You may have spotted this video going around of a man opening a bottle of wine using just a shoe, a wall, and a willfully optimistic attitude about the integrity of glass. It's a pretty slick kitchen-hack, but does it work? And if so, why?
NPR's The Salt put the trick to the test (with effective, but messy results) and also talked with fluid dynamics engineer James Wallace at the University of Maryland to find out just what's going on with the trick:
"When you hit the bottle against the shoe, the impact of the [shoe against the] wall provides a more or less constant force to the bottle, which is then transmitted to the liquid." As it turns out, wine is actually a rather good transmitter of force, kind of like a piston. "The force moves very rapidly down the liquid, just as it would in a solid," Wallace says. "When a liquid is confined, like the wine in the bottle, it can't flow. So the wine is going to act very much like a solid." And those wine molecules are going to transfer that force all way to the corking, making it pop out.
But you can't just grab any boot, sneaker or loafer to open the bottle. Shoes with soles that are too cushioned, like running shoes, don't work at all, Wallace says: "A running shoe is made with some kind of compressible material that can deform. So the force of the wall is being absorbed by the sole. Some of the force moves out to the side. The force is not very concentrated."
So, the physics of the trick are pretty solid. There is, however, still the very real possibility of the bottle breaking with this method, injuring yourself, ruining your shoe, and losing your bottle of wine all in one swoop.
It's a pretty neat physics trick, but we'll probably stick with a corkscrew.