RELATIVISTIC HEAVY ION COLLISIONS - IN SEARCH OF THE QUARK-GLUON PLASMA

According to quantum chromodynamics, colour should no longer be confined within hadrons at high enough temperature and/or quark density. Conditions for this to occur are such that there is a good hope of reaching them in heavy ion collisions, when the incident energy is of the order of a few hundred GeV per nucleon. CERN had an exploratory programme with oxygen ions in 1986 and sulphur ions in 1987, and there is much interest in new developments which could lead to a lead beam in the early Nineties. There is also an important programme going on at BNL. Present results are reviewed. All the information which will eventually come from the two past runs at CERN is not yet available in view of the complexity of the final states. High enough energy densities seem to have been reached. One predicted signal has been observed and so far has resisted many attacks aimed at trying to interpret it through standard means. The attacks continue. This is a general review, written for non-specialist readers