They may be microscopic, but cracks and fractures in crystals look remarkably like their larger counterparts in the Earth’s crust – caused by earthquakes.
Several years ago, when physicist Jan Astrom of the Finnish IT Center for Science in Esbo and colleagues began an experiment looking for evidence of dark matter, they found that their particle detectors, made from sapphire crystals, were giving off unexpected signals. Tight clamps, it turned out, were creating microscopic fractures in the crystals in a sequence of abrupt events not unlike earthquakes, in which the Earth’s crust suddenly shifts and releases pent-up stress.
Astrom’s team soon…
