Why is the speed of all electromagnetic waves the same in vacuum? Please try to explain in a simple manner.
This comes as a direct result of Maxwell's equations for electromagnetic fields, according to which the speed of an electromagnetic waves depends on the permeability and permittivity of vacuum.
It does not depend on what kind of electromagnetic wave it is. Different electromagnetic waves will have different frequencies and wavelengths but their speed in vacuum only depends on permeability and permittivity of vaccuum and hence will be the same for all electromagnetic waves