Refraction has always bugged me. If light doesn't interact with electrons in materials transparent to that wavelength (otherwise they'd be opaque, surely?), then why should it slow down in the first place? Even just accepting that light slows down, the "line of soldiers" analogy doesn't make much sense to me - why should light waves care that others have slowed down?

Nor do I fully understand reflection. I know that coloured surfaces have electrons that can absorb certain wavelengths of light but reflect others, and that white surfaces and mirrors differ only in smoothness, but what is the difference in terms of electron interaction between absorption (e.g. visible light on black material), reflection (e.g. visible light on a mirror, or a sheet of white paper) and transparency (e.g. visible light through glass)?

This has been troubling me for a while, and I'd love to have it explained by those who understand light.

Thanks.