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Cables, waves and satellites

From the first Atlantic telegraph to Starlink: the copper, glass, radio and orbits that carry every call and every packet.

8 lessons · 51 min

  1. 1The Atlantic telegraphFreeIn 1858 a cable joined Europe and America and died within weeks. In 1866 it worked. What failed and what was learnt still shapes every link.1857–1866 · 6 min
  2. 2The telephone and the switched networkA telephone is useless alone. Exchanges, operators and then automatic switches turned it into a network that reserved a circuit for every call.1876–1892 · 6 min
  3. 3Copper today: twisted pairBell twisted wires together in 1881 to stop calls bleeding into each other. Every Ethernet cable still does it. Categories, shielding, 100 m and T568A/B.1881–today · 7 min
  4. 4Fibre opticsIn 1966 Charles Kao argued that glass could carry light for kilometres if it were pure enough. He was right, and it won him the 2009 Nobel Prize.1966–today · 6 min
  5. 5Submarine cables todayHundreds of fibre cables on the seabed carry most international traffic. How they are laid, why they break, and what happened when Tonga lost its only one.2022–today · 6 min
  6. 6Radio and Wi-FiMarconi heard three dots cross the Atlantic in 1901. A century later radio links every laptop: 802.11 generations, bands, channels and interference.1901–today · 7 min
  7. 7Mobile networks from 1G to 5GAnalogue voice, digital voice and texts, mobile data, all-IP broadband, and a network built for machines. What each generation actually changed.1973–today · 7 min
  8. 8Satellites: high and lowA geostationary satellite hangs 35,786 km up and costs half a second per round trip. Low Earth orbit cuts that to tens of milliseconds.1945–today · 6 min