Theories of the Universe: You Can't See It, but It Has to Be There

You Can't See It, but It Has to Be There

An important question to ask about light behaving as a wave is what does it wave in? The idea that there was some type of invisible fluid or element that was part of the universe can be dated all the way back to Aristotle. Remember the four Greek elements: earth, air, fire, and water? It was thought that there was a fifth one that helped to explain the movement of the celestial bodies in the heavens, because it was believed that something was needed to support and guide them in their perfect circles.

In a speech delivered in 1889, Heinrich Hertz said:

• … the great problem of the nature and properties of the ether which fills space, of its structure, of its rest or motion, of its finite or infinite extent. More and more we feel that this is the all-important problem, and that its solution will not only reveal to us the nature of what used to be called imponderables, but also the nature of matter itself and of its most essential properties—weight and inertia …. These are the ultimate problems of physical science, the icy summits of the loftiest range.

That statement really reflected how many prominent scientists felt. Isaac Newton along with Michael Faraday and James Clerk Maxwell all believed that there had to be some substance that acted as a medium to transmit the forces of gravity, electricity, and electromagnetic waves through space. However, they had different views on exactly what this substance was. Newton himself had no idea what it was, as seen in this letter to a friend.

• … that gravity should be innate, inherent and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to another, is to me so great an absurdity that I believe no man who has in philosophical matters a competent faculty of thinking can ever fall into it. Gravity must be caused by an agent acting constantly according to certain laws, but whether this agent be material or immaterial, I have left to the consideration of my readers.

Faraday's Fields

Remember Michael Faraday? As an experimenter Faraday was extraordinary. His ideas were unlike anybody else's and he had little to do with the experts at the universities. He was an intuitive thinker and many of the ideas that he expressed were difficult for the typically rational approach of many of the other scientists. He was not that good at the higher mathematics of algebra and calculus, so he worked out his theories strictly through experimentation rather than mathematical equations.

According to Faraday, matter is atomic, which was something that most scientists agreed upon. Each atom had an “atmosphere of force” around it, an idea that had never been clearly defined and had no better name. He later developed this idea into the term “field,” a form of ether that had lines of force running through it. As mentioned before, the best way to see this is to put iron filings on a piece of paper and place a magnet under the paper. You will see a pattern in the filings created by the magnetic field. Here again was the idea that this field had to exist in something; it couldn't just float about in empty space.

After years of experimentation, Faraday's discoveries suggested that electric and magnetic fields were more than just forces; they also had a dynamic interaction. This capacity to use one to create the other led to the term “electromagnetic field.” And perhaps his greatest insight was that an electromagnetic field could affect a ray of polarized light. He realized that there had to be some connection between electromagnetism and light waves.

Maxwell's Mathematics

The man who would bring electromagnetism and light together was James Clerk Maxwell. He developed mathematical formulas that connect electric fields with electric charges, magnetic fields with electric currents, and those that connect electric and magnetic fields together. These are the formulas that express the mathematical unification of electricity and magnetism. There is not a word about the properties of ether in all of this; he was only concerned with fields and their sources. However, he was still an ardent believer in it as can be seen in this article he wrote for the Encyclopedia Britannica:

• Whatever difficulties we may have in forming a consistent idea of the constitution of ether, there can be no doubt that the interplanetary and interstellar spaces are not empty, but are occupied by a material substance or body, which is certainly the largest and probably the most uniform body of which we have any knowledge.

Maxwell, like Newton and Faraday, believed that the existence of ether was necessary, but like them, he had no clue as to what it really was. He kept his views about ether out of his mathematical formulas, not just because he didn't know what it was, but because it wasn't necessary in developing his mathematical formulas. However, his belief in ether did lie behind his theories of how electromagnetic waves moved through space.

Maxwell's theories explain so many different facts of electricity and magnetism that there is no serious doubt that they are accurate. His mathematical formulas are the cornerstone of classical physics in electromagnetic radiation. From the work that he did, he was able to calculate the speed of electromagnetic waves, and because the speed of light (which had been discovered by Lon Foucoult) was essentially the same, he deduced that light was electromagnetic, although he gave no experimental evidence to support this.