Number 33 (Story #3), May 8, 1991 by Phillip F. Schewe and Ben Stein THE SLOWEST PROCESS OBSERVABLE IN NATURE , with a lifetime between 1019 and 1021 years, is double beta decay. In this rare phenomenon two neutrons inside a nucleus decay simultaneously into a pair of protons along with two electrons and two antineutrinos. Observed for the first time a few years ago in selenium-82, double beta decay has now been seen also in germanium-76- and molybdenum-100. (CERN Courier, April 1991.)