Short of putting a magnet in your finger, humans aren't able to directly sense magnetic fields — but we can see some of the effects that they have on the world around us. Artist Carsten Nicolai has built an installation with an effect that anyone who's owned a CRT display may be familiar with: as a magnet passes near its surface, the electrons that build the display's picture are pushed around, warping the image into a psychedelic spectacle.
Nicolai has made this effect easy to see, so that observers can visualize how magnetic fields interact with the world. On a pair of CRT TV screens, the artist displays a series of straight white lines that viewers can watch morph as a magnet mounted to a pendulum is swung across them. "I like to visualize that kind of invisibility," Nicolai said in a short documentary on his exhibit "crt mgn." Though magnetic fields can seem ethereal to humans, certain animals and bacteria are capable of detecting their forces, and sometimes use the sense to orient themselves with a field that stems from the Earth's core.