An Imaginary Tale

The Story of The Square Root of Minus 1

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by Paul J. Nahin

Princeton University Press

Due/Published October 1998, 274 pages, cloth

ISBN 0691027951

Ok, so it's very unlike 99.5% of the other books offered at Frontlist. Still, it is one of those fascinating stories that I just can't ignore. Nahin tells the 2000-year old history of this most elusive of numbers, also known as i. Complex or imaginary numbers (others name if you remember your high school math) have many practical applications from engineering to aeronautics, but where did they come from? Under what circumstances? Here is an outline of the history, but without the characters or the mathematical problems that enliven the story as Nahin tell it:

In 1878, when two brothers stole a mathematical papyrus from the ancient Egyptian burial site in the Valey of Kings, they led scholars to the earliest known occurrence of the square root of a negative number. The papyrus offered specific numerical example of how to calculate the volume of a truncated square pyramid, which implied the need for i. In the first century, the mathematician-engineer Heron of Alexandria encountered i in a separate project, but fudged the arithmetic; medieval mathematicians stumbled upon the concept while grappling with the meaning of negatie numbers, but dismissed their square roots as nonsense. By the time of Descartes, a theoretical use for these square roots was suspected, but efforts to solve them led to intense, bitter debates. i finally won acceptane and was put to use in complex analysis and theoretical physics in Napoleonic times.

Maybe you have a friend who's having a birthday soon . . . or a cousin who teaches math. It sounds like a great story.