Why do ordinary glass windows look colorless?

Colorless is actually transparent.

The so-called transparency actually means that all light passes through without reflection or refraction. If all the light cannot pass through, reflection and refraction will occur, that is, it is opaque. The principle of transparency and opacity lies in whether the aggregated structure of matter is isotropic or anisotropic. If the material aggregate structure is isotropic, all light can pass through without reflection and refraction, that is, it is transparent; on the contrary, if the material aggregate structure is anisotropic, all light cannot pass through and reflection and refraction occur, that is, opaque. . Glass is amorphous and its molecular aggregate structure is isotropic, so all light can pass through it; therefore it is transparent. Common iron, because it is crystalline, has an anisotropic aggregate structure, so light cannot pass through it all and will be reflected and refracted, so it is opaque. If the molten iron is cooled rapidly so that it does not crystallize during the rapid cooling process and its aggregated structure becomes isotropic, transparent iron can theoretically be produced. However, this is not currently possible. Rebound glass is generally made of non-crystalline polyethylene.