Throughout most of the nineteenth century, people thought that electricity, magnetism, and light were three separate, unrelated things. Research proceeded from that assumption. Then Maxwell discovered that they are all the same, forms of electromagnetic radiation.
It was a startlingly grand discovery, often called the greatest discovery in physics in the nineteenth century. Maxwell did for electromagnetic radiation what Newton did for gravity, gave science mathematical tools to understand and use that natural force.
Maxwell unified magnetic and electrical energy, created the term electromagnetic radiation, and discovered the four simple equations that govern the behavior of electrical and magnetic fields. While developing these equations, Maxwell discovered that light was part of the electromagnetic spectrum and predicted the existence of radio waves, X-rays, and gamma rays.
James Clerk was born in 1831 in Edinburgh, Scotland. The family later added the name Maxwell. James sailed easily through his university schooling to earn top honors and a degree in mathematics. He held various professorships in math and physics thereafter.
As a mathematician, Maxwell explored the world, and the universe, through mathematic equations. His chose the rings of Saturn as the subject of his first major study. Maxwell used mathematics to prove that these rings couldn’t be solid disks, nor could they consist of gas. His equations showed that they must consist of countless small, solid particles. A century later, astronomers proved him to be correct.
Maxwell turned his attention to gasses and studied the mathematical relationships that governed the motion of rapidly moving gas particles. His results in this study completely revised science’s approach to studying the relationship between heat (temperature) and gas motion.
In 1860 he turned his attention to early electrical work by Michael Faraday. Faraday invented the electric motor by discovering that a spinning metal disk in a magnetic field created an electric current and that a changing electric current also changed a magnetic field and could create physical motion.
Maxwell decided to mathematically explore the relationship between electricity and magnetism and the “electrical and magnetic lines of force” that Faraday had discovered.
As Maxwell searched for mathematical relationships between various aspects of electricity and magnetism, he devised experiments to test and confirm each of his results. By 1864 he had derived four simple equations that described the behavior of electrical and magnetic fields and their interrelated nature. Oscillating (changing) electrical fields (ones whose electrical current rapidly shifted back and forth) produced magnetic fields and vice versa.
The two types of energy were integrally connected. Maxwell realized that electricity and magnetism were simply two expressions of a single energy stream and named it electromagnetic energy. When he first published these equations and his discoveries in an 1864 article, physicists instantly recognized the incredible value and meaning of Maxwell’s four equations.
Maxwell continued to work with his set of equations and realized that, as long as the electrical source oscillated at a high enough frequency, the electromagnetic energy waves it created could and would fly through the open air, without conducting wires to travel along. This was the first prediction of radio waves.
He calculated the speed at which these electromagnetic waves would travel and found that it matched the best calculations (at that time) of the speed of light. From this, Maxwell realized that light itself was just another form of electromagnetic radiation. Because electrically charged currents can oscillate at any frequency, Maxwell realized that light was only a tiny part of a vast and continuous spectrum of electromagnetic radiation.
Maxwell predicted that other forms of electromagnetic radiation along other parts of this spectrum would be found. As he predicted, X-rays were discovered in 1896 by Wilhelm Roentgen. Eight years before that discovery, Heinrich Hertz conducted experiments following Maxwell’s equations to see if he could cause electromagnetic radiation to fly through the air (transmit through space in the form of waves of energy). He easily created and detected the world’s first radio waves, confirming Maxwell’s equations and predictions.
Astronomers have concluded that the most efficient way of making contact with an intelligent civilization orbiting another star is to use radio waves. However, there are many natural processes in the universe that produce radio waves. If we could translate those naturally produced radio waves into sound, they would sound like static we hear on a radio.
In the search for intelligent life, astronomers use modern computers to distinguish between a “signal” (possible message) and the “noise” (static).
