By Tom Anderson
Few inventions have changed the world more than radio, and the multitudinous technologies it then gave birth to in turn, including radar (which will be covered in a future article). The fact radio is all around us, and commonly referenced (especially in a military context) means it is an ideal example of a term which can be changed in an alternate history (AH) story to immediately suggest to the reader that history has proceeded differently in this world.
Firstly a bit of scientific background. Radio is a means of transmitting information without connecting cables or wires (unlike the older wired telegraphy system, whose messages were even commonly called 'wires' or 'cables' in informal use). Radio waves can be produced with an antenna through which an electrical current is passed; modulating some property of this current produces different waves (more detail later).
The waves can then propagate through space, with no conducting medium required (unlike, say, a sound wave which cannot exist in a vacuum) and strike another antenna, being converted back to the same modulated electrical current which contains the original information. Radio waves are just one type of electromagnetic (EM) radiation, which is the energy given off by any electrically charged body that is undergoing acceleration (which scientifically can mean any combination of speeding up, slowing down and changing direction - not just speeding up). Radio waves are relatively long-wavelength and low frequency (i.e. the wiggly line is less bunched up, to put it very scientifically!) which means they carry less energy per 'wave packet' or photon.
If we bunch up the wave more and more to get shorter-wavelength, higher frequency waves, we would get (in turn) microwaves, infrared (heat) radiation, visible light, ultraviolet light, X-rays and gamma rays. All of these are really just a form of light; we only think visible light is special and different from infrared heat or radio or X-rays in everyday life because that's the one our eyes can see. The word 'radiation' has taken on negative connotations due to its association with the deadly high-energy gamma radiation given off by nuclear reactions, but in fact 'electromagnetic radiation' describes any form of 'light' or vice versa. The glow from your lightbulb is radiation, as are the invisible infrared beams sent out by your TV remote. The name just stems from the face that light 'radiates' out from a source.
The discovery of radio ultimately goes back to work done by the great self-made British scientist Michael Faraday in the 1830s, when he discovered electromagnetic induction, the interaction between electricity, magnetism and movement that is now the basis of all our electricity generation and therefore our civilisation. Faraday wowed an audience at the Royal Institution by using this phenomenon to make a needle on a readout change position with no connecting wires, a form of action at a distance which at that time seemed almost magical. Remarkably, the same desk in the same lecture theatre is still used for the Christmas Lectures that Faraday helped created, and it is humbling to think that the plug sockets now installed in it are the end result of that early demonstration.
Faraday turned his observations into Faraday's Law, and the scientific Mozartian genius of Scotland, James Clerk Maxwell, developed this and his own breakthroughs into the four laws known as Maxwell's Equations in the 1860s. Maxwell had successfully modelled all of electromagnetism with equations so brilliant that they did not even need correcting for Einstein's theory of relativity later on. However, a troubling consequence (which led to controversy elsewhere) was that the equations predicted that electromagnetic waves could propagate without wires. From then on, scientists wondered if this theoretical conclusion could be made real and used as a means of communication. Some, such as electricity pioneer Nikola Tesla, assumed that all EM waves would have the same properties as visible light, i.e. it could only propagate in straight lines and thus would be of little use on the curved surface of the spherical Earth. Alexander Graham Bell of telephone fame did attempt to create a visible-light 'photophone' with Charles Sumner Tainter in 1880, which used beams of visible light to transmit sound data. A year later, the French scientist Ernest Mercadier suggested the name 'radiophone' ('radiated sound') for the device to Bell. As Tesla had guessed, the invention was a failure, but the name lived on.
Meanwhile, in the late 1880s the German physicist Heinrich Hertz designed apparatus to test the validity of Maxwell's Equations by attempting to produce the predicted high-frequency electromagnetic waves. Hertz's apparatus included 'spark gaps' to generate the waves by means of an electric spark jumping a gap between two conductors. Hertz successfully proved Maxwell right by producing what we would now call Very High Frequency (VHF) radio waves. His discovery was heralded by the waves being dubbed 'Hertzian waves', a name which they retained until the 1910s. (Hertz did, however, achieve lasting immortality when his name was used as the unit of wave-cycles per second, i.e. how many 'up and downs in the squiggle' in a wave go past each second, as a measure of frequency).
It was the Italian engineer Guglielmo Marconi who was able to use Hertz's waves as a commercial means of communication, which he first demonstrated in 1894. In hindsight it appears the scientist David E. Hughes had probably already used radio waves as a means of transmitting information in 1880, but he did not realise what he had achieved as it was before Hertz's work. Marconi's name became ineluctably associated with radio, which rapidly caught on across the world. Tesla had been wrong: radio waves do not only propagate in straight lines, but can be bounced off the ionosphere to travel beyond the horizon. Marconi himself mostly called radio 'wireless telegraphy', however, and indeed referring to radio simply as 'wireless' was more common for a long time. In an interesting illustration of how society changes, in the UK twenty years ago using the word 'wireless' was considered a sign of being of an older generation, yet now the word has returned with a vengeance to describe wireless internet.
The immediate global success of radio meant that almost all languages in our timeline (OTL) just use the term 'radio' rendered into a local form. The Chinese name, wuxiandian, literally means 'wireless electricity'. Another major exception is German, which--perhaps because of Hertz's founding role in the technology--usually uses the word Funk, meaning 'spark' (in reference to the old spark-gap transmitters, although this technology has long since been superseded). This gave rise to the name of a genre of music and a term for 'cool, hip' in English: funky. Radio, and its association with music, made it a natural choice for such terms, in the same way that record players gave rise to groovy (in reference to the grooves on vinyl records). In Jared Kavanagh's seminal AH work "Decades of Darkness", a more powerful and influential Germany means that 'funk' becomes the usual word for radio in English as well.
Radio has also given birth to many terms to describe different types of radio transmission. As mentioned earlier, sound or other data is transmitted through radio by modulating some property of the electric current in the transmitting antenna (and therefore the resulting radio wave). It is possible to adjust how much the wave wiggles up and down for 'amplitude modulation' (AM) radio, or alternatively to adjust how bunched up the wave is from front to back for 'frequency modulation' (FM). The distance from one wave peak to the next is called the wavelength, and the number of said wavelengths which goes past in one second and the speed of light is the frequency (measured in Hertz, as mentioned before). Radio waves have long wavelength and therefore low frequency compared to other EM waves like visible light, but historically could further be subdivided arbitrarily into long wave (LW) for waves over a kilometre long, medium wave (MW) for hundreds of metres, or short-wave (SW) for ten metres or less. Modern radio all falls into the low end of the historical SW region, which further includes terms such as Ultra High Frequency (UHF) and Very High Frequency (VHF). Any of these terms you may have seen at some point written on a radio, and any of them could easily have different names in an alternate timeline.
Possible alternative names for radio in AH are multitudinous: after all 'radio' from 'radiating' is hardly the most obvious name for the technology. It could have been named after a person (Maxwell, Hertz, Marconi, or any of the scientific researchers and engineering pioneers that Hertz and Marconi beat to it). It could have been named in reference to the invisibility of radio waves, with terms like crypto- (hidden) or that it is a form of light, as in 'photonic telegraphy' (Photel) in Look to the West. 'Wireless' or a similar word could also have remained the mainstream term. Some OTL languages like to use 'diffusion' for radio transmission in combination with words like radio or funk, and that could also have become the major term (perhaps abbreviated as e.g. 'diff'). If you ever write an alternate history work with a point of divergence before the turn of the twentieth century, don't be boring and just call it radio - come up with your own term!