After bright lights fade in the dark, our eyes can still see them as streaks, smears, and dots. Engineer Phillip Burgess drew inspiration from this “bug” of human vision to build the NeoPixel Painter: a meter-long strip of multicolor LEDs controlled by a palm-size computer. When swept across a camera’s view during a long exposure, the device rapidly blinks out an image, one column of pixels at a time, to create art in midair. So far Burgess has painted twisted rainbows, flying dragons, a map of Earth, and other complex digital graffiti using a customized bicycle. (1)

Light graffiti, created out of nothing.
Fake images, generated with tricks.

What makes us know reality from fake?
The answer is so simple and yet alarming: Nothing!

We know the wall is not there. We know it is not "real".
But only because we have been told so...

Close your eyes.
Stop dreaming.