Jacek Krywko writing for Ars Technica covers a Science study that listened to the faint electrical crackle of current flowing into a copper-based superconductor. The team was led by Milan Allan of Ludwig Maximilian University of Munich and Ingmar Swart of Utrecht University.

Cuprates superconduct at higher temperatures than most materials, but above that point some of their electrons seem to go missing, a state called the pseudogap. One explanation is that the electrons freeze into patterns. Another is that they’ve already formed Cooper pairs, the paired electrons that carry current in a superconductor.

The group measured shot noise, the tiny fluctuations from individual charges arriving, using a scanning tunneling microscope on BSCCO crystals cooled to a few degrees above absolute zero. Allan compares it to rain on a roof: heavier drops make more noise. Pairs showed up right at the pseudogap energy.…