A supercritical fluid refers to a state in which the temperature and pressure of a substance exceed its critical point, where no distinction exists between liquid and gas phases. Traditionally, it has been regarded as a single, uniform phase. However, a research team at POSTECH (Pohang University of Science and Technology) experimentally demonstrated nonequilibrium phase separation within supercritical fluids by observing nanometer-sized "liquid clusters" that persist for up to one hour.