[Jimbee (OP)]

When I was a small kid, my mother used to tell us kids not to roughhouse around her cake when she was baking it. And she was right. Vibrations near a cake that's baking will make it fall. How does that happen? Why is it so important to avoid vibrations at that point in the baking process? And at what point is that no longer a problem?

[paul cotter]

Vibration causes small bubbles to coalesce forming voids. When the cake is fully baked the walls of these small bubbles have hardened sufficiently to prevent collapse. Before the cake materials have hardened these small bubbles are fragile. How to tell when it is vibration proof? I can't help you here, that question belongs to the art of baking, of which I know nothing.