What is an Electromagnetic Field?

To a physicist, it is an incorporeal entity, pure energy, whose physical existence is required by the set of four linear differential equations that explain electricity. It’s not possible to have electricity without having fields. On the other hand, it’’s a lot simpler and easier for the layman to think about electricity as something flowing through wires, cellular telephones, microwave ovens, high-voltage powerlines, or batteries, without resorting to the notion of an EMF.

An intrepid layman who did inquire into the nature of EMFs would have to try to assimilate the fact that there was not one field, but rather two fields—electric and magnetic. Further, sometimes these fields propagated through space with the speed of light, whereas at other times they simply stayed near the hardware that gave rise to them, as in the case of powerline EMFs. Sometimes the two fields could be separated from one another, but in other situations it was essentially impossible to do so.

The notion an EMF is Kafkaesque. It’s easy to be afraid of something you understand poorly, but it’s hard to be afraid of something you never heard of, and in the 1970s I think the American public had no meaningful understanding of the reality of electromagnetic fields. That situation changed dramatically during the next 2 decades.