It has been said that you can't start a fire without a spark, but as Hannah and Dara are about to discover, that's not true!

Welcome to the fiery phenomenon of spontaneous combustion, when something can ignite all on its own: no matches, no sparks, no external flame. It happens when certain materials heat themselves up internally through chemical or biological reactions, and if that carried on unchecked and the material gets hot enough, it can eventually ignite itself.

This process can occur in various everyday items such as piles of hay or grass clippings, oily rags and in certain instances lithium batteries; but there are also several useful chemical substances that autoignite when they come into contact with air - as Hannah, Dara and a wary BBC fire officer witness in the studio...

So how can we stop things regularly bursting into flames? How scared should we be about oiling floorboards and our increasingly battery-powered life? And is spontaneous human combustion really a thing? Our investigators are on the case.

To submit your question to the Curious Cases team, please email: [email protected]

Contributors:

Producer: Lucy Taylor

A BBC Studios Production

Are you a lucky person? Do the cards just fall well for you? Whether it's always finding a parking spot when you need one or chance encounters that change your life's trajectory for the better, some people seem to have more luck than others. Hannah and Dara explore the world of probability and psychology to figure out if some people are luckier than others, and if there's anything we can do to turn things around.

You can send your everyday mysteries for the team to investigate to: [email protected]

Contributors

Producer: Emily Bird

It turns out that the whole world wobbles. Everything has a natural frequency - the rate at which it moves when disturbed - be it a cup of tea, a building or a human organ.

Even more incredibly, if an external force matches an object's natural frequency, it causes it to absorb that energy and vibrate with increasingly large waves; and that can have consequences, from helping a spider find its lunch to making a bridge collapse.

On the trail of good and bad vibes and everything in between, Hannah and Dara investigate whether the famous 1940 collapse of the Tacoma Narrows Bridge in the USA was really down to resonance, explore examples of resonance in nature, and find out what this mysterious vibration can do to the human body: from the pressures of repetitive tractor-driving, to absorbing the reverberations of certain instruments...

To submit your question to the Curious Cases team, please email: [email protected]

Contributors:

Producers: Lucy Taylor & Emily Bird

A BBC Studios Audio Production

We can all picture a crab, but did you know that nature has reinvented those claw clicking, sideways scuttling crustaceans at least five separate times? In recent years the internet has run wild with the idea that crabs are the ultimate life-form, and that even humans might one day end up with pincers too. But is there any truth behind the memes? Hannah and Dara scale the tangled tree of life and tackle taxonomy to figure out if ‘crab’ really is evolution’s favourite shape. Exploring coconut to spanner, ghost to hermit, soldier to spider they learn how to tell the ‘true’ crabs from the impostors.

You can send your everyday mysteries for the team to investigate to: [email protected]

Contributors

Producer: Emily Bird

Hannah Fry and Dara Ó Briain return to Curious Cases HQ for a brand-new series. And curios, there’s a lot to unpack! Coming soon to BBC Sounds.

The term 'bird brain' might suggest our feathered friends are stupid, but Hannah and Dara learn it's completely untrue. They play hide and seek with a raven called Bran, and hear how his behaviour changes depending on his mood. Corvid expert Nicola Clayton explains these creatures are actually cleverer than the average 8-year-old, and can learn how to choose specific tools for different scenarios. And neurobiologist Andreas Nieder tells them that while crows evolved totally different brains from humans - 300,000 years apart - they might just be capable of the same type of intelligence.

Contributors:

Bran the raven

Producer: Marijke Peters

A BBC Studios Audio Production

Could you ever trade memories with someone else? Fancy downloading the experience of landing on the moon, winning an Oscar or performing at Glastonbury? Listener Adam wants to know, and Hannah Fry and Dara Ó Briain are on the case.

With expert insights from Professor Chris French and Professor Amy Milton, they dive into the mind’s tendency to blur the lines between reality and imagination - often embellishing, distorting, or downright making stuff up.

Discover how memory conformity makes us “see” things like spoons being bent by paranormal forces, how scientists can implant artificial memories in mice, and hear Al Hopwood’s hilariously vivid tales of things that definitely never happened. Chris even spills the secrets of how to deliberately plant false memories in others (don’t try this at home!).

From rewiring trauma to curing phobias, the potential of memory manipulation is both exciting and unnervingly sci-fi. Prepare to question everything you think you remember.

Contributors:

Amy Milton - Professor of Behavioural Neuroscience at the University of Cambridge

Producer: Ilan Goodman

Can you slow down time by hurtling through space at breakneck speed? Could listener Saskia’s friend - currently one year older - end up the same age as her if he went fast enough? It sounds bananas, but it’s all part of Einstein’s mind-warping theory of relativity.

With expert copilots Professor Sean Carroll and Dr. Katie Clough, Hannah Fry and Dara Ó Briain embark on a cosmic roller coaster through space and time. They uncover why GPS satellites - whizzing around Earth at 14,000 km/h - need to account for time bending, why penthouse dwellers age faster than those on the ground floor, and, most importantly, why clowns on trains might just hold the key to understanding modern physics.

Contributors:

Katy Clough - Research Fellow at Queen Mary University of London

Producer: Ilan Goodman

How big can animals really get before they collapse under their own weight or run out of snacks? Could a 12-foot comedian survive their first punchline without snapping in half? Listener Andrew sends Hannah and Dara on a deep dive into the science of supersized species.

With evolutionary biologists Ben Garrod and Tori Herridge as their guides, they explore the quirky rules of scaling: why giant bones need air pockets, how pressure stockings aren’t just stylish but essential, and why massive creatures have to choose between inefficient chewing or letting dinner ferment in their cavernous stomachs.

Discover why scaling up a mouse would turn it into a blood-boiling disaster and learn the curious logic behind whether the meat bear should eat the two meat dogs, or vice versa (it’s a maths thing…you’ll have to listen). Oh, and here’s the weird constant: whether you’re a mouse or an elephant, everyone takes roughly the same time to pee!

Join Hannah and Dara for a colossal romp through the wild world of ancient giants and the gross super blobs of the (possible) future.

Contributors:

Tori Herridge - Senior Lecturer in evolutionary biology at the University of Sheffield

Producer: Ilan Goodman

Think of a shark and you'll probably conjure up images of Jaws, but it turns out their skin is also covered in tiny teeth. Hannah and Dara investigate the incredible properties of these so-called dermal denticles, to find out whether they could be replicated at a nanoscale to increase vehicle speeds. They learn that while sharks might look like they have beautifully sleek surfaces, up close their skin is covered in something extremely rough and textured, a property that helps them swim up to 12 percent faster. And it's already inspiring airlines to design ultra-thin films that can reduce drag and increase efficiency.

Contributors

Dr Jess Wade

Producer: Marijke Peters

A BBC Studios Audio Production