In the early 2010s, an experiment asked 21 four-year-old children to look at a screen and select one of two boxes displayed — whichever they thought contained the fewest dots. Three-quarters of them chose correctly when both boxes contained one or more dots. But when a box with zero dots was added as an option, that proportion fell to below 50 per cent. Whether it’s because learning to count often starts with “one”, or because it is associated with the presence (rather than absence) of real-world objects, the idea of nothingness as a number just didn’t compute as intuitively.
As a concept, “zero” might seem to us like an obvious one. But it is among the many mathematical phenomena in Kate Kitagawa and Timothy Revell’s new history The Secret Lives of Numbers that have a surprisingly complex story. It eluded ancient mathematicians until around the 7th century in India — when the figure went from being a mere place holder to a number that could actually be computed.
As demonstrated by Kitagawa, director of the Space Education Office at the Japan Aerospace Exploration Agency, and Revell, deputy US editor at the New Scientist, previous generations have not always looked at numbers as we do now. “Though mathematics is often presented as consisting of neat, logical sequences of ideas, proofs and theorems,” they write, “its history is rarely so straightforward.” Not least because it is a narrative that has been dominated by western figures and arguments, often at the expense of other trailblazers.