Back (page) in the day

Alan Turing’s contribution to computer science is legendary, but others have helped historically and geographically the world over to advance computing. Here are just a sample of some of them.

Made in Greece

Sponge divers, ancient loot and the Antikythera mechanism

In the early 1900s a group of sponge divers, taking a dip while a storm passed, discovered the wreck of an ancient ship on the seabed of Point Glyphadia on the Greek island of Antikythera. This historic discovery, believed to be a shipwreck from around 200 BC carrying the loot of the Roman general, turned out to contain computing treasures too. Along with the usual haul of statues of philosophers’ heads and discus throwers, a small disc containing an intricate mechanism of at least 30 cogwheels was uncovered. Archaeologists believe the Antikythera mechanism, as it came to be known, was used by ancient Greeks to calculate the position of the moon and stars for a given date. It’s also the oldest known hand-held computing device.

Motto: a computer in the hand owes much to this wreck

Made in Arabia

The cure for the common code

Yaʻqūb ibn Isḥāq al-Kindī (c. 801–873 AD), often known as ‘the philosopher of the Arabs’, was an outstanding mathematician and philosopher. Like Turing many centuries later, he was a code breaker. He is credited as being the first to develop the technique of frequency analysis to break secret codes. Al-Kindi realised that if he knew how often particular letters turned up normally in writing, he could use this to match particular symbols in the secret code. Common letters would occur as often in normal writing as in secret code, so he could crack the code by simply counting the number of times letters appeared in both. Al-Kindi was a renaissance man about 500 years before the renaissance: he also published numerous works on medicine and music.

Motto: clever codes can be frequently broken

Made in Scotland

Scotsmen, bones, and the end of the world

Born in Merchiston, Edinburgh, in 1550, John Napier was a bit of a problem at school. His nobleman father was told in a letter from his uncle, "I pray you, sir, to send John to the schools either to France or Flanders, for he can learn no good at home." But when young John grew up he found learning really excited him. He became a world-class mathematician, astronomer, physicist and astrologer. Not only did he make the use of the decimal point commonplace, but he also created a new type of abacus, a mechanical computing device, based on his study of earlier Arabic mathematics. Napier’s bones, as his abacus became known, allowed the rapid multiplication and division of numbers by moving around appropriately labelled wooden rods. The bones turned multiplication into simple addition, and division into subtraction, opening up a whole new world of applications. Like all of us, though, Napier didn’t always get it right. As an astrologer his study of the biblical book of Revelation led him to believe that the end of the world would occur in 1688 or 1700.

Motto: always predict the end of the world to be after you’re dead

Made in India

Inventing the importance of nothing

Computers live in a binary world of 1s and 0s, but where did 0 come from? We owe the big something that is nothing to the Indian mathematician and astronomer Brahmagupta (598–668 AD). Brahmagupta was the first person to use zero as a number: he invented nothing! He also founded the modern rule that two negative numbers multiplied together equals a positive number. Like other Indian scholars at the time, he wrote his books in elliptical verse, so his work was not only mathematical but poetic.

Motto: nothing can turn out to be a really big something

Made in America

A star computer, period

Henrietta Swan Leavitt worked as a ‘computer’ in 1893 at the Harvard Observatory. From around the mid-17th century the name computer referred to a person rather than a machine: someone who carried out mathematical calculations as their day job. Henrietta was employed to count the images of stars on astronomical photographs. While she counted she also thought, and her thoughts helped change the way we understand our universe. Henrietta noticed that some stars would appear, go away, and then come back again. Rather than being fixed points in the night sky, they varied in the amount of light they shone over a period of days, months or years. She had helped to discover a class of star called a Cepheid variable, stars that are used today to help us calculate the distances between galaxies.

Motto: computers need people too