Marcus Chown:

*TWO plus two equals four: nobody would argue with that. Mathematicians can rigorously prove sums like this, and many other things besides. The language of maths allows them to provide neatly ordered ways to describe everything that happens in the world around us.*

Or so they once thought. Gregory Chaitin, a mathematics researcher at IBM’s T. J. Watson Research Center in Yorktown Heights, New York, has shown that mathematicians can’t actually prove very much at all. Doing maths, he says, is just a process of discovery like every other branch of science: it’s an experimental field where mathematicians stumble upon facts in the same way that zoologists might come across a new species of primate.

Mathematics has always been considered free of uncertainty and able to provide a pure foundation for other, messier fields of science. But maths is just as messy, Chaitin says: mathematicians are simply acting on intuition and experimenting with ideas, just like everyone else. Zoologists think there might be something new swinging from branch to branch in the unexplored forests of Madagascar, and mathematicians have hunches about which part of the mathematical landscape to explore. The subject is no more profound than that.