A Physicsy History of Telecommunications

Our modern internet comes to us from lasers through thousands of kilometers of glass tubes. But how did we get here? What are the ancestors to our modern high-speed, high-tech, high-falutin fibre optic tech? And what part did physics play?

Modern telecommunications began with the optical telegraph, invented in 1792 and used widely across Europe until the mid 1800’s. The optical telegraph was a line of towers within line of sight to each other, each with arms that could be moved to convey a message, each passing along the message of the previous tower.

Although this was much more efficient than mail carriers on horseback, it was nothing compared to the electronic communication revolution that comes next. The electrical telegraph was popularised in the 1840’s and used electrical signals through metal wires to transmit messages over long distances.

The telegraph key is used at the sender’s end to manually open and close an electrical circuit, this allows for the encoding of messages. Morse code was used to convert messages to short key presses, long key presses, and breaks so they could be sent as an electrical current through copper wires. When they arrive at the receiver, the signal was decoded.

The next great step in telecommunication came with the landline telephone, a device that could convert the human voice into an electrical signal which could in turn be transmitted through wires. First, a number is dialled using the keypad. A microphone converts the sound waves of your voice into electrical signals. Next, these signals are then sent over a telephone line. It goes through switches which are responsible for connecting the call to the appropriate destination based on the dialled number. At the receiving end, another phone converts the electrical signal back to their original sound waves through a speaker. This allowed people to speak to each other across great distances, with little delay, using nothing but their voices.

The invention of the radio and the development of radio broadcasting in the early 20th century revolutionized mass communication by allowing information, news, music, and other forms of entertainment to be transmitted wirelessly over long distances. This breakthrough enabled broadcasting to reach a wide audience, and it quickly became a popular means of communication, entertainment, and information dissemination. Radio waves, which are a form of electromagnetic radiation, are transmitted by a radio transmitter through an antenna and then received by another antenna connected to a radio receiver.

Nowadays, radio and copper telephone lines simply do not have the capacity for to carry the volume of data we want to send. Modern optical communications infrastructure uses light to transmit information over long distances through optical fibres, which are bundled into fibre optic cables and amplified as needed. Optical switches, or “routers” route the light signals, and receivers at the receiving end convert the light signals back into electrical signals for retrieval of the transmitted information. This technology enables high-speed and high-capacity communication over long distances, forming the backbone of modern global communication networks.

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