The Large Hadron Collider fired up for the first time, a temple of science opened its doors, several companies promised cheap genome sequencing and President-elect Obama hired a fantastic team of science advisers. After decades of work, researchers made rat stem cells, built the first memristor and watched a language evolve like an organism. But none of those accomplishments impressed us as much as the breakthroughs on this list. Below are 10 biggest scientific discoveries of the 21st century.