Yang Wang

A bathtub full of water is a simple thing. You fill it, the level holds, and then it slowly drains away. Entropy, the measure of disorder, behaves much the same way in a living organism over the course of a lifetime. First, in childhood and youth, the body puts things in order: cells divide, organs grow, entropy falls. In maturity, order holds on a plateau, like water sitting in the tub.

When the first stars ignited, their ultraviolet light began stripping electrons from hydrogen atoms. The universe transformed from a neutral fog into transparent plasma. This process, cosmic reionization, proceeded unevenly: slowly at first, like a fire catching in damp wood, then faster as the flames spread through dry tinder.

Toss a handful of glitter into a river, and some flakes will drift straight while others spin in tiny eddies. Galaxies in the universe do something similar: they don't just recede due to cosmic expansion: they also swirl in giant currents, like wood chips caught in invisible whirlpools.

Imagine a kinked garden hose: water meets resistance, and pressure drops. A similar process occurs in arteries when they lose their straight geometry. Vascular tortuosity is not just a cosmetic defect but a factor that disrupts hemodynamics and poses a threat of ischemic stroke.