Asked by: Bob Bullock, Swansea
Water contains dissolved air, molecules of which accumulate around tiny imperfections on the glass. This process of “nucleation” continues until a bubble forms, breaks free and rises to the surface. Dropping something light but crinkly like a lemon pip into fizzy water can trigger repeated cycles of nucleation and bubble formation, making it rise and fall repeatedly.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Authors
Robert is a science writer and visiting professor of science at Aston University. He likes maths, West End musicals and hamsters.
