Number 289 (Story #2), October 3, 1996 by Phillip F. Schewe and Ben Stein QUARK-GLUON PLASMA is a hypothetical state of nuclear matter in which quarks and the gluons which normally bind the quarks into clumps of two quarks (mesons) or three quarks (baryons) would spill together in a seething soup analogous to the condition of ionized atoms in a plasma. Such a nuclear plasma may have existed in the very early universe and might exist again at accelerators if only physicists could sufficiently heat up ordinary nuclei by smashing them together. One of the products of these collisions (whether or not a plasma is formed) is psi mesons. Once hatched, the psi's must make their way out of the collision wreckage which, when two lead nuclei (each with more than 200 nucleons each) are involved, can be considerable. Preliminary results from the NA50 experiment at CERN indicate that only about half the expected psi's survive the journey (Science, 13 Sept.; Science News, 21 Sept.). Some theorists interpret this shortfall to meant that many psi's are being absorbed in a hotter-than-usual nuclear environment which might signify the presence of a quark-gluon plasma in at least part of the collision fireball. (Blaizot and Ollitrault, Phys. Rev. Lett., 26 Aug.)