'All light is a type of electromagnetic wave, and they all have the same speed in a vacuum (3 x 10^8 meters per second). When light travels through a vacuum, however, the same is not true. The most obvious visual example of this occurs in rainbows, which typically have the long, faster red wavelengths at the top and the short, slower violet wavelengths at the bottom, according to a post by the University of Wisconsin-Madison (opens in new tab). One such reason, she said, is that 'as light travels through a medium - for instance, glass or water droplets - the different frequencies or colors of light travel at different speeds.' If we look at light as a wave, then there are 'multiple reasons' why certain waves can travel faster than white (or colorless) light in a medium, de Rham said.

Light exhibits both particle-like and wave-like characteristics, and can therefore be regarded as both a particle (a photon) and a wave. But there are certain caveats to consider, she said. 'Technically, the statement 'nothing can travel faster than the speed of light' isn't quite correct by itself,' at least in a non-vacuum setting, Claudia de Rham, a theoretical physicist at Imperial College London, told Live Science in an email.

What is the speed of light