Scientists have already accomplished a LOT in the 21st century! For this list, were looking at the most groundbreaking scientific discoveries, inventions, and breakthroughs in the first two decades of the 21st century. Our countdown includes the human genome project, graphene, artificial intelligence, the discovery of a new dwarf planet, reusable rockets, and more! What do YOU think is the best scientific discovery of the century so far? Let us know in the comments! Watch more great science videos here: Top 10 Amazing Scientific Discoveries You May Have Missed: