In the 1860s, the Scottish physicist James Maxwell predicted the existence of a new kind of ‘electromagnetic’ waves that travel at a speed of ~300 million metres/second. A couple of decades on, Heinrich Hertz experimentally verified Maxwell’s theory and, in 1895, Sir Jagadish Chandra Bose demonstrated for the first time wireless communication with electromagnetic waves over a distance of 23 metres in Calcutta, establishing the foundation of a modern system of communication.
To understand how we communicate or send messages today via the Internet across continents – and then how this communication is disrupted – we first need to understand the fundamental nature of electrical force.
Electrons in communication.
- All matter consists of many, many electrons. Like the other Lego bricks, electrons have a property called mass, which indicates how strongly the gravitational force acts on them, and is therefore directly related to their weight.
- Another property of electrons called electric charge indicates how strongly the electrical force acts on them. The electron’s charge also decides the strength of the electrical force they apply on other objects that, too, have a charge (like the two other Lego bricks, for instance). This force, like the force of gravity, acts at a distance. So, two electrons separated by a long distance apply electrical forces without ever making contact. Since an electron is charged, the space around it is filled with an electric field.
- During communication process ,an electromagnetic wave is initiated at some location by wiggling electrons, which then washes over electrons at some distant location. The word ‘signal’ specifically means electromagnetic waves. The electrons in your eyes can also respond to these waves, provided the wavelength – the distance between peaks in the wave – is within a specific range. In this particular wavelength range, electromagnetic waves are visible to us; they are light! The most basic form of long-distance communication – flashing a bright light and using Morse Code – uses the transfer of electromagnetic waves from one location to another.
Optical fibres & the rain
- There are two primary ways to transport waves — by optical fibre, and cellular towers (via satellite link). Optical fibres are long, thin glass rods of thickness less than human hair. Light is confined in the rod due to the phenomenon of total internal reflection. When light travelling from a denser medium to a less dense one (for instance, from glass to air) hits the surface between two transparent media at a critical angle, it is entirely reflected back into the denser medium. This way, electromagnetic waves are trapped inside the fibre, and travel down the length of it. Splicing or joining hundreds of thousands of kilometres of fibres together, and burying them underground or undersea, allows communication across the globe. The electromagnetic waves used for communication (infrared waves) are generated by lasers, and have a slightly longer wavelength than visible light, so they are invisible to us.
- All Internet Service Providers connect in some way to this ‘Tier 1’ network, and eventually to your home. These secondary connections are not necessarily optical, and involve several electrical components. (Electrical components are also required along the entire optical fibre network to amplify and switch the light on and off for digital communications.
- Monsoon rain might interrupt this subterranean network in many ways. The combination of water seeping into the ground and landslides can damage the various electric components in the network, or cause physical damage at locations where the fibres are spliced together.
- There can also be similar damage, or power outages at intermediate locations, where your local service provider connects to the Tier 1 optical network, and then to your home. The fibre has a core, cladding, and plastic protective coating and is held in a watertight protective enclosure, so the signal transmission is least affected by rain. The coating is removed while joining two fibres. At locations where fibres begin or end (known as ‘splice boxes’) there is a possibility of fibres being exposed to rain water, causing a reduction in signal strength . Additionally, water molecules may find a way via micro cracks in the fibres, eventually affecting the life of the fibre.
Cell phones in the rain
- When your cell phone is connected to the Internet, electromagnetic waves travel from your device through the air to a cell tower. You could think of this as a giant antenna. The electrons in this antenna bounce up and down. When they do this, they produce their own electromagnetic waves, which travel to a central location managed by your service provider. At this location, the waves get ‘processed’ in some way, and are sent either to the optical fibre network (the Internet) or another phone (phone call, text message, etc.).
- There are various kinds of processing that might occur. For instance, one important difference between the electromagnetic waves emitted from your phone and those from the laser that travels in the optical fibre is the wavelength. The radio waves emitted from, and received by your phone, are approximately a metre long. In contrast, the infrared waves that travel through the fibre network are approximately a millionth of a metre in length. Note that neither of these wavelengths affects the electrons in your eye, since they are not visible wavelengths (around 500 billionths of a metre long).
- Somehow, the message from your phone needs to be ‘translated’ from radio to infrared waves. If you were using Morse Code, you might imagine that the radio waves detected by your provider flash on and off, containing your message. The laser managed by your provider needs to be made to produce the same sequence of flashes that travel through the fibre network.
- The reasons for interruption in this communication chain during the monsoon are different compared to the optical fibre network.
- The radio waves travelling between your phone and the cell tower can make electrons in water drops wiggle, interrupting communication. The size and number of rain drops reduce the signal strength due to the scattering of the radio waves, while water vapour in the atmosphere absorbs the radio waves, converting them to heat (like in your microwave oven).
- Further, heavy monsoon rain, wind, and lightning can cause damage to cell towers, resulting in interruptions in the area they cover. Note that this is also why you find yourself without any signal in some areas – there is no cell tower nearby. But perhaps the most common cause of interruption is ‘jamming’. When too many people try to communicate through signal processing locations at the same time, some messages get lost.