Electromagnetic physics seeks to explain both the interaction of electrically charged particles and magnetic phenomena. While originally thought to be separate, electric and magnetic fields have been shown to be related. Except for gravitational effects, the electromagnetic force governs nearly all natural interactions observable to the naked eye. Whether electromagnetic physics is fundamentally related to other fields of physics is a topic of ongoing research.
British physicist James Clerk Maxwell showed in 1873 that electricity and magnetism were linked. He demonstrated not only how charged particles interact with each other, but also how moving charges create magnetic fields. His hypotheses have since been extensively confirmed by experiment. Since then, electromagnetic physics has been thought of as a single theory; it is embodied in a set of four laws known as Maxwell’s equations.
There are four fundamental forces in nature— the electromagnetic, gravitational, strong nuclear and weak nuclear forces. Each applies over all distances in space, but, like all fields of science, the electromagnetic force has a range in which it dominates. On very large scales, such as with stars and galaxies, gravity dominates. Electromagnetic interactions still occur, but they are overwhelmed by the gravitational force; in a sense, electromagnetic physics is “drowned out.”
At extremely small scales, such as within the nucleus of a single atom, the strong nuclear force dominates. It is the force responsible for keeping protons inside the nucleus, even though the electromagnetic force tends to push them apart. This leaves an intermediate scale that is largely dominated by electromagnetic physics.
Even though the electromagnetic force interacts with each charged particle individually, it is collectively responsible for larger interactions. When electrons of one atom intermingle with the electrons of another, a molecule can form. Molecules can be more stable than some individual atoms. Furthermore, molecules can interact with each other in a process fundamentally governed by electromagnetic physics. These molecular exchanges are the basis of chemistry.
Recent developments in physics have suggested that the electromagnetic force may be related to the other fundamental forces. The weak nuclear force, which is responsible for radioactive decay, appears to be very different from the electromagnetic force in everyday circumstances. At extremely high temperatures, however, the two distinct forces seem to merge together in what is called the electroweak force. Furthermore, the electromagnetic and gravitational forces seem to vary in space in the same way. The possibility that all the fundamental forces are related, which has been popularized by British physicist Stephen Hawking and others, is called the Theory of Everything.
