Curious Cases

From pharaohs' tombs in Ancient Egypt and medieval currency, to priceless royal jewellery and Spandau Ballet songs - gold has been prized for millennia. But it's only really in the last century or so that we've started uncovering its usefulness in less decorative applications.Today, gold is used in masses of electricals; it's also revolutionised part of the manufacturing sector by stopping a dangerous reliance on mercury as a catalyst; and it's vital to space missions. Although there are also some more frivolous modern uses for gold, as Hannah and Dara discover. (Gold-leaf in your cocktail, anyone?)Challenged to find out whether all the world's mined gold would really fit in an Olympic swimming pool, our science-savvy duo discover that this antisocial element might just be the best darn thing on the periodic table... Contributors: - Graham Hutchings, Regius Professor of Chemistry at the University of Cardiff - Frances Wall, Professor of Applied Mineralogy in the Camborne School of Mines at the University of Exeter - Tim Peake, AstronautProducer: Lucy Taylor Executive Producer: Sasha Feachem A BBC Studios Production

What exactly is 'phantom pain' and how does it work? Hannah and Dara investigate a medical phenomenon that's been known about for centuries but is often misunderstood; and involves masses of unanswered questions.The condition 'phantom pain' is when someone gets a sensation of pain that feels like it's coming from a part of their body that's no longer there - so that could be an amputated limb, or perhaps something that has been removed, such as a tooth or an organ. It's thought to be caused by how the brain and body process pain and physical awareness, but there's still debate around what exactly is going on neurologically.Researchers around the world are looking into the condition; in the meantime, people who experience phantom pain - like today's studio guest Lynn - often have to try out a range of treatments, to find out what combination works best for them. But as the team discover, pain is deeply subjective - and in this case, there is really no 'right answer'...Contributors: - Tamar Makin, Professor of Cognitive Neuroscience at the MRC Cognition and Brain Sciences Unit at the University of Cambridge, where she leads the Plasticity Lab; - Lynn Williams, a qualified therapist and upper limb amputee who volunteered as a subject for one of Tamar’s research programmes; - Carlos Roldan, Associate Professor in the Department of Pain Medicine at the University of Texas MD Anderson Cancer Center; - Keren Fisher, a Consultant Clinical Psychologist who’s worked in the NHS for more than four decades; largely in pain management at the Royal National Orthopaedic Hospital.Producers: Emily Bird & Lucy Taylor Executive Producer: Alexandra FeachemA BBC Studios Audio Production

Tortoises have traditionally been the poster child for slowness. These ancient, armoured reptiles are solitary, territorial and all-too-often dismissed as dull.In fact, tortoises have distinct personalities. They have changeable moods, can learn simple tasks, remember certain useful information for years and even recognise familiar people. But can they play?Hot on the trail of tortoise tomfoolery, Hannah and Dara explore the stereotype-smashing studies that show there's far more to these creatures than previously thought; and find out that these complex behaviours might apply not only to the turtle clan, but potentially other reptiles as well...To submit your question to the Curious Cases team, please email: [email protected]: - Anna Wilkinson, Professor of Animal Cognition at the University of Lincoln - Unnar Karl Aevarsson, Herpetologist at ZSL London Zoo - Gordon Burghardt, Distinguished Service Professor in the Departments of Psychology, Ecology and Evolutionary Biology at the University of Tennessee Producer: Lucy Taylor Executive Producer: Alexandra Feachem A BBC Studios Production

Could you survive an eternal winter? Or is endless summer sun a more appealing prospect? Lots of us are grateful for the seasonal changes that shape the world around us, but this week Hannah and Dara are asking what life would look like without the axial tilt that brings each hemisphere closer and further away from the sun as the seasons change each year. Listener Andrew from Melbourne wants to know what would happen if the planet stood perfectly upright, no lean, no tilt, no seasons. But what else could happen? Is Earth’s 23-degree slant the cosmic fluke that made life possible? To find out, Hannah and explore how losing the tilt reshapes climate, ecosystems, evolution and maybe even the fate of the dinosaurs.You can send your everyday mysteries for the team to investigate to: [email protected] Contributors Dr Robin Smith - Climate modelling researcher at the University of Reading Professor Rebecca Kilner - Evolutionary Biologist and Head of the Department of Zoology at Cambridge Professor Amaury Triaud - Professor of Exoplanetology at the University of Birmingham Aidan McGivern - Meteorologist and Senior weather presenter at the MET OfficeProducer: Emily Bird Executive Producer: Sasha Feachem A BBC Studios Production

Could immortality ever be possible for humans? It sounds like something from a sci-fi movie, but floating in oceans around the world is a tiny, transparent jellyfish that could hold the answer...Turritopsis dohrnii, known as 'the immortal jellyfish', isn’t immortal in the true sense of word - it can die - but it has a nifty way of avoiding that fate. In times of stress, this miniscule jelly can biologically reverse its aging process, reverting from 'medusa' (adult jellyfish) to a juvenile form and starting its life-cycle again; potentially ad infinitum.Abilities like these could hold the key to - if not exactly 'immortality', then at least regenerative or long-life treatments for humans in future. But of course there's a catch: these extremely delicate jellyfish can still easily die from predation, disease, or environmental threats and are extremely difficult to keep healthy in a lab environment. Hannah and Dara hear about new technology that could change the way we study immortal jellyfish, and discover various other super-abilities in the animal kingdom that could help in our quest for healthier, longer lives.Contributors: - Miranda Lowe, Principal Curator of Crustacea and Cnidaria at London’s Natural History Museum - Alex Cagan, Assistant Professor in the Department of Genetics, Department of Pathology and Department of Vet Medicine at the University of Cambridge - Maria Pia Miglietta, Associate Professor of Marine Biology at Texas A&M University in Galveston - Nicole Xu, Assistant Professor of Mechanical Engineering, Robotics and Biomedical Engineering at the University of Colorado, BoulderProducer: Lucy Taylor Executive Producer: Sasha Feachem A BBC Studios Production