PROTONS PERSIST for at least 1.6 x 10³³ years. With few exceptions (electrons?) everything in the universe falls apart. Even protons, the lightest baryon (particles comprised of three quarks) are, according to grand unified theories of particle physics, supposed to decay, principally into positrons and neutral pi mesons. The versatile Super-Kamiokande underground detector in Japan (where neutrino oscillations were discovered earlier this year) can also look for just this sort of proton decay. Not finding any such evidence, scientists there have now established a new, more stringent, lower limit on the lifetime of the proton. (Shiozawa et al., Physical Review Letters, 19 October 1998.)