You can read something and hope that it’ll all be beamed into your brain for future application. Or you can read it and write down what you just learned, as if you were teaching someone else, and ...

Illustration of a polaron The bright sphere is the electron, which is distorting the surrounding lattice. The wavy lines are high-order Feynman diagrams for the electron–phonon interaction. (Courtesy: ...

Illustration of a polaron in a crystal: the central bright sphere is the charge carrier, distorting the surrounding lattice. The wavy lines represent high-order Feynman diagrams for the ...