Jim Al Khalili on Time: the Physics That Makes the Universe Tick

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What exactly is time? Why does it always move forwards and never backwards? Could we travel into the past or future, and did time itself begin with the Big Bang? Although we have made extraordinary progress in understanding the laws of the universe, time remains one of the greatest unsolved mysteries in physics.In this fascinating talk, based on his acclaimed new book, On Time: The Physics That Makes the Universe Tick, renowned quantum physicist, bestselling author and BBC broadcaster Professor Jim Al-Khalili takes us on a mind-bending journey through one of the most fundamental and mysterious aspects of existence. Described by physicist Carlo Rovelli as "one of the best science writers", Al-Khalili explores questions that have puzzled philosophers and scientists for thousands of years, revealing why something so familiar to us all remains so difficult to understand.Drawing on the three great pillars of modern physics - quantum mechanics, Einstein's theory of relativity and thermodynamics - Al-Khalili explains how time can be understood in radically different ways: as a coordinate, as a dimension inseparable from space, or as an irreversible direction or "arrow". Why does time appear to slow down as we approach the speed of light? Why do clocks run at different rates depending on gravity? And why, if many of the fundamental laws of physics work equally well forwards and backwards, can we remember the past but not the future?Al-Khalili also explores some of the most extraordinary possibilities raised by modern physics, from the nature of the Big Bang to the possibility of time travel. Challenging the idea that time might simply be an illusion, he argues that its direction is a fundamental feature of the universe itself. His remarkable ability to make complex ideas accessible has won widespread praise, with New Scientist describing his explanation of the subject as "one of the clearest I have read".Having presented the Royal Institution's prestigious 2026 Christmas Lectures on the mysteries of time, Al-Khalili joins us to explore what science can really tell us about the past, present and future. Is time something that genuinely flows, or is the passage of time merely how our minds experience the universe? And could understanding its true nature transform our understanding of reality itself?Professor Jim Al-Khalili CBE FRS is one of Britain's best-known physicists, science broadcasters and authors. He is Distinguished Professor Emeritus of Physics at the University of Surrey, where his research has encompassed nuclear physics, quantum mechanics, quantum biology and the fundamental nature of time. He received his PhD in nuclear theory in 1989 and has published more than 100 scientific papers. He is the author of fifteen books on popular science and the history of science, translated into more than twenty-six languages, including The World According to Physics, The Joy of Science, Pathfinders and his novel Sunfall.A Fellow of the Royal Society and former President of the British Science Association, he is best known to many for presenting BBC Radio 4's long-running programme The Life Scientific, alongside numerous acclaimed television documentaries. His awards include the Royal Society's Michael Faraday Medal, the Institute of Physics Kelvin Medal and the Stephen Hawking Medal for Science Communication. He was appointed CBE for services to science. His latest book, On Time: The Physics That Makes the Universe Tick, was published by Princeton University Press in September 2026.A Q&A Session will follow.