Scientists in Spain recently executed an impressive and cool physics experiment. 25,000 mini dice (measuring half a centimetre in size) were placed in a large plastic cylinder to investigate what happens to a granular material where all particles are identical cubes.
After the scientists filled a translucent cylinder with the mini dice, they proceeded to rotate it back and forth about once per second, described as a "Twist".
The scientists were shocked with the perfect-ordered arrangement of the dice after "sufficient vigorous twisting" of the vessel. The researchers noticed the cubes would only move when the direction of the twist changed.
"Of note, the system is only perturbed when the angular velocity is inverted, and the cubes remain at rest during the rest of the rotation cycle," the team writes in the study.
The findings did, however, vary on how fast and how many times the cylinder was twisted. "Accelerations above about half the acceleration of gravity (0.5 g) were the most fruitful; the dice reached their maximum density after 10,000 twists or so".
Previous studies and experiments have shown that this method is efficient for reorganising elongated and 'platy' particles. The scientists dabbled with the intensity of the twists by changing the speed of the rotation. With this, scientists discovered that the more they increase the speed, the bigger the jolt would be when the revolution switched.
As you would expect, the gentler the rotation shift, the longer it would take for the dice to pack in a neat fashion. By testing the lower rotation, the researchers hypothesised that it would probably take "ten years of twisting" to reach the densest possible configuration for the dice.
"Indeed, contrary to the behaviour observed with the standard tapping protocol, the system reaches the same final state, regardless of the excitation intensity (provided it is large enough)," they wrote.
The team said they found that it's inevitable that the flat surfaces on the dice will align with each other. This is because the rotation pushes them outwards to the edges of the container under shear force.
But, although this experiment is fun and may sound silly, it could lead to more important things. This could be a stepping stone towards working with materials in places with "an absence of gravity".
The team is currently preparing experiments for studying granular materials on the International Space Station.