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BBC World Service


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


CrowdScience

CrowdScience listener Devin in Canada has just had a baby. Worried that all the good email addresses might be taken by the time his child needs one, he has already set up an account. But it got him wondering: how many email addresses belong to people who have died? 

From websites and blogs to email accounts, social media profiles, gaming avatars and even our conversations with AI, we’re all leaving behind a trail of digital footprints that can outlive us. So what happens to them when we die? Are they deleted, recycled or preserved? And who gets to decide? 

Presenter Anand Jagatia travels beyond the digital veil and into the internet’s afterlife to find out. 

Professor Edina Harbinja from the University of Birmingham Law School in the UK, an expert in ‘digital death’ and ‘post-mortem privacy’, explains how the law has struggled to keep pace with our digital lives. While it’s relatively straightforward to decide who inherits physical letters and photographs, what happens when those memories are stored in emails or on social media? 

For artist Janilda Bartolemeu, encountering messages from her father on Facebook long after his death was like interacting with a ghost. Anand visits her artwork at IMPAKT gallery in Utrecht, Netherlands, part of the exhibition Data Never Dies, where curator Rosa Webers explores how art can help us understand the human impact of technology. 

Finally, sociologist Professor Carl Öhman of Uppsala University in Sweden reveals that the number of dead people online will outnumber the living sooner than we might think. It raises profound questions about how we understand the internet, and ourselves within it. 

Presenter: Anand Jagatia 

Producer: Emily Knight 

Editor: Ben Motley

(Photo: Grave on laptop computer, 3d render - stock photo Credit: Brankospejs via Getty Images)

How many dead people are on the internet?

CrowdScience listener Lisa, who is from South Africa but now lives in the UK, has been a vegetarian for many years. Sometimes though, she still finds herself craving meats – like spaghetti bolognese or a burger. To satisfy these cravings, she eats ‘alt-meats’, products meant to look and taste like meat but made from vegetables. 

This has her wondering though, are these alternative meats better for the planet than actual meat would be? And what about her health? Given that many of these foods are highly processed, would eating meat be better for her? 

Presenter Chhavi Sachdev speaks to food systems researcher Charlotte Bunge from Uppsala University on Sweden, US health journalist Alice Callahan and researcher Christopher Gardner from Stanford University in the US to try and pick apart the positives and negatives of replacing ‘real’ meat with ‘pretend’ meat, before visiting an Indian company producing meat that was grown in a lab. 

Presenter: Chhavi Sachdev 

Producer: Margaret Sessa-Hawkins 

Editor: Ben Motley

(Photo:Raw frankfurter sausage on a fork isolated - stock photo Credit:Andrey Sayfutdinov via Getty Images)

Can my veggie sausages save the world?

Your heart pounds, your chest tightens, your stomach drops and your legs feel weak and shaky. Your palms are sweating and a tingling rush spreads through your arms and fingertips as your brain is overwhelmed with feelings of tension and fear. And yet, you’ve asked for this. You wanted to be on this ride, at this theme park, hurtling towards the ground at a frightening speed. But why? 

An adrenaline rush is the body’s fight-or-flight response to intense fear, stress or excitement. It sends signals from the brain to the body, releasing hormones and redirecting the flow of blood around our veins. It’s designed to help us survive dangerous situations – so why would we deliberately want to put ourselves into those situations, just to feel the rush? 

That’s the question from CrowdScience listener Gunnar, aged 11, in Washington State USA. He wants to know why we try and seek an adrenaline rush by doing wild and crazy things, and CrowdScience’s wild and crazy Alex Lathbridge is on the case. 

Andy Hine, from the Rollercoaster Club of Great Britain, gives us a potted global history of the rollercoaster, revealing that it all started with Russian ice. Inevitably it’s not long before we start discussing ‘G-force’, so Canadian astronaut Dr Shawna Pandya explains what that means, and how it affects you when a rollercoaster is hurtling downwards or looping the loop. 

But what’s going on in our bodies and brains when we experience these forces? Brendan Walker is Professor of Creative Industries at Middlesex University in the UK. He tells Alex that a rollercoaster is a giant industrial machine which has been engineered to process humans, a little bit like tins in a factory, to deliver an ingredient. That ingredient is thrill – so how do they do it? 

Alex takes a ride on ‘Rage’ at Adventure Island in Southend on Sea in the UK to find out. Brendan claims that this ride is, scientifically speaking, the most thrilling rollercoaster in the country. Even Adventure Island owner Philip Miller declines to join Alex for a ride, but will it help Alex understand why Gunnar likes them so much? 

Presenter: Alex Lathbridge 

Producers: Harrison Lewis and Emily Knight 

Editor: Ben Motley

(Photo: Spiraling Roller Coaster - stock photo- Credit: Alan Schein Photography via Getty Images)

Why do I love rollercoasters?

Some fish can deliver electric shocks with four times the voltage of the electricity in your plug sockets at home . Crowdscience listener Mouhammed in Cameroon was stunned by this, so he charged us with finding out how they do it. 

Presenter Caroline Steel heads to Bayreuth in Germany to meet some eels who have this amazing ability. Dr Stefan Schuster and Susanne Proschke introduce us to their collection of electric fish, and help us conduct some experiments to work out how the fish are wired. We’ll be diving into electric fishes' anatomy, learning how a specialised organ allows them to generate massive voltages of electricity. 

Harold Zakon from the University of Texas will help us understand their evolutionary history, while Brazilian ecologist Nonato Junior takes us on a journey into the currents of the Amazon River where electric eels live. 

And we’ll answer a question that has boggled philosophers, thinkers, and scientists for over 2000 years. If these fish can stun a human, a crocodile or even a horse, how do they survive the electric shocks themselves? 

(Photo: Blue lightning bolt streaks. Credit: Ludmila Snimshikova/Getty Images. Electric Eel, Venezuela. Credit: Reinhard Dirscherl/Getty Images)

Presenter: Caroline Steel 
Producer: Robbie Wojciechowski 
Editor: Ben Motley

How do electric fish make electricity?

CrowdScience listener Matt wants to know why he's warm blooded. He started thinking about this when he was watching some ants during the recent heatwave in Europe and wondered why their blood didn't boil. What are the pros and cons of being warm-blooded like us or cold-blooded reptiles like lizards? 

Caroline Steel meets evolutionary biologist Dr Manuel Leal from the University of Missouri in the US, who explains the differences between ectotherms (cold-blooded animals) and endotherms (warm-blooded animals). She discovers that the terms cold blooded and warm blooded are actually misleading, because reptiles can reach a high body temperature and some might even become warmer than us. 

She talks to Simon Hodder, Professor of Environmental Ergonomics at Loughborough University in the UK, who describes how our bodies regulate heat, how we cool down when we get too warm and how that's all controlled by our brains. 

Caroline also gets to meet some hedgehogs in the wild with Julia Nowack, an ecophysiologist from Liverpool John Moores University, who researches thermoregulation and is monitoring hedgehogs when they hibernate. Changing body temperature is one of the ways that some endotherms survive the winter when it's colder and there's less food around. 

So who has the advantage? The warm-blooded endotherms who can heat their own bodies or the cold-blooded ectotherms who rely on the sun? Reptiles can get away with eating very occasionally while mammals and birds have to keep fuelling their energy with food to keep the heat going. That means we can live in most climates and have a better chance of escaping predators, but is it really best? 

Presenter: Caroline Steel 

Producer: Jo Glanville 

Editor: Ben Motley 

(Photo: European hedgehog (Erinaceus europaeus) adult animal in a snow covered garden in winter, England, United Kingdom - stock photo Credit: imageBROKER/Kevin Sawford via Getty Images)

Why am I warm blooded?

Why is it hard to concentrate, and why does it feel like such hard work? The CrowdScience inbox is full of questions like that, so for this show we’re concentrating on concentration and focusing on how we focus. 

We’ll be answering questions about the extra energy the brain uses when we’re concentrating, whether mental effort can tire you out more than physical effort, why we zone out when faced with a difficult task and how the ability to multitask is governed by our overall cognitive load. 

To find the answers, presenter Alex Lathbridge is paying attention to a team of experts. Psychology professor Sophie Leroy from the University of Washington in the USA studies the impact of being interrupted on our ability to perform, cognitive neuroscientist Professor Salvador Soto-Faraco from the Universitat Pompeu Fabra in Barcelona, Spain researches how sight, sound and touch are blended together by the brain, and psychology professor Polly Dalton runs the Attention Lab at Royal Holloway University in London, UK. 

We’ll be trying to distract them with gossip about what we had for lunch, finding out why the brain is like a bike and, most importantly, discovering how you can concentrate better on shows exactly like this one. 

Presenter: Alex Lathbridge 

Producer: Tom Bonnett 

Editor: Ben Motley

(Photo: Woman with glasses thinking and pointing upward- stock photo - Credit: ismagilov via Getty Images)

Why can't I concentrate?

Tuberculosis kills more than a million people every year. It’s the world’s leading cause of death from a single infectious agent. This is despite the fact that we've had a cure for TB since the 1940s and a vaccine that’s over 100 years old. So why is TB still causing so many people to die? 

That’s what CrowdScience listener John in Tanzania wants to know, and presenter Marnie Chesterton is on the case. Over in Paris, she’s joined by Dr Claas Kirchhelle, historian of science, medicine and technology at French National Institute of Health and Medical Research (INSERM) to look into the history and efficacy of the vaccine, known as BCG. 

As Dr Maximiliano Gutierrez, Associate Research Director at the Francis Crick Institute adds, the BCG is both effective and ineffective, protecting children well against severe TB, but offering inconsistent and often poor protection in adults. He also explains that antibiotics are a trickier treatment than we might expect. Over in Kenya’s Kibera slums, Janet tells us her about her experience of the drugs first hand. 

Dr Dany Beste, Senior Lecturer In Microbial Metabolism, University of Surrey, has been described as a dietician of mycobacterium tuberculosis. She explains the limitations of our knowledge of this bacterium, and why it is proving such a tricky customer. 

And since a better vaccine is the main hope for reducing the TB burden, Professor Angelique Luabeya Kany Kany, Chief Research Officer at University of Cape Town, shares her hopes for the first new alternative vaccine in 100 years: m72. Large phase 3 clinical trials are currently underway, and, if successful, could prevent millions of cases, and deaths a year. 

Presenter: Marnie Chesterton

Producer: Marnie Chesterton

Editor: Ben Motley 

(Photo: Doctor with vial of the doses vaccine for BCG Bacillus Calmette Guerin against tuberculosis disease. Medicine and health care concept - stock photo - Credit: angelp via Getty Images)

Why is TB still killing people?

Stare up at the night sky, and if you’re lucky, you might see a shooting star. Some people might make a wish, but CrowdScience listener Scott in California in the USA, thinks differently. He’s wondering how dangerous they might be. 

Shooting stars are actually meteors, ending their incredible journey whizzing through the depths of space by burning through our atmosphere, and crashing down to earth. And Scott’s not wrong to worry about them! In May 2026, an enormous meteor exploded off the coast of Massachusetts, causing a loud sonic boom before crashing into the ocean, releasing the equivalent energy of 300 tons of TNT! 

So, should we be worried? Marnie Chesterton is on the case. 

In Australia, Hadrien Devillepoix is the chief scientist for the Desert Fireball Network, which tracks meteors through the sky, and tries to recover any meteorites which make it to earth. He explains just how many of these smaller space rocks arrive on our planet every day, how many of them survive long enough to make it to the surface, and tries to figure out how much should we be worried about it happening to us. 

Over in the USA, NASA are less worried about the meteors, and more concerned about their big brothers – asteroids. These are the ones which could take out your whole neighbourhood. Or your whole city. Or even the whole planet. Kelly Fast, with NASA's Planetary Defense Coordination Office explains what the chances are one might be headed our way, and what we could do about it if they are. Push them away, pull them off course, or blow them up, are the options on the table. 

But space rocks, small OR large, aren’t the only things which could be tumbling down on our heads from outside our atmosphere. In fact, you might be more likely to be hit but something of our own – a man-made piece of space junk, falling out of orbit and whizzing towards the surface. Stephen Wokes, chief engineer at Astroscale, explains their mission: to use their innovative satellite to clean up Low Earth Orbit, and reduce the risk to us here on the ground. 

PRESENTER: Marnie Chesterton 

PRODUCER: Emily Knight 

PRODUCTION COORDINATOR: Stuart Laws 

EDITOR: Ben Motley 

(photo: Meteor Impact On Earth - Fired Asteroid In Collision With Planet - Contain 3d Rendering - elements of this image furnished by NASA - stock photo- Credit: RomoloTavani via Getty Images)

Will I get hit by a meteor?

We’re delving into the CrowdScience archive to give you another chance to hear an award-winning show from 2025. 

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

(Photo: Many wooden dice - stock photo- Credit: akiyoko via Getty Images)

Is anything truly random?

Space missions are searching for evidence of extra-terrestrial life. CrowdScience listener George in Kenya wants to know what could be up there, and if there’s a risk it could harm humanity. 

With rovers currently analysing samples on Mars, missions searching for the building blocks of life on Jupiter’s icy moons, George’s concern that there could be diseases in space is timely. Presenter Anand Jagatia sets out to try and find an answer while keeping his feet on the Earth. 

He meets astrobiologist Dr Michaela Musilova, who runs experiments to try and understand what kinds of microbes could survive on other planets. In her work at NASA’s Jet Propulsion Laboratory, she recreates Mars-like environments that test lifeforms’ resilience to the rigours of the Red Planet. 

And if there are harmful pathogens in space, how do we make sure these missions don't bring them back to Earth? Anand talks to ‘planetary protection officer’ Silvio Sinibaldi from the European Space Agency, who explains what experts are doing to protect us. He helps Anand get suited and booted in specialist clothing so they can enter a highly sterile environment called a ‘clean room’, where things being sent to space are built. 

He also meets Paul Meacham, former chief engineer on the Rosalind Franklin Rover. The rover is being sent to Mars to try to determine whether life ever existed there, and even whether it still does. 

Paul shows us around the Airbus Defence and Space site where his team built the rover and explains high-tech measures to avoid contamination. 

And what would a programme on space be without an astronaut? Anand meets Kate Rubins, who spent 300 days on the International Space Station. While she was there, she ran experiments investigating what happens to microbes in space. It turns out that microbes affect humans differently in orbit to how they affect us on Earth. 

 Presenter: Anand Jagatia 

Producer: Tom Bonnett 

Editor: Ben Motley

(Photo : 3D render of the Coronavirus Covid-19 floating in the air with astronaut wearing space suit. - stock photo- Credit: Artur Debat via Getty Images)

Are there diseases in space?

Do you stick your tongue out or scowl when you concentrate? Maybe, like one of our listeners, you screw up your face when you’re playing music. Do these facial expressions actually help with the task in hand? And could they hold clues to humans’ evolutionary past?
 
In this edition of CrowdScience we tackle the science of face-pulling, along with several more burning science questions sent in from listeners around the world. We explore why it’s almost impossible to talk without moving your hands; and why bilingual people often switch to the first language they learned when they’re counting, even if they speak another language the rest of the time.

Presented by Anand Jagatia and Marnie Chesterton
Produced by Cathy Edwards

(Photo: A boy sits at a table, looking down in concentration as he draws in a note pad. Credit: Getty Images)

Why do we pull faces when we concentrate?

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