Two random questions in this episode. "Is anything truly random, or is everything predetermined?" asks Darren Spalding from Market Harborough.

Hannah and Adam go in search of random events, from dice throws to lava lamps. Can we predict the outcome of any event? And "how do computers manage to pick random numbers?", asks Jim Rennie from Mackinaw in Illinois.

Joining them are a random selection of experts: mathematician Colva Roney-Dougal, technology journalist Bill Thompson, Science Museum Curator Tilly Blyth and quantum physicist Jim AlKhalili.

Presenters: Adam Rutherford, Hannah Fry

"How fast can a human run and would we be faster as quadrapeds?" This question flew in via Twitter from historian Greg Jenner.

Is there a limit to human sprinting performance? In this episode we investigate the biomechanics of running, statistical trends in human performance and which kind of monkey runs the fastest.

But first, an experiment. Due to some spurious and possibly fictional injuries, neither Hannah nor Adam are fit enough to take part in a sprint trial at the University of Bath. So long-suffering Producer Michelle steps up to the challenge and into the starting blocks. Not known for her love of athletics, or exercise of any sort, how will she fair in the ultimate speed test?

Biomechanist Peter Weyand from Texas discusses the role of different muscle types in speed versus endurance. Sports scientist Polly McGuigan reveals why Usain Lightning Bolt is still the fastest man in the world. And Prof of Sports Engineering Steve Haake reveals how fast a man can run like a monkey.

Presenters: Hannah Fry, Adam Rutherford

Do alien civilisations exist? When will ET phone home?

In the second part of our alien double bill, Hannah and Adam boldly go in search of intelligence. They may be some time.

What will aliens look like? Where should we look for them? And what are the chances of finding complex life in the cosmos?

Featuring astronomer Seth Shostak from the SETI Institute in California, exoplanet hunter Sara Rugheimer from the University of St Andrews and zoologist Matthew Cobb from Manchester University,

Presenters: Hannah Fry, Adam Rutherford

Mike Holcombe from Largs in Scotland asks, "How do we look for alien life and what are we expecting to find?"

In the first of two episodes on the search for ET, Hannah and Adam look for life inside the Solar System. How do we define life and why we obsessed with finding it on Mars? Or should we be looking for space squid on Europa instead?

Features interviews with planetary scientist Monica Grady from the Open University, senior astronomer Seth Shostak from SETI and zoologist Matthew Cobb from the University of Manchester.

Send your Curious Cases for consideration in to [email protected]

Presenters: Hannah Fry, Adam Rutherford

"Winter is finally over and the birds are all singing their hearts out at dawn. What's all the noise about? And why are some songs so elaborate?" asks Tony Fulford from Ely in Cambridgeshire.

We find out how birds produce multiple notes at once, which one has the widest repertoire of songs, and why males like to show off quite so much. Plus, we talk to researcher Lauryn Benedict about the project which aims to solve the mystery of why female birds sing - www.femalebirdsong.org.

Featuring interviews with RSPB President and nature presenter Miranda Krestovnikoff, and world-renowned birdsong expert and sound recordist, Don Kroodsma.

Archive of 'singing like a wren' courtesy of The One Show, BBC TV.

Send your cases for consideration to [email protected].

Presenters: Adam Rutherford, Hannah Fry

"My boss insists that if you choose the same numbers in the lottery each time your probability of winning will increase. Is this true?" asks Vince Scott from Edinburgh.

National lotteries are played in more than 80 countries worldwide, but can you increase your chances of winning? Hannah consults statistician Jen Rogers to discover the best way to select your lucky numbers.

Adam talks chance and luck with David Spiegelhalter and hears how the field of probability began with a philandering gambling polymath in 16th century Italy. Plus, we meet the Oxford professor who tried to beat the house in a Las Vegas casino, using a computer concealed inside his shoe.

Presenters: Adam Rutherford, Hannah Fry

"Do we know what causes déjà vu?" asks Floyd Kitchen from Queenstown in New Zealand.

Drs Rutherford and Fry investigate this familiar feeling by speaking to world-leading reseacher Chris Moulin from the University of Grenoble in France and memory expert Catherine Loveday from Westminster University. Plus, they find out why early investigations classed déjà vu as a type of paranormal phenomenon.

For most of us, it's a fleetingly strange experience, but for some people it can become a serious problem. Lisa from Hulme in Manchester started experiencing déjà vu when she was 22 with episodes that could last all day. The origin of her déjà vu has been the key to helping psychologists investigate its cause.

Presenters: Hannah Fry, Adam Rutherford

"What happens to the human voice as we age? If I hear a voice on the radio, I can guess roughly how old they are. But singer's voices seem to stay relatively unchanged as they age. Why is this?" All these questions were sent to [email protected] by Jonathan Crain from Long Island in New York.

The Doctors discover how the human voice is produced and listen to how our voice sounds when it emerges from our vocal cords. Acoustic engineer Trevor Cox, author of 'Now You're Talking', explains why German and French babies have a different accent. And neuroscientist Sophie Scott describes what happens when boys' voices break, and why a similar thing can happen to women during the menopause.

Finally, our voices often change dramatically in later life, as demonstrated by impressionist Duncan Wisbey from Radio 4's Dead Ringers. Expect cameos from David Attenborough, Dumbledore and Paul McCartney.

Presenters: Hannah Fry, Adam Rutherford

"What is the fifth dimension?" asks Lena Komaier-Peeters from East Sussex.

Proving the existence of extra dimensions, beyond our 3D universe, is one of the most exciting and controversial areas in modern physics. Hannah and Adam head to CERN, the scientific cathedral for quantum weirdness, to try and find them.

Theoretical physicist Rakhi Mahbubani explains why we think that dimensions beyond our own might exist. Adam meets Sam Harper, who has spent 14 years hunting for an elusive particle called the 'graviton', which could provide a portal to these extra dimensions.

But if they exist, where have these extra dimensions been hiding? Sean Carroll from Caltech explains various ideas that have been dreamt up by physicists, from minuscule hidden planes to gigantic parallel worlds.

Producer: Michelle Martin

"How do we measure the age of the Universe?" asks Simon Whitehead.

A hundred years ago this wouldn't even have been considered a valid question, because we didn't think the Universe had a beginning at all. Even Einstein thought that space was eternal and unchanging.

This is the tale of how we discovered that the Universe had a beginning, and why calculating its age has been one of the greatest challenges in modern astronomy.

We also uncover the mysterious dark energy that pervades the cosmos and discover why it's been putting a scientific spanner in the works.

Helping to unravel today's question are physicists Andrew Pontzen, Jo Dunkley and Jim Al-Khalili.

Presenters: Hannah Fry, Adam Rutherford