You’ll probably have been exposed to the visual phenonemon known as “persistence of vision” (POV) in those animated flip-books from days past (the good ole’ days). The human eye’s refresh rate, as it were, is just slow enough that momentary flashes of light (especially moving light) seem to hang in mid-air for a tick, and that’s what makes iPhone apps like “Light Writer” possible. The new iPhone application allows you to trace glowing messages in the air using nothing more than the iPhone’s LCD display and a bit of elbow grease.
If you’re a fan of those Sprint commercials that had streaks of light tracing intricate patterns into the night air, you’ll love Light Writer for the iPhone. Simply configure Light Writer with the message or image you’d like to flash to the world and start waving your iPhone around like a madman – what you’ll see is a streak of light with the words “Hello World” (or whatever else you decide to write). Light Writer uses your iPhone’s accelerometers to determine how fast and in what direction you’re moving your iPhone, and adjusts the speed with which it flashes your desired message. The overall effect is just geeky cool.