Lost Knowledge

Short, surprising cards on lost knowledge. Each one is labelled Established, Debated or Speculative, so you always know how solid the evidence is.

• The ancient Greeks built a pocket computer for the sky.

  Established. In 1901 divers found a lump of corroded bronze in a shipwreck off the island of Antikythera. Inside were dozens of precise gears. It could…

• Kings once asked questions of the future by cracking bones with fire.

  Established. In Shang dynasty China, around 3,200 years ago, diviners carved questions into ox bones and turtle shells, then heated them until they…

• Did ancient people make electricity?

  Debated. A clay jar found near Baghdad holds a copper tube and an iron rod. Filled with vinegar, a replica makes a small electric current. Some…

• There's a 600-year-old book no one can read.

  Established. The Voynich manuscript is written in an unknown script and filled with drawings of strange plants, stars and bathing women. Its vellum…

• A Greek scholar measured the Earth with a stick and a shadow.

  Established. Around 240 BCE, Eratosthenes heard that at noon on midsummer, the Sun shone straight down a well in Syene, Egypt. In Alexandria, a stick…

• Medieval swordsmiths made nanotubes without knowing it.

  Established. Damascus steel blades were famed for their wavy patterns and sharp, tough edges. In 2006, scientists found carbon nanotubes inside a…

• The Byzantines had a fire that water couldn't put out. Its recipe is lost.

  Established. From the 600s, the Byzantine Empire sprayed 'Greek fire' at enemy ships through tubes. It kept burning on water. The formula was a state…

• A Roman cup changes colour when light shines through it.

  Established. The Lycurgus Cup, from the 300s CE, looks jade green in normal light. Light it from inside and it glows red. Scientists found tiny…

• The Maya invented zero on their own.

  Established. Zero as a number seems obvious now, but most ancient cultures had none. The Maya developed a symbol for zero independently, shaped like a…

• The oldest known map of the sky was recovered in a police sting.

  Established. The Nebra sky disc is a bronze plate inlaid with a gold Sun or Moon, a crescent and stars, including what looks like the Pleiades. It is…

• Is a 20,000-year-old bone our first maths homework?

  Debated. The Ishango bone, found in what is now the Democratic Republic of Congo, is a baboon leg bone notched in groups. Some researchers see prime…

• A 1,600-year-old iron pillar in Delhi has barely rusted.

  Established. The iron pillar in Delhi's Qutb complex stands over seven metres tall and dates to around 400 CE. It has survived centuries of monsoons…

• Polynesian navigators crossed thousands of kilometres of ocean with no instruments.

  Established. Using stars, swells, birds and clouds, Polynesian voyagers settled islands across the Pacific, from Hawaii to New Zealand. In 1976, the…

• The I Ching and your phone speak the same language.

  Established. The ancient Chinese I Ching builds 64 hexagrams from broken and solid lines. In 1703, mathematician Gottfried Leibniz, who developed binary…

• Does a map from 1513 show Antarctica?

  Speculative. Ottoman admiral Piri Reis drew a world map in 1513 from older sources, including one he said came from Columbus. Some claim its southern…