Foam

A bubble is a visualization of the tension of the difference between the air pressure inside it and the air pressure outside it. It's in an uneasy balance. The wobble and shimmer of a bubble  demonstrates the equalization of the forces. The bubble skin thins out unequally as well, making ephemeral lenses that bend light into swaths of color.  After some time, the bubble stabilizes. Heating it slightly will make the bubble float, as the density of the air inside it is less than that outside it. And so the bubble floats off. The action of movement disrupts the equilibrium, sending ripples of air currents internal to the bubble which need to be stabilized again. The skin defines the bubble, but also visualizes the struggle of forces both internal and external. When two or bubbles collide, the equation changes, and a flat surface appears between them as they merge, which is bent toward the bubble with the lower internal pressure. The act of merging sets off another chain of wobbly motion. Clusters of conjoined bubbles form a foam, which as a byproduct of the forces previously mentioned, and builds a highly resilient structure where all the forces strive toward balance. It is said that the structure of the universe, the placement of galaxies, is that of a foam. This would be the side effect of simultaneous gravitational forces acting as air pressure does.