I wonder if maybe this is a question that a lot of people have asked; if so, I apologize; a quick search didn't seem to turn up any relevant results. Why isn't there an equivalent of general relativity for electromagnetism? Coulomb's law, at least, has the same form as Newton's law for gravity. And, in my very limited understanding of the matter, I don't see what there is in the motivation for general relativity that doesn't also apply to electric forces. For example, a person weightless in an elevator can't tell whether the earth has vanished or he is in free fall. Similarly, an electron shouldn't be able to tell whether it's free-falling in an electric field or floating in a field-free region. What gives? Is magnetism the difference?