Can someone please assist? My question is regarding visible light. If, for example, red light and blue light are waves of different wavelengths and frequencies then how do they combine with all the other em waves on the visible spectrum to produce one wave of visible light? If waves of varying frequencies blend together then couldn’t all waves on the spectrum do so? I probably have a fundamental misunderstanding but I can’t seem to get my head around it.
In some way this is similar to sound. The eardrum moves in response to the total sound pressure of all incoming waves. Then the ear does a kind of analog Fourier analysis, splitting the signal in different frequencies, mapped to different nerve cells in the auditory nerve.
The eye filters the total electric field by different pigments in different visual receptors (the cones). Some of these cone cells respond primarily to frequencies in the red, others to blue, others to green.
Electromagnetic fields add with superposition, meaning that the field at a certain point in space is the sum of all present field components. We'd have a single resulting field with with different spectral component.
For example sunlight contains the visible light that we can observe but also contains UV-components which are very much there, but we can still see them.
Theoretically all waves on the electromagnetic spectrum can blend together in this way since the principle of superposition applies.