While it might not quite match the robot invasion
of the 2005 World Expo in Aichi, Japan, it looks like Zaragoza, Spain's 2008 World Expo won't be lacking for displays of technology either, with an MIT-designed "digital water pavilion" greeting visitors at the entrance. While its practicality may be in question, the pavilion certainly looks to be impressive enough, boasting computer-controlled walls of water that can display scrolling text or images, or automatically form a doorway when it detects a person approaching. To manage that feat, the MIT engineers employed a series solenoid valves that can be opened and closed at high frequency, effectively working, as MIT describes it, "like an inkjet printer on a large scale." It's also apparently not as wasteful as it seems at first glance, relying entirely on recycled water, with the water also eliminating the need for air conditioning.