At some point early in life it hits us all: the adults around us, who we assumed knew what they were doing, have no more idea than we do. Most of the time we are all making it up as we go.

Even in science there are few absolute truths. And yet uncertainty makes us deeply uncomfortable. Our brains like binary answers to binary questions, however flawed these may be. It’s very useful in fight or flight mode but not for the nuances of modern life.

There are endless tomes about the things we do know. In mathematician Hannah Fry's whipsmart new book, we learn to embrace what we don’t. Fry shows how acknowledging uncertainty enables better decision-making and that this applies in fields from space exploration to medical treatments.

Led by compelling story-telling and packed with revelatory examples, she demonstrates that almost everything lives along a spectrum of uncertainty - and when we realize this, even the most contentious subjects become less divisive. Accepting we can't be sure will always lead to better outcomes.

Doubt is a superpower, and it's time we understood how much richer the world is when we employ it as our guide.

Praise for Hello World by Hannah Fry, one of the ‘Best Books of the Year’ in The Times, Financial Times, Guardian and New Scientist

‘Brilliantly clear...Fry succinctly outlines the ethical issues that beset AI.’ - James McConnaiche, Sunday Times

‘With refreshing simplicity, Fry explains what AI, machine learning and complicated algorithms really mean …This book illustrates why good science writers are essential.’ - Katy Guest, Guardian

‘Stylish, thoughtful, and scrupulously fair-minded account... A beautifully accessible guide that leaps lightly from one story to the next without sparing the reader hard questions... deserves a place in the bestseller charts.’ - Oliver Moody, The Times

‘Hannah Fry is quickly becoming the David Attenborough of maths.’ - Guy Kelly, Telegraph

© Hannah Fry 2027 (P) Penguin Audio 2027