3.141592653 … then, a million decimal places ... 5779458151 ... and finally, for now, 62.8 trillion decimal places and ... 7817924264 …
Pi, as good as it gets: Swiss researchers have just announced their calculation of the latest and most accurate yet version of the mathematical constant which relates the diameter of a circle to its circumference, to 62.8 trillion decimal places.
It took them 108 days and 9 hours on a supercomputer and the result would fill all the books in the British Library ten times over.
The search for the true value of this irrational number, one which cannot be expressed as a common fraction and has an infinite number of non-recurring decimal places, has been going on since Babylonian times. Pythagoras came up with a reasonably accurate 3.2, while the Bible (1 Kings vii 23) sems to imply it is three: “and he made a molten sea, 10 cubits from brim to brim… and a line of 30 cubits did encompass him round about.”
The amateur mathematician William Shanks calculated Pi by hand to 707 figures in 1873 and died believing it so. Decades later, however, it was discovered he'd made a mistake at the 528th decimal place.
Such was the frustration of some non-mathematicians that in 1897 one nearly persuaded the Indiana legislature to enshrine a value of 3.2 in law, but its Senate saved the state at the last minute from mathematical ignominy and its future bridges from falling down.
Admittedly there’s little point to such Swiss precision. With only ten decimal places, we can calculate the circumference of Earth to less than a millimetre, with 32 decimal places, the circumference of the Milky Way galaxy to the width of a hydrogen atom. But a bit like mountaineers climbing uselessly to higher peaks, mathematicians will continue to explore the further reaches of the knowable.
Pi has a strange habit of appearing mysteriously throughout maths and even more strangely in life - the American date 3.14 is, appropriately, the birthday of none other than Albert Einstein.