Swiss Review / December 2021 / No.6 19 circumference and its diameter. We use pi to calculate the size of any circle, large or small. Youmay even recall its first fewdigits: 3.1415. But it doesn’t end there, because pi is what mathematicians call a transcendental number. In other words, pi is comprised of an infinite number of decimal places. Pi is a number that never settles into a repeating pattern, says Rölke. Every decimal place must be calculated individually. “This is the unique and fascinating thing.” Which is why scholars have been studying pi for some 3,600 years already – from the ancient Egyptians to the Greek mathematicians Archimedes and Ptolemy; fromChina’s LiuHui to Iran’s Jamshīd al-Kāshī and Germany’s Leibniz. According to Rölke, there have been mathematicians and physicists who have spent a whole lifetime calculating the odd hundred or so decimal places of pi. The invention of the computer was a game changer, with the advent of electronic mainframe computers at the end of the 1940s extending Pi to 2,037 digits. Methodology matters At the end of the 1980s, the Ukrainian-born Chudnovsky brothers developed an algorithm for calculating the digits of pi –whichRölke and his team alsoemployedtohit62,831,853,071,796 decimal places on their supercomputer. To print out thismind-boggling number, youwould have to fill around 17.5 billion A4 sheets of paper on both sides. Enough to take your breath away. And the FHGR scientists got nearer to the true value of pi than anyone else has before. But what is the point of identifying so many digits? “There is no practical benefit,” Rölke confesses cheerfully. Just a few decimal places are sufficient for most purposes. You need a lotmore to calculate orbits in space. “But certainly not trillions.” But the world-record number was never meant to be of use per se. The scientists weremore interested in the methodology. Their recently purchased supercomputer was an essential tool, but what was also important was having the necessary expertise to set up the hardware properly and ensure that it calculated non-stop over a period of weeks. Hence, the world-record attempt was a way to test the performance of their infrastructure. It also helped to expand their knowledge. Fit for data-intensive research projects “In preparing and performing the calculations, we were able to develop significant expertise and optimise our processes,” says Rölke. And identify weaknesses such as shortfalls in back-up capacity. It took vast amounts of storage space to conduct such a lengthy pi calculation and record its progress. The scientists repeatedly had to shift the data to commercial external hard drives. As such, the whole process gave them good training for collaborating on data and CPU-intensive projectswith partners in research and development. Together with the Swiss Institute of Allergy and Asthma Research, which is also based in Grisons, they are currently studying the causes of allergies in children – an area inwhich still very little is known, says Rölke. This wide-ranging project requires extensive calculations for evaluating blood samples, focusing onmessenger RNA from genes: “Standard calculations could only take us so far.” Intense processing power is necessary for other projects such as climate simulations to predict floods and avalanches. Switzerland’s universities of applied sciences are responsible for providing knowledge with a clear practical orientation. A short-lived record The pi world record is therefore of genuine scientific benefit, says Rölke. It has been registeredwith theGuinness Book of Records, but any bragging rights are likely to be short-lived. The mark tends to be broken again after one or two years. And the previous Swiss to extend the record did so only four years ago, when physicist Peter Trüeb calculated the number to 22.4 trillion decimal places in 2017. Google employee Emma Haruka Iwao beat this just two years later, with 31 trillion. Rölke is relaxed about it. The small matter of publishing the new pi number is proving to bemore of a headache for him. He says hewould love tomake the number freely available, but someone would need to cough up enough storage space for 62 terabytes of data. In uncompressed form, that is one huge slice of pi. “We will probably ask Google for help,” he sighs. Our column inches are limited too, so we have decided to publish only the last tenmost recently proven decimal places of pi. These are: 7817924264. Higher, further, faster, more beautiful? In search of the somewhat different Swiss records. Today: the “world champions” of pi come from Switzerland. e tremes Swiss
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