Standing with the edge of this large mirror bisecting your body, you appear whole to a person who’s observing from the front. To the observer, the mirror image of the visible half of your body looks exactly like the real half that is obscured behind the mirror.
You look whole because the human body is symmetrical. The observer’s brain is tricked into believing that an image of your right side is really your left side. So just straddle the mirror, raise one leg, and you’re flying.
You can try this out anywhere where there’s a good-sized mirror that you can straddle or stand alongside—at home, in a department store, or in a dance studio with a doorway cut into a mirrored wall.
"Reflections on Anti-Gravity Mirror" (pdf) by artist Bob Miller
The illusion of flight you see at this exhibit was used to create a low-tech, precomputer graphics special effect in the original Star Wars movie. The anti-gravity Landspeeders that floated across the desert landscape of Tatooine actually had wheels, but these were hidden by a full-length mirror attached along the vehicles’ lower edge. A camera filming a rolling Landspeeder saw a view of reflected sand and shadow in the mirror instead of wheels—so the car appeared to float above the sand.