Physics

CRITICAL PHENOMENA are eventful processes during which the strife between dull conformity and catastrophic chaos creates a mellifluous harmony—a state of perfect fractal universality and cooperative connectivity between all of a system’s component parts.

CRITICAL POINT OF A PHASE TRANSITION

Consider as an example the phase transformation of water, from liquid to gas. The boiling temperature of 100 degrees Celsius occurs at the pressure of 1 atmosphere. The liquid phase coexists with the gaseous phase at these values, with each phase retaining its own unique properties (e.g., water is denser than steam). The boiling temperature rises as the pressure increases and, as before, at each new temperature-pressure combination a distinct liquid phase coexists with a distinct gaseous phase. But at the specific temperature of 374 degrees Celsius and the pressure of 218 atmospheres, something very special, critical, happens. Then, at such critical point of temperature-pressure combination, we no longer have two distinct phases coexisting. Rather, the system then, undergoes a critical phase transition into a single fractal-like supercritical fluid phase, and becomes a critical phenomenon! The structure of this supercritical fluid phase fluctuates continuously more violently than ever before, with bubbles and droplets of all different magnitudes blended everywhere, forming, dissolving, and interchanging their natures (phases), and transforming the substance into a perfect fractal—with the same pattern of intermixed bubbles and droplets persisting at all magnifications, from microscopic to macroscopic.

In a normal phase (solid, liquid, gas) the cooperativity (forces) between water molecules is short range; it extends only to nearest neighbors. It is as if you (a molecule) hold hands with two of your nearest friends/molecules, who in turn hold hands only with their nearest neighbors/friends, and so on. By contrast, in a supercritical phase, cooperativity is long range; it extends throughout the substance (it is communicated between all the molecules) and therefore, is much stronger and consequential. It is as if everyone is friends, and everyone has as many hands as needed to hold everyone (that is, every molecule is in constant interaction with every other molecule), via all the different combinations and regardless of each other’s distance or relative location—for hands (the intermolecular forces), in this case, are imagined to be able to reach everyone. This complex web of interactions, from such long-range correlation, is what creates and preserves the fractal universality in critical phase transitions, even amidst the wild frenzy of fluctuations in the structure of the substance, and what makes the system critical—neither boringly ordered nor hopelessly chaotic, but interestingly energetic. Criticality is to a phase transition, what the golden ratio is to geometry—an aesthetically pleasing point of harmony that lies beautifully between two extremes.

The critical point of a phase transition is the eventful harmonizing state during a supercritical phase, characterized by perfect fractal universality and cooperative connectivity between all of a system's component parts, that emerges from the fierce competition between such system's warring antithetical potential phases: its temptation to conform to dull order vs its unwillingness to surrender to catastrophic chaos.

*For a well-researched rich reading on twentieth-century history of (solid) matter—(part) of the stuff that makes the universe—and its relevance to the evolution of physics (but also of technology and engineering), in particular, the interconnection between pure and applied science, as well as the equal importance in both, the study of the minuscule (and elemental) and the study of the large (and complex), I recommend Solid State Insurrection: How the Science of Substance Made American Physics Matter, by Historian of Science Joseph D. Martin.