Let's say someone has gotten a little sassy at your family's holiday gathering. Or maybe it's New Year's, and not everyone is getting in the spirit. Here's how to break a beer bottle so it turns into a weapon — using science!
Perhaps others are more used to drunken bar fights than I am, but I always had a problem with that scene in which someone breaks the end of a beer bottle off by smashing it against a counter. Taking a random piece of glass and smashing it against a random object seemed, to me, a quick way to cut up your own hand and leave the arena whimpering. Fortunately, it seems there is an easier way.
Take an open beer bottle — filled to within two inches of the top with liquid — firmly by the neck. (Apparently, the neck can shatter as well. Maybe wrap a bar rag around the neck first.) Hold it in front of you. Then thwap it hard with the heel of your free hand. The bottom should neatly break off of the bottle, leaving a long weapon with a jagged side that you can brandish while screaming, "You want a piece of me? You want a piece of me, huh? You don't call the lightning if you don't wanna face the thunder!" You can also scream something else. I don't want to limit your bar-brawl banter.
How do you get this neat result? When you thwap the bottle on top, the bottle leaps downwards. The liquid (beer? water? urine?) inside doesn't make the same leap. It lags behind, and so a void opens up at the bottom of the bottle. This isn't air sneaking into the bottom of the bottle, it's an extreme drop in pressure between liquid and glass. The void then collapses, fast. This means the water doesn't just fall back into place, but hits the bottom of the bottle with a great deal of force, breaking out the bottom of the bottle. And voila — you have just the thing you need to cause holiday mayhem.