Physicists at the University of Chicago (USA) dropped a marble into a loosely packed sand container, causing a jet of sand to erupt with properties similar to a special form of dense liquid. They describe it as an unusual state of matter.
“We have discovered a new state of liquid that exists as a combination of gas—in this case, air—and dense material particles. This phenomenon is truly astonishing,” said lead researcher Heinrich Jaeger.
How does it work?
Unusual states of matter are sometimes created under extremely cold conditions, close to absolute zero. Everything becomes bizarre at that critical point (molecules virtually stop moving). However, this experiment took place at room temperature.
“The jet of sand erupts like a super dense, super cold gas. The term ‘cold’ here does not refer to surrounding temperature, but to how we define temperature through the random motion of the particles,” Jaeger explained. “In this sand jet, there is very, very little random motion.”
Although reported yesterday, this phenomenon was first noted back in 2001 by Sigurdur Thoroddsen and Amy Shen, who later worked at the University of Illinois at Urbana-Champaign (USA).
Jaeger encouraged his student Andrew Flior to replicate the experiment, and a research team led by Detlef Lohse at the University of Twente, Netherlands, utilized high-speed video and computer models to hypothesize that the flow of sand results from gravitational forces when the material rushes in to fill the void left by the marble.
The researchers produced X-ray images at a speed of 5,000 frames per second. They concluded that the air compressed between the particles provides most of the energy to drive the sand jet (a similar experiment conducted under low air pressure did not create such a strong flow).
“This result is far from our predictions,” Lohse stated. “We used to think that the influence of air would weaken the gas flow, but in this case, it is the opposite.”
The sand jet is divided into two distinct parts, one being a solid stream and the other a flow of particles.
“One of the biggest mysteries we have yet to solve is why the sand jet has such a clear boundary.”
You can replicate this basic experiment at home, although there will be no funding for photography, so you may not fully observe the phenomenon. Pour sugar into a container so that it is in a loose state. Drop a marble into the container and observe.
T. An (according to LiveScience)
