“Diamonds are nonsense!” Hannah boldly proclaimed in a previous episode. But listener Guy is a diamond enthusiast, and he and his diamond-loving pals were NOT OKAY WITH THIS. He demanded we re-open the case, and here we are...

SO in this glittering showdown, Dara is on a quest to flip Hannah’s perspective from “meh” to “marvelous.” And for Hannah, some uncomfortable facts soon emerge. It turns out that diamonds are much more than just overpriced bling. They're the secret ingredient in all sorts of high-tech gadgets with a whole arsenal of little-known superpowers.

Enter electrochemist Julie Macpherson, who blows Hannah’s mind by showing how diamonds can slice through ice like butter, thanks to their unmatched ability to conduct heat. Not impressed yet? Physicist Mark Newton makes a diamond glow in the dark, using nothing but his phone flashlight.

And that’s just to start! These ultra-robust gems can scrub nasty chemicals from water, serve as supercharged electrodes, and even reveal deep-earth secrets locked away for billions of years.

By the end of this episode, will Hannah finally admit diamonds are forever cool?

Contributors:

Charlie Bexfield - Gemmologist and diamond specialist

Producer: Ilan Goodman

Hannah Fry and Dara Ó Briain return to tackle listener's questions with the power of science!

The buzz of a fly hovering just above your head has got to be one of the most irritating sounds around, but this week we try to work out just how fast they could be flying. Could a claim horseflies reach speeds of up to 90 mph possibly be true, and Dara wants to know if this is what makes them so difficult to swat?

Entomologist Erica McAlister is better known as the ‘fly lady’ and speaks up in defence of these tiny creatures, explaining there are 7,000 known species in the UK alone. Which makes it all the more shocking there are several that don’t have wings.

For Professor Graham Taylor the question of speed comes down to a simple calculation, and the team try to work out whether a horsefly beats its wings fast enough relative to its size to travel so rapidly. He explains horseflies aren't clever, but scientists are interested in their simple brains and are studying them to use as models for drones and mini robots.

Contributors:

Dr Erica McAlister, Natural History Museum

Producer: Marijke Peters

Anyone who has ever done a long car journey with kids will be familiar with the idea of being bored to death – but can this feeling really be fatal?

Hannah and Dara hear about a club where members count roundabouts and collect milk bottle tops, but boredom expert Wijnand van Tilburg explains these dull-sounding hobbies might actually have mental health benefits. He explains that science and comedy are stereotypically both seen as exciting subjects but warns them their chat about Venn diagrams might tip the balance the other way.

Mind-wandering specialist Mike Esterman reveals why we're rubbish at staying on task when there are more rewarding things to do, and sets the pair a challenge to play a computer game that distracts them with pictures of cute babies and fluffy animals.

Contributors:

Dr Wijnand van Tilburg: University of Essex

Producer: Marijke Peters

When you die, would you want to be frozen so that one day you might be brought back to life? Listener Elspeth wants to know if that’s even possible. So Hannah and Dara embark on a quest to explore the chiling science of ‘cryobiology’: preserving living things at really low temperatures.

It turns out there are already thousands of people alive who were once suspended in antifreeze and stored in liquid nitrogen - when they were just a small clump of cells! There’s even a frog which can turn into a ‘frogsicle’ for months on end. But re-animating full size humans is a challenge no one has solved…yet. Will some miraculous nanotechnology of a distant future solve the problem?

Contributors:

Professor João Pedro de Magalhães: University of Birmingham

Producer: Ilan Goodman

Wake up! It’s time for a dreamy new episode of Curious Cases all about the science of sleepwalking.

Listener Abigail has done some strange things in her sleep, from taking all the pictures off the wall, to searching for Turkish language courses. And she wants to know: WHY IS THIS HAPPENING?

It turns out Abigail is not alone. Hannah and Dara hear weird and wonderful stories of extreme sleepwalkers - from the lady who went on midnight motorbike excursions, to the artist who does all his best work while asleep. They delve into the neuroscience to find out how you can remain in deep sleep while walking, talking or even peeing in your mum's shopping basket. They learn about some cutting edge research where the participants were sleep deprived and then half-woken with scary sounds, and they zero in on the key triggers, from a boozy night out to a squeaky bed.

Contributors

Producer: Ilan Goodman

Fruit-powered batteries are the ultimate school science experiment, but they’re normally used to power a pocket calculator. This week’s listener wants to know if they could do more, and sends the team on a quest to discover whether they could used to send a rocket into space?

Professor Saiful Islam is the Guinness World Record holder for the highest voltage from a fruit-based battery, but disappoints the team when he reveals they produce very little power. He used 3,000 of them and only managed a measly 2 Watts. Given that spaceships are famously difficult to get off the ground, it seems a lemon battery might just fail the acid test.

Author Randall Munroe is undeterred and suggests alternative ways to get energy from citrus, including burying them to make oil. Then the team discuss the pros and cons of switching to a lemon-based diet.

For battery expert Paul Shearing, all this raises a serious question, about how we will power the planes of the future. He suggests solar power could play a part in short-haul flights and discusses some of the exciting battery materials being tested today.

Contributors:

Randall Munroe, author

Producer: Marijke Peters

Are you more of a rhino or a kitten? More like a tortoise or a hare? Listener Ivy wants to know what makes a good athlete and so Hannah and Dara tackle the science of sport.

Our curious duo get to grips with the rigours of training tailored for endurance events vs those based on more explosive bursts of activity. They consider the contribution of genetics, fast vs slow twitch muscle fibres, the unique advantage of Michael Phelps's body proportions and whether butterfly really is the most ridiculous stroke in swimming.

And after a rigorous scientific analysis, Dara turns out to be ideally suited for…netball. Much to his surprise.

Contributors

Producer: Ilan Goodman

Listener Vivienne has heard that tardigrades - aka moss piglets - have special powers of survival. Radiation? Drought? Extreme cold? NO PROBLEM. Does that mean they could survive an apocalypse? And could they even help us master space travel!?

Hannah and Dara learn how to find these little moss piggies in roof gutters and garden corners. And they're amazed by their capacity to dry out and hunker down for decades before springing back to life. But calamity strikes when it turns out that fine glass tubing - in the form of pipettes - is their natural predator. And worse is to come: our curious duo learn that there may be some tardigrades stuck on the moon, and one researcher has even fired them out of a gun. All in the name of science.

But they have survived at least 5 mass extinctions so far. So their chances of surviving the next one are pretty good. As long as pipettes aren't involved.

Producer: Ilan Goodman

If there’s one type of discharge you really want to avoid, it’s lightning, but what happens when it hits you?

We hear from lightning survivor Kerry Evans, and discover that the best place to shelter – if you ever find yourself in a similarly charged storm – is in a car, or low to the ground. And why this is never a good time to take a selfie.

Dr Dan Mitchard from Cardiff University’s excitingly-named Lightning Lab explains why there's no lightning at the poles, and the presenters lament that polar bears and penguins are missing out.

We all know about the gods of lightning, but the mysticism doesn't stop there. Above cloud level there are many other types of unusually-named phenomena, reaching to the edge of space, including sprites, trolls and even pixies.

And Professor Karen Aplin reveals that lightning has even been discovered on other planets, in a science story that could affect our plans to colonise Mars.

Contributors:

Dr Daniel Mitchard, Lightning Laboratory, Cardiff University

Producer: Marijke Peters