What exactly is light/EM wave/photon/quantum/radiant energy/radiation?

Light is not particle or wave. Light is alternating current at visible frequency carried by oscillating atoms.

There is no light existing in vacuum space, light must coexist with matter/medium.

Sunlight does not radiate or propagate in space at light speed 3 x 10^8 m/s. Sunlight induces lights on earth and moon and other planets instantly simultaneously due to the universal repulsion force between the line of sight surfaces of the masses at a distance.

Learn about universal repulsion force from my book or this forum post  I asked top 500 physics professors a question, no one answered, why?