Why does a beer overlow when someone hits the top of a beer with the bottom of theirs?

Question

Why does a beer overlow when someone hits the top of a beer with the bottom of theirs?

In: Other

Answer 1

The impact causes a series of alternating expanding and compressing waves to bounce between the bottom of the bottle and the surface of the beer. These waves have an effect on the beer that cause large air bubbles to form. The same waves then break the big bubbles into many tiny bubbles. These tiny bubbles have a higher surface to volume ratio causing them to expand rapidly and that’s where the overflow comes from