= Lecture 4
https://www.youtube.com/watch?v=fnMcaq6QqTY&list=PLDfPUNusx1EpRs-wku83aqYSKfR5fFmfS&index=4
* quantization. Uses a more or less standard way to guess the quantized system from the classical one using <Hamiltonian mechanics>.
* https://youtu.be/fnMcaq6QqTY?t=1179 remembers how to solve the non-field <quantum harmonic oscillator>
* https://youtu.be/fnMcaq6QqTY?t=2008 puts hats on everything to make the field version of things. With the <Klein-Gordon equation> <Hamiltonian>, everything is analogous to the harmonic oscilator