The speed of light c in relativity is always its value in free space of ~3.00×10^8.
In all material media ,such as air ,water,or glass ,light travels more slowly than this,and atomic particles are able to move faster in such media than does light .
In all material media ,such as air ,water,or glass ,light travels more slowly than this,and atomic particles are able to move faster in such media than does light .