Bubbles. Big ones entertain children and tiny ones tickle champagne aficionados. Even witches appreciate what they bring to a boiling cauldron. If you, too, are a bubble lover, then you'll enjoy this latest bubble study published in the journal Nature. In it, scientists show that a bursting bubble can leave in its wake a ring of smaller bubbles, a finding that could have implications for disease transmission. Bubbles are engaging because of their effervescence. Here one minute and then they're gone. Or so we thought. What the new study shows, however, is that when bubbles break open on the surface of a liquid or solid, they don't simply disappear. Using high-speed videography, scientists observed surface bubbles as they burst. And they saw that when the skin of the bubble ruptures, it retracts. As this film folds in on itself, it can trap air, thus forming smaller, daughter bubbles. These daughters can then do the same, leaving behind a generation of grandbaby bubbles. And so on. The tinier the bubbles, the greater their internal pressure. So when these babies blow, they can disperse their contents far and wide, which is fine if you're sipping champagne. But less welcome in a hot tub that might be full of cold and flu.