Bubbles

Not the basis for blown film, but the bubbles that kids play with and that make life a nightmare for anyone trying to coat an emulsion.

Here's a perspective on bubbles that I never saw before, one that captures the awe in the simplicity and complexity all at once:

"A bubble...is a remarkable object. It cannot exist in one phase of matter only. It is neither a gas nor a liquid or solid or plasma. It needs at least two phases of matter to come into existence. Here, a bubble in a liquid is considered: a volume of gas and vapour (and at times plasma) surrounded by a liquid. This is the normal case. When the bubble touches a solid, part of the bubble boundary is, of course, constituted by the solid surface. In many cases the bubble attains a spherical shape due to surface tension and floats around in the liquid driven by the various forces that it is susceptible to, notably pressure forces of all kinds from static to dynamic (for instance acoustic), from buoyancy to drag. A bubble seldom comes alone. In the ocean, billions of them appear side by side in breaking waves or are introduced by rain. They thus surely play a role in climate and climate change as they connect the ocean with the atmosphere more strongly than a smooth or even rough surface.

I always thought that the neat thing about bubbles were that their formation from a liquid was philosophically impossible: the smaller the bubble, the greater the internal pressure (it scales with the inverse of the bubble's radius) so to form a bubble from a point would require infinite pressure.

Source: Reports on Progress in Physics 2010 (73) 106501 (Open access with registration for the first 30 days after publication.)