Dr Seth Berkley is an epidemiologist and global health leader whose career has been shaped by one central problem: vaccines save lives, but only if people can actually get them. His 40-year career has spanned the global, from helping to build Uganda’s first HIV surveillance system and founding the International AIDS Vaccine Initiative; to leading Gavi, the Vaccine Alliance for more than a decade – overseeing the immunisation of hundreds of millions of children worldwide. And when COVID-19 struck, Seth co-founded COVAX, the global initiative designed to stop wealthy nations monopolising vaccines. In conversation with Professor Jim Al-Khalili, Seth discusses the highs and lows of his globe-trotting career - from saving millions of young lives through vaccine distribution, to setting his own shattered leg after a climbing accident in Namibia - and addresses the huge challenge of tackling vaccine scepticism.

Hiranya Peiris is playing a starring role in a movie that promises to tell perhaps the greatest story of all time. However, it’s a movie with a difference – there’s no director and no script. The Legacy Survey of Space and Time is one of the most ambitious projects in the world of astronomy, with a mission to create a decade-long time-lapse movie of the visible universe, to answer fundamental questions about its origin, evolution and, ultimately, its fate.

Hiranya is Professor of Astrophysics 1909, the prestigious Chair at the Institute of Astronomy at Cambridge University. Over her career she’s been one of the pioneers of a revolution in astronomy, bridging fundamental physics with the observational data coming back from space, to establish the first evidence-based standard model for the origin, evolution and fate of the universe. The endeavour has transformed the field from the ‘wild west’ of physics to the modern era of precision cosmology.

Ironically, it was another movie, of sorts, Carl Sagan’s documentary series ‘Cosmos’, that first sparked Hiranya’s interest in the universe as a young girl. Always keen to inspire women to follow in her footsteps and choose careers in science, if this interview were a live show she’d have reserved the front row for schoolgirls.

As a child growing up on the shores of Lake Victoria in western Kenya, Washington Yotto Ochieng once watched a plane cross the night sky and told his mother he wished he could travel on it. But he remembers her encouraging him to dream bigger... Today, Washington is a Professor of Engineering at Imperial College London, and President of the Royal Institute of Navigation. Over a career bridging industry and academia, he has helped shape the movement of urban transport; how satellites guide us and locate us; and how governments manage the technologies underpinning so much of modern life. Professor Jim Al-Khalili speaks to Washington about his inspirational upbringing, how reliant we've become on technologies such as GPS, and his work encouraging the next generation of engineers in both the UK and Africa.