It uses the same principle that makes mirages of water appear in the desert -- when air changes temperature a lot in a short distance, light rays get bent back on themselves. In the desert we see patches of blue sky reflected through the temperature differential that our brains process as pools of water. The UTD researchers used sheets of something called carbon nanotubes to artificially heat the air around them and make the sheets seem to disappear.
President Obama put in an immediate order for one and is believed to be planning on making it an early Christmas gift for Attorney General Eric Holder.
Starfleet Captain James T. Kirk, meanwhile, suggested that UTD researchers be on the lookout for dark-haired strangers who seem to be loathe to show their ears.