Turing's Enduring Importance

When Alan Turing was born 100 years ago, on June 23, 1912, a computer was not a thing--it was a person. Computers, most of whom were women, were hired to perform repetitive calculations for hours on end. The practice dated back to the 1750s, when Alexis-Claude Clairaut recruited two fellow astronomers to help him plot the orbit of Halley's comet. Clairaut's approach was to slice time into segments and, using Newton's laws, calculate the changes to the comet's position as it passed Jupiter and Saturn. The team worked for five months, repeating the process again and again as they slowly plotted the course of the celestial bodies.