Re: (wave characteristics)Can matter be expressed on the EMF spectrum?

It is too simplistic to say that "matter and energy are
interchangeable".  What Einstein's formula, E=mc^2, means is that mass
is a form of energy.  It does not mean that matter is an electromagnetic
wave.  In quantum mechanics, the wave equation for a massive particle is
different from the wave equation for a massless photon.

When electromagnetic waves of different frequencies overlap in vacuum,
the interaction between them is very weak.  There are many interesting
effects which can be seen by allowing waves of different frequencies to
interact with atoms at the same time, however.

You might enjoy reading the book "QED: The Strange Theory of Light and
Matter", by Richard Feynman.