TV Guide BBC Four Wednesday

The presenter embarks on a two-day walk along the Worcester and Birmingham Canal, which cuts a 30-mile path to the River Severn, discovering how it helped to generate wealth in the Industrial Revolution. Along the way, she follows a two-mile flight of 30 locks that lower the canal 220ft

Without people noticing, modern life has been taken over. Algorithms run everything, from search engines on the internet, to satnavs and credit-card security - they even help people travel the world, find love and save lives. Here, mathematician Marcus du Sautoy demystifies this hidden world by showing some of the most essential algorithms. He reveals where these 2,000-year-old problem-solvers came from, showing how they work, what they have achieved and how they are now so advanced they can even program themselves

Part two of two. Professor Jim Al-Khalili visits the Gran Sasso National Laboratory in Italy, where scientists are attempting to capture and study dark matter. He also reveals how the discovery that the expansion of the universe is accelerating has led to theories that a mysterious new force called dark energy is in the process of gradually tearing the universe apart

In the early 19th century Staithes was as one of the largest east coast fishing ports, and even now the harbour building renovations reveal the seaside village's impressive financial boom. Archaeologist Ben Robinson explores the harsh North Yorkshire coastline that surrounds Staithes, as he finds out how the village was built to be a safe haven. It was also a settlement rich in the natural resource of shale. Contributors include local author Peter Appleton and fellow archaeologist Caroline Barrie Smith

The presenter takes a 20-mile walk along the Kennet and Avon Canal, learning about the history of the waterway, which provided a connection between the country's two most important ports, Bristol and London. She also examines how the canal was restored to its former glory with lottery funds, before concluding her journey at the Caen Hill flight of locks

Victoria Coren Mitchell narrates this Timeshift documentary telling the story of how Britain's phone network was built over the course of 100 years, from early call boxes to the Post Office Tower, and its impact on the public