Michael Stevens of VSauce explores the idea of what might happen if every person on earth - all seven billion plus of us - jumped into the air at the same time. Turns out...not much at all. Even if everybody stood shoulder-to-shoulder (which, interestingly, would only take about 500 square miles), we'd only move the earth about 1/100th of the width of a single hydrogen atom. And then, it'd move right back when we landed.
But, do watch this video - it's fascinating stuff:
[via Geek & Sundry]