CrowdScience

BBC World Service
  • 4.8 (109)
  • SCIENCE
  • UPDATED BIWEEKLY
CrowdScience

We take your questions about life, Earth and the universe to researchers hunting for answers at the frontiers of knowledge.

  1. 20 HRS AGO

    Is water wet?

    The wetness of water seems blindingly obvious - but dive into the science and things aren’t so clear. CrowdScience listeners Rachel and Callum were washing their hands one day and it got them thinking about wetness. Why does water feel the way it does? And what makes a liquid wet? To find out, presenter Anand Jagatia takes a closer look at the behaviour of liquids with materials scientist Mark Miodownik, and finds out why they might not be as wet as we think. We learn what’s really behind the sensation of feeling something wet on your skin, with the help of physiologist Davide Filingeri and PhD student Jade Ward. And we turn to a philosopher, Vanessa Seifert, and a chemist, Tim Neudecker, to puzzle out exactly how many water molecules you need before the property of wetness emerges. Presenter: Anand Jagatia Producer: Anand Jagatia Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Bob Nettles and Andrew Garratt (Image: A photo of a droplet falling into a body of water Credit: Flaviu Cernea / 500pxvia Getty Images)

    26 min

  2. FEB 28

    Whatever happened to tangerines?

    It’s citrus season in the northern hemisphere, and fruit trees are bursting with oranges and lemons. But CrowdScience listener Jonathan wants to know what happened to the tangerines he ate as a child in the 1960s? He remembers a fruit that was juicy, sweet and full of pips, found each Christmas at the bottom of his stocking. Tangerines today, he thinks, just don't compare. Crowdscience tries to track down this elusive fruit. Presenter Anand Jagatia traces the tangerine's origins back to Ancient China, as botanist David Mabberley explains that the name ‘tangerine’ comes from a fruit that made its way from Asia, to Africa and the Moroccan port of Tangier, before arriving in the US in the early 1800s. Professor Tracy Kahn from UC Riverside tells us about the hybridisation process that goes into breeding modern tangerines, but says that while the season for these fruits has been dramatically extended, there’s a cost in terms of diversity and flavour. Who better to help us track down this missing mandarin than a fruit detective? Well, that’s one of pomologist David Karp’s other job titles, and he reveals exactly which cultivar we might be looking for: the Dancy. So where can we find one? Over on Friend’s Ranches in Ojai, California, Emily Ayala shows us two trees planted by her late grandfather, and explains that nothing grown since really matches its unique flavour. So what will listener Jonathan think when we send him a box? Presenter: Anand Jagatia Producer: Marijke Peters Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Jackie Margerum (Image: Citrus oranges grow on tree, Hong Kong Credit: CHUNYIP WONG via Getty Images)

    29 min

  3. FEB 21

    Why isn't the sky green?

    Vermillion red, vibrant orange, golden yellows, even violet – we're enchanted by the colours that make up a stunning sunset or sunrise. CrowdScience listener Paulina, a lighting designer from Chile, often uses the sunsets she sees from her balcony as inspiration for her designs. And during the day and night, the sky can be all sorts of shades of blue. But Paulina wonders why, in the colour palette of the sky, she never sees any green. CrowdScience gazes skywards to investigate. Presenter Caroline Steel travels to the Arctic Circle to meet atmospheric physicist Katie Herlingshaw. Katie explains why we usually see the sky as blue, and what makes it transform into fiery reds and oranges at sunrise and sunset. We also peer into the science of perception, as neuroscientist Bevil Conway tells us what’s going on in our eyes (and brains) to make the colours we see in the sky. But there are some rare occasions when the sky can appear to be green, such as in a rainbow or a green flash at sunset. And then there is the spellbinding green glow of the aurora - the Northern and Southern Lights. We visit the northernmost aurora observatory in the world to try to understand this phenomenon. Are green skies more common than we think? Presenter: Caroline Steel Producer: Hannah Fisher Editor: Cathy Edwards Production Co-ordinator: Ishmael Soriano Studio Manager: Sarah Hockley (Photo: View of sunset in Santiago, Chile. Photo montage courtesy of Paulina Villalobos)

    27 min

  4. FEB 14

    Is anything truly random?

    CrowdScience listener Dorit has a problem. She wants the tiles in her new bathroom to be arranged randomly but, no matter what she does, it still looks like they form some kind of pattern. This has got Dorit thinking about randomness – what is it, how do you create it, why do we find it so hard to recognise, and is anything really random at all? And if nothing is truly random, does it mean that everything is theoretically predictable? Tiling your bathroom is a much more existential problem than you might have thought. Never afraid of a question, whether big (is everything pre-determined?) or small (how do I tile my bathroom?), CrowdScience is on the case. Anand Jagatia heads to Switzerland to meet Hugo Duminil-Copin, a mathematician at the University of Geneva who specialises in probability theory. On the top floor of an old bank, Hugo has Anand flipping an imaginary coin in a random order. Hugo explains that randomness is something that cannot be predicted by any means – so why is it so easy for Hugo to guess what Anand’s next move is? Meanwhile, at the National Institutes of Mental Health in Maryland USA, Susan Wardle is a cognitive neuroscientist who researches how the human brain processes visual information. Can neuroscience help Dorit with her tiling problem, and is there a reason why the human brain likes to put random objects into some kind of order? Geneva is also the birthplace of the first Quantum Random Number Generator for smartphones, and CrowdScience has persuaded some of the University of Geneva’s finest quantum physicists to hook a photon detector up to a synthesiser. Thanks to Tiff Brydges and Nicolas Brunner, we can actually hear quantum particles behaving randomly. But is quantum randomness truly random, or just a pattern that we can’t see? And could quantum physics help Dorit tile her bathroom? Presenter: Anand Jagatia Producer: Ben Motley Editor: Cathy Edwards Production co-ordinator: Ishmael Soriano Technical producer: Jackie Margerum

    26 min

  5. FEB 7

    Why can't I remember my early childhood?

    Some of our biggest achievements happen in the first years of our lives. Taking our first steps, picking up a complex language from scratch, and forming relationships with some of the most important people we’ll ever meet. But when we try to remember this period of great change, we often draw a blank. After losing his Dad aged four, CrowdScience listener Colin has grappled with this. Why can’t he recall memories of such a monumental figure in his life, yet superficial relationships from his teens remain crystal clear in his mind? Colin takes presenter Marnie Chesterton to visit some of the significant locations of his childhood, places he would have spent many hours with his late father; and he recounts his earliest memories. On this trip down memory lane, Marnie discovers the psychological reason behind our lack of early childhood memories comes down to a phenomenon known as infantile amnesia. Tomás Ryan, neuroscientist at Trinity College Dublin, discusses some of the theories behind this universal experience, and Sarah Power from the Max Planck Institute for Human Development discusses her groundbreaking study exploring this form of forgetting in real time. Elaine Reese from the University of Otago digs into how our environment and culture can influence the age of our earliest memories, and why some of the first things we remember might not be the big, huge events you’d expect. And we hear about fascinating new insights from animal studies that hint these memories could still be lurking inside our heads... Presenter: Marnie Chesterton Producer: Julia Ravey Content Editor: Cathy Edwards Production Co-ordinators: Ishmael Soriano & Josie Hardy Technical producer: Emma Harth (Photo: Marnie Chesterton and CrowdScience listener, Colin, on the swings in Belfast.)

    27 min

  6. JAN 31

    Is my smartwatch good for my health?

    Smartwatches are increasingly popular and many of us use these wearable devices to monitor our performance and improve our fitness. But how reliable is the data they collect, and can they actually make us healthier? CrowdScience listener Caitlin from Malawi is a big fan of her smartwatch. Her husband Fayaz, however, is much more sceptical of its accuracy, and has asked us to investigate. We meet up with them both at the gym, where Caitlin and presenter Caroline Steel put their fitness trackers – and themselves – to the test. We visit public health researchers Dr Cailbhe Doherty and Rory Lambe, who investigate the accuracy of wearable consumer devices, at University College Dublin. Caroline again pushes herself to the limit to see how her smartwatch results measure up to those from gold standard laboratory equipment. But is it crucial for smartwatches to be accurate? If they get us off the couch, is that what makes the difference to our health? Health behaviour expert Dr Ty Ferguson from the University of South Australia has studied this very question. And finally, how does quantifying our every move affect the way we think about ourselves and how we live? Professor Deborah Lupton from UNSW Sydney, shares some insights. Presenter: Caroline Steel Producers: Jo Glanville and Sophie Ormiston Editor: Cathy Edwards Technical producer: Sarah Hockley Production co-ordinator: Ishmael Soriano

    28 min

  7. JAN 24

    How high can birds fly?

    While watching a feisty cockatoo chase after a hawk, CrowdScience listener Alison saw the hawk catch a thermal and rise effortlessly into the sky. The cockatoo gave chase, but the hawk climbed higher and higher until it became just a tiny speck, barely visible to the naked eye. And that got Alison thinking: just how high can birds go? Are there altitude limits for our feathered friends? Could a cockatoo, a sparrow, or even a duck reach such dizzying heights if they really put their wings to it? Presenter Alex Lathbridge sets out to investigate. Biologist Catherine Ivy reveals that life above the clouds isn’t easy. At high altitudes, the air is thinner, oxygen is scarce, and wings don’t generate as much lift. But some bird species have evolved incredible adaptations to overcome these challenges. Among them: bar-headed geese, renowned for their daring flights over the world’s tallest mountains. Physiologist Lucy Hawkes delves into how these geese defy the odds with their remarkable physiology, revealing the surprising discoveries she made while putting some of them on a treadmill. From super-powered hearts to clever lungs, we uncover the secrets behind nature’s impressive aviators. Presenter: Alex Lathbridge Producers: Ilan Goodman and Jeremy Grange Editor: Cathy Edwards Production co-ordinator: Ishmael Soriano Technical producer: Sarah Hockley (Image: OIE A TETE BARREE (Anser indicus) EN VOL Credit: Jean-Patrick DEYA / Contributor via Getty Images)

    27 min

  8. JAN 17

    Which animal has the biggest carbon footprint?

    Carbon footprints are a measure of how much we each contribute to the greenhouse gases that warm the Earth’s atmosphere. The global average of carbon dioxide emissions is nearly 5 tonnes per person per year, although it can be triple that in certain countries. But one CrowdScience listener in Ghana is wondering about the bigger picture. After all, humans aren’t the only species on this planet. So which other animal has the biggest carbon footprint? CrowdScience presenters Caroline Steel and Marnie Chesterton are on the case, examining and arguing over the animal that deserves the top spot for this title. Caroline, a vegan, points to the cow as the top contender, since the livestock sector produces 14.5% of total greenhouse gas emissions, and cows, whether as meat or dairy animals, are responsible for the majority of that. The team look at initiatives around the world to be more efficient with each animal out there. But maybe it’s time to put another sector in the spotlight? Pets. We love our dogs and cats but do their meat-based diets win them a place on the podium? From most loved to most detested, we look at the role that key pests play in upsetting the carbon budget. Could a small beetle with a large appetite for greenery be an unusual winner, thanks to the trees these pests destroy over their lifetimes? Is the biggest offender a carbon footprint, hoofprint, pawprint, or clawprint? Presenters: Caroline Steel and Marnie Chesterton Producer: Marnie Chesterton Editor: Cathy Edwards Production co-ordinator: Ishmael Soriano Technical producers: Sarah Hockley and Donald MacDonald

    29 min
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    Hosts & Guests

    4.8
    out of 5
    109 Ratings

    About

    We take your questions about life, Earth and the universe to researchers hunting for answers at the frontiers of knowledge.

    Information

    • Creator
      BBC World Service
    • Years Active
      2016 - 2025
    • Episodes
      430
    • Rating
      Clean
    • Copyright
      © (C) BBC 2025
    • Show Website
      CrowdScience

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