

CrowdScience
BBC World Service
We take your questions about life, Earth and the universe to researchers hunting for answers at the frontiers of knowledge.
Episodes
Mentioned books

Jul 18, 2025 • 26min
What if the Earth spun backwards?
Your whole life is governed by spin. The rotation of our planet tells you when to wake up, and Earth’s orbit around the Sun is the reason why some of us dig out a jumper for half the year and a t-shirt for the rest. But what if that all changed?
That’s exactly what 8-year-old Geronimo in Ecuador wants to know. He and his dad, Fabian, have got themselves dizzy trying to figure out what would happen if the Earth stopped spinning, or better yet, started spinning in the opposite direction. Would everyone fly off into space? Would school be at night? Eager for answers, they decided to ask CrowdScience. Presenter Anand Jagatia embarks on an interstellar journey, blasting off with the celestial origins of spin itself. Astronomer Amy Bonsor from the University of Cambridge in the UK explains how Earth’s rotation began, with collapsing clouds of gas, planetary pile-ups and crushing gravitational force. At Keele Observatory, things get apocalyptic. Anand meets astronomer Jacco van Loon, who explains what would happen if Geronimo somehow waved a magic wand and brought Earth’s rotation to a halt. With months of unbroken daylight or darkness, devastating storms and even the loss of the Earth’s magnetic shield, it’s like the script of a disaster movie. Wave that magic wand again and we imagine a world where the Earth not only stops... but starts spinning the other way. Meteorologist Joao Basso from the University of Leipzig in Germany walks us through a mind-bending 2018 study that tells us the surprising things that would happen to the global climate. Presenter: Anand Jagatia
Producer: Harrison Lewis
Series Producer: Ben Motley

9 snips
Jul 11, 2025 • 31min
Where did Earth’s water come from?
Sara Russell, a planetary scientist at the Natural History Museum, and Richard Greenwood, a meteorite researcher at The Open University, dive into the origins of Earth's water. They discuss how water likely didn't exist when the planet formed from molten rock and explore theories suggesting asteroids, like Bennu, might have contributed to our water supply. Additionally, they examine oxygen isotopes linking Earth and the Moon, shedding light on cosmic impacts and the timeline of water's arrival on our planet.

Jul 4, 2025 • 26min
Can we harness solar energy from other stars?
A listener wonders if we can capture energy from stars beyond our sun. Each star emits a staggering amount of energy, leading to fascinating possibilities. Experts discuss measuring star brightness and showcase a unique telescope experience. The idea of a Dyson Sphere emerges—an ambitious concept of harvesting energy by placing panels in orbit around distant stars. Advanced solar technologies may one day enable us to harness this cosmic power, pushing the boundaries of renewable energy. The future of starlight as a resource sparks creative innovation.

Jun 27, 2025 • 26min
Why are twins special?
No one really cares that CrowdScience listener Sam has a younger brother, but they do care about his sister. In fact, they’re fascinated by her. That’s because Sam and his sister are fraternal twins. He’s been wondering all his life why he’s treated differently. Could it be cultural? Twins have long appeared in classical mythology, revered literature, and playful comedies—captivating artists and audiences alike across time and continents. Or is there something more scientific behind our fascination? Why are twins special? Anand Jagatia investigates with Karen Dillon from Blackburn College in the USA, who says it’s more complicated. Over the years we have created stereotypes of who and what twins are. Our perception has been warped by history and pop culture. As an identical twin herself, she knows firsthand how stereotypes can shape a twin’s identity. Philosopher Helena De Bres from Wellesley College in the USA believes these stereotypes play on human anxieties. Their similarities and differences are derived from their biology, maybe our genes have more of an influence over our personalities and behaviours than we like to think? And Nancy Segal agrees, Director of the Twin Studies Centre at California State University in the USA. She has spent her career studying twins. She’s found that nearly every trait, whether it be behavioural or physiological, has a genetic component to it. Anand is sure to leave you thinking that Sam, his sister and all the other twins across the globe, really are special! Presenter: Anand Jagatia
Producer: Harrison Lewis
Series Editor: Ben Motley (Image: Twin girls (8-10) wearing matching coats and pigtails. Credit: Jade Albert Studio, Inc via Getty Images)

10 snips
Jun 20, 2025 • 26min
How can we persuade more people to cycle?
In this discussion, Pelle Guldborg Hansen, a Professor of behavioral science at the University of Roskilde, dives into innovative strategies to persuade more people to cycle. He suggests shifting from rational arguments to appeals that resonate with our desires and vanity. The conversation explores how psychological factors influence cycling choices, the importance of safety measures in urban settings, and the effectiveness of marketing to change perceptions. Insights from experts in Denmark highlight how a fresh approach can transform cycling into a trendy and enjoyable choice.

Jun 13, 2025 • 26min
Was there an idyllic time before carnivores?
Dive into the chaotic world of early life on Earth, where microscopic organisms battled for survival in a violent dance of existence. Discover a tranquil Ediacaran period with unique, creature-like beings and explore the explosive Cambrian era, where sophisticated predators with teeth and claws emerged. Unravel the evolutionary arms race that shaped animal traits and learn how ancient predators influenced primate evolution, enhancing their survival strategies. Was there ever truly a peaceful time in nature, or has it always been 'eat or be eaten'?

Jun 6, 2025 • 28min
What’s that background hum I hear?
In the dead of night at his home in Machinjiri, Malawi, CrowdScience listener John can hear a small, but persistent, hum. Whenever it’s quiet enough, the hum is there – but what’s causing it? And is John the only one who can hear it?Reports of consistent, low-pitched noise have been popping up around the world for decades. No one knows this better than Dr Glen MacPherson, who runs the World Hum Map. He tells presenter Caroline Steel his theory for what’s behind these hums.And Caroline does some investigating of her own. We visit the Isle of Lewis off the coast of Scotland, where residents are reporting a hum. We hear about the impact that persistent noise has on people’s lives, and find out… can Caroline hear the hum too?We also ask why some people can hear a hum but others can’t. We head to an anechoic chamber – one of the quietest places in the world – to speak to Professor Jordan Cheer, who puts Caroline’s low-frequency hearing to the test.From industrial activity to internally generated sounds, we sift through the noise to try and find out what could be causing listener John’s hum.Presenter: Caroline Steel
Producer: Sophie Ormiston
Series Producer: Ben Motley

8 snips
May 30, 2025 • 30min
What on earth is quantum?
James Millen, a quantum scientist and leader at King's College London, joins a panel to decipher the mysteries of quantum mechanics. They tackle mind-bending topics like quantum entanglement, where particles influence each other across distances. Delving into the double-slit experiment, they illustrate light's dual nature as both particle and wave. The discussion unveils how these bizarre behaviors are at the forefront of technological advancements, reshaping our understanding of reality and enhancing quantum computing capabilities.

May 23, 2025 • 27min
Can eating honey help save bees?
Can honey help save bees? A deep dive into the intricate relationship between honey production and environmental conservation unfolds. Experts reveal the thriving honeybee populations, yet highlight a worrying decline in wild bee species. Innovative beekeeping practices in Kenya illustrate how honeybees protect elephants and support local farming. The ethical dilemma surrounding honey consumption is examined, while rooftop strategies in urban settings unveil how to bolster wild bee species. Join the conversation on protecting biodiversity and supporting our buzzing friends!

6 snips
May 16, 2025 • 26min
Is my yoghurt really alive?
Nazko Stamanov, a Bulgarian science teacher and communicator, dives into the fascinating world of yogurt and fermentation. He discusses whether the ‘live’ cultures in yogurt are still alive when consumed and the health benefits of traditional foods vs. processed options. The conversation explores the cultural pride of Bulgarian yogurt, the risks associated with eating moldy cheese, and how a simple drop of vanilla can flavor an entire liter of milk. Expect delicious insights and a humorous take on food science!