Soap Bubble Physics

Soap bubbles display iridescent colors through thin-film interference: light reflecting off the inner and outer surfaces of the soap film interferes constructively or destructively depending on the film's thickness. As gravity drains the liquid downward, the film thins at the top, shifting through a spectrum of colors before eventually popping. When two bubbles meet, they share a flat wall (per Plateau's laws), minimizing total surface area.