Scientists and engineers dream about big advances that could change the world, and then they try to create them. On the following pages, Scientific American reveals 10 innovations that could be game changers: an artificial alternative to DNA, oil that cleans water, pacemakers powered by our blood, and more. These are not pie-in-the-sky notions but practical breakthroughs that have been proved or prototyped and are poised to scale up greatly. Each has the potential to make what may now seem impossible possible. —The Editors