How could humans communicate by emmiting and receiving EM waves?

Question

So, one of the magic systems in my world involves light manipulation. This allows the user to manipulate the EM spectrum, becoming exponentially harder the farther from the light spectrum the EM is. So, my question is, by only recieving and emmiting any type of wave could the users communicate with some kind of telepathy, or it would need some type of morse code?

And if they need that type of code, how would the differentiate it? By increasing or decreascing intensity of the wave? How it would translate to human senses?

They already have short range communication (20 meters at most) so I'm thinking of longer ranges than that, but suggestions for close range are also appreciated.

EDIT: To clarify some doubts:

• The users of this power can manipulate light around them, increasing or decreasing its frequency, reflecting it and other manipulations.
• The user can also create light in the visible spectrum in low intensity.
• The light is generated from a single point source, i.e, the user emmits the waves from themselves, in all directions at the same time from the a few micrometers above their skin like a human antenna.
• The users' power are not unlimited. The greater change from the visible spectrum, to low or high frequencies, the greater is the effort and control necessary to realize it.
• When I say light I mean all of the electromagnetic spectrum.
• The users can sense the light reaching them, that means light that gets in contact with their skin, and, with training, sense its properties, like wave length, intensity and frequency, though in a very basic sense, with no inherent ability to translate it.

Answer 1

That would depend on how much function is done subconsciously.

For example, humans have natural ability to emit and receive sound waves that encode our languages - spoken sentences which are essentially a sequence of sounds, each different in pitch and quality. You do not have to consciously compare harmonics of an "a" sound to recognise it, nor do you explicitly memorise how to make one. They all happen subconsciously.

If there are spells or other ways that allow one to manipulate one's mental processes, it may be possible to automate EM wave communication to the point of telepathy (or at least talking) - the process of extracting thoughts, encoding them to EM waves, receiving the waves, decoding them back to thoughts, all done as subconsciously as speaking and listening.

Assuming that said magic users do not have special mental processes that deal with encoding and decoding EM waves, the best bet would be reusing existing communication procedures i.e. languages and codes.

If there is a spell that translates EM wave of specific frequency to vibration of air (in our world this spell is called radio), then communication through it most likely works like radio as well: you speak into it and transform your voice to EM waves, while the receiver do the reverse.

If all they have is EM wave emission and reception, then the situation might be similar to that of optical telegraph or, as you've said, morse code, just on different spectrum. There are many code schemes that can be used, once again depend on the capability of receiver to distinguish frequencies and intensities. A simple, human-doable code can be one that uses six frequencies simultaneously, each is either on or off, and transmits a Braille letter each time. Very complex codes (e.g. the Turbo code used in actual telecommunication) are too hard for humans to do consciously, but may be doable with electronic/magical assistance.

Answer 2

How far does this power extend? Can they "cancel" light, or just create it? Can they create photons moving in a particular direction, or just omnidirectional bursts? How fine is their control? You're missing a lot of details right now, so I'm just going to throw out some ideas.

Humans, by themselves, are only sensitive to "visible" light (~400 nm to ~750 nm). If you want to be "detected" by a human without technological assistance, you're limited to this, and the recipient may have to be looking in your direction.

If you can create light far away from yourself, you can just create stuff right in front of the eyeballs of the person with whom you want to "talk". If you have enough fine control, you could "print" text, or even create images, practically right on their eyeballs. This would be relatively undetectable, or at least indecipherable, to anyone else nearby. If your control is really good, maybe you send a particular coded flash that's less subtle, after which the recipient closes their eyes and you create the image right on the inside of their eyelids (so it's much harder for anyone else to see even leaving aside being really tiny). Of course, if you can create light that's only going into the recipient's eyes, no one else is going to be able to see it or pick it up anyway, but "close your eyes so we can 'speak' privately" would make for good story-telling.

If you can't create light really far from yourself, you can create larger text nearby and hope your recipient is looking in the right direction. Range will be an issue unless you can focus the light into a laser-like beam, but if you can, you should be able to communicate with someone over a distance of a few km, at least. How far away from yourself you can create light will determine effective distance and/or whether you can create text/images or just pulses, since the angular resolution of human vision is limited. If you can also "cancel" light moving in the same direction, you can make this pretty visible under most conditions (but you'll still be affected by atmospheric scattering, so you need line-of-sight and smoke and/or fog are going to really impair this; rain, also, to a lesser extent). Otherwise it's mostly going to be useful at night.

Short version, though; if you have some decent spatial control, you can just make "text" (or images), and your recipient doesn't need to learn anything (assuming they're literate, anyway). If you're limited to a single point source, you can probably do better than fairly simple on/off systems, though you're still going to be limited by how finely your recipient can discern changes in intensity or frequency (and don't forget that a good chunk of people are color-blind, which is going to limit what you can do with frequency modulation). This is going to be a lot like learning a language, however, for both parties. OTOH, this may be common enough in your world that most people learn "light-speak" in childhood.

Now, if your recipient has a device with a radio, you can certainly send something like Morse code over other wavelengths. If you have really, really good control, maybe you can send at a much higher rate of speed, but being able to, say, spoof a WiFi connection is pretty unlikely. Even something like "proper audio" seems unlikely, unless you drag in the excuse that it's "instinctive", somehow.

Answer 3

Hypothetically yes

We know that EM waves can penetrate materials as well as being received. X-rays or radio waves are prime examples in both being able to penetrate as well as being absorbed in a meaningful way. One for X-ray pictures, the other for audio and information.

Both are EM waves. Especially radio is interesting here. It costs more and more energy to reach further. Short range you want omnidirectional, but long ranges would be directional to focus the beam and save power. To receive it, you need something to absorb the wave and resonate with it (technically the electrons in the material if I remember correctly). Much like our ears do with sound waves. If there's common biological material able to resonate with radio frequencies I don't know.

As for the information you can send, it's quite diverse. We use it mostly for music and news, but pictures, text and more can all be transferred. Sound is also a wave that can transfer a ton of information, so it isn't a stretch to send out EM and someone receiving this as 'audio'. You can potentially use several bands of radio to transfer different things. Much like you can select the radio station, the different bands can represent different modalities of the person. One for audio, one for approximate images, maybe things of understanding. Not all is a perfect representation, just like listening is a different experience with different meanings per person. Yet it could be very close to 'telepathy'.

Answer 4

In a short story I started and never finished, a schism of humans created and inserted a special organ into the human genome. People with the altered genetics are born with this artificial organ, which could transmit and receive high-frequency radio waves, independently process and store information, and interface with the brain.
The organs could communicate with those of other individuals as well as with machines, allowing interpersonal telepathy and seamless thought-control of technology.

Somewhat similar to Peter F. Hamilton's "biononics" in his Commonwealth saga, or the Conjoiner's net of cellular nanomachines from Alastair Reynold's Revelation Space universe.

Perhaps your humans are born with a similar organ that allows them shortwave radio telepathy and control of the EM spectrum.

Answer 5

Electromagnetic waves can be used to transmit data. You can vary the amplitude or strength. This can be a simple on / off such as used by Morse code or a continuous variance which is called amplitude modulation or AM. You can also vary the frequency shift it about a center frequency. This is commonly called FM. There are also way to modulate the phase relative to a unmodulated frequency or clock. This often used to today to send data.

Receiving EM waves would be fairly easy at certain frequencies. The "antenna" used to receive works best id it is 1/4 of the wavelength of the center frequency of the EM signal. For UHF, the length is a few inches. For VHF, a couple of feet. For HF signals, they need to se several yards long. UHF and VHF (Ultra high frequency and very high frequency) are only good for a couple of miles. They are very directional and will not follow the curve of the earth. HF (high frequency) can be reflected by the ionosphere (assuming you world has one) and can be received over very long distances.

Sending or transmitting EM waves does require power and such EM waves can damage tissue. A couple of watts for a short distance would be survivable. Hundreds or Thousands of watts for long distance communication would be like putting the body part in a microwave oven(most microwaves are between 400 and 1000 watts).

Learning to interpret a EM signal would be fairly easy, equivalent to learning a language. Send such as EM wave would be more difficult.