To me, a key lesson from both Newton and Friedmann is this simple mantra: “Dare to extrapolate!” Specifically, take your current understanding of the laws of physics, apply them in a new uncharted situation, and ask whether they predict something interesting that we can observe. Newton took the laws of motion that Galileo had established on Earth and extrapolated them to the Moon and beyond. Friedmann took the laws of motion and gravity that Einstein had established in our Solar System and extrapolated them to our entire Universe.
