Pioneering Australian scientist Robert May, whose work in biology lead to the development of chaos theory, has died at age 84. Known as one of Australia’s most accomplished scientists, he served as the chief scientific adviser to the United Kingdom, was president of the Royal Society, and was made a lord in 2001. Born in Sydney on 8 January 1938, May’s work was influential in biology, zoology, epidemiology, physics and public policy. More recently, he applied scientific principles to economics and modelled the cause of the 2008 global financial crisis. On Wednesday, his friends and colleagues paid tribute to a man who they said was a gifted polymath and a “true giant” among scientists. Professor Ben Sheldon, the head of Oxford’s department of zoology, said May’s work had “changed entire fields” of science. The current president of the Royal Society, Venki Ramakrishnan, said May was “an extraordinary man” who “drove great change in every domain he committed his talents to”. “Bob was a natural communicator and used every available avenue to share his message that science and reason should lie at the heart of society, and he did so with a fervent pursuit that resonates with those of the society’s founding members.” Professor Joss Bland-Hawthorn, the director of the Sydney Institute for Astronomy, said May’s death was a “a great loss for Australian research.” Bland-Hawthorn first met May at the University of Sydney in the early 2000s and the two frequently had dinner together as fellows at Merton College, Oxford. “His career, in simple terms was getting to the bottom of what makes things complicated,” he told Guardian Australia. “He didn’t go for titles very much. He was Lord May, Baron of Oxford but he was very unpretentious. Quite a lot of my stories about him are quite rude, in fact. He used to swear a lot. “He told me one night at dinner that he was the first person in the history of the Royal Society to get a swear word in the minutes. He said not even Isaac Newton achieved that.” Dr Benjamin Pope, an Australian astrophysicist and student at Oxford from 2013 to 2017, said May was a role model, and meeting him was a highlight of his university career. “I became aware of his achievements almost as soon as I learnt anything about physics in university,” Pope told Guardian Australia. “My first contact with computer programming was at the University of Sydney, in first year physics, where the example is to recreate Robert May’s experiment with the bifurcation diagram and the logistic map. “His bifurcation diagram is one of the iconic diagrams in physics,” he said. “[And] he made what was between three or four independent discoveries that lead to chaos theory. You might have heard of the butterfly effect … May’s is probably the other foundational, computational model of chaos.” May attended Sydney Boys High School and the University of Sydney, where he completed a PhD in superconductivity. Between 1995 and 2000 he was the chief scientific adviser to the UK government, was knighted in 1996, and was president of the Royal Society between 2000 and 2005. In 2007, he won the Copley Medal, the Royal Society’s most prestigious prize, previously won by Stephen Hawking, Albert Einstein, Charles Darwin and Isaac Newton among others. Pope said he had always admired May for his interest in political and environmental issues. “He contributed not only to theoretical physics, but also to very applied knowledge, advising governments about serious issues of public policy,” he said. “Robert May is a great example of how a scientist can contribute to all those different spheres in that way.” Pope said he met May in 2015 at a student dinner he helped organise, where May was a keynote speaker. “He knew everything about economics, politics, philosophy and mathematics. He was garrulous, he had this deep, Australian-accented voice which was quite rare for a baron. “He really showed he cared about people, he had a social conscience,” Pope said. “It was really a high point of my whole physics degree in England to get to meet my role model and to have dinner with him.” May was first elected as a fellow of the Royal Society in 1971, and his other prizes include the Craaford prize, the Blue Planet prize, and the Balzan prize.