faucet, with the only difference being that the water molecules are held together by forces 100,000 times stronger than in sand.

“You walk on the beach, and the sand supports your weight. Pick up a handful, and it runs through your fingers, like a liquid. But you can’t walk on water. In the top of an hourglass, sand is this strange solid. It’s at the verge of being a solid; it flows through the middle as something like a liquid, and then it’s a solid again,” the UC expert added, quoted by Wired. “You have many interacting particles. Energy is put in, sometimes they get stuck, and sometimes it flows. If it flows, what properties does it have? With many interacting players, that behavior is typically very complex and crosses between solid- and liquid-like behavior.”

“Physicists have a rich toolbox for dealing with solids, liquids and gases. But we don’t have a manual for when the old categories don’t apply,” the scientist concluded, saying that more investigation into the amazing properties of granular materials could one day lead to less spending on over-sized industrial processes, and could ultimately make the economy run smoother.