Have you popped a can of Guinness and heard that fwoosh sound? You have surely waggled the can and heard that little thing knocking about inside?
That little thing is one of the 20th century's greatest contributions to mankind -- the beer widget.
This little guy is what gives Guinness and other "good" beers their creamy head. How does this happen?
Into each can is dropped this little plastic ball punctured with a tiny hole. Then the beer is poured in. Finally, a shot of liquid nitrogen is added and the can is sealed. The nitrogen quickly raises the pressure inside the can, forcing some beer into the ball. The spring is set... now we wait...
Until you pop the top of the can. At this point the pressure inside the can equalizes with the pressure outside, creating the same POP you hear when you open a can of soda. But you also hear a sustained fwoosh. THAT is the beer escaping from the widget, being forced out by the compressed gas. And in the process, it agitates the surrounding beer releasing carbon dioxide and generates the head.
So next time some fool JW starts talking about the world "getting worse and worse", you remind him of the beer widget, bringing frothy heads to mankind the world over. Put him in his place!
All hail the widget!
Dave