The Impossible Number

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 Professor Karen Aplin, University of BristolProducer: Marijke Peters Executive Producer: Alexandra Feachem A BBC Studios Audio Production

11 year old Esther visualises days of the week in a kind of 3D structure. It’s something called ‘synaesthesia’ and she wants to know why it happens - and why other people don’t experience things the way she does. Hannah Fry and Dara Ó Briain explore the vibrant and varied ways different people experience the world, from the man who tastes individual words - including all the stops of the tube - to the composer who sees music in shapes and colours. And along the way, they figure out why Mozart is white wine while Beethoven is red. Contributors:Professor Julia Simner: Professor of Psychology,University of Sussex Professor Jamie Ward: Professor of Cognitive Neuroscience, University of Sussex James Wannerton, President of UK Synaesthesia Association CoriAnder: electronic music producer Producer: Ilan Goodman Executive Producer: Alexandra Feachem A BBC Studios Audio Production

It’s sometimes said that timing is everything and this week the pair investigate the mystery of rhythm, discovering why some of us might be better at staying in tempo.From the daily cycle of dawn and dusk to sea tides and circadian clocks, rhythm governs many aspects of our lives, and cognitive psychologist Dr Maria Witek says it makes sense we also place great importance on its presence in music. She specialises in ‘groove’, or the feeling of pleasure associated with moving to a beat – and it’s not just something the dancers among us enjoy; groove has even been used to treat patients with Parkinson’s Disease.Neuroscientist Professor Nina Kraus has studied drummers’ brains and found their neurons fire with more precision. She explains that teaching kids rhythm can improve their language and social skills. But no need to take her word for it, because Skunk Anansie’s drummer Mark Richardson is in the studio to put Hannah to the test. Can she handle a high hat at the same time as a snare?Contributors: Dr Maria Witek, University of Birmingham Professor Nina Kraus, Northwestern University Mark Richardson, drummer with Skunk Anansie Producer: Marijke Peters Executive Producer: Alexandra Feachem A BBC Studios Audio Production

9 year old listener Koby sends Hannah and Dara on a mission to find the shiniest thing in the world. And so they enter a world of mirrors… The journey takes them into the subatomic goings on of shiny metal surfaces, where electrons waggle and dance and send light waves back at *just* the right angle. Our curious duo play with an astonishingly reflective plastic film that can be found hidden in devices we all use. And they probe the mysterious power of refraction, harnessed to make the $2 million mirrors which reflect the lasers at the huge LIGO experiment. And everyone ponders the surprisingly reflective properties of a pint in space. Contributors:Dr Felix Flicker: University of Bristol, author of The Magick of Matter Professor Stuart Reid: University of Strathclyde Quinn Sanford: optical engineer from 3M GariLynn Billingsley: Optical Sciences Group Leader at LIGOProducer: Ilan Goodman Executive Producer: Alexandra Feachem A BBC Studios Audio Production

Would you eat food that fell on the floor? That’s the question Hannah and Dara are getting their teeth into this week as they put the so-called ‘5 second rule’ through its paces. For some people it’s 3 seconds, and for others its 10 – especially if it involves a dropped ice cream and a screaming child. But microbiologist Don Schaffner says there’s no safe amount of time to leave food on the floor if you’re planning to eat it. And while you might think buttered toast would pick up the biggest number of bugs, it may surprise you to hear that wet foods like watermelon are actually the worst when it comes to attracting harmful bacteria. If all this is putting you off your dinner, the bad news is that the rest of your kitchen is also a microbiological minefield. Research shows nearly 70% of us keep our fridges are the wrong temperature, which sparks a lively discussion about whether it’s ever safe to reheat rice. For home hygiene guru Sally Bloomfield it’s all a question of being a bit more clever about the kind of germs we expose ourselves to and weighing up risks. Contributors:Dr Don Schaffner: Rutgers University Dr Ellen Evans: Cardiff Metropolitan University Professor Sally Bloomfield: International Scientific Forum on Home HygieneProducer: Marijke Peters Executive Producer: Alexandra Feachem A BBC Studios Audio Production

While chatting at the back of class, best mates Abi and Sofia got curious about bubbles. How do you make really giant ones? Could you even get one around the entire planet?Hannah and Dara set out to investigate. They hear from a renowned 'bubbleologist', and learn how NASA helped him blow his way to a world record. They coax a physicist to reveal the secrets of his peer-reviewed bubble-juice formula, and investigate how bubbles work in space and in the ocean. Our curious duo also discover an audacious project aiming to build a Brazil-sized raft of bubbles... in space! Contributors:Dr Helen Czerski, UCL Dr Justin Burton, Emory University Dr Awesome, Bubbleologist Professor Carlo Ratti, MIT Producer: Ilan Goodman Executive Producer: Alexandra Feachem A BBC Studios Audio Production

Curious Cases is returning! Superstar mathematician and broadcaster Hannah Fry teams up with legendary comedian and fellow science nerd Dara Ó Briain for an all-new series of the show which takes your quirkiest questions and solves them with the power of SCIENCE.In this short preview ep, our dynamic duo tease some of the upcoming episodes in which they enlist the world’s top experts to tackle the most profound and puzzling questions to have ever trickled through your curious minds: Could you power a spaceship with a lemon? Can you actually die of boredom? Why do some people *taste* words? Why does Hannah have absolutely no sense of rhythm? And could we stop climate change with massive space bubbles!? Producers: Marijke Peters and Ilan Goodman Executive Producer: Alexandra Feachem A BBC Studios Audio Production

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 RutherfordProducer: Ilan Goodman