For others who like to learn from video, here is lenghtier explanation of quantum fields, discrete energies, plane waves, etc. from Sean Carroll: https://www.yo

For others who like to learn from video, here is lenghtier explanation of quantum fields, discrete energies, plane waves, etc. from Sean Carroll: https://www.youtube.com/watch?v=Dy1LNk_B6IE https://www.youtube.com/watch?v=Dy1LNk_B6IE