The world is full of things you can't see: the heat coming off your hand, the spray of a sneeze, even the sound of two hands clapping. But a simple camera trick called Schlieren flow visualization turns those invisible waves of light into beautiful plumes of movement. With this trick you can literally see invisible things.
A couple months ago, New Mexico Tech mechanical engineering professor Mike Hargather posted a few gifs of these invisible things. And now there's a full video from NPR with a fascinating description of how the shots were taken. Ever wonder what the sound of a gun shot looks like? Or a lighter being lit? It looks like this:
The first GIF looks not unlike a gun firing underwater. That shouldn't be a surprise. At the end of the day, we're talking about waves here, some of which as easy to see with the naked eye and some of which are impossible. But that's nothing that bending a little light can't fix.
GIFs via Mike Hargather