Comment by wjakob

The renderer accurately simulates a good chunk of geometric optics -- light propagation along rays, multiple scattering, specular reflection, refraction, and surface roughness due to random microstructure using state-of-the-art models.

It does not simulate wave-optical effects, polarization, fluorescence, and phosphorescence. Some of them are easy to add (e.g. polarization), others such as wave optics are very challenging to solve in a fully general setting and would make the resulting system impractical to use.

However, that's not the whole story: even when simulating the underlying optics meticulously, a rendering of plane is not going to look photorealistic. Some detail must also go into modeling of the input, which is beyond the scope of the book (though Section 10.6 talks a bit about creating detail with noise functions).