A short history of communication
Where we learn how we went from communicating with smoke signals, to post cards and to the modern day Internet
When I was a kid my father used to go to the US on business trips and since phone calls were expensive, he would often send a postcard to say that he was fine. However, every now and then he did call, but the phone call was as brief as possible to save money. Today we can stream video content from all continents without even thinking about this. What has changed? And why is it now so cheap to exchange information?
Originally humans communicate quite efficiently using their voice, but this requires physical proximity. In fact, even talking across a room quickly becomes difficult and exhausting. For millennia people have thus strived to overcome these difficulties, but the ultimate problem has always been a tradeoff between content and speed. For example, a written letter can contain a lot of information, but it would take days if not months to reach its destination. On the other hand, a more instantaneous signalling system, such as a fire on a hill or a church bell, could cover relatively large distances quickly, but the message had to be very simple to be interpreted correctly. In fact, it is often a simple type of binary information, such as the smoke still in use today to signal the successful election of a new Pope (it’s either black or white).
In modern times the use of electricity finally allowed for a communication system capable of covering larger distances than ever before, with the telegraphic cable. In fact, during the 19th century thousands of kilometres of wire were connecting many cities, and Europe and the US were connected via transoceanic cables. However, over long distances the electrical signals would become very weak, and the wires could thus not be used to transmit voice, but only much simpler pieces of information. This is why simpler symbols that can be easily identified, such as dashes and dots, were transmitted using the Morse code.
The invention of vacuum tubes finally provided a means to boost the signal over long cables and in 1956 the first transoceanic telephonic cable was put in operation with a capacity of 36 simultaneous real time phone calls! Technological advances soon led to cables that could carry thousands of calls in parallel. This was the time when my father used to call us from the US.
But the real game changer came with the recent digital revolution. Ironically, this meant a return to a Morse code world, since very simple signals could be correctly decoded even in the presence of fading and noise. In particular, repeaters could decode the signal correctly, and send it again in clean format for the next legs of the digital trip. By combining this digital transmission scheme with fibre optic technology, a modern transoceanic cable can now carry the amount of data equivalent to 15 billion simultaneous phone calls!
In fact, these underwater cables carry 99 percent of the worldwide Internet traffic today, on top of phone calls. The funny part: lots of the data is used to transmit pictures of cats.
