all light always travels at a constant speed because our universe is currently passing through another bubble universe in another dimension.
that other bubble universe naturally contains light, and ours contains matter (but they probably are the same thing).

our universes are passing through each other at a combined 299792458 metres per second, so we both (light and matter) see each other as travelling at light speed... like you would see another car passing by on the highway.
but it can come from any direction because it originates from another dimension or something.

where do i accept my nobel prize?