With a bit of practice, you can make foam gush out of the bottle just by touching the valve. Marshmallows are made of foamy cells with air inside so you can crush them with high pressure and they ...

A Helmholtz resonator consists of an enclosed cavity of air — like the inside of a glass bottle, or the space between clapping hands — with an opening connected to the cavity by a neck.

To get the egg out, blowing into the bottle increases the internal air pressure. The air gets trapped behind the egg like a valve, building up pressure until it forces the egg back out. The difference ...