"How do you make gold?" asks curious listener, Paul Ruddick.

Inspired by the promise of riches, Hannah and Adam embark on a mission to discover the origin of gold. It's a tale that takes them from the clandestine codes of Aristotle to the alchemy of Isaac Newton, alongside materials scientist Mark Miodownik.

They boldly go into the cosmos with astronomers Lucie Green and Andrew Pontzen, to learn what happens in the most exotic areas of space. By the end one thing is for sure - you'll never look at your gold jewellery in quite the same way again.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2020.

"What would become the dominant species if, or when, humans go extinct?"

This cheery question leads Drs Rutherford and Fry to embark on an evolutionary thought experiment.

Zoologist Matthew Cobb questions whether humans really are the dominant species. Ecologist Kate Jones explains why some species are more extinction-prone than others. Plus Phil Plait, AKA The Bad Astronomer, busts some myths about why the dinosaurs went extinct.

Send your questions for future series, along with any Curio correspondence for the podcast, to: [email protected]

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.

"Why is it so difficult to predict the weather?" asks Isabella Webber, aged 21 from Vienna.

"I am sure there are many intelligent meteorologists and it seems rather straight forward to calculate wind speed, look at the clouds, and data from the past to make accurate predictions, but yet it’s not possible."

Adam delves into the history of forecasting with author Andrew Blum, beginning with the mystery of a lost hot air balloon full of Arctic explorers.

Hannah visits the BBC Weather Centre to talk to meteorologist and presenter Helen Willetts about how forecasting has changed, and whether people get annoyed at her if she gets the forecast wrong.

Plus mathematician Steven Strogatz suggests a chaotic explanation as to why we can't produce the perfect forecast.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.

"How do you make antimatter?' asks Scott Matheson, aged 21 from Utah.

The team takes charge of this question with a spin through the history of antimatter. Adam talks to physicist Frank Close, author of 'Antimatter', about its origins in the equations of Dirac to its manufacture in the first particle accelerator, the Bevatron.

Cosmologist Andrew Pontzen tells Hannah why physicists today are busy pondering the mystery of the missing antimatter. Anyone who discovers why the Universe is made of matter, rather than antimatter, is in line for the Nobel Prize.

Plus, neuroscientist Sophie Scott describes how antimatter has been put to good use down here on Earth to peer into people's brains.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.

Stephen Fry (no relation) asks Adam and Hannah to investigate the following question:

"All my life I have been mildly plagued by the fact that I have a quite appalling ability to remember faces. I cut people I should know well dead in the street, or at least fail to recognise them in a way which must often be hurtful.

At a party I can talk to someone for ten minutes and then see them again twenty later and have no idea who they are unless I’ve made an effort to fix some accessory or item of their dress in my mind. If I see them the next day in another context I’ll have no idea who they are. It’s distressing for me in as much as I hate the idea that people might think I am blanking them, or think little of them, don’t consider them significant and so forth.

I’d be very grateful if my sister-in-surname and her eximious partner Adam could investigate prosopagnosia for me and offer any hint add to as to its cause or even possible – I won’t say “cure” as I am sure it’s chronic and untreatable – but at least any interesting ways of relieving it."

Hannah and Adam call in the experts, neuroscientists Sophie Scott and Brad Duchaine. Why is it that some people struggle with prosopagnosia, whilst others never forget a face?

You can find out more about Face Blindness, who it affects and how to cope with it by visiting www.faceblind.org.uk/

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.

Rutherford and Fry delve into the history of roller coasters in the second instalment of their investigation into why we enjoy being scared.

Amelie Xenakis asks: "Why do people enjoy rollercoasters? I am a thrill-seeker and I am always terrified before riding a roller coaster but I enjoy the ride itself. (I would like BOTH of you to ride a roller coaster if possible)."

Never ones to shy away from a challenge, the pair attempt to channel their inner adrenaline junkies with a trip on one the UK's scariest rollercoasters at Thorpe Park.

They discover the birth of the roller coaster in the 18th century, when Catherine the Great enjoyed careering down Russian Ice Mountains covered in snow. Adam talks to scary sociologist Margee Kerr, author of 'Scream! The Science of Fear', about how the modern roller coaster evolved.

David Poeppel from New York University studies the science of screaming, and we discover what makes screams uniquely terrifying. Plus, psychologist and broadcaster Claudia Hammond describes some early experiments which tested how fear affects our body.

Presenters: Adam Rutherford, Hannah Fry

First broadcast on BBC Radio 4 in 2019.

It was a dark and stormy night around the time of Halloween. A secret message arrived addressed to Rutherford & Fry from a mysterious woman called Heidi Daugh, who demanded to know: "Why do people like to be scared? For example, going on scary amusement park rides and watching horror movies that make you jump.”

What followed was an investigation over two chapters, which would test our intrepid duo to their very limits. In this first instalment, they explore the history of horror, starting with its literary origins in the Gothic fiction classic 'The Castle of Otranto'.

Adam challenges Hannah to watch a horror film without hiding behind a cushion. She quizzes horror scholar Mathias Clasen to find out why some people love the feeling of terror, whilst it leaves other cold.

Sociologist Margee Kerr and psychologist Claudia Hammond are also on hand to explore why scary movies are so powerful and popular.

Presenters: Hannah Fry, Adam Rutherford

FIrst broadcast on BBC Radio 4 in 2019.

"Is there is any way of knowing what noises, if any, dinosaurs would have made?" asks Freddie Quinn, aged 8 from Cambridge in New Zealand.

From Jurassic Park to Walking with Dinosaurs, the roars of gigantic dinosaurs like T.Rex are designed to evoke fear and terror.

But did dinosaurs actually roar? And how do paleontologists investigate what noises these extinct animals may have produced? Hannah and Adam talk to dinosaur experts Steve Brusatte and Julia Clarke to find out.

Plus Jurassic World sound designer Al Nelson reveals the strange sounds they used as dinosaur noises in their Hollywood blockbusters.

Presenters: Hannah Fry, Adam Rutherford

First broadcast on BBC Radio 4 in 2019.

In the second installment of our double episode on the Moon we ask what life would be like if we had more than one Moon.

From the tides to the seasons, the Moon shapes our world in ways that often go unnoticed. And, as we'll find out, it played a vital role in the creation of life itself. This week we celebrate the many ways the Moon and the Earth are linked.

If one Moon is so great, why not have two? We discover why multiple moons could spell disaster for our planet, from giant volcanoes to cataclysmic collisions.

Featuring astronomer Brendan Owens from the Royal Observatory Greenwich and physicist Neil Comins, author of 'What if the Earth had two Moons?'

Presenters: Adam Rutherford, Hannah Fry

First broadcast on BBC Radio 4 in 2019.

A double episode to mark the 50th anniversary of Apollo 11, and the first humans to walk on the Moon in 1969.

Harley Day emailed [email protected] to ask “Why do we only have one Moon and what would life on Earth be like if we had more? I'll be over the moon if you can help me solve this mystery.”

In this first episode, Hannah and Adam look at how the Moon was formed and why we only have one. Featuring Maggie Aderin-Pocock space scientist and author of 'The Book of the Moon' and cosmic mineralogist Sara Russell from the Natural History Museum.

Presenters: Adam Rutherford, Hannah Fry

First broadcast on BBC Radio 4 in 2019.