[This is an English translation of a tribute to Jon Borwein, written by Francisco Aragon Artacho, which appeared in El Pais, the highest-circulation newspaper in Spain. The original is here.]

On August 2nd the heart of one of the most brilliant and influential mathematicians of our time stopped beating. Professor Jonathan Borwein unexpectedly died when he was 65 years young. Jon, as he preferred to be called was passionate about mathematics: pure, applied and computational. Nowadays, academic researchers in general, and mathematicians in particular, tend to highly specialize. Without realizing it, we end up becoming experts: someone who knows absolutely everything about nothing. Jon, however, was an erudite who was interested in absolutely everything, not just things related with mathematics.

He had very relevant contributions in the areas of analysis, optimization, number theory, computer science, financial mathematics and, of course, in experimental mathematics, were he undoubtedly was a world authority. Jon saw computers not only as machines that allow to solve problems, but also as tools that play an important role for discovering and proving theorems.

He authored more than a dozen books, 388 research journal articles and more than one hundred articles in conference proceedings (as shown in his impressive CV of 71 pages, updated the day before his death). The database ISI Web of Knowledge shows more than 6500 citations to his work, Google Citation Tracker includes more than 22000. So far, he has been cited by more than 3,000 authors. Among his books, probably the best known is “Pi and the AGM”. This book, written together with his brother Peter Borwein (a very well-known researcher in number theory) is considered as the bible of the number π. Jon was nicknamed “Doctor Pi” because of this monograph and the discovery, together with his brother Peter, of several formulas that allow rapid calculation of long sequences of digits ofPi.

He currently was Laureate Professor in the School of Mathematical and Physical Sciences at the University of Newcastle in Australia, being the director and founder of the Priority Research Center for Computer-Assisted Research Mathematics and its Applications (known as CARMA, for its English acronym). Jon liked to say that “CARMA brought him to Australia”. He was born in Saint Andrews, Scotland, on May 20th 1951, in a family of academics: son of the mathematician David Borwein and the anatomist Bessie Borwein. After completing his studies of mathematics at the University of Western Ontario in Canada in 1971, he obtained his doctorate from Oxford University in 1974. He received numerous awards and honors, including the Chauvenet Prize by the Mathematical Association of America (1993), Doctor Honoris Causa by the University of Limoges (1999) and he was a fellow of several societies including the Royal Society of Canada (1994), the American Association for the Advancement of Science (2002), the Bulgarian Academy of Sciences (2003), the Australian Academy of Science (2010) and the American Mathematical Society (2015).

Jon directed 13 doctoral theses and was in charge of 42 postdoctoral students (I’m proudly one of them). Jon was a great mentor. Perhaps his best quality as tutor was his ability to discover and develop the potential of each of his students, while doing his best to promote the professional success of them all. Someone told me once at a conference, right after an interesting presentation of one of his students, that there was something special in all his disciples. Unquestionably, Jon left his mark. It was impossible to work alongside without learning, as his vast knowledge would inexorably force you to expand yours. He was an excellent communicator who always made an effort to make everyone learn something in each of his captivating presentations. Even during his more technical talks, he included anecdotes, quotes and cartoons on his slides, managing to catch the attention of anyone in the room. Hi great talk about π was without any doubts my favorite.

I had the chance to work with Jon, his brother Peter and David Bailey in one of the subjects that interested him the most: the number Pi. After a month of calculations that occupied 20 cores in a cluster of computers in CARMA, we managed to draw a walk based on the first one hundred billion digits of Pi in base 4. Our goal was to experimentally check if the digits of Pi behave randomly. We got a beautiful image with a resolution of 108 gigapixels (which would be equivalent to paste more than ten thousand photos taken with a normal camera, of ten megapixels each). I must admit that I am delighted that, among all the images created in his experimental work in mathematics, he chose this one as a background image for his webpage.

Jon had more than 150 coauthors scattered around the world. Among his Spanish collaborators are Roberto Barrio Gil (University of Zaragoza), Antonio José Guirao Sánchez and Vicente Montesinos Santalucía (Polytechnic University of Valencia), Mar Jiménez Sevilla (Complutense University of Madrid), Marcos López de Prado (Lawrence Berkeley National Laboratory), Victoria Martín Márquez (University of Seville), and José Pedro Moreno (Autonomous University of Madrid). He was recently in Spain with the occasion of two international conferences organized in Alicante and Cartagena. He came with his right hand and life partner, his lovely wife Judith Borwein, who drove from Barcelona to Alicante (Jon never learned to drive, I think he never even tried). They also made the most of the trip with a visit to Granada. I know that they enjoyed much their visit to Spain.

Besides being an enthusiastic and tireless researcher, he was a jovial person who seemed to only perceive the positive aspects of each person. Perhaps that is why his sudden absence has saddened us more to all who were lucky to know him. Personally, I feel that it has been created a void in the world that cannot be filled with all the digits of Pi. We miss you, Jon.