Focused x-ray laser beam is capable of creating unique phases of matter; specifically very dense plasma yet with rather low temperature. Physicists call it warm dense matter (WDM). WDM can be created by optical lasers but only in very specific and restricted conditions. X-ray lasers, on the other hand, can be used for WDM creation in much broader variety of conditions because of their ability to warm up the whole volume of the energized matter and not only the surface as...