Hannah Fry, the mathematician, best-selling author, award winning science presenter and host of popular podcasts and television shows, will join our home in Cambridge, the Department of Applied Mathematics and Theoretical Physics (DAMTP), in January 2025. She will be Cambridge's first Professor of the Public Understanding of Mathematics.

Fry brings a huge wealth of experience to the newly created professorship. Her work communicating mathematics and engaging diverse audiences has been recognised, among other things, by a Christopher Zeeman Medal in 2018 and the Royal Society David Attenborough Award in 2024. She is also the current President of the Institute of Mathematics and its Applications.

Mathematics and people

Fry's interest in the communication of mathematics grew as an integral part of her research as Professor of the Mathematics of Cities at University College London (UCL). "I joined the Centre for Advanced Spatial Analysis at UCL about ten years ago after my PhD," says Fry. "It was the beginning of Big Data, the point at which we had enough computational power and really good, rich data to start running mathematical models about human behaviour."

As part of an interdisciplinary team that included geographers, architects, urban planners, physicists, and mathematicians, Fry looked at systems and processes you might find in cities — from transport and shopping to crime and the spread of diseases. "Anything to do with people moving around in space and time. The idea was to mathematically model those systems." 

As an example Fry quotes her work on burglary. It turns out that your chances of being burgled are highest when you've only just been burgled — criminals have learnt the layout of your house and they know you're going to replace the items that were stolen. A mathematical idea that has also been used to model aftershocks of earthquakes (called self-exciting point processes) can describe a situation where random events become more likely once they have occurred. This can be used to come up with a mathematical model to give a prediction of where burglaries are likely to happen next, which might inform preventative strategies.

The general idea behind such modelling is that outputs are useful for the common good. The snag is that once the outputs are shared with the people being modelled, this may change their behaviour — immediately rendering models less accurate and also lending a moral dimension to the work you need to be aware of. This feedback problem became more than obvious during the COVID-19 pandemic. Scientific justifications for measures such as lockdown needed to be explained carefully to the public, while the resulting, rather drastic but not entirely predictable, behaviour changes needed to be taken account of in further modelling.

"These are clear examples of how when you create a mathematical model it doesn't really matter how good your maths is, how beautifully crafted your equations are, or even how accurate your simulations are," says Fry. "You have to think about how the work that you have created is going to be seen by other people and how it is going to be understood and misunderstood. This is a crucially important and often overlooked aspect of our work."

Currently, Big Data and artificial intelligence are causing a paradigm shift in terms of the role that algorithmic processes and automated decision making are playing in our lives. This, says Fry, makes communication and public engagement all the more important. 

"I think it's really important that people feel that this is being done with them, rather than to them. If you are creating something that is used by, interacts with, or comes up with decisions for members of the public, then it is your moral duty to engage the people who are affected by it."

A centre of excellence

Fry's broad vision for her new role is to further develop Cambridge into a centre of excellence for mathematics communication. The ultimate aim is to help build a population that is more appreciative of, and comfortable with, mathematical concepts.

The starting conditions for this endeavour are ideal. Fry will meet with the legacies of Stephen Hawking, who turned black holes and the Big Bang into household names through his writing and TV appearances, and the late John D. Barrow, who enthused millions of people about mathematics and its applications through his best-selling books. Barrow also used to be our boss as Director of the MMP (maths.org), a family of projects engaged in outreach, education, and public engagement that plus.maths.org is a part of.

Julia Gog, the current Academic Director of the MMP and Professor of Mathematical Biology at DAMTP, is thrilled to welcome Fry. "I first worked with Hannah back in 2017 when we co-developed, together with other disease modellers, a citizen science project that was linked up with a documentary called Contagion! The BBC Four Pandemic which Hannah presented. The aim was to gather data to understand better how people in the UK move and mix which came in very useful during the COVID-19 pandemic."

"For the BBC Pandemic programme, we were so lucky to have the ideal communicator in Hannah, as well as being part of the scientific team taking the analysis forward after the broadcast. Hannah has been an excellent mentor for me as an academic facing public media, right from first steps of TV filming through to practical and humane advice on handling the craziness of 2020."

Gog herself has a keen interest in public engagement. She has worked with the MMP to involve school students in mathematical research and embed research in classroom resources, and also contributed to the 2021 Royal Institution Christmas Lectures. This interest is shared by many other members of the Centre for Mathematical Sciences at Cambridge including, for example, John Aston, Harding Professor of Statistics in Public Life at the Department for Pure Mathematics and Mathematical Statistics

Making sense of numbers

One of Fry's aims for her new role links up with personal experience. "I made a film a couple of years ago called Making sense of cancer, which looked into the idea of understanding statistics when you yourself are the number," she says. "This was based on my personal experience of being diagnosed with cancer. I had been working with numbers, uncertainty and probabilities for years, but when I was diagnosed I realised I had no idea what 9 out of 10 means. I had no idea how to sit with that number and interpret it."

Crucially, communication of medical statistics involves people from all walks of life, including those that would never normally engage with mathematics. "The solution we have come to so far is to shout numbers at people and let them do the interpretation. But what I think we need to do is start with how people feel about their own future, how they feel about themselves, and then try and work out what numbers they would be willing to accept."

To develop such a new approach, Fry wants to build on the work of the great David Spiegelhalter and the Winton Centre for Risk and Evidence Communication, which was based at the Department for Pure Mathematics and Mathematical Statistics at the University of Cambridge until 2022. The communication of medical statistics was a major focus of the Winton Centre's research. "I want to work with medics and psychologists, people from across the board, taking an interdisciplinary approach to try and improve people's understanding of these ideas."

Fittingly, Fry announced her move to Cambridge at an event we, as Editors of plus.maths.org, organised together with the Newton Gateway to Mathematics, which took place at the Isaac Newton Institute for Mathematical Sciences (INI) on November 21, 2024. The aim of the event, titled Communicating mathematical and data sciences — what does success look like, was to chart the landscape of evidence that has been built for effective communication and identify further work that needs to be done.

Cambridge students too will benefit from having such an exciting mathematician in the department. Fry is particularly looking forward to the chance to mentor masters and PhD students, particularly because class sizes here are comparatively small, allowing "deep intellectual relationships" to develop.  Fry's expertise will come in very useful. "Over time I have picked up a few little tricks for how to make things extremely engaging without pulling punches on the intellectual heft."

About this article

Marianne Freiberger, Editor of Plus, interviewed Hannah Fry in November 2024.