Love of numbers: How equations changed the world

Ian Stewart is a mathematician at the University of Warwick in the United Kingdom. His new book "In Pursuit of the Unknown" is published by Basic Books in the United States in March. In the United Kingdom it is available from Profile Books with the title "Seventeen Equations That Changed the World."

I was one of those annoying kids who actually liked equations. I collected them in a notebook. I loved the way you could plug a few numbers into an equation and find out how bright the Sun would be if you were standing on Pluto. Or work out how big a rainbow looks from the refractive index of water and the time of day.

I realize I am a rarity in that respect. Stephen Hawking’s publishers allegedly told him that every equation he put into his runaway bestseller "A Brief History of Time" would halve its sales. So, if he’d left out Einstein’s E=mc2, he would have sold another 10 million copies. But his publishers had a point. Although the great equations have had more impact on humanity than all the kings and queens in the history books put together, they can look very off-putting.

That’s why I wrote "In Pursuit of the Unknown: Seventeen Equations That Changed the World." We need to stop being put off, and learn to value our equations. It’s hard to write a book about equations without including any, so I decided to follow the age-old theatrical advice: ‘if you’ve got a wooden leg, wave it.’ Make equations the main characters in a story of the rise — and occasional fall — of humanity.