Cosmological observations show that on the largest scales accessible to our telescopes, the universe is very uniform, and the same laws of physics operate in all the parts of it that we can see. As Andrei Linde, 2014 Kavli Prize Laureate in Astrophysics, explains, rather paradoxically, the theory that explains this uniformity also predicts that on extremely large scales, the situation may look totally different. Instead of being a single spherically symmetric balloon, our universe may look like a multiverse—a collection of many different exponentially large balloons with different laws of physics operating in each. In the beginning, this picture looked more like a piece of science fiction than a scientific theory. However, recent developments in inflationary cosmology, particle physics, and string theory provide strong evidence supporting this new cosmological paradigm.