Field-amplitude beating of coupled Klein-Gordon modes
= Field-amplitude beating of coupled Klein-Gordon modes
A single spatial Fourier pattern initially displaced in one field excites two different normal <frequencies>. Their sum and difference generate slowly varying amplitude envelopes in the original fields. Total coupled-field <energy> is conserved, but the separate uncoupled <energies> need not be, and zeros of one <displacement> envelope do not automatically imply exact complete <energy> transfer.