my point exactly! the "Fourier transform" is not something that you need to compute, but a trivial physical process that happens everywhere. You whistle a note, and the corresponding string of a harp nearby starts vibrating. The strings of the harp display the Fourier transform of the sound wave, but they are not computing anything. It is only when you try to simulate this process on a digital computer that it becomes somewhat difficult and interesting, but in the analog case it is a straightforward operation.