How is light, electricity, and magnetism all the same thing?

Light is just one part of the electromagnetic spectrum. It can be thought of as oscillations of electromagnetic fields, and as such it mediates the interactions between electrical charges. It itself has no electrical charge. Consequently light doesn't interact with light, except in producing interference effects. read more

And magnetism is a part of the electric field that one can experience when in realtive movement to an electric field. So they are all related. But they are not all the same. read more

However, we can put the electric and magnetic fields together into a single object called the electromagnetic field tensor and express Maxwell's equations in terms of this new combined object. This is what we mean when we say that electricity and magnetism are two aspects of the same thing. read more