Hello everyone! This is my first post as a member to this forum and as such will start out with a question that hopefully more brilliant minds than mine can help me with. I am an amateur physicist and simply enjoy pondering theories in regards to many topics in the field. Today I was thinking about light and ran into a question that even the great Google couldn't answer for me, so here I am! With respect to "Light" or the whole em spectrum, is it possible for different wavelengths to travel at different velocities?? Also, do we know the entire spectrum of light from end to end or are there still gaps in our current knowledge? Any help is appreciated. Thanks!!