Quantum theory – our best understanding of the world at the smallest level – is famously weird and notoriously confusing. It’s a theory that seems to say particles can be in two places at once, or somehow “know” if you’re looking at them. Or at least, that’s what you might have heard. But is that really what quantum theory tells us about reality?

To find out, presenter Marnie Chesterton travels to the birthplace of quantum theory: the remote, windswept island of Helgoland. Here, a century ago, a young scientist called Werner Heisenberg made a leap of understanding that laid the foundations of quantum mechanics, and changed the world.

To mark a century of quantum, leading physicists from across the globe have gathered on Helgoland for a conference, and Marnie joins them with an unconventional plan. She’s allowed to ask them JUST ONE QUESTION, in the hope it can get to the heart of what this strange and difficult subject is really about: “What IS quantum?”

Presenter: Marnie Chesterton

"My ideas are often labelled as impossible, or useless, or both. Usually when people say that I'm on the right track." George Church is a geneticist, molecular engineer, and one of the pioneers of modern genomics. He's also someone who makes a habit of finding solutions to the seemingly impossible. Over the course of his career so far, George developed the first method for direct genomic sequencing, helped initiate the Human Genome Project, and founded the Personal Genome Project: making huge quantities of DNA data publicly available for research. Today, as a professor at Harvard Medical School and MIT, he’s working on some of the most headline-grabbing - and controversial - science on the planet: from the so-called "de-extinction" of woolly mammoths, to growing transplant-suitable organs in pigs, to virus-proofing humans. When inspiration strikes, there seems to be little that will slow him down - even the fact that he has narcolepsy, the neurological disorder that causes sudden sleep attacks. In fact, as George tells Professor Jim Al-Khalili, some of his best ideas come in those moments between waking and sleep...

Movies might have us believe that bomb disposal comes down to cutting the right wire. In fact, explosive devices are complex and varied - and learning how to dispose of them safely involves intense training, as well as the ability to stay calm under pressure. This was the world of Dr Gareth Collett, a retired British Army Brigadier General and engineer, specialising in bomb disposal; whose 32-year military career took him around the world, including heading up major ordnance clearance projects in Iraq and Afghanistan. After retiring from the army, Gareth became a university lecturer – but following his diagnosis with bladder cancer, started researching a possible link between bomb disposal veterans and higher rates of urological cancers. In conversation with Professor Jim Al-Khalili, Gareth discusses this ongoing research, dealing with PTSD - and why he just can't watch Oscar-winning movie The Hurt Locker...

Many people will be familiar with Parkinson’s disease: the progressive brain disorder that causes symptoms including tremors and slower movement, leading on to serious cognitive problems. You might not know that it’s the fastest-growing neurological condition in the world. Today it affects around 11.8 million people and that’s forecast to double by 2030. Dr Sonia Gandhi is one of the scientists working to change that trend. As Professor of Neurology at University College London and Assistant Research Director at the Francis Crick Institute, her work involves using stem cells to build models of the human brain, helping to drive the development of drugs and other therapies for Parkinson’s patients. Talking to Professor Jim Al-Khalili, Sonia explains why this destructive condition is on the rise - and the promising routes they're studying to find new ways to tackle it.

How do you feel about snakes? What about highly venomous ones?

For Mark O’Shea, close encounters with the world’s most rare and deadly snakes are not only his profession, but his passion.

After dropping out of college in his teens, Mark's life could have taken a very different direction; but prompted by a fascination with reptiles that started with a childhood trip to the zoo, he's gone on to have a career spanning research, international expeditions and broadcasting. He's also worked with international medical teams, studying deadly species and helping to generate antidotes for some of the world’s deadliest venoms.

In conversation with Professor Jim Al-Khalili, Mark reveals the challenges around generating antivenom for countries that need it, the pros and cons of keeping snakes as pets, and what you need to know if you ever get bitten...

Presented by Jim Al-Khalili

What’s it like to wake up with a brand new voice? For those with foreign accent syndrome, this is their reality. Patients who develop this rare speech disorder start speaking in a brand new accent that they often have no connection to.

So how does losing the voice you’ve known your entire life shape, or break, your identity?

Presenter Ella Hubber speaks to Althia Bryden, who developed foreign accent syndrome last year, and Sarah Colwill, who has lived with the condition for the past 15 years. They share the deep impact it has had on their identity and connection to those around them.

And to understand what is happening in the brain to cause this complete change in accent, and whether it’s really even an accent at all, Ella speaks to professor Nicholas Miller, who has been unpicking the mystery of foreign accent syndrome for decades. Also, professor Stefanie Keulen shares that there are actually multiple types of the condition.

Even though foreign accent syndrome is rare, it is found around the world, can affect anyone, and highlights just how deeply our voices influence all aspects of our lives.

Presenter: Ella Hubber

We live in a time of automation and robotics; the machines run the factories, and AI will soon take all the jobs. Yet, even today, there are certain niche jobs where only an animal will do. Comedian and biologist Simon Watt meets some of them and the people who train them, study them, and love them.

He starts with a business of ferrets (yes, that is their collective noun) at the National Ferret School in Derbyshire, who have swapped rabbit holes and trouser legs for drain-clearing, rewiring, and laying fibre optic cables. Ferret Trainer James McKay demonstrates why they are perfect for the job, as he casually folds one trainee into a tight pretzel.

Simon visits the HQ of Medical Detection Dogs, a training facility in Milton Keynes where dogs are being trained to sniff the tell-tale signs of a host of diseases. You may have heard of their 'cancer dogs', but it goes much further - epilepsy, malaria, Parkinson's, even Covid-19. Dr Claire Guest explains.

Although we have no real idea exactly how dogs do what they do, AI may be on the cusp of solving this puzzle for us. Simon speaks to Dr Andreas Mershin from start-up Realnose, which is developing “electronic noses".

Finally, Simon meets some real heroes - HeroRats, to be precise. Not the same species that haunts our sewers, these are African Giant Pouched Rats, and their job as landmine detection specialists is saving lives across Thailand, Mozambique, Cambodia and Zimbabwe. Dr Cynthia Fast from UCLA trains them for the job.

Presenter: Simon Watt

The London Anatomy Office accepts around 350 human bodies donated for medical research and education annually. You may imagine that these bodies are presevered in chemicals for medical students to study over weeks and months. And some are. But many are used - almost fresh - to train surgeons in the procedures which may one day save your life.

Journalist Jenny Kleeman gains rare access to a surgical training course at Brighton and Sussex Medical School which uses these "fresh" donor bodies. She talks to the people who work with them every day and the surgeons who have come to be trained to find out how they feel about the people who have given the ultimate gift and if we still need real human cadavers in medical education.

Presenter: Jenny Kleeman

There can't be many people in the world who've saved lives in hospital emergency rooms and also helped care for the wellbeing of astronauts in space – but Kevin Fong’s career has followed a singular path: from astrophysics and trauma medicine, to working with NASA, to becoming an Air Ambulance doctor.

Kevin is a consultant anaesthetist and professor of public engagement and innovation at University College London. He’s worked on the front line in hospitals, dealing with major incidents and helping shape policy; but he's also stayed true to his childhood passion for space, working on multiple projects with NASA and even going through the astronaut application process himself. As if that wasn’t enough, he’s also become a well-known figure in science broadcasting through his various radio and TV shows.

Speaking to Professor Jim Al-Khalili, Kevin admits it hasn't always been an easy path – but his passion for both space and medicine have got him through. And today, he's channelling his energies into ensuring we protect the NHS's most precious commodity: its staff.

Presented by Jim Al-Khalili

Chemical reactions are the backbone of modern society: the energy we use, the medicines we take, our housing materials, even the foods we eat, are created by reacting different substances together. If we zoom in, it’s the atoms within these substances that rearrange themselves to give rise to new substances with the properties we need.

However, chemical reactions are far from perfect. They're often inefficient and their waste products can be harmful to the environment. Getting to grips with what goes on at the scale of individual atoms has long been a sticking point.

Dame Pratibha Gai has spent much of her career pioneering novel microscopes to bring this seemingly inaccessible atomic world into sharp focus. Now Emeritus Professor of Chemistry at York University, her microscope, known as the environmental transmission electron microscope, is housed in labs around the world. It allows scientists, like herself, to observe chemical reactions in real-time, in exquisite atomic detail, and tinker with them to create products that are not only better for all of us, but also the environment.

Presented by Jim Al-Khalili