What Happens
You'll notice that just holding the jug upside down with no additional movements doesn't work. That's because the flow of more dense water exiting the bottle is slowed as the water collides with the less dense air entering the bottle. In most cases, players who swirl their jug, creating a vortex, win the race. The vortex creates a large inner pathway for air to enter the bottle as water escapes. Also, just shaking the bottle causes the water to travel up and down many times. This increases the distance it must travel before leaving the bottle, which takes longer. For the same reason, swirling the bottle too much will also slow the exit of the water out of the bottle.
