Abstract:
'Nothing' is a relative concept, but the emptiness of the little vacuum pocket created by Wei-Qiang Han and A. Zettl could hardly be more absolute. The so-called ultrahigh vacuum of conventional technology typically achieves pressures of less than 10-9 torr, but Han and Zettl have made a cavity in which they estimate the pressure to be around 10-84 torr. In comparison, outer space - at around 10-12 to 10-13 torr - is positively crowded.