the.com/condensed matter physics

means The branch of physics that studies the solid and liquid phases of matter — especially how huge numbers of atoms, packed closely together, organize themselves into materials with properties like magnetism, superconductivity, or crystal structure.

from The field's name formalized in the mid-20th century, when physicists split off from the older, narrower label 'solid state physics' — a name that was starting to feel too cramped once liquids, liquid crystals, and other 'condensed' phases turned out to follow the same deep principles. 'Condensed' here just means matter packed densely enough that its particles constantly interact, as opposed to the diffuse, mostly-noninteracting particles of a gas. The rebranding is often credited to physicist Philip Anderson and colleagues around the 1960s, who pushed the broader term partly to reflect how rich and unified the physics of 'densely packed stuff' really was.