Today radio waves are not something we typically think about, even though we use them very frequently. They are an idea I am so used to that I don't consider what life was like prior, or what a novel concept they were. Looking back at history, it took over 100 years and the combining several scientists’ works to achieve the feat of sending radio signals across the Atlantic Ocean.
This scientific journey began with Alessandro Volta, an Italian physicist, with his invention of the voltaic battery in 1800. The electrical unit “voltage” was named after him for the discoveries he made in electricity. Progressing from there, in 1820 the physicist and philosopher Hans Christian Oersted happened to place a compass near a wire with an electric current running through it. He discovered that the compass experienced a force, and thus current in a wire creates a magnetic field. Andre Ampere, a French mathematician and physicist, expanded Oersted’s findings. He proved that running current through parallel wires in the same direction causes them to attract, and running current in opposite directions causes them to repel. He also demonstrated that current running through a coil of wires behaves like a permanent magnet. Ampere laid the foundation for electrodynamics (as he called it), or what we call electromagnetism.
Michael Faraday, a former book binder expressing an interest in chemistry and physics, began his works with electromagnetism around the same time (1820’s). He is responsible for the discovery of induction: a current being present in a coil of wires placed near a coil of wires connected to a battery. Another form of induction occurs when a magnet is moved through the coil of wires, or if the wires are moved over a magnet. Unfortunately, since Faraday lacked the formal training, he was unable to model his experiments mathematically.
On the contrary, another man named James Clerk Maxwell was able to do so quite well. Maxwell was a Scottish mathematician and physicist, and he was able to take Faraday’s finding and express it through a mathematical equation. This became known as Faraday’s law of induction. Maxwell observed that an electric field on its own, or a magnetic field on its own, was stationary. But the changing of a magnetic field could cause a change in an electric field. Thus you could use the two together to create electromagnetic waves. During some of his calculations, he also noticed that these waves travel at a frequency very similar to the speed of light and hypothesized the existence of radio waves. Maxwell published three papers on the subject from 1856-1864 and they were combined into his book Treatise on Electricity and Magnetism in 1873
About a decade later the German physicist Heinrich Hertz was able to test and confirm Maxwell’s theory, proving the existence of radio waves. He was also able measure their frequency to not just be close to the speed of light, but equal to the speed of light. This meant that radio waves were a form of light. His findings were published in his first book in 1892. Hertz was the first to actually produce and receive radio waves, and the unit for frequency—Hertz (Hz), is named after Heinrich. Just a couple years later Guglielmo Marconi was able to apply these finding to a larger scale, sending and receiving signals from two miles away! Marconi took out a patent in 1896, and by 1901 he was able to send a signal across the Atlantic Ocean.
The evolution of electromagnetism shows that the invention of the radio wave cannot be fully accredited to one man, because each scientist built off the last. Without their collaboration, our wireless life couldn’t exist. The history of mathematics and sciences are so important because without them there would be no progress.
Sources:
