Nope. See https://en.wikipedia.org/wiki/Permittivity https://en.wikipedia.org/wiki/Permittivity. But basically the material resists the formation of an electric

Nope. See https://en.wikipedia.org/wiki/Permittivity https://en.wikipedia.org/wiki/Permittivity. But basically the material resists the formation of an electric field, which means the photons actually travel slower.