If everyone on Earth stood shoulder-to-shoulder, they would occupy an area roughly the size of Los Angeles — about 500 square miles. Now imagine if every single one of them jumped. Together. All at the same time. What would happen?
The answer? Basically squat. Humans — even in exceptionally large numbers — are small fry relative to the Earth (in the latest installment of his What If? series, XKCD's Randall Munroe explains that Earth outweighs humans by a factor of over ten trillion); but as this highly entertaining video from vsauce makes clear, sometimes the physics behind the question is more interesting than the answer itself. Let Michael Stevens run you through the physics of global-population-sized jumps, including a cameo by none other than Felicia Day!
[Via Bad Astronomy]