Restoring universality to the pinch-off of a bubble

We observe the formation of bubbles and drops on a daily basis, from dripping faucets to raindrops entraining bubbles on the surface of a lake. The ubiquity of the phenomenon masks the fascinating underlying nonlinear dynamics that is such an important aspect of modern physics. Here, we report on the surprising observation that confinement makes the pinch-off of a bubble a universal process, as opposed to the unconfined case, where pinch-off is sensitive to the details of the experimental setting. We explain how the motion of the contact line, where the liquid, gas, and solid phases meet, leads to self-similar dynamics that effectively erase the memory of the system. Our observations have implications for immiscible flow phenomena from microfluidics to geophysical flows, where confinement, together with fluid–solid physicochemical interactions, play a key role.