Picture yourself at a busy pedestrian crossing. When the light is red, everyone waits – until one person starts to cross. Soon, others follow, and eventually everyone follows the crowd and crosses. Amsterdam physicists have discovered that a very similar process happens at the microscopic level, when two touching surfaces start to slide. Their results were published in Physical Review Letters this week.

For the first time, researchers can study the microstructures inside metals, ceramics and rocks with X-rays in a standard laboratory without needing to travel to a particle accelerator, according to a study led by University of Michigan engineers.