A Finnish company says that it has solved a problem that has vexed the designers of ultra-tall skyscrapers such as the 828-meter Burj Khalifa in Dubai or the 509-meter Taipei 101 in Taiwan – and we'll pause for a moment to let you guess what that problem might be. Ready? It's the fact that elevators are currently limited to a maximum travel distance of around 500 meters. The Burj Khalifa, in fact, has an elevator that holds the world record for the longest travel distance: 504m (1,654 feet). And what's keeping elevators from exceeding that limit? Time for another pause...