In many respects, the science of materials has only fully utilized two of its three fundamental tools —the variables of temperature and chemical composition. Pressure, the third fundamental variable altering materials, is in many ways the most remarkable, as it spans some 60 orders of magnitude in the universe. Yet, its true potential for exploring the nature of materials was for years unfulfilled for a number of reasons: the accessible pressure-temperature conditions were too modest to cause significant changes in many materials, samples under high pressure could not be subjected to thorough analyses, or theory was not sufficiently well developed to understand or predict the variety of phenomena.
