Abstract
The coming into operation of the Intersecting Storage Rings (ISR) at the European Centre of Nuclear Research (CERN), near Geneva, has made it possible in the past two years to study the behaviour of matter at the highest densities ever obtained artificially, hundreds of times greater than the density of matter in nuclei and even in the densest stars. An account is given of some of the results obtained thus far; this is followed by a brief discussion of possible future developments. (17 refs)