The Curious Cases of Rutherford & Fry

Behind every line on a graph, there lies an extraordinary human story. Mathematician Hannah Fry is here to tell us ten of them.

There is a bizarre number in maths referred to simply as ?i?. It appears to break the rules of arithmetic - but turns out to be utterly essential for applications across engineering and physics. We?re talking about the square root of -1. WHICH MAKES NO SENSE.

Professor Fry waxes lyrical about the beauty and power of this so-called ?imaginary? number to a sceptical Dr Rutherford. Dr Michael Brooks tells the surprising story of the duelling Italian mathematicians who gave birth to this strange idea, and shares how Silicon Valley turned it into cold hard cash. It's all about oscillations, Professor Jeff O?Connell demonstrates. And finally, Dr Eleanor Knox reveals that imaginary numbers are indispensable for the most fundamental physics of all: quantum mechanics.

Imaginary, impossible?but essential!

Contributors: Professor Jeff O?Connell, Ohlone College California, Dr Michael Brooks, Author of 'The Maths That Made Us', and Dr Eleanor Knox, Philosopher of Physics at KCL and a Senior Visiting Fellow at the University of Pittsburgh.

Producer: Ilan Goodman

This episode will render you oblivious, conked out and blissfully unaware. It?s about anaesthetics: those potent potions that send you into a deep, deathly sleep. Listener Alicia wants to know how they work, so our sleuths call on the expertise of consultant anaesthetist Dr Fiona Donald. Fiona shares her experience from the clinical frontline, and explains what we do and don?t know about how these chemicals work their mind-numbing magic. We hear about ground-breaking research led by Professor Irene Tracey, which reveals how a pattern of slow brain waves can be used to determine the optimum dosage of these dangerous drugs.

And finally, Drs Rutherford and Fry wonder: what does all this tell us about normal consciousness? Professor Anil Seth shares how we can use brain tech to measure different levels of conscious awareness ? from sleepy to psychedelic.

Presenters: Hannah Fry and Adam Rutherford Producer: Ilan Goodman

?Can we bring back extinct species?? wonders listener Mikko Campbell. Well, Professor Fry is pretty excited by the prospect of woolly mammoths roaming the Siberian tundra once more. And everyone is impressed with the science that might make it happen. But Dr Rutherford comes out STRONGLY against the whole thing. Can our expert guests win him over?

Dr Helen Pilcher shares the tale of Celia the lonely mountain goat, and makes the case for cloning to help protect species at risk of extinction. Professor Beth Shapiro sets out how biotech company ?Colossal? plans to engineer Asian elephants? DNA to make a new group of mammoth-like creatures. And we hear how genetic technologies are being used in conservation efforts around the world.

BUT WHAT ABOUT T-REXES? Not gonna happen. Sorry.

Contributors: Dr Helen Pilcher, author of ?Bring Back the King: The New Science of De-Extinction?, Professor Beth Shapiro from the University of California Santa Cruz, Dr Ben Novak of Revive and Restore and Tullis Matson from Nature?s SAFE.

Presenters: Hannah Fry and Adam Rutherford

Producer: Ilan Goodman

The Great Pyramids of Giza are awesome feats of engineering and precision. So who built them - and how? Was it a mysteriously super-advanced civilization now oddly extinct? Was it even aliens?

Nah, course not! Rutherford and Fry investigate how these inspiring monuments were really constructed, and learn about the complex civilisation and efficient bureaucracy that made them possible.

Professor Sarah Parcak busts the myth that they were built by slaves. In fact, she reveals, it was gangs of well-paid blokes fuelled by the ancient Egyptian equivalent of burgers and beer. And Dr Chris Naunton explains how it was not some mysterious tech, but incredible organisation and teamwork which made it possible to transport massive stone blocks over long distances several thousand years before trucks arrived.

Dr Heba Abd El Gawad points out how racism led to bizarre assumptions in the history of archaeology, and how those assumptions linger in contemporary conspiracy theories which refuse to accept that Egyptians could have built the pyramids themselves!

Presenters: Hannah Fry and Adam Rutherford Contributors: Professor Sarah Parcak, University of Alabama, Dr Chris Naunton, Egyptologist and broadcaster, Dr Heba Abd El Gawad, University College London Producers: Ilan Goodman & Emily Bird

Magnets are inside loads of everyday electronic kit - speakers, motors, phones and more - but listener Lucas is mystified: what, he wonders, is a magnetic field?

Our sleuths set out to investigate the mysterious power of magnets, with the help of wizard / physicist Dr Felix Flicker - author of the The Magick of Matter - and materials scientist Dr Anna Ploszajski.

They cover the secrets of lodestones - naturally occurring magnetic rocks - and how to levitate crystals, frogs and maybe even people.

Matthew Swallow, the Chair of the UK Magnetics Society, explains why magnets make the best brakes for rollercoasters, and Dr Ploszajski explains how magnetically-induced eddy currents are used to sort through our recycling.

Finally, Dr Flicker persuades Adam and Hannah that to really understand magnetic fields you have to leave classical physics behind, and go quantum... So our sleuths take a leap into the strange subatomic realm.

Contributors: Dr Felix Flicker, Lecturer in Physics at Cardiff University and author of ?The Magick of Matter?, Dr Anna Ploszajski, materials scientist and author of ?Handmade?, Matthew Swallow, Chair of the UK Magnetics Society

Presented by Hannah Fry and Adam Rutherford Producer: Ilan Goodman

Close your eyes and think of a giraffe. Can you see it? I mean, *really* see it - in rich, vivid detail? If not - you aren?t alone! We?ve had scores of messages from listeners who report having a ?blind mind?s eye?. They don?t see mental images at all and they want to know why. Jude from Perth wants to know what makes her brain different, and Diane from Scotland wonders whether it affectes her ability to remember family holidays.

Our sleuths learn that this is a condition recently termed ?aphantasia?. They meet the chap who came up with the name, Professor Adam Zeman, a neurologist from the University of Exeter, and quiz him on the brain mechanisms behind this mystery. Professor Julia Simner - a psychologist who, herself, doesn?t see mental images - shares the surprising research into how aphants differ slightly from others in a range of cognitive skills. We also hear about the world class artists and animators who can?t visualise - but can create beautiful, imaginary worlds. Philosophy professor Fiona Macpherson from the University of Glasgow, deepens the mystery: perhaps this largely hidden phenomenon is behind some of the most profound disagreements in the history of psychology. Our mental experiences are all very different - maybe that?s why thinkers have come up with such different theories about how our minds work. Search for the ?VVIQ? or Vividness of Visual Imagery questionnaire to take the test yourself. Look for ?The Perception Census? to take part in this massive online study of perceptual variation. And look up the 'Aphtantasia Network' if you're curious to find out more.

Presenters: Hannah Fry and Adam Rutherford Contributors: Professor Adam Zeman, Professor Julia Simner, Professor Fiona Macpherson Producer: Ilan Goodman

The new series kicks off very soon! As a little aperitif, Hannah and Adam review some surprising studies published in scientific journals. Warning: contains fruity language and grisly medical scenarios?

What do you get if you smash two hydrogen nuclei together? Helium and lots of energy. That?s no joke ? it's nuclear fusion!

Nuclear fusion is the power source of the sun and the stars. Physicists and engineers here on earth are trying to build reactors than can harness fusion power to provide limitless clean energy. But it?s tricky...

Rutherford and Fry are joined by Dr Melanie Windridge, plasma physicist and CEO of Fusion Energy Insights, who explains why the fourth state of matter ? plasma ? helps get fusion going, and why a Russian doughnut was a key breakthrough on the path to fusion power.

Dr Sharon Ann Holgate, author of Nuclear Fusion: The Race to Build a Mini Sun on Earth, helps our sleuths distinguish the more familiar nuclear fission (famous for powerful bombs) from the cleaner and much less radioactive nuclear fusion.

And plasma physicist (another one!) Dr Arthur Turrell describes the astonishing amount of investment and innovation going on to try and get fusion power working at a commercial scale.

Contributors: Dr Melanie Windridge, Dr Sharon Ann Holgate, Dr Arthur Turrell

Producer: Ilan Goodman

Sneezes, wheezes, runny noses and red eyes - this episode is all about allergies. An allergic reaction is when your immune system reacts to something harmless ? like peanuts or pollen ? as if it was a parasitic invader. It?s a case of biological mistaken identity. Professor Judith Holloway from the University of Southampton guides our sleuths through the complex immune pathways that make allergies happen and tells the scary story of when she went into anaphylactic shock from a rogue chocolate bar. Professor Adam Fox, a paediatric allergist at Evelina Children?s Hospital, helps the Drs distinguish intolerances or sensitivities ? substantial swelling from a bee sting, for example - from genuine allergies. Hannah?s orange juice ?allergy? is exposed as a probable fraud! Hannah and Adam explore why allergies are on the increase, and Professor Rick Maizels from the University of Glasgow shares his surprising research using parasitic worms to develop anti-allergy drugs! Producer: Ilan Goodman Contributors: Professor Judith Holloway, Professor Adam Fox, Professor Rick Maizels

Hungry for pi? Chow down on this!

Pi is the ratio between a circle?s diameter and its circumference. Sounds dull ? but pi turns out to have astonishing properties and crop up in places you would never expect. For a start, it goes on forever and never repeats, meaning it probably contains your name, date of birth, and the complete works of Shakespeare written in its digits.

Maths comedian Matt Parker stuns Adam with his ?pie-endulum? experiment, in which a chicken and mushroom pie is dangled 2.45m to form a pendulum which takes *exactly* 3.14 seconds per swing.

Mathematician Dr Vicky Neale explains how we can be sure that the number pi continues forever and never repeats - despite the fact we can never write down all its digits to check! She also makes the case that aliens would probably measure angles using pi because it?s a fundamental constant of the universe.

NASA mission director Dr Marc Rayman drops in to explain how pi is used to navigate spacecraft around the solar system. And philosopher of physics Dr Eleanor Knox serves up some philoso-pi, revealing why some thinkers have found pi?s ubiquity so deeply mysterious.

Hannah grins with delight for most of show. It?s all maths!

Producer: Ilan Goodman

Contributors: Matt Parker, Dr Vicky Neale, Dr Marc Rayman, Dr Eleanor Knox

Why are some smells so nasty and others so pleasant? Rutherford and Fry inhale the science of scent in this stinker of an episode.

Our sleuths kick off with a guided tour of the airborne molecules and chemical receptors that power the sense of smell. Armed with a stack of pungent mini-flasks, Professor Matthew Cobb from the University of Manchester shows Hannah and Adam just how sensitive olfaction can be, and how our experience of some odours depends on our individual genetic make-up.

Dr Ann-Sophie Barwich from Indiana University reveals how most everyday smells are complex combinations of hundreds of odorants, and how the poo-scented molecule of indole turns up in some extremely surprising places.

With the help of a flavoured jellybean and some nose clips, Hannah experiences how smell is crucial to flavour, adding complexity and detail to the crude dimensions of taste.

Speaking of food, listener Brychan Davies is curious about garlic and asparagus: why do they make us whiff? Professor Barry Smith from the Centre for the Study of the Senses reveals it's down to sulphur-containing compounds, and tells the story of how a cunning scientist managed to figure out the puzzle of asparagus-scented urine.

Finally, another listener Lorena Busto Hurtado wants to know whether a person?s natural odour influences how much we like them. Barry Smith says yes - we may sniff each other out a bit like dogs - and cognitive neuroscientist Dr Rachel Herz points to evidence that bodily bouquet can even influence sexual attraction!

Producer: Ilan Goodman

Contributors: Professor Matthew Cobb, Professor Barry Smith, Dr Ann-Sophie Barwich, Dr Rachel Herz

How do winds start and why do they stop? asks Georgina from the Isle of Wight. What's more, listener Chris Elshaw is suprised we get strong winds at all: why doesn't air just move smoothly between areas of high and low pressure? Why do we get sudden gusts and violent storms?

To tackle this breezy mystery, our curious duo don their anoraks and get windy with some weather experts.

Dr Simon Clark, a science Youtuber and author of Firmament, convinces Adam that air flow is really about the physics of fluids, which can all be captured by some nifty maths. The idea of pressure turns out to be key, so Hannah makes her own barometer out of a jar, a balloon and some chopsticks, and explains why a bag of crisps will expand as you walk up a mountain.

Professor Liz Bentley, Chief Executive of the Royal Meteorological Scoiety, reveals how the dynamics of a simple sea breeze ? where air over land is heated more than air over water ? illustrates the basic forces driving wind of all kinds.

Then everyone gets involved to help Adam understand the tricky Coriolis effect and why the rotation of the Earth makes winds bend and storms spin. And Professor John Turner from the British Antarctic Survey explains why the distinctive features of the coldest continent make its coastline the windiest place on earth.

Producer: Ilan Goodman Contributors: Dr Simon Clark, Professor Liz Bentley, Professor John Turner

DO WE HAVE YOUR ATTENTION?

Good! But how does that work!?

Our intrepid science sleuths explore why some things immediately catch your eye - or ear - while others slip by totally unnoticed. Even, on occasion, basketball bouncing gorillas.

Professor Polly Dalton, a psychologist who leads The Attention Lab at Royal Holloway University, shares her surprising research into ?inattentional blindness? - when you get so absorbed in a task you can miss striking and unusual things going on right in front of you.

Dr Gemma Briggs from the Open University reveals how this can have dangerous everyday consequences: you are four times more likely to have a crash if you talk on the phone while driving - even handsfree.

Drs Rutherford and Fry also hear from stroke survivor Thomas Canning, who developed the tendency to ignore everything on the left side of space, despite his vision being totally intact. And Dr Tom Manly, from the University of Cambridge?s Cognition and Brain Sciences Unit, helps our sleuths unpack the neuroscience of this fascinating condition.

Producer: Ilan Goodman Contributors: Professor Polly Dalton, Dr Gemma Briggs, Dr Tom Manly

We asked you to send us the boldest, barmiest bits of published research you could find and, dear Curios, you didn't disappoint! It?s time for some silly science.

The world is full of colour! But, wonders listener Maya Crocombe, ?how do we see colour and why are some people colour blind??

Dr Rutherford and Professor Fry set out to understand how special light-sensitive cells in our eyes start the process of colour perception, why people sometimes have very different experiences of colour and whether, in the end, colour is really just ?in our heads?.

Dr Gabriele Jordan from Newcastle University explains why lots of men struggle to discriminate between certain colours and why there were lots of complaints from colour-blind viewers when Wales played Ireland at rugby.

Professor Anya Hurlbert, also from Newcastle University, tackles the most divisive of internet images: The Dress! Did you see it as blue-black or yellow-gold? Anya explains why people see it so differently, and why our ability to compensate for available light is so useful.

Finally, Dr Mazviita Chirimuuta, a philosopher at the University of Edinburgh, gives us her take on what all this means: are colours real, or just in our minds?

If you want to see some of the images and activities referenced in the episode read on... To take the colour perception test which Hannah and Adam do in the epsiode, search for the 'Farnsworth Munsell Hue test' - you can do it online for free. To see the Dunstanborough Castle illusion as described in the episode, check out the Gallery section on the Curious Cases BBC website. To learn more about colour blindness, and for support and resources go to colourblindawareness.org

Producer: Ilan Goodman

First broadcast on BBC Radio 4 in March 2022.

Mathematician Hannah Fry and geneticist Adam Rutherford investigate your everyday science queries.

They get stuck into two questions about tides.

Lynn Godson wants to know why isn?t high tide at the same time at all points around the coast? Whilst Tim Mosedale asks, could we ever harness tidal power commercially?

Did you think tides are caused by the pull of the Moon? And that they come in and out twice a day?

Well, yes, that?s true but it turns out there?s so much more to it than that, especially here in the UK, which has the second largest tidal range in the world at the Seven Estuary near Bristol, coming in at an average of 15 metres (50ft in old money). But why should high and low tide times be so different even in places that are relatively close to each other?

The answer partly lies in something called bathymetry (which has more to do with baths than you might think ? well basins at any rate).

As for harnessing sea power, there are some ambitious projects currently in development and predictions that wave and tidal could make up as much as 15 percent of the UK?s energy needs in future. But how realistic is this and how do you ensure that your power generators can survive the rigours of the ocean ? storms, saltwater and all those pesky barnacles?

To help answer these queries, Hannah and Adam are joined by Physicist and Oceanographer, Helen Czerski and Professor Deborah Greaves OBE, who heads up the COAST lab at the University of Plymouth which studies marine renewable energy technologies.

Producers: Rami Tzabar and Jen Whyntie

First broadcast on BBC Radio 4 in March 2022.

Why does human hair go grey and is it ever possible for it to go white overnight from shock?

Hannah and Adam explore why hair goes grey, how much stressful life events and a lack of sleep can speed up the process.

They hear from the pilot whose hair turned white after a flight where all 4 of his engines failed after flying through a volcanic ash cloud - was the shock responsible?

They also uncover new research which has shown it's possible for greying hair to return to its natural colour and ask if this finding could be exploited to uncover a cosmetic way to reverse hair greying?

Presenters: Hannah Fry and Adam Rutherford Producer: Pamela Rutherford

First broadcast on BBC Radio 4 in March 2022.

Two eyes, two arms, two legs - we?re roughly symmetrical on the outside, but inside we?re all over the place!

We just have one heart, which is usually on the left, one liver on the right, one spleen and one appendix.

Why is that?? wonders listener Joanne.

Our science sleuths discover that being symmetrical down the middle - at least on the outside - is by far the most common body plan across the animal kingdom.

Professor Sebastian Shimeld from the University of Oxford takes us on a journey into the deep evolutionary past, to uncover how two-sided body structures first emerged in ancient worm-like creatures, and why this layout eventually proved so useful for swimming, walking and flying.

Garden snails turn out to be a surprising exception ? their shells coil in one direction and on just one side of their body. Professor Angus Davison from the University of Nottingham tells the tale of his international quest to find a romantic partner for Jeremy ? a rare left-coiling snail who could only mate with another left-coiling snail!

Dr Daniel Grimes from the University of Oregon unfolds the delicate mechanisms by which an initally symmetrical embryo starts to develop differently down one side, and everyone puzzles over the mystery of the left-handed 'mirror molecules' - so called L-amino acids - which turn out to be the building blocks of every living organism. A curious case indeed!

Presenters: Hannah Fry and Adam Rutherford

Producer: Ilan Goodman

First broadcast on BBC Radio 4 in March 2022.

We use Wi-Fi every day, but do you know how it works? ?Is it waves and science or just some mystical magical force?? wonders listener Abby.

Well, our science sleuths are on the case. To help them navigate the strange realm of electromagnetic waves they are joined by Andrew Nix, Professor of Wireless Communication Systems from the University of Bristol. He explains why your wi-fi router won?t heat up your baked beans, but your microwave will.

Andrea Goldsmith, Professor of Electrical and Computer Engineering at Princeton University, also joins to reveal how these waves are crammed full of 0s and 1s- whether that's a pic of your pets or a video chat with pals.

And finally, how do you get the best Wi-Fi at home?

Dr Rutherford, it turns out, has made some rookie errors...

Listen out for our top tips so you don't make them too!

Presenters: Hannah Fry and Adam Rutherford

Producer: Ilan Goodman

First broadcast on BBC Radio 4 in 2022.

?Why are teens prone to risky behaviour?? asks Dr Mark Gallaway, ?especially when with their friends??

13 year old Emma wonders why she?s chatty at school but antisocial when she gets home.

And exasperated mum Michelle wants to know why her teens struggle to get out of bed in the morning.

Swirling hormones and growing bodies have a lot to answer for but, as Professor of Psychology from the University of Cambridge Sarah-Jayne Blakemore explains, there?s also a profound transformation going on in the brain.

Dr Adam Rutherford and Dr Hannah Fry discover how the adolescent brain is maturing and rewiring at the cellular level and why evolution might have primed teens to prefer their peers over their parents.

Frances Jensen, Professor of Neurology at the University of Pennsylvania, tells us how all these brain changes can impact social relationships.

And Dr Rachel Sharman, a sleep researcher from the University of Oxford, reports the surprising findings from her sleep study tracking 100 teenagers around the UK.

Producer: Ilan Goodman

First broadcast on BBC Radio 4 in February 2022.

Our sci-curious detectives will be investigating a menagerie of mysteries sent in by listeners - from teenage brains to the magic of Wi-Fi and our strangely symmetrical bodies.

As huge tech companies race to develop ever more powerful AI systems, the creation of super-intelligent machines seems almost inevitable. But what happens when, one day, we set these advanced AIs loose? How can we be sure they?ll have humanity?s best interests in their cold silicon hearts?

Inspired by Stuart Russell?s fourth and final Reith lecture, AI-expert Hannah Fry and AI-curious Adam Rutherford imagine how we might build an artificial mind that knows what?s good for us and always does the right thing.

Can we ?programme? machine intelligence to always be aligned with the values of its human creators? Will it be suitably governed by a really, really long list of rules - or will it need a set of broad moral principles to guide its behaviour? If so, whose morals should we pick?

On hand to help Fry and Rutherford unpick the ethical quandaries of our fast-approaching future are Adrian Weller, Programme Director for AI at The Alan Turing Institute, and Brian Christian, author of The Alignment Problem.

Producer - Melanie Brown Assistant Producer - Ilan Goodman

The refrain ?robots will take your job? is one heard with increased frequency, but how quickly is automation of the labour force really happening and would it really be such a bad thing if many jobs were powered by artificial intelligence?

In this third episode, inspired by this year?s BBC Reith lectures from AI expert Stuart Russell, Adam Rutherford and Hannah Fry - together with expert guests - imagine what the future of work might look like. Will the move towards increased use of artificial intelligence in areas like healthcare, customer service and manufacturing see jobs disappear or will it simply create new ones we cannot yet imagine?

Economists are divided on what the effects of machines doing our jobs will be. Some argue it could lead to wide scale unemployment, or skilled workers being forced in into lower skilled jobs. Others believe this might be an opportunity to reshape our socio-economic systems to one where workers are freed from tedious repetitive jobs and instead have more leisure time to pursue their own interests and find meaning outside of work. Will we all one day receive a universal basic income and stop asking each other what we do for work when we meet someone new?

Producer - Melanie Brown Assistant Producer - Ilan Goodman

What if a despotic leader could programme a swarm of drones to kill a set of identified targets with just the push of a button? Due to ever expanding AI capabilities this extreme dystopian vision may not be technically unfeasible. In this second of a four part series responding to this year's BBC Reith lectures from Stuart Russell, Adam Rutherford and Hannah Fry unpick the role of AI in warfare.

Joining them to help them navigate the battlefield of information is Ulrike Franke, a senior policy fellow at the European Council on Foreign Relations who specialises in the future of warfare.

Together they will be investigating 'lethal autonomous weapons' - these are weapons that can find, chose and kill human targets without human supervision. We will be discussing how advanced this technology actually is - some think the world may have already experienced the first ever autonomous strike in Libya. What are the repercussions of this technology for safety on the battlefield , and what are the wider geo-political ramifications?

Stuart Russell has deep concerns over the development of these types of weapons and Rutherford and Fry pick apart some of the ethical debates this technology raises. Who would be responsible if a system malfunctioned and killed a civilian? What's to stop it getting into the wrong hands? Should we even be creating these weapons in the first place - do we instead need a convention banning them? And is that even possible?

Artificial Intelligence (AI) is already ubiquitous in our lives. It curates our nightly TV entertainment, connects us to our friends online and navigates us, mostly successfully, to our destinations. However these uses are just the beginning, and it will likely bring societal changes we can?t yet imagine.

In this year?s BBC Reith lectures, AI expert Professor Stuart Russell will be exploring how AI has been represented in popular fiction, envisaging how this technology might shape our futures and how we best prepare for it. So who better to unwrap his ideas than science sleuths Adam Rutherford and Hannah Fry, with their customary curiosity and irreverent insights?

In this, the first of four episodes, Rutherford and Fry ? together with guests author and podcaster Azeem Azhar and AI scholar Kate Crawford - will be unravelling what we actually mean by AI, exploring how far machine learning already underpins our lives, imagining the functions it might provide in the future and asking what challenges and risks might lie ahead. Can AI transform society as profoundly as electricity once did leading to a golden age for humanity, or have we all watched too many sci-fi movies?

Whilst watching a documentary about some poisonous frogs, Curio Janni in Amsterdam, started to wonder what would happen if a frog licked itself or another frog of the same species.

She asks Dr Adam Rutherford and Professor Hannah Fry to investigate whether an animal would react badly to a toxin it itself produces?

In essence 'can a venomous snake kill itself by biting itself?'

Of course the answer is complicated, but the sleuths know exactly who to ask.

Steve Backshall, award-winning wildlife explorer, best known for his BBC series 'Deadly 60'. Author of 'Venom ? Poisonous Creatures in the Natural World'. Steve has been bitten, stung and spat at by a plethora of venomous creatures during his career. He also studied the first known venomous newt - the sharp-ribbed newt - a creature that has sharpened ribs that when it's under attack, it will squeeze its body force those ribs out through its skin, coating them in venom, which is then delivered into the mouth of an attacker.

Professor Nick Casewell, studies venomous snakes and their impact on humans. He works on treatments for snakebites at the Liverpool School of Hygiene and Tropical Medicine. Snakebites have a huge impact on communities in South Asia, Sub-Saharan Africa and South America. It's now been reinstated as one of the most serious neglected tropical diseases by the World Health Organisation. Traditional treatments - antivenins - can be expensive, difficult to access and don't always work - Nick is looking into alternative medicines to treat snakebite victims.

Dr. Ronald Jenner is Principal Researcher in the Comparative Venomics group at the Natural History Museum's Life Sciences, Invertebrates Division and co-wrote the book ?Venom -the secrets of nature's deadliest weapon.? He explains the evolutionary arms race between venomous predators and their prey and poisonous prey and their predators. He explains how resistance to venom has evolved and how venom has evolved to be more or less powerful over time, answering another Curio - Scott Probert's question on the evolution of venom.

Christie Wilcox wrote 'Venomous ? How Earth?s Deadliest Creatures Mastered Biochemistry'. She studied the molecular basis of lionfish venom. Christie describes how venom and immunity to venom works at the molecular level.

Presenters: Adam Rutherford and Hannah Fry

Producer: Fiona Roberts

First broadcast on BBC Radio 4 in November 2021.

'What is the slipperiest thing in the world?' asks 8 year old Evelyn.

Why do my feet slip on a wet floor but when my feet are even slightly moist it's nearly impossible to put on a pair of socks without falling over and cursing the universe. What is going on here?' asks Evelyn's Dad, Sam.

Hannah and Adam investigate the science of friction and lubrication - so called 'tribology' with the help of tribologists and mechanical engineers Professor Ashlie Martini from California University Merced and Professor Roger Lewis from the University of Sheffield.

With their help Hannah and Adam find out why leaves on the line are so slippery, what happens to graphite in space and what is the slipperiest food. Professor of Materials, Mark Miodownik from University College London explains what's going on when friction stops two materials sliding past each other and wonders whether the slipperiest substance was actually discovered accidentally in a lab by scientists looking for something completely different.

Also in the programme why the ability to reduce friction, even by minuscule amounts could have a huge impact for sustainability and reducing energy use.

Producers: Jen Whyntie and Pamela Rutherford

First broadcast on BBC Radio 4 in November 2021.

Why does my heart not ache after exercise? asks listener Keith. Rutherford and Fry explore how and why heart muscle cells are special.

Dr Mitch Lomax is a sports scientist at the University of Portsmouth. She helps actual Olympic swimmers get faster. She explains how most of the muscles attached to our skeletons work: Tiny fibres use small-scale cellular energy, which, when all these fibres work in concert, turns into visible muscular movement. Mitch also explains how the dreaded Delayed Onset Muscle Soreness, or DOMS, can hit, taking a stair-wincing 48-72 hours to peak after exercise.

But skeletal muscles turn out to be quite different to heart muscles, as consultant cardiologist Dr Rohin Francis explains. Heart cells are more efficient and don't get fatigued like skeletal muscle cells. They are extremely energetic and 'just want to beat'. He also explains that the sensory feedback from the heart muscles is different too. They have a different sort of nerve supply, with fewer sensory nerves, so that there is less chance of pain signals being sent to the brain.

However, heart cells' incredible abilities are counterbalanced by one Achilles-like flaw: They cannot easily heal. Professor Sanjay Sinha is a British Heart Foundation (BHF) Senior Research Fellow and a Professor in Cardiovascular Regenerative Medicine at the University of Cambridge. His job is to fix broken hearts and he explains to Adam how new research into stem cells could be used to fix normally irreparable heart cells.

Presenters: Hannah Fry and Adam Rutherford

Producers: Jennifer Whyntie and Fiona Roberts

First broadcast on BBC Radio 4 in October 2021.

?I don?t really understand why water has so many properties on different scales ranging from very large and cosmic to very small quantum and quarky - Could you help by zooming in and out on water to explain what is known about it? "Asks Neil Morton in Stirling.

?Why does boiling water sound different to cold water?? asks Barbara Dyson in Brittany in France

Ollie Gordon, in Christchurch in New Zealand, wants to know ?why water is essential for all life as we know it??

And many more questions on the weirdness of water are tackled by super science sleuths Hannah Fry and Adam Rutherford.

With assistance from:

* Quantum physicist Professor Patricia Hunt, at the Victoria University in Wellington in New Zealand

* Science writer and author of ?H2O ? a biography of water? Philip Ball

* Physicist and bubble expert in the Department of Mechanical Engineering at UCL, Dr Helen Czerski.

Producer: Fiona Roberts

First broadcast on BBC Radio 4 in October 2021.

?I don?t really understand why water has so many properties on different scales ranging from very large and cosmic to very small quantum and quarky - Could you help by zooming in and out on water to explain what is known about it?" asks Neil Morton in Stirling.

Rutherford and Fry learn about the special hydrogen bonds that makes water such an unusual liquid.

Quantum physicist Professor Patricia Hunt, at the Victoria University in Wellington in New Zealand explains to Hannah the quantum properties of individual water molecules and how they link up with other water molecules in liquid water and solid ice. She describes the hydrogen bonds that give water some of it?s weird and wonderful properties such as why ice floats, why water is able to store huge amounts of heat and why water has such a strong surface tension.

Science writer and author of ?H2O ? a biography of water? Philip Ball describes how in the 18th century it was discovered that water was not one of the classical elements, but a compound liquid of water and hydrogen and explains to Adam why there are at least 15 different types of ice.

Physicist Dr. Helen Czerski sets the record straight on how ice forms in oceans and lakes and why water is at its densest at 4 degrees Centigrade and not zero.

Presenters: Hannah Fry & Adam Rutherford

Producer: Fiona Roberts

First broadcast on BBC Radio 4 in October 2021.

How do guide dogs know where they're going? It's not like their handler whispers in their ear and asks to go to the pharmacy, maybe the toothpaste aisle. So how does it work? asks Charlotte, aged 42.

Dogs and humans have gone paw in hand for thousands of years. Historic and genetic evidence shows we?ve shaped each other's existence over millennia. But dogs were only first trained as guides for blind people in the UK 90 years ago. What?s the biology behind this extraordinary partnership? Hannah heads to Guide Dogs UK?s training school in Royal Leamington Spa. She meets up with expert Graham Kensett to find out what it takes to make a guide dog from nose to tail, starting from before birth and following the life course through to retirement.

Hannah also meets the delightful Wendy and Wilmott, a German shepherd and a retriever cross. Despite both still growing into their ears, they show her their already extraordinary skill set, from tackling obstacle courses to safely crossing roads. Cool, calm, patient, unflappable: Guide dogs are the astronauts of the canine world. But, as trainer Jenna explains, it?s all in the partnership with the owner, who needs to do plenty of work in terms of training and learning routes to journey in harmony with their furry guide.

Richard Lane has owned guide dogs for over 25 years, and confirms this first hand. He reveals just how he gets to the toothpaste aisle, and tells Adam how at its peak a partnership can navigate London Waterloo station better than some sighted people, even at rush hour. Richard also explains how deeply felt the bond that forms between owner and dog is, and describes the hardest part of guide dog ownership: Letting go at the end.

Presenters: Hannah Fry & Adam Rutherford Producer: Jen Whyntie

A BBC Audio Science Unit production for BBC Radio 4

Rutherford and Fry are back in the business of solving your science queries and rooting out the quirks and conundrums of everything that is science!

It was a dark and stormy night. 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, which would test our intrepid duo to their very limits. 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. Then Rutherford and Fry investigate the more physical side of fear, when they delve into the history of roller coasters to investigate why we enjoy being scared.

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 roller coasters at Thorpe Park.

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.

This episode is a remake of two earlier broadcast episodes.

Producers: Fiona Roberts & Michelle Martin

Presenter: Adam Rutherford & Hannah Fry

First broadcast on BBC Radio 4 in February 2021.

Why are some people left-handed, whereas the majority are right handed? Rutherford and Fry revisit The Sinister Hand episodes to further investigate handedness in humans and animals. They considered cockatoos, chimpanzees and Hannah's dog, Molly, to discover that humans are unique, with just one in ten of us being left-handed.

They ask if there is an evolutionary reason for just 10% of the human population being southpaws

Hannah talks to primatologist Prof Linda Marchant from Miami University about Neanderthal teeth and termite fishing.

Adam consults handedness expert Prof Chris McManus from University College London. He's been trying to track down the genes responsible for whether we're right or left handed.

And what about left-handed brains or eyes or molecules?

Prof Andrea Sella explains handedness, or chirality, at the molecular scale and why when we consider Thalidomide, something seemingly so trivial can be extremely important.

They also explore the left-handed brain. Some researchers point to a link between left-handedness and impairments like autism or dyslexia. Others claim that lefties are more creative and artistic.

So what's the truth? The team consults Professors Sophie Scott, Chris McManus and Dorothy Bishop to find out.

This episode is an updated version of two earlier broadcast episodes.

If you have any Curious Cases for the team to investigate please email [email protected]

Producers: Fiona Roberts & Michelle Martin

Presenter: Adam Rutherford & Hannah Fry

A BBC Audio Science Unit production for BBC Radio 4, first broadcast in 2021.

The doctors continue their investigation into gravity, and answer Peter Fraser?s question:

Is dark matter a proper theory or just a fudge to fit existing 'proper' theories to otherwise inexplicable observations?

Whilst scientists are pretty convinced our understanding of gravity is largely correct, there are still some significant gaps. Namely, given the way galaxies are observed to behave, around 85% of the matter that they think should be in our universe is missing. So where ? and, as importantly, what ? is it? Cosmologist Andrew Pontzen introduces the evidence from our observations of the cosmic microwave background, light leftover from the Big Bang, which indicate that dark matter exists.

However, this evidence alone is not enough for science. Physicist Chamkaur Ghag is trying to find particles of dark matter here on Earth. Unsurprisingly, no-one is quite sure where these critters are hiding in the particle zoo of protons, neutrons, electrons, quarks, bosons, muons and the rest ? or even what they look like. One theory suggests a weakly interacting massive particle, or WIMP, may be the dark matter minibeast. Hundreds of thousands of these could be flying through our fingertips every second. To tell whether they?re there, Cham and hundreds of scientists are building detectors, huge vats of liquid xenon in underground caverns.

Bond villain-esque lairs don?t come cheap, and listener Peter?s query is valid ? what if dark matter goes the same way as the aether, an all-permeating (and ultimately non-existent) material that was hypothesised to carry light through the vacuum of space?

Astrophysicist Katy Clough reiterates that experiments are the way to test predictions. Building a picture of how gravity works continues to take many people enormous effort, but this is the scientific process.

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

A BBC Audio Science Unit production for BBC Radio 4, first broadcast in 2021.

The doctors investigate a millennia-old query, as listener Emma in New Zealand asks:

?How does gravity pull us??

People have been thinking about how gravity works for a very long time. Way longer than when that particular apple almost certainly didn?t fall on the head of Isaac Newton. Cosmologist Andrew Pontzen begins guiding us through our journey by taking us back to the almost entirely incorrect writings of ancient Greeks.

We then fast forward past Galileo and Newton, and throw in an extra dimension. Using an all-too-believable analogy where some merry cyclists suddenly ride into a meteor crater, astrophysicist Katy Clough tells us how Einstein?s spacetime works.

Limitations of analogies accepted, this explains some of the observations that didn?t fit with Newton?s workings alone. But there are other snags with our understanding of gravity, both at the very small quantum scale and the very large galactic scale. Physicist Chamkaur Ghag introduces what scientists think may account for some of these issues: the mysterious dark matter.

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

A BBC Audio Science Unit production for BBC Radio 4, first broadcast in February 2019.

Do individuals perceive time differently?

Psychologist and presenter of All in the Mind, Claudia Hammond wrote the book ?Time Warped ? Unlocking the Mysteries of Time Perception?. She explains how emotion and memory are big factors in how time is perceived. She stresses how time can stretch and squeeze depending on whether you are looking backwards or forwards. And she explains how lockdown has warped time in different ways for different people.

Professor David Eagleman, from Baylor College of Medicine in Houston, conducted a very famous experiment on time dilation, to see whether time slows down when you are very frightened. He wanted to see whether people actually have increased time resolution during a terrifying moment, and tested whether his students actually see in slow motion when they leapt off a tall building (in a safe manner).

Professor Marc Whitman is a neurologist who has spent his career looking for the clock in our brains. He says that time is dealt with in many parts of the brain, with some parts dealing with different durations, from milliseconds to decades.

Katya Rubia is Professor of Cognitive Neuroscience at Kings College London and is an expert on time perception in children with ADHD. She links the impulsiveness of children with Attention Deficit Hyperactivity Disorder to problems with time perception and has found that the pre frontal lobe, which is key for perceiving time is both functionally and structurally different in children with the disorder, which means that time goes much slower for them. This goes some way to explain their impatience and inability to sit still.

Producer: Fiona Roberts

Presenters: Dr Hannah Fry and Dr Adam Rutherford

A BBC Audio Science Unit Production for BBC Radio 4, first broadcast 2021.

The doctors put mosquitoes on trial, as listener Cathy in the UK asks, ?What is the point of mosquitoes?? in response to our show about wasps.

Mosquitoes have undeniably played a role in killing millions of people. Malaria is the single biggest cause of death in human history. But Erica McAlister, senior curator of flies and fleas at the UK?s Natural History Museum, reveals that not all mosquitoes are interested in biting us for a blood meal, or are involved in transmitting disease. Only the females of about 10 species are the most problematic for humanity, from around 3600 true species of mosquito. Limited research indicates that many play important roles in ecosystems, for example as pollinators on land and as food sources during their larval stage in aquatic environments.

Nonetheless, those roughly 10 species cause devastating disease. Kate Jones? research at University College London examines the interface of ecology and human health. Malaria and dengue fever alone cause over 300 million infections annually.

And there are many more diseases transmitted by mosquitoes: Zika, West Nile fever, Yellow fever, Japanese encephalitis ? the list goes on, and with urbanisation and climate change, the picture is constantly changing.

So what can be done? Should we try to annihilate the disease-carrying species?

Insecticide use has historic and ongoing controversy, as the difficulties of needing to stop deaths in the short term risks longer term environmental damage, with unforeseen and possibly greater consequences for humanity. So Adam turns to new, genetic technology with zoologist Matthew Cobb. Can and should we modify mosquitoes to wipe themselves out, by wrecking local populations with sterile males, or use a technique called a gene drive to perpetuate debilitation through generations? Or could life find a way to evolve past our attempts at control, and cause greater problems?

The doctors deliberate and try to decide a verdict on mosquitoes? fate.

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

A BBC Audio Science Unit production for BBC Radio 4, first broadcast in 2021.

Astrology ? could there be something to it? asks Dan from Australia. Rutherford and Fry investigate the science that has investigated astrology.

Professor Richard Wiseman, (sceptical of all things paranormal and a Virgo) and Professor in the Public Understanding of Psychology at the University of Hertfordshire, explains the long history of the scientific investigation of astrology. He has also run his own experiments to test whether astrology can help you play the stock market and to investigate if people born in the summer are luckier than those born in the winter ? the results may surprise you.

Journalist and author, Jo Marchant (Leo and fascinated non-believer) has written all about the history of astrology in her new book ? 'The Human Cosmos ? A Secret History to the Stars'. In the beginning astrology and astronomy were one and the same. She explains how astrology flourished with the elite and ruling classes of ancient Babylon, Egypt and Greece.

Data scientist, Alex Boxer (Taurus and cautious astrology tourist) explains that astrology may have been humanity's first attempt to predict the future with algorithms, something we?re doing more and more of now. In his book, ?A scheme of heaven, astrology and the birth of science?, he describes how astrological and scientific algorithms are all just big data science looking for patterns. The issue lies in what that data is.

Presenters: Hannah Fry (Pisces) & Adam Rutherford (Capricorn) Producer: Fiona Roberts (Libra)

First broadcast on BBC Radio 4 in 2021.

Why do some people find noises like a fork scraping a plate so terrible? asks Findlay in Aberdeenshire. Rutherford and Fry endure some horrible noises to find out the answer.

Warning - This episode contains some horrible sounds

Trevor Cox, Professor of Acoustic Engineering at the University of Salford, has run experiments to find out the worst, most cringe-making sound. He divided horrible sounds into three categories: scraping sounds, like nails down a blackboard; disgusting sounds like a snotty sniffy nose; and sounds that make us cringe because of what we associate them with, like the dentist?s drill. All horrible sounds have some sort of association whether it?s a primal scream or fear of catching a disease, and they?re dealt with in the ancient part of the brain ? the amygdala.

Professor Tim Griffiths is a Cognitive Neurologist at Newcastle University?s Auditory Cognition Group. He has been studying people with misophonia, a condition where ordinary, everyday sounds, such as someone eating or breathing causes a severe anxiety and anger response. Misophonia may affect around 15% of the population and Tim thinks that different parts of the brain ? the insula and the motor cortex - are involved in this fight or flight response to seemingly innocuous sounds.

Cat Thomas?s job is to make horrible sounds. She is a foley artist at Boompost. If you watch Call the Midwife or Peaky Blinders, all the incidental sounds are created by Cat and her team. She also created some of the sounds for the horror film Camilla, which involved evisceration and disembowelling with the aid of some squishy oranges and bananas. Adam Rutherford and Hannah Fry try their own horror sounds when they chop off a finger with the aid of some large pasta shells, an orange and a knife.

If you want more information on misophonia ? http://www.misophonia-uk.org https://www.allergictosound.com

Presenters: Hannah Fry & Adam Rutherford

Producer: Fiona Roberts

A BBC Audio Science Unit production for BBC Radio 4 first broadcast in January 2021.

Can I make a pizza that contains my recommended daily intake of everything? asks listener Paul in Manchester. We investigate whether a pizza can meet our full dietary requirements.

The optimum diet for humans has been long contested. From William the Conqueror's alcohol diet to the infamous apple cider vinegar diet, discovering the healthiest nutrition is a centuries-long work in progress. So could The Pizza Diet be the next food fad?

We investigate a theory that a basic margherita pizza ? with its components of a flour-filled base, along with a cheese topping ? should meet our needs for carbohydrate, protein and fat. Adam meets up with body-weight geneticist Giles Yeo from their respective kitchens for a remote cook-off to find out if it's possible to make this mythical one-meal wonder in practice.

On closer inspection of the evidence-based government dietary requirements, this task appears somewhat challenging. Dietitian Clare Thornton-Wood analyses the components of a margherita and unsurprisingly finds they do not entirely meet the guidance.

She then scrutinises our attempt to retrofit a recipe that might do the job. Giles attempts to put our proposed pizza into practice. He has to ad-lib, as the resultant mountain of eclectic toppings ? chickpea and sweetcorn pizza, anyone? ? and giant base won?t fit in his oven.

Disappointingly for hardcore pizza fans like Paul who may be attempting healthier eating habits in 2021, it seems that this particular approach is not the way forward. Food choice psychologist Suzanna Forwood explains why there is so much more to our dietary decisions than digestive physiology, and offers tips for listeners hoping to make seasonal steps in a healthy direction.

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

A BBC Audio Science Unit production for BBC Radio 4 first broadcast in 2020.

"Why are some fungi helpful and others harmful?" asks Paul Glaister in Reading. Rutherford and Fry try to outdo each other with fungal top trumps to get to grips with the answer.

Decomposition ecologist Lynne Boddy, Professor of Microbial Ecology at Cardiff University, helps Hannah calculate the amount of dead plant material we?d be buried in across the globe, if we didn?t have fungi to recycle it. And she describes her first fungal encounter in her student flat which was riddled with dry rot, and explains how without fungi, we wouldn?t have plants.

On Adam?s team is Curator of Mycology, Dr. Bryn Dentiger, at the Natural History Museum of Utah. Bryn tells Adam that he can?t think of a single food that doesn?t have some association with fungus. And the links are mostly positive rather than just mould on the top of your jam or rotten fruit in your fridge. He introduces Adam to the Humungous Fungus ? the biggest living organism on Earth - and they get excited at the prospect of 20,000 different fungal sexes.

The pros and cons of fungi don?t stop there. Microbiologist Dr. Ada Hagan, in Michigan lists some of the fungal diseases we?re prone to, and the numerous drugs derived from fungi that help treat a whole host of common diseases.

Presenters: Hannah Fry & Adam Rutherford Producer: Fiona Roberts

A BBC Audio Science Unit production, first broadcast on BBC Radio 4 in 2020.

What would it take for humans to live permanently on Mars? asks Martin in Weston-super-Mare, UK. The doctors dig into requirements and possibilities of a long-term Martian outpost.

We know that many missions to Mars have failed, for a range of reasons ? malfunctions, crashes and even a mix-up between imperial and metric units. Getting to Mars ? let alone decelerating from 30,000 miles per hour to a safe landing speed in about seven minutes ? is not straightforward. Aerospace engineer Anita Sengupta helped land NASA?s Curiosity rover on Mars. She knows first-hand the challenges of putting a robot on the red planet.

But getting robots to Mars is an easier proposition than doing the same for humans. Even if we work out how to survive the radiation exposure on the eight-month journey and the pulverising descent, Mars? surface isn?t easily habitable. Principal investigator for NASA?s Mars Atmosphere and Volatile Evolution Mission (MAVEN) Bruce Jakosky describes the conditions on Mars: Freezing, with an atmosphere containing mostly carbon dioxide and very little water, and subject to annual global dust storms.

However, this isn?t deterring space agencies and private companies from researching the challenge. The European Space Agency and Russian Institute for Biomedical Problems focussed on finding out the physiological and psychological tolls by selecting six candidates to spend 520 days in a simulated spacecraft and landing module. Diego Urbina explains the personal challenge of taking part in the Mars500 experiment.

Some private company owners have gone even further. As well as making technology based on the current physical conditions, could those constraints themselves be altered? Could Mars be terraformed, or warmed, for easier human survival? Bruce Jakosky shares just what that would take ? and compares these requirements with what?s actually available.

Presenters: Hannah Fry & Adam Rutherford Producer: Jen Whyntie A BBC Audio Science Unit production, first broadcast on BBC Radio 4 in 2020.

"How many hamsters on wheels would it take to power London?" asks Judah from Virginia in the USA. Rutherford & Fry return with engineering, ethics and economics to answer this electric query.

Smart grid engineer Lynne McDonald helps keep the lights on for 8.3 million homes and businesses across London at UK Power Networks. She explains how the kilowatt hours we see on our electricity bills relate to the thousands of gigawatt hours required when thinking about powering the whole of London. In theory, a hamster in a wheel might be able to produce about half a watt of power ? enough to run a small LED light bulb.

Whilst the doctors argue the case on the resultant practicalities and ethics of even considering such a scenario ? as, for example, the required cubic kilometre stack of hamster habitats would cover Canary Wharf ? Royal Veterinary College researcher Zoe Davies points out some biological and anatomical home truths. As an expert in biomechanics currently investigating athletic performance in racehorses, she walks Adam through the impossibilities of using pretty much any animal, bird or insect as a source of power.

There may be one exception though: humans. Veteran lecturer of undergraduate chemistry for biologists and cycling enthusiast, Andrea Sella discusses whether human power might realistically work. We consider what this or other more realistic sources of renewable energy could mean for the future of our national grid.

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

A BBC Audio Science Unit production for BBC Radio 4, first broadcast in December 2020.

Rutherford and Fry are back in the business of solving your science queries and rooting out the quirks and conundrums of everything that is science!

Is there a point in space where the Sun could heat a burrito perfectly? asks Will.

The doctors tackle this and a plethora of other conundrums from the Curious Cases inbox.

Featuring expert answers from:

Astrophysicist Samaya Nissanke Cosmologist Andrew Pontzen Cognitive neuroscientist Sophie Scott

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

First broadcast on BBC Radio 4 in July 2020.

?Today I learnt that tigons and ligers are what you get when lions and tigers interbreed?!? surprised listener Jamz G tells the doctors. ?What determines whether species can interbreed??

Geneticist Aoife McLysaght studies molecular evolution. She explains the modern definition of a species, built on ideas from Aristotle, Linnaeus and Darwin: a species is a group of organisms capable of interbreeding to produce fertile offspring. Hybrids ? such as ligons and tigers ? are usually infertile, because their common ancestors long ago diverged into the lions and tigers we know today. However, this definition isn?t absolute, and there are many ways a new species can be formed.

Hybrids also offer rich study subjects for scientists. Mathematical biologist Kit Yates discusses why he?s been reading research papers about hebras and zorses (horse x zebra) as their patterns offer insights into how cells spread and develop into organisms, building on a prediction made by codebreaking mathematician Alan Turing.

And it turns out that these hybrids are even more intriguing. As speciation and evolution expert Joana Meier explains, hybrids are not always infertile. Hybridisation can lead to successful new species arising, such as in Lake Victoria?s cichlid fish, who it seems have been having a wild evolutionary party for the last 15,000 years. And the picture gets even murkier when we discover that modern genetics reveals our human ancestors successfully mated with Neanderthals.

Presenters: Hannah Fry & Adam Rutherford

Producer: Jen Whyntie

First broadcast on BBC Radio 4 in July 2020.

Everyone knows about the Big Bang being the beginning of the universe and time - but when and how is it going to end? ask brothers Raffie and Xe from Rome.

For this series, with lockdown learning in mind, Drs Rutherford and Fry are investigating scientific mysteries for students of all ages. The doctors sift science from philosophy to find out.

Cosmologist Jo Dunkley studies the origins and evolution of the universe. She explains how astrophysical ideas and techniques have evolved to tell us what we now know about our galaxy and far beyond, from the elegant parallax technique to standard candles. This particular distance measure, which uses stars of a known brightness to work out how far away other objects in the universe are, was discovered by American astronomer Henrietta Swan Leavitt in 1912, who worked at the Harvard University as one of several ?computers? ? women who processed and calculated data and made significant contributions to astronomy.

Curious Cases? universal guru Andrew Pontzen puts this into context. Because the universe is so enormous, it turns out that these measurements are just the first steps on the cosmic distance ladder ? a suite of tools that astrophysicists use to determine distances to celestial objects. Scientists know that objects are moving away from us because the wavelengths of light from them get stretched and appear redder in our telescopes ? the so-called red shift effect. But having a handle on the distances to and between those objects allows cosmologists to monitor what?s happening to them over time. And it turns out that not only are they getting further apart, indicating that the universe is expanding, but that this process is accelerating.

So what might happen in the end? Expansion and then collapse ? a big crunch? Expansion into the void ? a big freeze, or a big rip? Or what if there is more than one universe ? might a new one bubble up with totally different laws of physics that would cause our own to cease existing?

It turns out that when dealing with predictions for something involving infinite space and time, the possibilities are largely limited by human imagination alone. Ideas are where science starts, but experiments are required to build evidence confirming or rejecting them as fact. The doctors discuss how gravitational wave detectors and quantum computers might one day provide this.

Presenters: Hannah Fry & Adam Rutherford Producer: Jen Whyntie

First broadcast on BBC Radio 4 in June 2020.

"What?s the point of wasps?" asks listener Andrew, who is fed up with being pestered. For this series, with lockdown learning in mind, Drs Rutherford and Fry are investigating scientific mysteries for students of all ages. Do wasps do anything to justify their presence as a picnic menace?

Ecologist Seirian Sumner researches social wasp behaviour and champions their existence. Not only do yellow jacket wasps perform important ecological services as generalist pest controllers of aphids, caterpillars and flies in the UK, they have complex societies and may even perform pollination services, making them more like their better-loved bee cousins than many might think.

However, much remains unknown about wasps? contribution to our ecosystem. Seirian works with entomologist Adam Hart, and together they run The Big Wasp Survey each summer, a citizen science project dedicated to find out more about UK wasp species and their populations. Prof. Hart sets up an experimental picnic with Dr Rutherford to try and attract some native wasps, and discusses why they are so maligned.

But in some parts of the world UK wasp species have become a major problem. Just after World War II, having unwittingly chosen some aircraft parts destined for New Zealand as their overwintering home, some wasp queens woke up in the city of Hamilton. With no natural predators or competitors, they quickly established a growing population. Fast forward to today, and by late summer the biomass of wasps becomes greater than all the birds, rodents and stoats in the southern island?s honeydew beech forests. Multiyear nests have been discovered that are over three metres tall and contain millions of wasps. Researcher Bob Brown is digging into wasp nests back in the UK to discover which species keep wasps in check here, and whether they might work as biological control.

This causes the doctors to ponder the problems of humans moving species around the planet. Accidental or even well-meaning introductions all too often become invasive. As climate change and urbanisation accelerate, wasps may become more helpful in some ways and more harmful in others.

Presenters: Hannah Fry, Adam Rutherford Producer: Jen Whyntie

First broadcast on BBC Radio 4 in 2020.